Steps towards a cosmogenic neutrino detector at the South Pole

• Summary of meeting on Sep 14• Opportunities - outer ring extension• Acoustic & Radio technique, parameter space• Science case• Strategy discussions

Utrecht Sep 14, R&D pre-meeting on GZK neutrino detection at the Pole:

• Attendance: • ~25 people from the

– acoustic group and

– radio group

including • Leif Gustavsson - Uppsala• Amy Connolly, Ryan Nichols - UC London

Diffuse E-2 µ-spectrum peaks at 1 PeV (after atm. Background rejection)

• Neutrino event energy spectrum after energy cut for a 3 year diffuse analysis.

• Signal events peak at ~1PeV

• Optimize final detector configuration for higher energy range, to maximize sensitivity of IceCube.

The first 40-string event(data taken March 10, 2008)

Flash 46-27 “Tulip”

Flash 46-57 “Qi”

Larger geometries:Higher cross overGreater gain at high energies

High Energy IceCube Optimization study

Investigating options for optimized positioning of last 9 stringsMotivation: Improve high energy response.Significant impact on drilling.

RESULT:• Gain in effective area 10% to 30% (50% at

GZK energies ) (depending on configuration)

• IceTop coincidence event rate increases

80 total strings including 12 in the outer ring (1 km radius)

6 outer ring strings + 1 in centerwith optical + radio + acoustic

Simulated array geometry: HORUS

normal optical string with 60 DOMs1 every 17 m from 1.45 km to 2.45 km

60 acoustic sensors 1 every 15 m from 215 to 1100 m

5 radio antennas1 every 100 m from 200 to 600 m

Hybrid Optical Radio Ultrasound Setup

EHE - Experimental limits

IceCube 80, 1yr

arXiv:0711.302, apjarXiv:0705.1315, prd

Figure from

Summary of review based on Auger results by T. Stanev and D. Seckel at APS

• Revisit GZK in light of AUGER• AUGER:

– Spectrum, AGN, Mixed composition, E Calibration

• Reasonable choices: – AGN luminosity evolution w/ = 1.4– Ec = 1021.5 – Mixed composition– HIRES normalization (AUGER * 1.25)

• Results ~ 2-3 below ESS.

Neutrino induced cascades produce 3 types signals: optical, acoustical and radio signals

air

interactionparticle shower

~1012 particlesinteractionparticle shower

~1012 particles

(1) Optical Cherenkov pulse: ~500 m (works below 1400m because of ice and cosmic rays)

(2) Askaryan radio cone~1 km (100MHz - 1GHz)

(3) Askaryan acoustic pancake: ~km?

Total internal reflection at surface (firn layer)?

Depending on angle.

ice

radio and acoustic waves travel farther than light in iceThey require less drilling as they can travel through bubbly ice and firn (radio)

Energy scale in this cartoon: o(1 EeV)

Ray tracing reminder

Radio waves Sound waves

HL JV

R&DFuture extension ideas:

UHE Radio Augmentation- here IceRay version AURA-18 -

and possiblyacoustic instrumentation

ICERAY

• GZK neutrinos (1017-19.5 eV), at lowest possible cost: o(10)/3yr– Version shown may be too small

• Chance of hybrid events with IceCube– Primary vertex calorimetry in radio, HE muon or tau secondary in IceCube

Detector comparison of GZK rates per year

Cosmogenic neutrino Model 3m, N=60 events yr-1

50m, N=36 events yr-1

50m, N=60 events yr-1

100m, N=36 events yr-1

200m, N=18events yr-1

Iron-only UHECR 0.3 0.5 0.7 1.0 0.6

Engel, Seckel, Stanev 2001, base model 1.5 2.4 3.1 4.2 2.9

ESS model (stronger) m=0.3, =0.7 2.4 3.8 4.9 6.7 4.6

Waxman-Bahcall-based GZK flux model 2.7 4.2 5.5 17.6 5.0

Protheroe/other Std-model GZK fluxes 3-4.7 4.7-7.8 6.2-9.6 8.5-12.5 5.6-10

Models with strong source evolution 7.6-13 12-21 15-25 20-35 14-36

Maximal GZK fluxes, saturate all bounds 14-27 24-40 29-55 40-80 32-47

Detector probable cost evaluation excellent Very good good OK OK

Detector performance evaluation: OK good Very good excellent good

Disfavored by data

StandardModels

tooStrong?

• Select 50 m depth, N=36 array as preliminary IceRay baseline• Best cost-performance (weighted more by cost)• Uses proven firn-drill technology

3 events/yr (divide by 2 to 3)

LHC

Bigger picture - Staged IceCube EnhancementsHow to get from here to there?

D. Besson et al.astro-ph/0512604

Optical:

80 IceCube + 13 IceCube-Plus (astro-ph/0310152)

- unlikely at this point

Radio / Acoustic:

~ 10 events/yr

(divide by 2 - 3)

Large detector: effective volumes & event rates

• I: IceCube O: Optical R: Radio A: Acoustic

• ESS GZK flux model (= 0.7)[R. Engel, D. Seckel and T. Stanev Phys. Rev. D 64, 093010 (2001)]

Detection option

GZK events/year*)

IceCube 0.7

Optical 1.2

Radio 12.3

Acoustic 16.0

Optical+Radio 0.2

Optical+Acoustic 0.3

Radio+Acoustic 8.0 !!!

