Enabling the Discovery Potential of the Sanford Underground

Research Facility at the Intensity and Cosmic Frontiers

Institution: South Dakota School of Mines & Technology501 East Saint Joseph StreetRapid City, SD 57701-3995

Lead Principle Investigator: Dr. xxxxx(605) 394-xxxxxxxx.xxxx@sdsmt.edu

Administrative Point of Contact: Karmen Aga(605) 394-1218Karmen.Aga@sdsmt.edu

Funding Opportunity FOA Number: DE-FOA-0001140

DOE/Office of Science Program Office: Office of High Energy Physics

DOE/Office of Science Technical Contact: Dr. Alan Stone(301) 903-7998alan.stone@science.doe.gov

Kathy Turner301-903-1759kathy.turner@science.doe.gov

PAMS Letter of Intent: LOI-0000007936

Research Area: Experimental High Energy Physics Research / Intensity FrontierExperimental High Energy Physics Research / Cosmic Frontier

Advisor Student Frontier Experiment Task(s)

Corwin David S. IF 1/2 NOvA/LBNF Muon CaptureCF 1/2 Radon Rn Monitor

Brendan R. IF 1/2 NOvA/LBNF CC1πCF 1/2 Radon Rn Monitor

Bai D. Tiedt CF 1 LUX & LZ LUX analysis, simulation,operation + LZ airborne contamination

J. Stock IF 1 LBNF Cleanliness

ReichenbacherMark H. CF 1 LUX Rn plate-out + analysis TBDTBD IF 1 LBNF Radioactive Source Calibration

Schnee Tyler L. CF 1 LZ Rn assay and LZ data analysisJosephStreet

CF 1 Super-CDMS

Rn Mitigation and SuperCDMS dataanalysis

Table 1: This arrangement gives us 8 graduate students in total, with 3 in the Intensity and 5 inthe Cosmic frontiers.

1 Introduction

Grad student assignmentTarget Length: 1 pageFirst Author: JuergenPrimary Internal Editor: RichardNeutrino physics and dark matter searches are highlighted science drivers in the US Particle

Physics Project Prioritization Panel (P5) report. This proposal seeks base support for a fast grow-ing particle physics group at the South Dakota School of Mines & Technology to work on prominentprojects including the LBNF, NOvA, LUX/LZ and SuperCDMS. Supported by the new Ph.D. Pro-gram in physics that was launched in the fall of 2013, five faculty and eight Ph.D. students in thegroup are actively involved in these projects. SDSM&T is the only science and technology univer-sity close to the Sanford Underground Research Facility (SURF) in Lead, SD. A strong team atSDSM&T will not only help obtain physics results from ongoing neutrino and dark matter projectsbut also efficiently support future experiments and increase the discovery potential of SURF atboth the Intensity and Cosmic Frontiers in years to come.

Our intensity frontier efforts will focus on LBNF and NOvA.Dr. Bai and Dr. Reichenbacher will lead two graduate students on LBNF hardware/calibrationefforts. Dr. Reichenbacher will also lead the charge of determining radiological cleanliness re-quirements for the far detector. This has synergies with the calibration of the low-energy regime,relevant for detection of supernovae, and we will contribute to characterize the optimal design ofradioactive calibration sources deployable inside the LBNF detector.

Dr. Bai will continue to lead one graduate student in our characterization of and monitoringof dust contamination at SURF. Dr. Corwin will continue as co-convener of the LBNF Cleanlinessworking group, which will use the resulting data.

Dr. Corwin will lead two graduate students in our simulation and data analysis efforts onNOvA and LBNF. We will continue developing reconstruction techniques that could discriminateneutrinos from antineutrinos in beam and atmospheric sources. The graduate students will pursueparallel analyses on NOvA and LBNF.

Dr. Reichenbacher will work with his graduate students to analyze the atmospheric muon

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charge ratio by studying the effective muon lifetime with Michel electrons in NOvA, the LBNFnear, far and 35 ton detectors. This study performed in the low-energy regime of these detectorscould significantly reduce their systematic uncertainity on the discrimination of neutrinos fromantineutrinos.

Our plan for the SURF cosmic frontier experiments coherently focuses on reducing dangerousradon backgrounds through mitigation, screening, monitoring, emanation and plate-out studies.

Dr. Schnee will lead radon exclusion efforts for LZ, including overseeing the construction of alow-radon cleanroom at SURF. He will lead a graduate student in developing a lower-cost, moreeffective radon-mitigation system, testing on a low-radon cleanroom being installed at SDSM&Tusing start-up funds.

Dr. Schnee and Dr. Reichenbacher will lead two graduate students on our screening efforts.Using start-up funds we will build at SDSM&T two complementary devices for material surfaceα-screening that allow for large detector components to be tested in a non-destructive way beforeassembly. Dr. Reichenbacher’s provides a low-risk path to allow screening of large non-planarcomponents, while Dr. Schnee’s should allow better sensitivity than is currently available. Dueto the proximity of SURF to SDSM&T, suspect large components of LZ could easily be taken toSDSM&T for testing in these unique screeners without the need for shipping. The screeners atSDSM&T will be complementary to our commercial α-screener that can scan large planar compo-nents onsite at SURF. We will use these and conventional screeners in performing radon daughterplate-out measurements under realistic conditions. We also plan to operate an expandable systemat SDSM&T that can test material samples for emanation of radon gas.

Dr. Bai and Dr. Corwin will lead two graduate students in developing improved monitoringof the particulate and radon levels in the air. A dedicated effort is planned to develop a newhyper-sensitive radon monitoring system that can support all of the low-background experimentsat SURF, building on an advanced radon monitor under construction in Dr. Corwin’s lab. We willcollaborate with another group on campus that owns an XRF.

We will lead additional work on increasing experimental sensitivity to low-mass WIMPs. Dr.Reichenbacher is participating in the design and simulation of a unique Y-Be neutron source tocalibrate LZ at low energies. Dr. Schnee will lead simulations of radon-induced backgroundsin LZ, and he will lead SuperCDMS analyses focusing on providing event-by-event or statisticalsubtraction of backgrounds for CDMSlite detectors.

Year Amount

1 $394,7282 $410,3853 $408,367

Total $1,213,480

Table 2: Progression of annual budget

2 Intensity Frontier

2.1 Preparing for Simulation and Data Analysis at SURF

Target Length: 9 pages

2

PI Cosmic Frontier Intensity Frontier

Dr. Bai LUX/LZ: 50% LBNF: 50%

Dr. CorwinRadon 40% NOvA: 48%

LBNF: 12%

Dr. SchneeLZ: 50%SuperCDMS: 50%

Dr. Reichenbacher LZ: 50% LBNF: 50%

Table 3: Distribution of efforts

First Author: LukePrimary Internal Editor: JuergenNeutrinos were first postulated by Wolfgang Pauli [1] in 1930, and their discovery was published

in 1956 [2]. They are subatomic particles with no electric charge and extremely small masses that arethe subject of intense study in particle physics [3–17]. Neutrinos occur in three known “flavors”: νe,νµ, and ντ . A neutrino that is produced in one flavor can be detected as any flavor. Understandingthe parameters and mechanism governing these “oscillations” is the primary goal of long-baselineneutrino physics.

Dr. Corwin’s research group consists of two graduate students (Mr. David Smith and Mr.Brendan Reed) and three undergraduate students (Mr. Travis Dammann, Mr. Thomas Kadlecek,and Mr. Cameron Peterson). David has been Dr. Corwin’s advisee since 2013 and Brendan joinedthe group during the summer of 2014. David and Brendan are about to begin their second yearas graduate students. Thomas and Travis were the President and Vice-President of the SDSM&TSociety of Physics Students this past academic year.

Undergraduate junior and senior physics majors at South Dakota School of Mines & Technologyare required to take Design Project classes, during which they earn class credit for research or otherprojects with professors. Mr. Damman and Mr. Kadlecekare both Dr. Corwin’s students in DesignProject and will be during the final part of the first year of this proposal.

2.1.1 Charge Discrimination

Bestowing a new ability upon the flagship present and future US long-baseline neutrino experimentsis the kernel of this our simulation and data analysis efforts. We develops this part of our researchprogram around enabling the NOvA (NuMI Off-Axis electron neutrino Appearance) and LBNF(Long-Baseline Neutrino Facility) experiments to distinguish neutrinos from antineutrinos. Earlyversions of the necessary tools have been used in short-baseline experiments, and this plan integratesand extends them in NOvA and LBNF. We will develop, extend, and demonstrate tools for theevent-by-event and statistical separation of neutrinos (ν) from antineutrinos (ν) in detectors wherethis is otherwise impossible.

Normally, discrimination between neutrinos and antineutrinos is achieved by immersing thedetector in a magnetic field. The charge of particles produced in charged-current (CC) neutrinointeractions (examples shown in the top two panels of Figure 1) identifies whether the incidentparticle was a neutrino or antineutrino, and the curvature of particles in a magnetic field identifiestheir charge. This technique was used very successfully in the MINOS experiment [19].

The absence of magnetic fields in NOvA and LBNF [20] presents a great oppoprtunity todevelop new data analysis techiques. We propose to simulate, develop, test, and deploy promisingmethods for distinguishing neutrinos from antineutrinos using available data. We will begin withmethods developed by the MiniBooNE collaboration to measure the contamination of neutrinos

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Muon

Proton

Michel e-

Electron

Proton

π0 (→γγ)

νμ + n → μ + p

νe + n → e + p

ν + X → ν + X'Proton

1m

1m

νμ Charged Current

νe Charged Current

Neutral Current

Figure 1: Event topology and Feynman Diagrams of νµ charged current (top), νe charged current(middle) and neutral current interactions in NOvA [18].

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in an antineutrino beam. We will then expand into methods that take advantage of the superiorgranularity of the NOvA and LBNF detectors, selecting and pursuing those that show promise formaking statistical or event-by-event distinctions between neutrinos and antineutrinos.

Three distinct methods have already been developed by the Mini Booster Neutrino Experiment(MiniBooNE) collaboration and will form the basis of the initial work done under this proposal: thecharged current single pion production (CC1π) analysis, the charged current quasi-elastic (CCQE)analysis, and the muon capture analysis. The CCQE method is already being addressed by anothergroup within the NOvA Collaboration; we will collaborate with that group and focus our effortson the other two methods.

The MiniBooNE collaboration has successfully used these methods to measure the neutrinocomponent of their anti-neutrino beam. The three techniques produce independent and consistentresults, as shown in Figure 2 [21–23]. The charge discrimination techniques that have been devel-oped by MiniBooNE are susceptible to systematic uncertainties due to intra-nuclear effects duringthe neutrino interaction; therefore, we wish to gather as much information as possible about eachinteraction in order to study and disentangle these effects.

