IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE Workshop 1 Beyond IceCube @...

April 2006

D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE Workshop

1

IRA

Beyond IceCube @ the South PoleOutline

Introduction: Optical vs. Radio & Acoustic Moving to the GZK scale: E > 1016 eV sensitivities Radio

● RICE● Near-term future ideas

ROCSTAR/DRM Surface array

Acoustic● Near-term future ideas

SPATS

Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector

Comments on IRA sensitivities Conclusions

April 2006


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IRA

Optical vs. Radio & Acoustic

IceCube has been optimized for energies in the range between roughly 1 TeV and 10 PeV

The buried array relies on one type of detection channel: optical● Cherenkov light from UHE -induced charged

particles att ~ 30m requires high module density

– IceCube has ~5000/km3

● To get sufficient statistics at higher energy scales (e.g., GZK scale), where one needs a fiducial volume closer to 100-1000 km3, need technology that is practical at lower module densities

April 2006


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IRA

Optical vs. Radio & Acoustic

Happily, ice is also well-suited for detection of UHE neutrino-induced radio and acoustic signals ● Cherenkov radio signals

~1km attenuation length proven technology (RICE)

● Acoustic signals ~10km attenuation length potentially very quiet environment (vs., e.g., ocean)

Coincident event capture offers many benefits● Therefore, in this talk we will focus on efforts using

ice at the South Pole● Will not cover other very interesting and promising

radio and acoustic efforts, like ANITA, SalSA, SAUND,…

April 2006


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IRA






SPATS



April 2006


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IRA

Focus on “Guaranteed” UHE Neutrinos

GZK flux models

From

Gorh

am

et

al., Phys.

Rev. D

72 (

2005)

023

002

● Roughly speaking, depending on various assumptions, to detect one GZK /yr at 1016-19 eV requires Veff ~ 4-50 km3

See, e.g., Engel, Seckel and Stanev, Phys. Rev. D64 (2001) 093010

April 2006


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IRADiscovery Aperture vs. E

Salt

zberg

, ast

ro/p

h 0

50

13

64

April 2006


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IRA






SPATS



April 2006


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IRA

UHE Neutrino Radio Detection: RICE

Design● 20-channel array of dipole antennas● 100-300m depths● 200x200x200 m3 deployment

volume● Analog readout into surface digitizers

5 m

10 cm

April 2006


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IRA

UHE Neutrino Radio Detection: RICE

Results (Kravchenko et al., astro-ph/0601148)● 1999-2005 RICE livetime of ~20500 hrs

(Veff×livetime ~ 1-10 km3۰yr۰sr @ 1017-19 eV)

● (Results from GLUE, ANITA, FORTE in the literature & at this workshop)

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IRA






SPATS



April 2006


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IRA

New Ideas for Radio at the South Pole

“ROCSTAR”● Retrofitted OptiCal SysTem Adapted for Radio● Piggybacks on existing IceCube DOMs

Use Main Board as-is for timing and power

Replace “flasher board” with radio digitizer board to process all radio-related signals

– use pre-existing interface bus to MB

Remove PMT, HV stuff, etc.

Rename it “DRM” for Digital Radio Module

April 2006


12

IRA

Possible ROCSTAR Node Configuration

Twisted pairprovides power and comms

IceCube surface to DOM cable

RF cable to antenna, also power

Antennaw. amp

DRM:Sphere with 6 penetrators, Radio digitizer +DOMMB

RF cable to transmitter antenna(calibration, very low power)

≈50m

April 2006


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IRA

Possible ROCSTAR Block Diagram

SRAMor similar

Power

up to 6W

A/Dconverter

Disc.

Amp.

A/Dconverter

Disc.

Amp.

A/Dconverter

Disc.

Amp.

A/Dconverter

Disc.

Amp.

FPGA

Flasherboard bus

DOM MBRadio digitizer board

Trigger to DOMMBfrontend & time stamp

Antennas

Local coincidencetriggering

April 2006


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IRA

ROCSTAR Deployment Depth

Optical-Radio coincident event rate can be substantial

Preferable to deploy close to surface, but temperature still reasonably cold (-42C) at 1450 m

Simulations needed to optimize geometry

ROCSTARNodes (~70)

April 2006


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IRA

ROCSTAR

Advantages● Uses existing hardware with minimal modification

to significantly enlarge radio array at the South Pole

● Straightforward to integrate into existing optical array data acquisition system to make functioning hybrid detector and see coincident events

● Minimal impact on IceCube deployments

Disadvantages● Geometry somewhat inflexible, not optimal● Use of existing hardware imposes some

constraints on design of in-ice radio electronics (probably not severe)

April 2006


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IRA






SPATS



April 2006


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IRA

Surface Array

Calibration of UHE neutrino detectors is tricky due to lack of a “test beam”● IceCube approach

in-situ light sources (LEDs, lasers) to mimic cascade events up to ~50 PeV

cosmic-ray muons and atmospheric -induced muons up to about 10 TeV

● Radio and Acoustic approaches in-situ (or nearby) transmitters

New idea (Seckel & Seunarine)● use Askaryan radio pulse produced when cosmic-

ray air shower core’s particles hit the earth (or the ice upon it) comprise a few % of the energy of the air shower