Opt.+Rad.+Acou. 0.1

TOTAL 21.1

5 antennas/string to 600m300 hydrophones/string to 1200m(assumed cost equivalent in study)

Parameters for evaluation

Configuration

Detection principle Radio Acoustic Optical

Granularity in x-y and in z

High Low clusters

Complexity of sensor and recorded information

Precise waveform capture

Simplistic: eg. T, ToT, or log(amp)

Polarization (radio)

Drilling Diameter Depth (50, 200, 1200 m)

Hot water or mechanical

Communication/power Wired/wireless bandwidth

Drilling

Parameters: Depth, diameter, Dry or hot water

Operation: Crew size, power, time per hole, cost

Findings from 2 drilling workshops held at UW in 2008, Organized by PSL

• Added for evaluation– Caltech drill: 2 km, 25 cm, 9 crew, hot water, 1200m, ~1000

gal fuel, several days.

Constraints

• Minimal number of events• Reliable detection and background rejection:

– Event information, enough hits and/or information on pulseshape and polarization

• Power draw from station (eg < 10 kW)• Construction impact: drilling, deployment, personnel• Total construction time• Cost

Discussion on hybrid, IceCube & radio & acoustic

• Reason: absence of natural calibration signals (such as atm. neutrinos).

• Hybrid is a powerful way to demonstrate that background is understood and to calibrate.

• Optical: can get lucky, but can’t make it a planning assumption to see events / coincidences.

• Simultaneous detection of radio and acoustic would be beautiful evidence of an event

• Challenge: Acoustic detection (even in optimistic assumptions otherwise) requires deep drilling -> quantum jump in drilling costs and time, that may be deciding factor.

• Question to answer is, – whether it is cost efficient to pursue redundancy and BG rejection

this way?– Or if sufficient redundancy can be achieved radio only.

Amy Connolly, UCL

Amy Connolly, UCL

Work towardsSimulating specific modelsAnd understanding detector response

RICE limit

Amy Connolly, UCL

Three-prong hybrid air shower studies (1) IceTop, (2) Muons in deep ice, (3) Radio

Proposal submitted for R&D to European funding agencies

Options for IceTop Radio Extension

Expansion of surface array

Veto for UHE neutrino detection InIce

Infill surface array

HybridCR compositon

EMI test bed

- EMI monitoring ~2km out of the station.

- Ground screen above array to block galactic, solar , aircraft and surface RF noise

- 115-1200 MHz

- Hardware exist

- Independent proposal submitted

- Also: checking option to use firn holes near and away station to study firn and EMI emission (not a part of IceRay).

Phases1) Explorations of techniques, sensor development,

experience, measurements of ice properties• R&D on acoustic and radio• SPATS, • RICE, AURA, NARC, other activities• Ongoing, conclusions in 2009 and 2010

2) IceRay scale detector Large enough to measure o(10) events in 3 years in

reasonably conservative assumption on flux and detector efficiency

Proposal 2010

3) Larger scale cosmogenic neutrino detectoro(100) events, beyond 2015

Possible near term timeline:2008-2009-2010

- Working group and collaboration building

-Write „Letter of Intent“ and sign in spring 2009 to demonstrate:

serious intention of signing groups to in- and out-side world (FA) sientific importance in comparison to other topics expected improvement to previous experiments time scenario and milestones

- Finish basic exploration of ice properties

- Start extensive MC studies of different detector options

- Start sensor and electronic prototyping

- Track down number of different detector options based on above results

- Write „Proposal“ for submission to FA‘s end 2010

expand letter of intent to give detailed information based on extensive MC and hardware studies still goes with flexible design plan and 2 phase structure works out realistic budget plan

2011- 2012

Write „Technical Design Report“ for project phase 1

basic requirement: identify ~15 GZK events in ~3 years clearly separated from background

Present technical solutions and construction plans forall components and systems of the 20% detector

Work out necessary logistics

Prepare time-profile for necessary manpower and funding

Season 2012/13Start construction of Phase 1

Miscellaneous: Phase 1 limits

Size:

difficult to estimate, depends on chosen technology, needs MC

Construction time:

not more than 5 years

Cost:

upper limit 30-40 M$ (would bring full scale project to 150-200 M$)

Future detector design

Some considerations:• Frequency range and band width.• Antennas type

Data type:• Full digitized WF • Transient array• Scope

Geometry (depth and spacing):• Space detectors (outer ring better as ring,

and not as pile)• Shadowing effect Deeper is better• Ice Temperature Shallower is better • Drilling cost and time– Deep=expensive• Hole diameter can limits design of antennas• Wet/dry hole

Denser Shallow holes

Spaced deep holes

Possible Time Scenario

2009 Letter of Intent

2010 Proposal

2011 Technical Design Report (Phase 1 – 20%)

2012 Phase1 Construction Start

2015 Phase 1 Operation + TDR (Phase 2)

2018 Phase 2 Construction Start

2025 Phase 2 Full Operation

Scenario already now challenging, needs immediately more manpower