(GeV)νTrue E0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2

να f

lux

scal

e µν

0

0.2

0.4

0.6

0.8

1

ALL

+πCC1

CCQE

capture-µ

Figure 2: Summary of the three νµ flux measurements in the antineutrino beam from the Mini-BooNE experiment. Measurements are placed at the mean of the generated energy distribution foreach reconstructed energy sample [23].

We will proceed along a multi-phased approach in parallel for both the Muon Capture andCC1π techniques. In Phase 1, we will reproduce and adapt the techniques of MiniBooNE to NOvAand LBNF. For both experiments, we will apply the techniques to simulated data to assess theireffectiveness and vulnerability to systematic uncertainties. As an example, we will use a simulateddata sample that has an weighted ratio of ν to ν to test how accurately the techniques can measurethat weight. For NOvA, we will apply these techniques to data to measure the ν contamination inthe ν beam (and vice-versa) in the NDOS and Near Detector. We will need to accumulate severalyears of statistics before meaningful discrimination can be achieved in the far detector.

In Phase 2, we will extend the techniques to take advantage of the superior granularity and

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Nucleus (Z) Probability of µ− capture12C (6) (7.78± 0.08)%Ar (18) (76± 6)%Fe (26) (90.6± 0.5)%

Table 4: The capture rate of negative muons by nuclei is calculated as 1 − τµ−/τµ+ , where τµ−and τµ+ are the lifetimes of negative and positive muons, respectively, in the material in question.Lifetimes are taken from Ref. [29].

particle identification capabilities of the detectors. Unlike MiniBooNE, the NOvA and LBNFdetectors can reconstruct particle tracks and will be able to detect νe in addition to νµ interactions.NOvA and LBNF can detect particles with much lower energies than MiniBooNE. We will use thevast amount of additional information available in NOvA and LBNF to realize the full potential ofthese detectors in discriminating ν from ν.

In Phase 3, we will combine all of the techniques and extensions outlined above and described indetail below, as well as those yet to be discovered, into a single integrated discrimination package.Each event will be assessed with as many discrimination tools as possible and assigned a probabilityof being ν or ν. The event will then be assigned a value similar to singular variables crated bythe library event matching (LEM) [3,24,25] or artificial neural network (ANN) [26,27] techniques.Other analyses can then optimize and place constraints on that variable as they need.

All of our analyses will be performed blind, that is, all analysis tools and procedures will beestablished and verified on simulation and data outside of the signal region. Only afterwards, withthe approval of the relevant collaboration, will we “open the box” and analyze the real data. Thistechnique is widely used in particle physics to avoid bias in developing and assessing data reductionan analysis techniques [28].

2.1.2 Muon Capture Method

Only negatively charged muons (µ−) can be captured on atomic nuclei; those that are captured aredistinct because they produce no detectable decay products. The probability of nuclear capturefor several relevant elements is given in Table 4. MiniBooNE used the relatively low capture rateon carbon to achieve a good result. We propose to replicate this in NOvA and to use the muchhigher capture rates on argon and iron (a possible component of the LBNF near detector) to ouradvantage in LBNF.

The separation is statistical, and we will conduct the simplest analysis as an early objectivewith NOvA simulation, NOvA data, and LBNF simulation. The real and simulated data will bedivided between events with a visible Michel electron and those without. The number of events ineach sample is then used to extract a scale factor on the simulation, using the equation

αν =(µ− only)data(µ+ e)MC

ν − (µ+ e)data(µ− only)MCν

(µ+ e)MCν (µ− only)MC

ν − (µ− only)MCν (µ+ e)MC

ν

, (1)

where “only” and “e” denote reconstructed muons without and with visible decay electrons, re-spectively. “MC” and “data” refer to event numbers in simulation and data, respectively. Thesubscripts denote whether the variables refer to numbers of neutrinos or antineutrinos. This tech-nique is probably not applicable to νe CC interactions since electrons do not decay, thus removingthe distinction between e+ and e−.

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2.1.2.1 Plans for LBNF In LBNF data, we will be able to significantly improve upon theMiniBooNE result simply by virtue of the higher µ− capture rate on argon nuclei. In LBNFsimulations, Michel electrons are assumed to be 100% identifiable and are assumed to occur 100%of the time for µ+ and 25% of the time for µ− [20], which is consistent with Table 4.

The Borexino experiment demonstrated that positrons could be separated from electrons atthe ∼ 50% level if the positron was low in energy (∼ 1 MeV) and formed an ortho-positronium(o-Ps) state before annihilating [30,31]. The o-Ps state and to a lesser extend direct e+ annihilationintroduce a distortion into the scintillation timing spectrum relative to an e− track.

2.1.2.2 Testing on NOvA Mr. Smith is already working to run and improve the Michelelectron package for NOvA, and he will supervise Mr. Dammann in this effort. From there, hewill use simulated NOvA data to maximize its ability to identify Michel electrons. We will thendevelop the full analyses to calculate the scale factor for “as-is” simulated data and simulated datawith the ratios skewed to determine if our analysis correctly extracts the skewed factors.

NOvA electrons will be higher in energy that those of Borexino by at least an order of magnitude,and the NOvA timing resolution is too coarse to recreate this analysis. However, NOvA does recordthe pulse shape of each cell in a track, divided into twelve timing bins. Using simulated and reale± events, we will search for characteristic shape differences between the two on the track andcell level. For example, we may expect more energy to be deposited sooner by e+ annihilation asopposed to e− atomic capture.

2.1.3 CC1π Method

Charged current single pion (CC1π) interactions take the form ν`N → N`−π+ or ν`N → N`+π−.MiniBooNE distinguished neutrinos from antineutrinos by exploiting the near 100% capture rateof π− by carbon nuclei [32]. The absence of the π− decay signature was indicative of a νµ inter-action [23]. Starting from an event population from their beam that is 70% antineutrinos, thissimple signature remarkably yields a sample that is 80% neutrinos. Mr. Reed has taken charge ofour CC1π efforts on NOvA and LBNE; he will supervise Mr. Kadlecek in those efforts.

The capture rate in NOvA sill be similarly high; however, both charges of pion will traveland produce tracks. We will develop discrimination techniques based on topological differencesbetween π+ and π− beginning with the small hadronic burst produced by π− at capture [33, 34].Mr. Kadlecek, under the supervision of Mr. Reed and I, will begin by hand-scanning simulatedNOvA CC1π data to develop reconstruction tools to distinguish between the two charges. We willfollow a similar proceedure with the higher-resolution simulated data from LBNF.

2.1.3.1 Plans for LBNF The LBNF collaboration has already performed a preliminary studyof proton tagging in their atmospheric neutrino simulations. The simulation assumes protons aretagged identified with 100% efficiency if their kinetic energy is greater than 50 MeV [20].

While the first two phases involve parallel development of tools, this phase is intended tocombine the tools previously developed with those from the CCQE work into a single coherentdiscriminating package. For example, combining the detection of a proton stub with the indicativecomponents of an electron shower to more precisely determine whether a given events is νe or νeCC. Each event would then have a calculated figure of merit which would be proportional to theprobability that it is a neutrino or antineutrino. This figure can be constrained as necessary byany group analyzing the data.

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2.1.3.2 Testing on NOvA Neutron tagging is more challenging, but will be extremely useful inthe identification of ν CC1π events. Neutrons are expected to leave small hadronic showers displacedin space but nearly coincident in time with the interactions that created them. In early experiments,the neutrons have been identified using liquid scintillator with efficiencies of ∼ 40% [35].

All of the CC1π techniques will be applied to νe as well as νµ events. After identifying theelectron shower, the remaining particles and procedures are expected to be very similar. Further-more, we will test the e± discrimination techniques developed for the Michel electrons for theireffectiveness on electrons generated directly from νe CC interactions

2.1.4 Relevance for Experimental Goals

Discriminating between neutrinos and antineutrinos in NOvA would be desirable for several reasons.It would enable measurement of the antineutrino contamination in the neutrino beam [21] and viceversadevelopment of several reconstruction techniques for low-energy interactions measurementof the neutrino and antineutrino composition of supernova neutrinosseparation of atmosphericneutrinos and antineutrinosand a search for νµ → νµ or νe → νe oscillations, the existence of whichwould prove that neutrinos violate lepton number conservation

2.1.4.1 Wrong Sign Contamination Measurement The contamination of neutrinos in theantineutrino beam (and vice versa) is expected to be very small for both the NOvA and LBNFbeams. However, this expectation needs to be confirmed by experimental measurement in order toensure the precision of several oscillation measurements, such as θ13 and the mass hierarchy. For theNOvA cross-section measurements, an effective suite of discrimination tools between neutrinos andantineutrinos would be advantageous because it would allow removal of wrong-sign contaminationas with other beam analyses.

2.1.4.2 Reconstruction of Low Energy Interactions Several aspects of the discriminationtools detailed in this proposal require precision reconstruction of low-energy interactions: Michelelectron reconstruction, π+/π− separation, π0/e± separation, neutron reconstruction, and detailedpulse height measurements for several particles. The development of effective reconstruction toolsat low energies will be necessary for several NOvA and LBNF goals, including

2.1.4.3 Search for ν → ν Transitions The transition from ν → ν is forbidden by CPTconservation in the Standard Model, so discovering it would be a sign of physics Beyond theStandard Model (BSM). The MINOS collaboration has already searched for this transition [36].An effective discrimination between ν and ν would enable a search for this forbidden transition inNOvA and LBNF.

Multiple parameterizations and limits from reactor and long-baseline experiments exist [36–38].We will improve upon these limits using the extremely high purity of the NOvA beam, whichwould reduce the possible faking of the transition from beam ν backgrounds. We will distinguishthe forbidden transition from wrong sign contamination by measuring the wrong-sign contaminationin the near detector before searching for ν in the ν beam at the far detector.

2.1.4.4 Supernova Neutrinos Detection of a neutrino burst from a galactic core-collapsesupernova is a primary goal of every active neutrino experiment capable of detecting them, includ-ing NOvA and LBNF. Separating neutrinos from antineutrinos at the low energies of supernova(∼ 10 MeV) will be difficult, but if it is possible, it will allow the extraction of much valuableinformation from this rare event.

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Figure 3: Reconstructed L/E distribution of high-resolution µ-like atmospheric neutrino events inLBNF with a 340 kt ·MW · year exposure with and without oscillations (top); the ratio of the two,with the shaded band indicating the size of the statistical uncertainty (bottom) [20].