April 2006


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IRA

Surface Array Use an array of radio antennas near the surface at the Pole

Trigger with IceTop, the air shower array atop the IceCube buried array

With Ep>3PeV, a 30 m × 30 m array would see ~1 ev/hr

Not just for radio array calibration ● cosmic-ray

composition studies may be possible too

RICE might be able to do this

More simulation work needed

April 2006


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IRA






SPATS



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IRA

UHE Neutrino-Induced Acoustic Signals

A -induced cascade will produce localized heating in the medium, creating a pressure wave

Detect sound, peaked at ~40kHz, with detectors distributed in the ice at the South Pole

Short-term issues:● absorption length

probably large; must measure● refraction● background noise

probably small; must measure– man-made on surface– slip-stick of glacier on

bedrock– micro cracks

N.B.: No noise from dolpins, ships, wind, waves,…

S.

Boese

r/D

ESY

April 2006


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IRA

UHE Neutrino-Induced Acoustic Signals

Predicted attenuation length for sound in ice looks very promising (plot below is for 10kHz):

Depth variationis due to changein temperature ofthe ice at Pole.

J. V

and

enbro

uck

e/A

REN

A 2

00

5

April 2006


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IRA

Acoustic Detection Contours in Ice

Contours for Pthr = 9 mPa:

raw discriminator,

no filter

J. V

and

enbro

uck

e/A

REN

A 2

00

5

lon

git

ud

inal coord

.

lateral coord.

April 2006


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IRA

Acoustic Signals: SPATS

South Pole Acoustic Test System

Purpose: measure● noise● refraction● attenuation length

Design for 06/07 season● Deploy in 3 IceCube holes at

400m depth● 7 acoustic stages per hole

sensor and transmitter

● 3 surface interface boxes power, network interface

● 1 master CPU network interface, GPS

timestamp

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IRA

SPATS Module

Modules at DESY/Zeuthen

Sensor Module One Full Module

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IRA

After SPATS…

If the measurements made with SPATS during the 2006/2007 season at the South Pole are encouraging, the next step will be to plan and hopefully build a much larger device● ~100 km3 effective volume at GZK energies● ~100 strings on 1 km spacing grid● ~300 receivers per string (co-deployed with

radio)

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IRA






SPATS



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IRA

Hybrid “IRA” Detector As in HEP and Auger, using more than one detection

technique to view the same fiducial volume is highly advantageous● Detecting events in coincidence between 2-3 methods is

more convincing than detections with 1 method alone● Coincident events allow calibration/cross-checks one method

relative to the others● Hybrid reconstruction will give superior energy and direction

resolution than with one method, or at least will allow reconstruction of coincident events that cannot be reconstructed with one method alone

Good complementarity● Overlapping sensitivities in energies around 10-100PeV

At lower energies, optical device is better At higher energies, radio/acoustic are better

The resulting hybrid detector would have sensitivity to neutrinos over about 10 orders of magnitude in energy! Halzen & Hooper “IceCube Plus” JCAP 01 (2004) 002

April 2006


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IRA

Hybrid IceCube+Radio+Acoustic Simulations* have

been made of a hybrid detector consisting of● IceCube plus 13

“outrigger” strings (×)● 91 additional

radio/acoustic holes with 1 km spacing (o) 5 radio receivers 200-

600 m 300 acoustic receivers,

5-1500 m

2 acceptance, hadronic shower only (LPM stretches EM showers), Esh = 0.2E *See D. Besson et al., ICRC 2005

April 2006


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IRA

Hybrid IRA Simulation Result:

● Veff at E>1017 eV increased by a factor of 5-25 over IceCube alone (Veff > ~100km3)

● ~20 GZK events/year

Notes:● ESS flux,

Gandhi ’s, = 0.7

● For R, A, R+A all flavors NC and CC

● For O** only

I=IceCubeR=RadioA=Acoustic(GZK ’s/yr)

Veff (

km3)

Log10[E/eV]

April 2006


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IRA

Some Comments on UHE with IRA

High energy tau neutrinos are especially good candidates for coincident event capture; Veff increases by a lot● Double bangs

one bang in radio/acoustic array, one in optical array

● Lollipops detect tau lepton track in optical array, tau decay

cascade in radio/acoustic array

● Sugardaddies (see talk by T. DeYoung) detect tau lepton creation in radio/acoustic, tau decay to

muon in optical array

April 2006


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IRA






SPATS



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IRA

Conclusions-I We believe we can get to effective volumes large

enough to detect a large sample of GZK neutrinos at the South Pole using radio and/or acoustic techniques● If IceCube or ANITA see some events, IRA will see ~100 with

several years’ operation—start to do astronomy with them● Also, start to do particle physics—measure neutrino-nucleon

cross section at ~100 TeV CM to 30% (Ref.: Connolly, ARENA 2005)

The cost of drilling (shallower and narrower) holes and of the individual radio and acoustic elements is very reasonable (very roughly, ~$30k/hole for drilling, ~$50k for radio + acoustic sensors)

Operating optical, radio and/or acoustic detectors in coincidence will not only produce more convincing individual events, but also extend the reach and accuracy compared to any one detector alone

April 2006


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IRA

Conclusions-IIIceCube will be a vast improvement over AMANDA, but some things never change…

IceCube

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE Workshop 1 Beyond IceCube @...

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