MiniBooNE UpdateSince Last PAC Meeting (Nov 2007)

Steve Brice (FNAL)

PAC Meeting

27 March 2008

March 2008 PAC Meeting Steve Brice (FNAL) 2

• CC +

– 2 papers expected • CC 0

– Reconstruction challenges overcome– 1 paper expected

• NC 0

– 1 paper submitted PLB– Coherent/resonant in nu and anti-nu

modes– Flux averaged cross-section measurement– 2 further papers expected

• NC Elastic– Flux averaged cross-section measurement– 1 paper expected

• -e Elastic– Nu mag. Mom– 1 paper expected.

• Oscillation– Refined Nue appearance– Nuebar appearance– Numu and numubar disappearance– 1 PRL, ~3 further papers expected

• Low Energy Excess– Big effort– 2+ papers expected

• Alternative Oscillations– Phenomenology– CP violation, Lorentz violation, ...– 3+ papers expected

• NuMI Events– Large event rate from NuMI beam– Check on osc. and Low E– 1 paper being written

• CCQE– 1 PRL, 2 further papers expected

Broad Range of Analyses

• No organizational separation between neutrino and anti-neutrino mode• 12 PhD Students + 6 graduated

= PhD Student (6 already graduated)

March 2008 PAC Meeting Steve Brice (FNAL) 3

Publication Update Since Nov 2007• CCQE paper accepted by PRL (Phys. Rev. Lett. 100, 032301 (2008))

• 0 paper submitted to PLB and the archive (arXiv:0803.3423 [hep-ex])

• Paper on e background from muon internal Bremsstrahlung submitted to the archive (arXiv:0706.3897 [hep-ex] )

• 3 students graduated– D.C. Cox, "A

Measurement of the Neutral Current Neutrino-Nucleon Elastic Cross Section at MiniBooNE", PhD Thesis, Indiana University, 2008

– A.A. Aguilar-Arevalo, "An Improved Neutrino Oscillations Analysis of the MiniBooNE Data", PhD Thesis, Columbia University, 2008

– R.B. Patterson, "A Search for Muon Neutrino to Electron Neutrino Oscillations At Δm2 > 0.1 eV2", PhD Thesis, Princeton University, 2007

March 2008 PAC Meeting Steve Brice (FNAL) 4

Publications Coming Soon

• Beam PRD (65 pages) circulating in final draft form

• Detector NIM (43 pages) circulating in final draft form

• First draft of combined e analysis paper circulating

• First draft of combined experiment paper circulating (LSND, MiniBooNE, KARMEN, & Bugey)

• 4 further analyses in internal review phase

March 2008 PAC Meeting Steve Brice (FNAL) 5

Low Energy e Candidates

• Aiming to have this work completed and presented at Neutrino 2008 (end of May)

• A great deal of effort gone into studying our background predictions and uncertainties at low energy (below ~475 MeV)

• Work also on reducing backgrounds at low energy

• No significant changes expected above 475 MeV

March 2008 PAC Meeting Steve Brice (FNAL) 6

Low Energy Changes

After a comprehensive review of all the backgrounds to e appearance and their uncertainties

• Included Photonuclear effect• More comprehensive hadronic errors• Better handling of beam + production uncertainties• Improved measurement of induced 0s• Better handling of ± interactions• Several modifications to the handling of the background from 0s• Better handling of the radiative decay of the resonance

Arrows indicate whether effect is to increase or decrease the low energy data excessThe effects have different magnitudes despite the arrows all being the same size

?

Distance to Wall Backward Cut

Evis

RED: CCQE NueBLACK: Background

Dirt events tend to be at large radius, heading inwardAdd a new cut on “DistancetoWall backward” to reduce these.

Has significant effect below 475 MeV• Big reduction in dirt • Some reduction of 0s• Small effect on es

Has almost no effect above 475 MeV

shower

dirtIn low energy region there is a significant background from neutrinointeractions in the dirt

Comparing Neutrino/AntineutrinoLow Energy e Candidates

Green: Effective pi0’sBlue: DirtPink: Delta’sYellow: OtherLt Blue: Nue (CCQE)

Neutrino AntiNeutrino

The e background breakdown is very similar between neutrino and antineutrino mode running

But different hypotheses for the excess can have measurably different effects in the two modes

Can compare the two modes to test some of the hypotheses

2.33x1020 POT

EQE EQE

March 2008 PAC Meeting Steve Brice (FNAL) 9

The eBDT +

eTBL + CCQE results:

Limits from fits to open data

10%-30% improvement in 90% C.L. limit below ~1eV2.