2.1.4.5 Atmospheric Neutrinos Atmospheric neutrinos are produced by cosmic rays collid-ing with nuclei in the atmosphere. They travel from their production point thought the body ofthe Earth to a neutrino detector. This leads to a wide range of travel distances (L) and energies(E), allowing access to a range of L/E values not accessed by the beam analyses. We have, fromMINOS [19], Super-Kamiokande [39], and IceCube [40] results that demonstrate the feasibilityand usefulness of analyzing atmospheric neutrino data. MINOS in particular, found that addingthe atmospheric neutrino data noticeably reduced the uncertainties on the oscillation parametersobtained from beam-only neutrino data, especially for antineutrinos.

The large LBNF LAr TPC Far Detector, if placed at sufficient depth to shield from cosmicray backgrounds, will provide a unique opportunity to study atmospheric neutrino physics withexcellent energy and path-length resolutions. As shown in Figure 3, a 35 kt Far Detector could besensitive to two or three oscillation maxima in the range ∼ 200 to ∼ 2000 km/GeV.

The LBNF collaboration has already begun an atmospheric neutrino simulation program. TheLBNF LAr Far Detector physics sensitivities using information from atmospheric neutrinos wereobtained using a fast Monte Carlo and a three flavor analysis framework developed for the MINOSexperiment [41]. The simulation uses fast Monte Carlo tools, a toy model of the detector geometryand smearing to approximate detector performance [20]. My leadership of a combined atmosphericand beam neutrino analysis on MINOS [19] and resulting experience with atmospheric neutrinosmake this group uniquely equipped for this task.

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2.2 Radiological Cleanliness Requirements in the LBNF Far Detector

LBNF far detector first scenario.Dust would go hereTarget Length: 4 pagesFirst Author: BaiPrimary Internal Editor: Luke

Many low energy phenomena are of great interest to the LBNF collaboration, including solarneutrino physics, neutrinos from supernovae, Michel electrons, neutron identification, and otherlow energy events for either physics or calibration purposes. In a deep underground site like SURF,radioactive decays may contribute the most to electron and gamma backgrounds below 10 MeV.Decay events are mainly from radioactive 39Ar in natural argon, nuclei in the 238U and 232Thdecay chains carried by airborne (dust) contamination in the detector, and radioactive elementsin detector construction materials that will also inevitably have U/Th components. In addition toreducing the event-to-noise ratio for neutrino events below 10 MeV, these decay events may alsohave impacts on the detector performance due to the large number of ions and scintillation photonsthey produce in the TPC. For example, the photons and ionizations may produce false triggers inthe Photon Detection System (PDS) or crosstalk between anode wires.

Our group will provided critical support to the LBNF Collaboration as it establishes a clean-liness model and database that includes material outgassing characteristics and radioactivity ofdetector construction materials. The goal is to develop a reliable cleanliness control and moni-toring procedure that can guarantee contamination levels low enough such that the multi-kilotonLBNF Far Detector will be able to reliably find signal energy deposits down to ∼ 10 MeV and behighly stable over 15 to 20 years of data taking.

Dr. Reichenbacher has taken the lead in determining the radiological requirements and a back-ground model for the far detector. Several studies of the relevant radiological backgrounds alreadyexist [42]. He will lead a group consisting of his students at SDSM&T and relevant members ofthe LBNF collaboration to complete the goals outlined in a charge from the Cleanliness WorkingGroup [43], of which Dr. Corwin is a co-convener.

1. Develop a complete radiological survey of the planned detector including what radioactivematerials we expect in the detector and how they decay.

2. Create a Monte Carlo radiological background model that can be incorporated into the de-tector simulation. Work with the Detector Simulation group.

3. Obtain reports from each Physics Working Group based on the radiological model that doc-ument their sensitivity, needs, and potential mitigation strategies (e.g. fiducial volume cuts)regarding radiological backgrounds

4. Form a plan containing a set of radiological requirements based on the requirements of thephysics working groups, procedures for implementing the requirements, and oversight at thefar detector.

Dr. Bai and Mr. Tiedt conducted systematic studies of the airborne contamination (dust) atSURF and SDSM&T, including a survey of the radioactivity of rock samples and other substancesat SURF, characterization of dust particles on the surface and underground at SURF, and a simu-lation study of decay events in liquid argon using GEANT4. These results have provided first-handinformation for the Far Detector cleanliness planning. For example, using the mass and activity

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deposition rates given in Table 1 and the measured dust particle deposition rate in Table 5, onecan estimate airborne activities corresponding to exposure time and area during the detector con-struction, which have to be considered in developing the LBNF radiological and cleanliness controlprotocol and procedures.

Table 5: Assuming ISO dust particle size spectrum with the measured “high activity” depositionrate at Sudbury Neutrino Observatory (SNO), the mass and activity deposition rates are calculatedusing 0.489 Bq/g of both β and γ above 1 MeV for Sanford Lab rock dusts. The fifth column showsthe expected airborne activity. Rock density 2.25 g/cm3 is used [44].

ISO Class ISO Density ISO Decay Rate Mass deposition Decay in deposition(using SNO depo. rate) (using SNO depo. rate)

(g/m3) (Bq/m3) (g/(m2 · day)) Bq/(m2 · day)

1 7.7929× 10−13 3.8107× 10−13 1.4213× 10−9 6.9502× 10−10

2 7.8259× 10−12 3.8269× 10−12 1.4273× 10−8 6.9796× 10−9

3 7.7702× 10−11 3.7996× 10−11 1.4172× 10−7 6.9299× 10−8

4 7.8034× 10−10 3.8159× 10−10 1.4232× 10−6 6.9596× 10−7

5 7.6767× 10−9 3.7539× 10−9 1.4001× 10−5 6.8465× 10−6

6 7.7153× 10−8 3.7728× 10−8 1.4072× 10−4 6.8810× 10−5

7 7.7153× 10−7 3.7728× 10−7 1.4072× 10−3 6.8810× 10−4

8 7.7153× 10−6 3.7728× 10−6 1.4072× 10−2 6.8810× 10−3

9 7.7153× 10−5 3.7728× 10−5 1.4072× 10−1 6.8810× 10−2

Table 6: Dust deposition rates (with units in g/(m2 · day)) measured at three different locationsat SURF. Data in columns of “With Backgrounds” and “Without Backgrounds” are results fromanalysis that assumes zero and non-zero airborne contaminants in the optics system. They indicatethe upper and lower limits [45].

Location Duration (days) With Backgrounds Without Backgrounds

Surface Cleanroom 69 0.020116 ± 0.3% 0.00950218 ± 0.5%Surface Lab 22 0.0403615 ± 0.4% 0.00707287 ± 1.3%

Davis Cavern 45 0.0880002 ± 0.2% 0.0641207 ± 0.2%

Another interesting phenomena observed in the dust characterization at different locations atSURF is that dust particles seem negatively charged in places with filtered air flow [45]. Electricallycharged particles may behave very differently from neutral particles in deposition and distributioninside the detector and may require different cleaning procedure. Their influence on the detectorperformance and noise level requires careful modeling. We are also in the process of measuring theradioactivity of dust particles collected at different locations in the underground site.

In this proposal, Dr. Bai will lead Mr. Tiedt and Mr. Stock in studies that will produceresults to be used by Dr. Reichenbacher and the LBNF collaboration in understanding radiologicalbackgrounds. They will develop and verify the simulation of the PDS response to the energy depositsfrom radiological impurities. We will assess the similarities and differences between radioactivedecays and low-energy neutrino events based on the simulated response of the PDS to determine

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which will be the most pernicious backgrounds in PDS triggers. They will then simulate multiplelevels of radioactive contamination to determine what levels of cleanliness are needed to observeeach category of low energy event at desired sensitivities.

Many techniques for particle identification in neutrino experiments involve reconstructing lowenergy particles and events, such as Michel electrons, gammas and electron-positron pairs. Theradiological cleanliness simulation functionality to be developed here is invaluable to extend ourstudy to other neutrino physics events in the LBNF Far Detector, including the study of novelanalysis techniques described in §2.1.

2.3 LBNF Calibration

Target Length: 4 pagesFirst Author: JuergenPrimary Internal Editor: BaiThe big advantage of having the LBNF far detector underground is that the physics potential

will be vastly increased beyond studies with beam neutrinos. For example, a large liquid argondetector, located deep underground, is an ideal observatory for astrophysical neutrinos originatingfrom supernova bursts (SNB), when such occur nearby in our galaxy. The low Q-value of just afew MeV for electron-neutrino CC interactions on 40Ar target nuclei (99.6% natural abundance) ishereby very advantageous to exploit full spectral information. Additionally, the direction of SNBneutrinos could be observed via neutrino electron scattering (ES) with visible energies mostly below10MeV (cf. figure 4). It is therefore paramount for the LBNF far detector to reliably detect visibleenergies in the low energy regime of 10MeV and below in order to seize the full physics potential ofSNB neutrinos. This can only be achieved by both meeting necessary radiopurity requirements inthe detector design and commissioning and presumably by studying deployable radioactive sourcesin the detector. Michel electrons from stopped cosmic muons are instead useful to calibrate thecontinuous detector response to intermediate energies up to 53MeV , as Dr. Reichenbacher did forthe KARMEN short-baseline neutrino experiment [?] (p. 106 − 110). Dr. Reichenbacher has alsoalready been studying the response of the LBNE 35 t liquid argon detector prototype at Fermilab byusing simulations based on the LArsoft software package. This work was performed in his previousposition as research scientist at the University of Alabama (UA) under Dr. Busenitz, who is thelead PI of the corresponding DOE grant. At SDSM&T Dr. Reichenbacher proposes to continue hisstudies of the detector response to depoyable radioactive sources in conjunction with Dr. Busenitz’efforts at UA, who has great expertise and infra-structure to make customized calibration sources.Dr. Reichenbacher’s proposed study of the low-energy calibration has also great synergies withhis official LBNE/LBNF responsibility in the cleanliness group as determiner of the radiologicalrequirements for the far detector. Curbing low-energy backgrounds and studying the calibrationof the detector response with radioactive sources go hand in hand. Moreover, Dr. Reichenbacher’sproposed work for the cleanliness group of the dark matter experiment LZ that focuses on mate-rial/radon screening and is described in the Cosmic Frontier part of this proposal, is synergetic withhis proposed LBNE/LBNF efforts as well. The purchased hardware components from his SDSM&Tstart-up fund, such as 3He-neutron-detectors, essential electronic modules and data acquisition aswell as large-area silicon detectors for α,β-radiation screening, are very beneficial too. So is thevicinity of SDSM&T to SURF, allowing for efficient collaborative access to underground germa-nium detectors for high sensitivity gamma-spectroscopy. Dr. Reichenbacher’s laboratory spaceat SDSM&T facilitates high bay capabilities that would be ideally suited for testing a mechanicalcalibration deployment system for the nearby far detector at SURF. Dr. Reichenbacher has alreadysuccessfully developed and deployed a multipurpose calibration deployment system for the Double

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Figure 4: Event rates in 17 kt of argon for the GKVM (Gava-Kneller-Volpe-McLaughlin) model(events per 0.5 MeV). Smeared rates as a function of detected energy [?]..

Chooz reactor neutrino experiment (during his time at Argonne National Laboratory and at theUniversity of Alabama). His experience and the closeness of SDSM&T to SURF for frequentlyperforming calibrations put him in a prime position to pick up the task if simulation results favora calibration deployment system and the collaboration then decides that it should be implementedin the LBNE/LBNF far detector design.

Dr. Reichenbacher proposes to work with a new graduate student on his Intensity Frontierefforts. The student would first join him running LArSoft simulations for low-energy calibrationand radiological cleanliness requirements, work out the impact on various LBNF physics goals, thenlater in his second year start making necessary radiopurity measurements of LBNE/LBNF detectormaterials both in the lab at SDSM&T and at SURF. In his third year the graduate student wouldget involved in the physics analysis of the atmospheric muon charge ratio with then available Michelelectron data from stopped muons in the 35 t LBNE prototype and potentially with data from theNOvA far detector in conjunction with Dr. Corwin, who is a collaborator on NOvA. The graduatestudent would relate in his thesis his results on the atmospheric muon charge ratio to the sensitivityof NOvA/LBNF to CP-violation in the neutrino sector, limited by systematic uncertainties frommuon charge identification.

Studied TPC signal with a radioactive source:

Figure 6 shows exemplarily the LArSoft simulated and reconstructed five wire hits caused by a60Co source located 10 cm in front of the APA wire-plane of the 35 t LBNE prototype (cf. figure5).

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Figure 5: Detector scheme of 35t prototype at FNAL for LBNF.

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Figure 6: Event topology of a Co60 induced 1.3 MeV gamma event in the 35t prototype in LBNF.

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Studied backgrounds in photon production and detection [?]:

Backgrounds in liquid argon were studied in the 2.3 l WARP detector [?]. The dominant in-ternal background is from 39Ar beta decays. The dominant external background comes from 60Cocontamination in the stainless steel. For a typical 0.5MeV β from 39Ar, Nprompt(Ar39) = 0.05PE; Ntot(Ar39) equals 0.2 PE and does not present a problem. For the Co60 in the stainless steel,the 1.2/1.3 MeV βs give Nprompt(Co60) = 0.06 PE and Ntot(Co60) = 0.3 PE. But this backgroundhas a rate that is an order of magnitude lower at 0.5 MeV and two orders of magnitude lower at1.25 MeV than the Ar39 background, thus presumably not presenting a problem.

3 Cosmic Frontier

3.1 Working on the Large Underground Xenon (LUX) Experiment and theLUX-Zeplin (LZ) Project

Target Length: 4 pagesFirst Author: BaiPrimary Internal Editor: Richard

Experiments in deep underground laboratories have provided new opportunities to study someof the greatest scientific questions among which the composition of dark matter is one of themost important topics. Current experimental results and theoretical expectations require us tocontinue the current experiments and prepare new experimental facilities that have larger exposure,further reduced cosmogenic backgrounds, and a much lower internal radiation level to make thebreakthrough.

As the most sensitive experiment in direct dark matter search, the Large Underground Xenon(LUX) experiment has set the best limit on the Weakly Interacting Massive Particles (WIMPs),see Figure 7. The LZ and XENON1Ton experiments are poised to set a new sensitivity record inthe direct dark matter search with their multi-ton scale two-phase Xenon detectors, one in SURFand the other in the underground lab at Gran Sasso, Italy. The leading candidate for the invisible”dark matter” are subatomic particles left over from the big bang, known as the Weakly InteractingMassive Particles (WIMPs) [46,47], Predicted by supersymmetry, the WIMPs are favored by a classof new particle physics models. Some current upper limits of the spin-independent elastic WIMP-nucleon cross-section are shown in Figure 7. The next generation dark matter experiments willincrease the sensitivity by another factor of 10 or higher [48].

Douglas Tiedt was involved in airborne contamination analysis when he was a M.S. studentduring 2011-2013. He has been working as a Ph.D. student on the LUX experiment since 2013.He has become skillful with the LUX Data Quality Monitoring (DQM) sub-system and Data Ac-quisition (DAQ) sub-system. He has been the onsite operator of several key sub-systems includingthe muon veto system, the thermosyphon, the xenon storage and recovery vessel (SRV) and liquidnitrogen (LN). He has worked multiple shifts as shift manager and the LUX detector operationsmanager.

Supported by this proposal, Tiedt will continue working on LUX and the LZ R&D for his Ph.D.degree, with emphasis on,

1. optimize the veto system and study muon signatures at 4850 ft level at SURF. Commis-sioning of the LUX muon veto system is currently underway, with preliminary data takingfor verification. Tiedt will analyze the verification data to specify settings for future LUX

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Figure 7: LUX Detector. Right: Current upper limits of the spin-independent elastic WIMP-nucleon cross-section as function of WIMP mass [49]. Recent result from the LUX experiment hasbrought the limit down by a factor of ∼ 2.5 [50].

science data taking, such as the valid pulse trigger gate (VPTG) and trigger hold-off times.Procedures will be developed to ensure that the 19 functioning PMTs are at usable voltagesthrough calibrations using the LEDs deployed in the water shield and that data taking withthe veto system does not interfere with the PMTs in the liquid xenon TPC either throughnoise or data throughput issues. Once the science data taking begins frequent tests of thesystem, including light leak checks and LED calibrations, will need to be performed on amonthly scale at a minimum.

Tiedt will also use the data from the veto system to characterize muon signals and the averagemuon rate at the LUX (and future LZ) site. He will also look for coincidence between signalsin the water shield and the liquid xenon detector.

Annual work plan:2015: Take data using the veto system and perform routine maintenance tasks (weekly cal-ibrations, troubleshooting any issues that occur); Compare muon flux rates to simulatedevents to verify accuracy of the muon generator (MUSUN) being implemented into the LUXsimulation package LUXSIm.

2016 - Perform analysis of Run 4 veto data, including overall muon rate studies and veto-LUXcoincidence study. Run 4 for LUX is a planned 300 day WIMP search, slated to begin inOctober 2014 and lasting through the end of 2015.

2017 - Potentially assist with commissioning of LZ veto system using experience from LUXveto.

2. participating in the analysis of LUX Run 4 WIMP search data.

During the LUX Run 4 constant analysis work will be needed to ensure that incoming datais of usable quality and to spot any issues with the detector. At the conclusion of the runa detailed analysis of the WIMP search data will be performed with the intent of placinglimits on the WIMP cross section. Work will also be done to ensure that the output ofLUXSim closely matches detector data (based on detector calibrations) in order to ensurethat it remains usable for analysis work. This work includes updating the optical parameters

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of relevant detector materials and checking that geometry refinements do not have an adverseeffect on the simulation output.

From now and through out the Run 4 period, Tiedt will also lead efforts on the LUXSimoptical photon update and GEANT4 modernization campaigns for both LUX and LZ. Inorder for LUXSim to have realistic responses the optical properties of materials in the innerdetector need to be tuned. A study of the optical simulation was originally done by Tiedtin early 2013. Ongoing updates to detector geometry to more closely match reality haveprompted an update to this study to ensure that these properties are still valid, or to updatethem for the LUX Run 3 data reanalysis. Current efforts have found a discrepancy betweenthe light collection efficiency of the detector and the asymmetry of the top and bottom arraysof PMTs, which point to an issue with some of the recent geometry changes. Analysis of datafrom a number of LUXSim revisions are ongoing to track down which change is affecting theresult. Future comparison with Run 4 data will be carried out as well.

Tiedt is well suited to participate these analysis. In the meantime, he will study more thecoincidence events that trigger both the veto system and the liquid xenon detector, lookingfor patterns in timing, signal size and their variations with respect to seasonal changes.

Annual work plan:2015: Analysis of data to ensure the detector is taking usable data, as well as work withLUXSim to ensure accurate simulations to use with analysis.

2016: Verification of simulations with Run 4 data, Run 4 WIMP search analysis.

2017: Continue Run 4 WIMP Search analysis.

3. to implement cleanliness into the simulation of upgraded LZ veto system

The LZ Veto system has a detailed (but not finalized) geometry implemented of the watertank and the liquid scintillator based outer detector (OD). Work has begun studying thebackgrounds as a result of muon effects and radioactivity of materials. Potential work includesperforming study on the effect of rock and dust radioactivity, and work on implementinggeometry into the simulation as the design is finalized. This will involve research into theradioactivity of the rock and dust found around the Davis Campus, as well as detailed studiesof the actual dust contamination of the water and scintillator of the Veto.

Tiedt worked on the radiological cleanliness survey and the characterization of dust particlesat SURF for his M.S. degree. Dr. Bai and two undergraduate students are studying some fastand effective dust particle sampling methods and the impact from environmental conditionsin his airborne cleanliness lab on campus. Such experience at SDSM&T is unique in the LZCollaboration.

Annual work plan:2015: Carry out more study of rocks and dusts in SDSM&T airborne cleanliness lab and atSURF, with aim to set baseline for environment monitoring, detector assembly and cleaningprocedures to meet cleanliness standards for LZ.

2016: Refine geometry of simulation and implement cleanliness into the simulation of up-graded LZ veto system. Carry out simulations to improve result of background studies.

2017: Perform detailed background simulation study using finalized detector geometry andactual levels of dust/rock radioactivity.

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3.2 Radon Mitigation

Target Length: 4 pagesFirst Author: RichardPrimary Internal Editor: LukeRWS: not real happy with the organization here, but it’s a startRadon and its daughters provide an important background for all underground physics rare-

event searches, such as for WIMP dark matter or neutrinoless double-beta decay. Radon is presentin all air, produced by radioactive decays in the uranium and thorium chains, and naturally hasespecially high concentrations deep underground. Gamma decays from radon’s short-lived daugh-ters may provide backgrounds, and radon daughters deposited from the atmosphere onto detectorsurfaces provide particularly dangerous backgrounds. Low-energy beta decays on detector sur-faces [51, 52] or in the bulk [53], the 206Pb recoil nucleus from 210Po α decay [51, 54–56] andneutrons from (α, n) reactions (especially on the fluorine in Teflon) [57] all may produce significantbackgrounds for future experiments. In order to reduce radon-induced backgrounds for Super-CDMS, LZ, and future experiments, the SDSMT group will build on its past work by developingimproved methods to reduce and sense the radon concentration in air, and to provide sensitiveassay of radon daughter backgrounds on surfaces and radon emanated from materials.