The combination of the three samples

gives a increase in coverage in the

region m2<1 eV2.

Differences in the details are due to the

specific fluctuations in the three data

samples and the interplay with

correlations among them.

The combination yields

a consistent result.(A.A. Aguilar-Arevalo)

(first draft of paper written)

March 2008 PAC Meeting Steve Brice (FNAL) 10

Complete MiniBooNE Disappearance Sensitivity

• MiniBooNE data 90% CL sensitivity

• CDHS CCFR 90% CL

• Combined analysis with SciBooNE data will significantly improve this sensitivity

(K. Mahn)

March 2008 PAC Meeting Steve Brice (FNAL) 11

NuMI Data/MC Comparisons

K

PRELIMINARY

PRELIMINARY

CCQE sampleCCQE sample

MC is normalized to data POT number

All

All e

PRELIMINARY

PRELIMINARY

ee CCQE sample CCQE sample

Good agreement between data and Monte Carlo:the MC tuned well.

Very different backgrounds compared to MB (Kaons vs Pions) Ongoing effort to reduce

ee CCQE sample systematics

(Z. Djurcic)

Phys. Lett. 100, 032301 (2008)

arXiv:0803.3423; submitted

to Phys.Lett. B

NuInt07, D.C. Cox, Ph.D. thesis, IU (2008)

Neutrino Cross Sections

PAC (Mar 2008)

NuInt07, results soon

March 2008 PAC Meeting Steve Brice (FNAL) 13

CCQE

• published in PRL earlier this year (100, 032301, 2008)

(T. Katori)

before fit

after fit

yields stunningdata/Fermi Gas model

agreement acrossentire phase space !

QE

• 2 parameter fit (MAQE=1.23 0.20 GeV, =1.019 0.011) in Q2

T(GeV)

March 2008 PAC Meeting Steve Brice (FNAL) 14

NC ElasticNC EL

Results (from 10% nu sample):

- NC elastic diff. cross section (per nucleon, n+p averaged, flux averaged)

- Flux Integrated Cross-Section = 8.8 ±0.6(stat) ±2.0(syst) x10-40 cm2

- Measured axial mass (NC) = 1.34 +0.38–0.25 GeV

- work of Chris Cox, Indiana U., Ph.D. 2008- further analysis on full nu data set and with goal of reducing systematic errors in progress (D. Perevalov, Alabama) - eventual analysis goal: NC/CCQE ratio measurement and antinu data

(D.C. Cox)

March 2008 PAC Meeting Steve Brice (FNAL) 15

NC 0

• largest NC 0 sample ever collected!

Rein-Sehgal prediction

• coherent0 fraction = (19.5 2.7)%; MC prediction = 30% arXiv: 0803.3423, submitted to Phy. Lett. B, March 2008

28,600 0 eventsm ~ 20 MeV/c2

(J. Link)NC 0

Cross-section x flux

MB result

March 2008 PAC Meeting Steve Brice (FNAL) 16

• developed a new 3-ring fitter ( + ) for this new analysis

(R. Nelson)

preliminary

CC 0

• provides a means to test a pure resonant single- sample (w/ no coherent contribution)

• 31,755 events

CC 0

PAC (Nov 2007)

Moriond EW

(March 2008)

PAC (Nov 2007)

PAC(Mar 2008)

Antineutrino Cross Sections

March 2008 PAC Meeting Steve Brice (FNAL) 18

NC 0

• shown at Moriond earlier this month • 1,744 events (plus, will be taking more data in mode soon)

(V. Nguyen)

NC 0

March 2008 PAC Meeting Steve Brice (FNAL) 19

• direct way to check predicted rate and energy dependence of backgrounds in mode (J. Nowak)

• as well as most forward + production (outside HARP data)

HARP

(abs

olut

ely

norm

aliz

ed)

CC + CC + in Mode

E (GeV)

March 2008 PAC Meeting Steve Brice (FNAL) 20

Future Run Plan

Current amountof antineutrinodata -Blue line is historical running with NuMI

on and slip stacking.-Green line is what we might get with RF load resistor upgrade (parts are being acquired).

Next shutdown is Spring 2009