For many cases, providing radon-reduced, breathable air is a powerful method to reduce con-tamination. Systems that reduce the radon concentration in air by continuous flow through a singlefilter (typically of cooled, activated charcoal) are designed so that most radon decays before it exitsthe filter [58]. Continuous systems are relatively simple and robust, are available commercially, andtypically achieve reduction factors of ∼ 1000, to ∼10–30 mBq/m3.

Alternatively, in a swing system, one stops gas flow well before the filter’s characteristic break-through time and regenerates the first filter column while switching flow to a second column. For anideal column, no radon reaches the output. Swing systems are more complicated than continuoussystems (both in terms of their analysis and operation). Vacuum-swing systems (e.g. [59–61]) canpotentially provide better performance than a continuous system at about 1/4 the cost.

While at Syracuse, Dr. Schnee’s group constructed a vacuum-swing radon-mitigation system [61].The system achieved the milestone of producing too low a radon concentration to be measured withany commercial detector, with the upper limit on this level the lowest achieved in the literature bya cleanroom-scale mitigation system in North America. Moreover, as shown in Fig. 8, the observedradon concentration in the cleanroom, 0.3 Bq/m3, a reduction of about 25×, is also the lowestdocumented level achieved in North America.

Tests of the system indicated that the cleanroom’s higher radon concentration than that of theinput air was due to leaks in the cleanroom’s HVAC that the group was unable to reduce (the lowpressure caused by the HVAC’s blower makes it especially susceptible to leaks). At SDSMT, a newcleanroom has been constructed, with improvements designed to simplify leak-free construction andprovide insurance against leaks in the HVAC. In particular, the HVAC unit is housed within thecleanroom, so that leaks draw in the cleanroom’s low-radon air instead of the higher-radon outsideair.

The Syracuse radon-mitigation system was disassembled in July 2014 and is being reassembled,led by Dr. Bunker and a new graduate student, Mr. Joseph Street, at SDSMT inside a custompumping room. In addition, SDSMT start-up funds have been used to purchase a more powerfulpump and two more carbon tanks, 50% taller to provide a longer adsorption bed, to improve theradon-mitigation system. Dr. Corwin’s custom radon monitor (described in Section 3.4) and anewly purchased Pylon flow-through radon source will allow easier and more complete testing ofthe system.

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Figure 8: Left: Initial radon activities measured for the input air (light ×’s and upper band) andoutput air (dark ×’s and lower band) of the vacuum-swing-adsorption filter, after subtraction ofthe RAD7’s intrinsic background (measured with boil-off nitrogen to be 0.19 ± 0.03 Bq/m3 andconsistent with expectation). Average values (shaded bands) of the multi-hour periods (error bars)derived by rebinning RAD7 measurements of 214Po and 218Po alpha decays (originally taken in1-hour intervals) indicate ∼20× reduction, from 7.47 ± 0.56 to 0.37 ± 0.12 Bq/m3. Right: Morerecently measured radon activities measured at the filter output (dark ×’s and narrow band aroundupper dashed line) and within the cleanroom (light ×’s and wide band around lower dashed line).Average values (shaded bands) of the 40-hour periods (error bars) indicate the output at the filteris consistent with zero, providing the greatest radon reduction of a cleanroom-sized radon filterusing the vacuum-swing technique, and that the cleanroom shows a ∼25 fold reduction (relative tothe input air), to 0.28 ± 0.15 Bq/m3, the lowest achieved radon concentration in a cleanroom bythis technique.

Assembly of the improved system should be completed this year supported by start-up funds.In Year 1 of this grant, Mr. Street will test the new system, measuring the time profile for radon tomove through a single tank (the “elution curve”) and determining the radon concentration at thefilter output and cleanroom as functions of input and purge flows, length of the carbon bed, andcycling time.

Radon mitigation is critical for the low-mass sensitivity of the SuperCDMS SNOLAB project.As shown in Fig. 9, backgrounds from radon daughters 210Pb (a beta emitter) and the recoiling206Pb nucleus from the alpha decay of 210Po would be the expected dominant background withoutimprovements. To achieve lower levels of radon daughter contamination on the detector sidewallsand copper housings, the inner four copper cryostat cans will be removable as a unit. Detectorinstallation underground will occur in a cleanroom with radon-reduced air provided by a radonmitigation system to be built by Dr. Schnee’s group, based on the existing system. The SuperCDMScollaboration is considering constructing a second radon mitigation system, to allow fabrication ofthe lowest-threshold, “CDMSlite” detectors in a low-radon cleanroom at SLAC.

In the longer term, reduction of radon daughters on future SuperCDMS detectors may al-low achievement of a low-background dark-matter experiment with the lowest possible thresh-olds. Only recently was it realized that CDMS phonon detectors are signal-bandwidth limitedand therefore their energy resolution can be greatly improved by lowering the superconductingtransition temperature of their tungsten sensors, potentially resulting in resolutions < 1 eV [62].Operation of the detectors under high voltage bias causes ionization to produce a large “Luke”

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Figure 9: Expected backgrounds for the SuperCDMS experiment without improvements to radondaughter plate out, in terms of the differential rates as functions of detected phonon energy. Theirreducible background from coherent neutrino scattering (light green) dominates at the very lowestenergies. Above ∼0.25 keV, radon daughters hitting the detector sidewalls would dominate (byabout an order of magnitude at 0.5 keV) without improved radon mitigation efforts. Figure providedby Matt Pyle, UC Berkeley.

phonon signal [63], permitting lower-threshold operation [64], usually at the cost of losing discrim-ination against electron-recoil backgrounds (although statistical background subtraction may beeffective [65]). For energies . 100 eV, however, electron-recoil spectra will be quantized in peakscorresponding to the number of drifted charges. In contrast, since low-energy nuclear recoils areinefficient at ionization, they may produce energy depositions between these peaks, providing aneffective means of removing the otherwise dominant electron-recoil background. Only neutrons andespecially 206Pb recoils from 210Po alpha decays would provide a background for such an experiment.Reducing and understanding the 210Po surface background may therefore enable measurement ofWIMP recoils below 20 eV in a massive detector with small backgrounds.

Dr. Bunker has been chosen to act as the Level 3 Manager of the Radon Exclusion subsystem ofthe SuperCDMS SNOLAB project. He will oversee the purchase, fabrication, and testing of itemsfor the SNOLAB radon mitigation system in Year 1 of this grant, and, if approved, of the secondradon mitigation system for SLAC. He will lead a technician (to be supported by SuperCDMSSNOLAB project funds) and Mr. Street in the construction and commissioning of the SNOLABsubsystem in Years 2–3 of this grant, and work with SLAC personnel on their system.

For LZ, the primary concern is radon daughter plate-out on the interior TPC wall, resultingin neutrons from (α, n) reactions as well as a high rate of 206Pb recoils from 210Po alpha decays,reducing the useable fiducial volume of the detector by a factor of two due to misfits if no improve-ments are made. For assembly at SURF, a larger cleanroom with higher airflow and greater radonreduction is required; the current plan is to purchase a significantly more expensive commercialradon mitigation system from ATEKO. As part of Dr. Schnee’s role as the Level 3 Manager of the

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Radon Exclusion subsystem of the LZ project, he is overseeing the specifications of the LZ low-radon Surface Assembly Laboratory at SURF, and he will continue to work with SURF engineersto ensure that the mitigation system and cleanroom meet LZ requirements. For assembly of thedetector underground, the current plan is to plumb the low-radon air from the surface througha 2-inch pipe. Should this plan prove expensive or risky, a backup is to build a second radonmitigation system underground at the Davis Campus.

The SDSMT low-radon cleanroom will provide an ideal facility for assembly of radon-sensitivesystems before moving to SURF. Large surface components such as the inner cryostat will be over-pressured with N2 dewar boil-off to prevent back diffusion of radon. When not being processed,components will be covered in radon-inhibiting materials and storage volumes will be purged withnitrogen gas if necessary.

An important component of the radon-reduction program is to implement procedures to verifythat adequate measures have been taken to control radon plate-out. Dr. Schnee will lead SDSMTundergraduates in using his commercial, low-background alpha counters to measure plate-out ontowitness samples handled in the same way as the detector material. Moreover, in order to test largepieces of equipment for surface contamination with radon daughters, Dr. Reichenbacher will builda large-volume alpha surface screener.

INSERT JUERGEN’S WORK HEREIn addition, improved data analysis may provide better means to identify the misfit surface

events. Dr. Schnee has strong expertise in this area that he has applied in the past to bothSuperCDMS and MiniCLEAN. He will lead graduate student Tyler Liebsch in Years 2–3 of thisgrant in performing likelihood ratio analysis as well as non-parametric methods of multivariateclassification (e.g. boosted decision trees) in an effort to improve discrimination of misfit events insimulations.

3.3 Radon Plate-out Measurements

Target Length:1 pagesFirst Author: RichardPrimary Internal Editor: JuergenThe process of plate-out, in which charged radon progeny is deposited onto the surfaces of

materials exposed to air, has been well modeled for standard rooms [66]. Unfortunately, there havebeen few studies of the process in cleanroom settings realistic for the assembly of sensitive detectors(see [67,68]). None has attempted to test means of reducing plate-out onto particular surfaces. Thesusceptibility to plate-out depends simply on the radon concentration but also on the material,what other surfaces are nearby, detailed air-flow rates and patterns, humidity, and presumably onartificial electric fields. In Year 1 of this grant, Dr. Schnee and Dr. Reichenbacher will lead theconstruction of a small soft-walled test cleanroom at SURF, using the same inexpensive techniquesused successfully for the clean area for the emanation system, and taking advantage of the naturallyhigh radon concentration underground at SURF. Students will expose different material samplesof interest, such as teflon, copper, synthetic fused silica. After waiting sufficient time for grow-inof the 210Po daughter, samples will be assayed in the group’s alpha counters nearby at SDSMT.

Methods to attempt to alter the plate-out rates will be attempted. Since 90% of radon daughtersfrom alpha decays are positively charged [69, 70], possibilities include affecting the electric field inthe vicinity of the sample (but with care to safety!) or running air deionizers nearby in an attemptto neutralize the daughters and slow down their migration to a surface, in preference to beingfiltered out of the room due to bulk air flow.

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3.4 Radon Monitoring

Target Length: 2 pagesFirst Author: LukePrimary Internal Editor: Bai

Dr. Corwin and Mr. Reed, with participation from several undergraduates, are currentlyassembling a custom radon monitor that reproduces a Japanese design [71–73]. The componentsof this device are funded from Dr. Corwin’s start-up package. The original Japanese device wasbuilt by the particle physics group at Kobe University, and they hosted Dr. Corwin for three weeksin January of 2014. During the stay he gained valuable experience assembling and operating thedevice.

3.4.1 Radon Monitor Design

As shown in the left-hand side of Figure 10, the heart of this radon monitor is an electropolishedstainless steel vessel with a capacity of 70 L. Air or other gasses can be circulated through it using apump, which is connected to the device via stainless steel electropolished tubes. A PIN photodiodeis placed at the top of the vessel and held at high voltage. The vessel is grounded.

When 222Rn decays, 90% the resulting 218Po daughter nuclei are usually positively charged [70,74]. When these daughters are produced or brought into the vessel, they are attracted and electro-statically attached to the photodiode, which is uncoated. They decay via α emission after half-livesof 3.1 min and 164.3µs, respectively. If the alpha particle impinges on the photodiode surface, wedetect the decay as an electronic signal.

The data from the photodiode is collected by an analog-to-digital (ADC) card on a desktopcomputer in Dr. Corwin’s lab. The resulting spectrum will look similar to the one obtained bythe Kobe group and shown in the right-hand side of Figure 10. Summing the total counts in thepeak from 218Po decays gives us the total number of radon decays detected. Using this methodand device, the Kobe group was able to detect radon levels of 0.7 mBq/m3 at the 90% C.L. abovebackground.

218Po+  218PoO2

+  

214Po+  -­‐1500  V  

Element    Eα  (MeV)    B.R.(%)    

214Po        7.69    99.99  218Po        6.00    99.98  210Po        5.30    100  212Po        8.78    100    

Figure 10: Left: A schematic view of the radon counting vessel developed by the Super-K group(slightly modified from [72]). A bigger vessel of ∼ 700 Liters operates at a much higher driftingvoltage. Right: A typical pulse height spectrum for α particles from radon daughter elements [72].Also shown are the energies of α particles from these daughter elements [75–78].

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3.4.2 Status and Plans

Currently, most of the required components from the monitor are present in Dr. Corwin’s labat SDSM&T, and Mr. Reed has led the undergraduates in testing and commissioning them inturn. When the remaining components arrive, which we expect before the end of 2014, we willfinish assembling and begin commissioning the detector by calibrating against a commercial RAD7detector and optimizing sensitivity with respect to voltage and air flow rate. The Kobe group foundthe optimal voltage to be 1500 V and used air flow rates of 1-3 L/min.

We expect to finish commissioning the radon monitor in the first year of this proposal. Oncecommissioned, we will move it to Dr. Schnee’s low-radon cleanroom where it will provide monitoringof radon levels once they are reduced below the sensitivity of commercial devices.

3.5 Radon Emanation

Target Length: 2 pagesFirst Author: RichardPrimary Internal Editor: LukeThe other important radon-related background, especially for LZ, is due to emanation of radon

from the detector materials. To achieve the desired LZ sensitivity, the experiment can tolerate amaximum 222Rn activity within the LXe volume of only 0.6 mBq, which corresponds to a steady-state population of approximately 300 atoms. This rate is dominated by the “naked beta decay of214Pb to 214Bi, whereas the 214Bi beta decay itself is readily identified by the subsequent 214Po alphadecay that would be observed within an LZ event timeline (T1/2 = 160mus). Similar coincidencerejection also occurs where beta decay is accompanied by a high-energy gamma ray.

There are multiple potential sources of radon emanation (e.g., PTFE reflectors, PTFE skin,PMT glass, PMT and HV cables, grid resistors, components in the circulation system), and radonemanation screening must be sensitive to sources that individually sustain smaller populations.With 10 assumed major components as sources of radon emanation and a target background 2×below the required activity of 0.6 mBq, screening to 0.03 mBq (14 atoms steady-state) is requiredper major detector component.

Critical materials will be screened for radon emanation, defined as all that come into directcontact with Xe during experimental operation. To achieve the required throughput robustly, theLZ collaboration requires at least three dedicated radon emanation screening stations. Dr. Schnee’sgroup is constructing one of these stations, in addition to those under development at Maryland,Alabama, and UCL.

Dr. Schnee’s emanation system has an expected sensitivity to emanation rates∼ 10µBq/m2. Hisdesign includes the most important attributes of the most sensitive radon emanation systems [79,80]but replaces their custom miniature proportional counters with a commercial Si PIN diode usingelectrostatic collection following [81,82], simplifying construction and operation as well as allowingthe detector to be used to monitor the radon level in air. The commercial detector’s disadvantagerelative to the proportional counters consists of a detection efficiency < 2× lower, not a significantshortcoming.

The emanation system includes two stainless steel chambers of 20 l and 300 l volumes for ema-nation of materials, Copper gaskets, electropolished stainless steel, and weldless, metal sealings areused throughout the system to limit radon permeation and emanation from the system. Chamberswill be purged with helium boil-off gas, reducing radon ingress if the vacuum is poor (a problemthat has plagued the robustness of systems with radon emanated into vacuum [83]). The smallamount of radon in the boil-off He will be reduced to negligible levels through a radon trap formed

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Figure 11: Spectra in the radon detection chamber showing the regions of interest for the 218Po(left, green) and 214Po (right, blue) decay peaks. Left: Spectrum from a sample of high-radonroom air, showing that the detector energy resolution EFWHM ≈ 4%, and the collection efficiencyε ≈ 60%. Right: Spectrum using low-radon nitrogen gas, showing that the intrinsic background ofthe detection chamber is < 100µBq. It is suspected that this background is dominated by smallleaks of the high-radon air in the laboratory. Moving to a low-radon lab, as is planned, shouldreduce the background by at least an order of magnitude. Note that the resolution is already goodenough that the neighboring 210Po peak is almost completely excluded from the regions of interest.

using low-radon charcoal [84]. After about a week of emanation, the contents of the chamber willbe pumped through first one, then a second nitrogen cold trap, collecting the radon. The cold trapis then warmed up and its contents are allowed to expand into the much larger detector chamber.In the chamber, the positively charged 218Po and 214Pb daughters will be efficiently collected onthe Si PIN diode electrostatically (see e.g. [81]). For measurements of the radon content of gasessuch as air, the gas may be allowed directly into the detector chamber.

Before moving the emanation system to SDSMT from Syracuse, At Syracuse, Dr. Bunker over-saw the assembly, installation, and testing of the gas panel for the emanation system. Dr. Schnee’sgroup also performed initial commissioning of the emanation detector system. The group addeddielectric shielding to reduce arcing in the chamber to acceptable levels,they integrated the detectorchamber with the gas panel and prepared for connection of the emanation chambers with the gaspanel. They optimized the readout electronics and connections to reduce noise pulses, performedinitial estimates of the detector collection efficiency, measured the detector energy resolution, andmeasured the background of the detection chamber, as shown in Fig. 11. At SDSMT, graduatestudent Tyler Liebsch and undergraduate Rayshall Leonard will rebuild the emanation system andcomplete its commissioning, measuring the collection efficiencies of the traps and detector as wellas the background blank rates of the chambers and gas panel.

As part of his responsibilities as the LZ level three subsystem manager for radon exclusion,Dr. Schnee will coordinate the commissioning of the radon emanation systems and the radonemanation measurements that will take place at the different sites. The prototype systems willbe evaluated on the basis of background rates and efficiency measured using calibrated sourcesof radon. Screening a single sample for LZ is expected to take two weeks or more, based onemanation and collection/detection times and repeated measurements to check reproducibility,as well as minimum sensitivity requirements and typical radon emanation MDAs. The radon

25

emanation screening campaign extends beyond initial material selection. During installation ofgas pipework for the LZ experiment, as pieces or sections are completed, they will be isolated andassessed for Rn emanation and outgassing for early identification of problematic seals or componentsthat require replacement or correction. The proximity of SDSMT to SURF will allow such routinetesting, either on campus at SDSMT or by relocating the SDSMT emanation system undergroundat SURF. Based on the sensitivity and operational experience of the screening systems developedat the individual institutions described above, we will construct a screening program underground,either by relocating one of the university systems or constructing a new one, in order to screenlarge-scale assembled detector elements and plumbing lines.

For SuperCDMS, radon emanation screening is not as critical, since operation of the iZIPdetectors under vacuum greatly inhibits migration of radon atoms to the detectors. However,the detectors may be more susceptible during storage and shipping, so Dr. Schnee’s group willsystematically test materials to be used for detector storage for SuperCDMS. Furthermore, Rnemanation studies may prove more sensitive than HPGe screening for determining the bulk Racontent of some materials.

3.6 LZ Neutron Calibration

Target Length: 1.5 pagesFirst Author: JuergenPrimary Internal Editor: Luke

3.7 SuperCDMS Soudan analysis

Target Length: 1.5 pagesFirst Author: Ray/RichardPrimary Internal Editor: JuergenOver the next 3 years, during the construction phase of the SuperCDMS SNOLAB project,

Dr. Schnee’s group will lead the ongoing analyses of the SuperCDMS Soudan datasets to betterunderstand the iZIP low-energy backgrounds, detector response, and electronics- and vibration-induced sources of noise. Further, the group will pursue advanced data-analysis techniques anddetector simulations to better utilize this improved understanding for the SNOLAB project and toextend (in the interim) the world-leading sensitivity to low-mass WIMPs using the Soudan data.Dr. Bunker will continue to lead this effort directly as the SuperCDMS Analysis Coordinator duringYear 1, and Dr. Schnee will provide complimentary leadership as the chair of the SuperCDMSPublications Committee to help ensure that several planned papers (based on the Soudan data)come to fruition. Mr. Street will contribute to analysis of Soudan data during Years 1 and 2 tohelp train him to lead analysis of the first SNOLAB dataset.

Drs. Bunker and Schnee will contribute to continued investigation of the SuperCDMS Soudanlow-energy data, used in [85] to set the current worlds best exclusion limit on the WIMP-nucleoncross section for low-mass WIMPs. The multi-component background model used in [85], based on acombination of Geant4 simulations and data-driven techniques, describes well the average observedbackground event rate. Use of likelihood-ratio studies to compare the individual components ofthe model to the WIMP-search data and side bands will improve understanding of the specificlow-energy backgrounds present at Soudan (and in particular, radon-related surface backgrounds),helping to better inform the levels of background mitigation required to achieve the science goalsof the SNOLAB payload. Further, Dr. Bunker will oversee incorporation (into the SuperCDMS

26

analysis effort) of an advanced detector simulation, to model the iZIPs detailed phonon and charge-collection physics (as described in [86, 87]), which should improve background modeling accuracyrelative to the data-driven techniques used in [85]. Dr. Bunker will also coordinate use of advancedphonon-pulse fitters (e.g., multi-dimensional digital optimal filters) to better utilize the intrinsicbackground-rejection capability of the iZIP design. These studies will advance the SuperCDMStoolset for extracting better sensitivity to WIMPs for the SNOLAB project, and they promiseimproved reach for low-mass WIMPs during the interim period between the Soudan and SNOLABexperiments. To this end, Drs. Bunker and Schnee will help coordinate and write a long paperbased on the analysis of the Soudan low-energy data described in [85] but augmented with theadvanced methods described above.

To push the SuperCDMS WIMP sensitivity to yet lower masses, Dr. Bunker will continue to co-ordinate analysis of special Soudan datasets taken with one Soudan iZIP operated in a high-voltagemode (called CDMSlite). We demonstrated in [88] that a Luke-phonon-amplified ionization mea-surement can be made by applying a relatively large bias voltage across an iZIP (∼30 vs. 1.5 V/cm),enabling a sub-keV energy threshold and thus access to low-mass WIMP models that would nototherwise be testable. The WIMP-search exposure described in [88]was fairly modest (∼1 week)and primarily intended as a proof of principle. Since then, we have recorded a 6 month CDMSlite“Run 2” that included an electronics upgrade to improve the stability of the bias current and moresophisticated monitoring of vibration-induced noise, from which we expect better resolution andan improved (i.e., lowered) energy threshold. Although these improvements will extend our reachto yet lower WIMP masses, the primary motivation of Run 2 is to measure with greater statisti-cal accuracy the low-energy event rate observed in this new mode. While the physical sources ofbackground should be the same as for the normal-bias mode, the electric field in the crystal is sig-nificantly altered and thus so is the detector response. Further, the CDMSlite mode does not makeuse of CDMSs traditional form of electron- vs. nuclear-recoil background discrimination (i.e., theratio of ionization to phonon energy). Consequently, the relative contributions of the various back-grounds are significantly different in the CDMSlite signal region, with electron recoils from gammarays emitted by bulk contamination in the passive shielding around the detector (particularly inthe copper) considerably more prominent. For the analysis in [88], no form of fiducialization (awayfrom the crystal surfaces) was attempted. With the Run 2 data, we will explore use of a radialfiducial volume to reject events near the detector sidewalls, where surface backgrounds are expectedto be larger and where non-uniform electric field lines can result in reduced signals. The primarychallenge of such a fiducial volume is understanding its acceptance. To this end, we will also useour advanced detector simulation to create a detailed background model for the CDMSlite mode.Accurate modeling of the backgrounds and detector response in this high-voltage mode is impor-tant for extracting the ultimate low-mass reach of the SNOLAB project, and it may significantlyextend the sensitivity of the Soudan experiment by enabling background subtraction via a fullmaximum-likelihood analysis. In Year 1, Dr. Bunker will personally oversee the initial processingof the Run 2 dataset and he will coordinate student analyses of these data, and Drs. Bunker andSchnee will help coordinate and write a paper based on the findings of the analysis and simulationprojects described above.

The Soudan iZIPs were not specifically designed for the high-voltage readout described above,with only a single side of these 2-sided detectors readout in the first two CDMSlite runs. ACDMSlite Run 3 is planned for early 2015 to explore 2-sided phonon readout and thereby informadvanced detector designs to be used for the high-voltage detectors planned for SNOLAB. InYear 1, Drs. Bunker and Schnee and Mr. Street will contribute to the acquisition of this Run 3data. Dr. Bunker will oversee the initial processing of these data, and Mr. Street will contributeto the Run 3 data-quality assessment. Combining 2-sided readout with a detailed detector model

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Year 1 Year 2 Year 3

commission SDSMT radon mitigation system construct SNOLAB mitigation system commission SNOLAB mitigation systemcommission radon emanation system begin emanation assay of materials

Table 7: Summary of Milestones for Proposed Work.

(provided by the advanced detector simulation) offers a rich program for optimizing high-voltagereadout for SNOLAB in Years 1 and 2. Further, the increased phonon signal-to-noise of a 2-sided readout may lower (relative to Run 2) the CDMSlite energy threshold by as much as 2x,thus extending the low-mass reach of the Soudan experiment yet further. Under the guidance ofDrs. Bunker and Schnee, Mr. Street will contribute to the CDMSlite Run 3 WIMP-search analysisin Years 1 and 2.

During the second half of 2014, extended neutron (252Cf) and gamma-ray (133Ba) calibrationswill be recorded with the Soudan experiment. These will compliment the calibration data acquiredduring the first 2.5 years of SuperCDMS operation at Soudan for use with the low-energy andCDMSlite analyses described above. Additionally, we will explore use of alternate gamma-raysources (e.g., 60Co, 137Cs, and 44Ti) to address the challenge at SNOLAB of calibrating a largerand better shielded payload. Finally, a special neutron calibration using an Y/Be source is plannedfor the end of 2014 to measure (in situ) the iZIP low-energy nuclear-recoil energy scale. In Year 1,Dr. Bunker will coordinate the initial processing of these data and will assign (and oversee) data-analysis projects to members of the SuperCDMS analysis team in Years 1 and 2. Drs. Bunker andSchnee and Mr. Street will also help assess the quality of these data in Year 1, and in Years 1 and2 Mr. Street will compare data from the alternate gamma-ray sources to Geant4 simulations.

A variety of tests geared to better understand electronics- and vibration-induced noise sourcesare planned for the second half of 2014 as well. The lower bandwidth of the iZIPs (relative to theCDMS II detectors) has resulted in greater sensitivity to vibrations. Initial studies indicate thatthe additional induced noise is most likely caused by phonons in the crystals, thus the detectorsare being physically jostled with a frequency that can mimic signals from true particle interactions.Targeted tests will be performed in which vibrations will be dampened and stresses will be relievedin the surrounding shielding structures while monitoring the noise performance of the Soudan iZIPsthat show the greatest sensitivity to vibrations. In Year 1 Dr. Bunker will oversee processing ofthese data, and in Years 1 and 2 he will coordinate noise analyses among members of the analysisteam to help inform the mechanical design of the SNOLAB shielding. Additionally, the electronic-noise environment at Soudan will be studied in detail, using both the CDMS II readout electronics(presently in use) and SNOLAB prototype electronics. Again, Dr. Bunker will oversee the processingof these data in Year 1 and will distribute and supervise data-analysis projects among the membersof the analysis team, including Mr. Street, in Years 1 and 2.

4 Timeline

Target Length: 1 pageFirst Author: Bai/RichardPrimary Internal Editor: All

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Appendix 1 Biographical Sketches

Luke A. CorwinBiographical Sketch

South Dakota School of Mines & Technology Phone: (605) 394-2728501 East Saint Joseph Street Fax: (605) 394-2365Rapid City, SD 57701-3995 E-mail: luke.corwin@sdsmt.edu

Professional Preparation

University of Minnesota - Twin Cities Physics B.S. 2003The Ohio State University Physics Ph.D. 2008Indiana University Long Baseline Neutrino Physics 2009-2013

Appointments

South Dakota School of Mines & Technology Assistant Professor of Physics 2013-presentSouth Dakota School of Mines & Technology Adjunct Professor of Physics 2013Indiana University Research Associate 2012-2013Indiana University Postdoctoral Fellow 2009-2012

Publications

Closely Related to the Project

1. P. Adamson et al. [MINOS Collaboration], “Measurement of Neutrino and AntineutrinoOscillations Using Beam and Atmospheric Data in MINOS,” Phys. Rev. Lett. 110, 251801(2013)

2. P. Adamson et al. [MINOS Collaboration], “Measurements of atmospheric neutrinos andantineutrinos in the MINOS Far Detector,” Phys. Rev. D 86, 052007 (2012)

Other Significant Publications

1. B. Aubert et al. [BaBar Collaboration], “A Search for B+ → `+ν` Recoiling Against B− →D0`−νX,” Phys. Rev. D 81, 051101 (2010)

2. B. Aubert et al. [BaBar Collaboration], “A Search for B+ → τ+ν,” Phys. Rev. D 76, 052002(2007)

3. L. A. Corwin [BaBar Collaboration], “The Search for B+ → τ+ντ at BaBar,” Nucl. Phys.Proc. Suppl. 169, 70-75 (2007)

Synergistic Activities

1. Co-convener of the MINOS Physics of the Universe Analysis Group (Oct. 2010 - Dec. 2012)

2. Implemented Fluka plus Geant 4 Geometry (FLUGG) neutrino beam simulations for NOvA

3. Set up equipment for quality control (QC) tests of liquid scintillator in NOvA and trainedothers to perform scintillator QC tests.

29

4. Classroom assistant, Boys’ & Girls’ Club of Bloomington, IN, September - December 2009

5. Co-organizer of Indiana Univ. InterVarsity Graduate & Faculty Ministry panel discussionfeaturing three faculty members, “Can a Biologist Trust an Evangelical Christian?” November12, 2009

Collaborators & Other Affiliations

Collaborators and Co-editors

Dr. Andrew Blake University of Cambridge, UKMr. Son V. Cao University of Texas at AustinDr. Justin Evans University of Manchester, UKDr. Alexander I. Himmel Duke UniversityDr. Jeffrey de Jong University of Oxford, UKMs. Michelle M. de Medeiros Universidade Federal de Goias, BrazilDr. Rashid Mehdiyev University of Texas at AustinDr. Stewart Mufson Indiana UniversityDr. Sarah R. Phan-Budd Winona State UniveristyDr. Raphael Schroeter Harvard UniversityDr. Richa Sharma Panjab University, India & Fermi National Accelerator LaboratoryDr. Xinjie Qiu Stanford UniversityDr. Nathaniel Tagg Otterbein CollegeDr. Stanley G. Wojcicki Stanford UniversityDr. Tingjun Yang Fermi National Accelerator Laboratory

Graduate Advisor and Postdoctoral Sponsors

Dr. Klaus Honscheid Graduate Advisor The Ohio State UniversityDr. Mark Messier Postdoctoral Sponsor Indiana UniversityDr. Stuart Mufson Postdoctoral Sponsor Indiana UniversityDr. Jim Musser Postdoctoral Sponsor Indiana UniversityDr. Jon Urheim Postdoctoral Sponsor Indiana University

30

Richard W. SchneeBiographical Sketch

Education and Training:

Princeton University, Physics, B.A., June 1989

University of California, Santa Cruz, Physics, M.S., March 1991

University of California, Santa Cruz, Physics, Ph.D., June 1996

Case Western Reserve University, Research Associate in Particle Astrophysics, 1996–1999

Case Western Reserve University, Senior Research Associate in Particle Astrophysics, 1999–2003

Research and Professional Experience:

Associate Professor of Physics, South Dakota School of Mines & Technology: August 2014 – present

Visiting Associate Professor of Physics, Syracuse University: May 2014 – August 2014

Assistant Professor of Physics, Syracuse University: August 2007 – May 2014

Visiting Assistant Professor of Physics, Case Western Reserve University: June 2003 – May 2007

Publications

• R. Agnese et al. (SuperCDMS Collaboration), “Search for Low-Mass WIMPs with Super-CDMS,” Phys. Rev. Lett. 112, 241302 (2014) [arXiv:1402.7137] .

• R. Agnese et al. (SuperCDMS Collaboration), “CDMSlite: A Search for Low-Mass WIMPsusing Voltage-Assisted Calorimetric Ionization Detection in the SuperCDMS Experiment,”Phys. Rev. Lett. 112, 041302 (2014) http://prl.aps.org/abstract/PRL/v112/i4/e041302.

• J. Cooley, P. Cushman, E. W. Hoppe, J. L. Orrell, and R. W. Schnee, “Low Background Ma-terials and Assay - A Supplement to the Cosmic Frontier CF1 Summary,” [arXiv:1311.3311].

• R.W. Schnee, R. Bunker, G. Ghulam, D. Jardin, M. Kos and A.S. Tenney, “Construction andmeasurements of a vacuum-swing-adsorption radon-mitigation system” in Topical Workshopon Low Radioactivity Techniques:LRT 2013, American Institute of Physics Conference Series,edited by L. Miramonti and L. Pandola (American Institute of Physics, Melville, New York,2013), 1549, 116–119 [arXiv:1404.5811].

• Z. Ahmed et al. (CDMS-II Collaboration), “Dark Matter Search Results From The CDMS-IIExperiment,” Science 327, 1619 (2010) [arXiv:0912.3592 [astro-ph.CO]].

• R. W. Schnee, “Dark Matter Experiments,” in Physics of the Large and Small: Proceedingsof the 2009 Theoretical Advanced Study Institute in Elementary Particle Physics, edited byC. Csaki and S. Dodelson (World Scientific, Singapore, 2010), pages 775-829, [arXiv:1101.5205].

• D.S. Akerib, M. Dragowsky, D. Driscoll, S. Kamat, T. Perera, R. Schnee, G. Wang, R. Gaitskell,L. Bogdanova, V. Trofimov, “Demonstration of feasibility of operating a silicon ZIP detectorwith 20 eV threshold,” Nucl. Instrum. Meth. A520, 163 (2004).

(d) Synergistic Activities

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• Member of Working Group A of Cosmic Frontier Subgroup 1 for SNOWMASS2013 process.Helped summarize status of New Ideas, develop criteria by which future direct dark mattersearch experiments can be evaluated, summarizing radon R&D needs.

• Leader of Low-Background Screening group of the Acquisition and Assay of Low-RadioactivityMaterials collaboration, 2009–2012. Helped design Facility for Acquisition and Assay of Low-Radioactivity Materials. Co-organized workshops on screening facilities and needs, collabo-rative efforts to improve simulation of cosmogenic and radiogenic neutron backgrounds.

• Led ILIAS Training Session, “From Data to WIMP Limits,” a four-day workshop for 30graduate students, post-docs, and faculty working on European direct dark matter detectionexperiments, in Aussois, France, 11–14 January 2008. Presented nine invited lectures, helped2 post-docs prepare two additional lectures, created exercises associated with each lecture,assisted participants in solving exercises.

(e) Collaborators & Other Affiliations

Collaborators: R. Agnese, Florida; Z. Ahmed, Caltech; D.S. Akerib, SLAC; A.J. Anderson, MIT;S. Arrenberg, Zurich; C. Bailey, CWRU; D. Balakishiyeva, Florida; R. Basu Thakur, FNAL;L. Baudis, Zurich; D.A. Bauer, FNAL; J. Beaty, Minn.; A. Borgland, SLAC; P.L. Brink, SLAC;T. Bruch, Zurich; R. Bunker, Syracuse; B. Cabrera, Stanford; D.O. Caldwell, UCSB; D.G. Cer-deno, Madrid; H. Chagani, Minn.; K. Coakley, NIST-Boulder; J. Cooley, SMU; B. Cornell, Cal-tech; E. do Couto e Silva, SLAC; P. Cushman, Minn.; F. DeJongh, FNAL; T. Doughty, UCB;M.R. Dragowsky, CWRU; P. Di Stefano, Queen’s; F. Duncan, SNOLAB; L. Duong, Minn.; A. Empl,UALR; S. Fallows, Minn; E. Figueroa-Feliciano, MIT; J. Fillipini, Caltech; J. Formaggio, MIT; M.Fritts, Minn.; G. Ghulam, Syracuse; G.L. Godfrey, SLAC; S.R. Golwala, Caltech; D.R. Grant,Alberta; V. Guiseppe, USD; J. Hall, PNNL; H.R. Harris, TAMU; J. Hasi, SLAC; R. Hennings-Yeomans, LBNL; S. Hertel, Yale; A. Hime, PNNL; B.A. Hines, UCDHSC; T. Hofer, Minn; D. Holm-gren, FNAL; L. Hsu, FNAL; M.E. Huber, UCDHSC; D. Jardin, SMU; A. Jastram, TAMU; O.Kamaev, Queen’s U.; B. Kara, SMU; E. Kearns, BU; M.H. Kelsey, SLAC; S.A. Kenany, UCB; A.Kennedy, Minn; J. Kenney, SLAC; J. Klein, Penn; M. Kiveni, FNAL; K. Koch, Minn.; M. Kos,PNNL; S.W. Leman, MIT; H. Lippincott, FNAL; B. Loer, FNAL; E. Lopez Asamar, Madrid;R. Mahapatra, TAMU; V. Mandic, Minn.; C. Martinez, Queen’s; K. McCabe, Syracuse; K. Mc-Carthy, MIT; R. McDonald, LBNL; D. McKinsey, Yale; D. Mei, USD; N. Mirabolfathi, UCB;J. Monroe, RHUL; R.A. Moffatt, Stanford; D. Moore, Stanford; P. Nadeau, Queen’s; H. Nelson,UCSB; R.H. Nelson, Caltech; J. Nikkel, RHUL; L. Novak, Stanford; R.W. Ogburn, Stanford; K.Page, Queen’s; R. Partridge, SLAC; M. Pepin, Minn; M. Pyle, UCB; H. Qiu, SMU; X. Qiu, Stan-ford; E. Ramberg, FNAL; W. Rau, Queen’s; P. Redl, SLAC; A. Reisetter, Evansville.; Y. Ricci,Queen’s; A. Rider, Caltech; K. Rielage, LANL; M. Rohnquest,LANL; T. Saab, Florida; B. Sadoulet,UCB; J. Sander, USD; R. Schmitt, FNAL; K. Schneck, SLAC; S. Scorza, SMU; S. Seibert, Penn.;D.N. Seitz, UCB; B. Serfass, UCB; B. Shank, Stanford; D. Sotolongo, Caltech; D. Speller, UCB;K. Sundqvist, TAMU; A.S. Tenney, Syracuse; A. Tomada, Stanford; A.N. Villano, Minn; B. Wang,Syracuse; B. Welliver, Florida; J. White, Syracuse; D.H. Wright, SLAC; S. Yellin, Stanford; J.J.Yen, Stanford; J. Yoo, FNAL; B.A. Young, Santa Clara; A. Zahn, Caltech; J. Zhang, Minn.

Advisors: D. Coyne (deceased), graduate; D.S. Akerib (CWRU), postdoctoral.Thesis Advisees (4): M. Kiveni, FNAL; B. Wang, Y. Chen, M.Bowles, Syracuse U.Postgraduate-Scholar Sponsorees (2): M. Kos, PNNL; R. Bunker, Syracuse

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Appendix 2 Current and Pending Support

Luke Corwin

Support Type: Current

Title: Start Up Package for South Dakota School of Mines & Technology

Abstract: Standard start up package for new faculty members

Organization Providing Support: South Dakota School of Mines & Technology Physics De-partment

Total Award Amount: $70,000

Award Period: Aug. 22, 2013 - No specified end date

Person-months per year to be devoted to the project: 7.5

Support Type: Pending

Title: Research and Education Consortium for Nuclear Science and Nuclear NonproliferationResearch

Abstract: This project is focused upon the establishment of an NNSA Research and EducationConsortium for Verification Technology. We will build upon the academic programs and researchin nuclear physics, nuclear engineering, accelerator science, geophysics, environmental and atmo-spheric monitoring, and large-scale modeling and computation to support DNN Mission Area 2:Consortium for Verification Technology. Our team is comprised of six universities (South DakotaSchool of Mines and Technology, Old Dominion University, Virginia Commonwealth University,Idaho State University, Washington State University, University of Nevada - Las Vegas, six nationallaboratories (SNL, LLNL, PNNL, INL, and Office of Science laboratories LBNL and Jefferson Lab),and one state laboratory (Sanford Lab).

Organization Providing Support: National Nuclear Security Agency

Total Award Amount: $24,101,836 for the entire consortium, of which $5,650,439 is proposedfor the South Dakota School of Mines & Technology.

Award Period: Oct. 01, 2013 - Sep. 30, 2018

Person-months per year to be devoted to the project: 1.1

Support Type: Pending

Title: Cutting Edge R&D to Enhance the Performance of the Long-Baseline Neutrino Experiment(LBNE) Far Detector

Abstract: The objective of the project is to enhance both engineering and scientific performanceof the LBNE Far Detector by carrying out several well-defined R&D tasks, with foci on the radi-ological cleanliness and low energy aspects of the LBNE project. The proposed R&D foci includethe development of a multi-purpose liquid argon measurement stand (LAMS) at the South DakotaSchool of Mines and Technology (SDSMT) and the Sanford Underground Research Facility (SURF),simulation study of the radiological cleanliness requirements in the LBNE Far Detector, and sim-ulation study of atmospheric neutrino analyses and novel reconstruction techniques to assess the

33

potential for discrimination between neutrinos and antineutrinos. Dr. Xinhua Bai is the PI, andDr. Corwin is the co-PI.

Organization Providing Support: Dept. of Energy Office of Science

Total Award Amount: $625,847

Award Period: June 2014 - May 2017

Person-months per year to be devoted to the project: 5.5

34

Appendix 3

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Appendix 4 Facilities & Other Resources

The facilities, equipment and other resources available at South Dakota School of Mines & Tech-nology for this project include are:

• One computer cluster consisting of 568 CPUs (ranging from 2.05 GHz to 2.54 GHz) and 5 TBof disk space can be used for the simulation, analysis and data storage for this project

• A web that server can be used to support project website.

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Appendix 5 Equipment

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