RICE = “Radio Ice Cherenkov Experiment”

• The Problem:– Mean free path of UHECR’s (E>1020 eV) limited by photoproduction on CMB:

pCMBp(“GZK”)

– m.f.p. ~ 10 Mpc only sensitive to processes in last 30Myr!

– At lower energies (1017-18 eV), reactions such as pCMBpe+e-

– Similar limitations for gamma-ray astronomy (pair production on CMB)

• A solution (kinda): neutrino astronomy!– However, low fluxes at ZeV (1/km2/century) necessitate neutrino targets of

scale 100-1000 km3

• “Conventional” technology: PMT’s (AMANDA, Baikal, Antares, IceCube, Nestor, NEMO, SuperK) limited by absorption/scattering length of PMT photons (~40 m)

• Radio attenuation length in-ice2 km (DATA!); acoustic attenuation length estimated at 10 km!! (SPATS measurements this year)

measure radio-wavelength rather than optical-wavelength portion of Cherenkov radiation: “Radio Ice Cerenkov Experiment”

Radio Detection of High Energy Neutrinos

Neutrino collision

Receivers (Rx)

Cones are +/- 3dB

Neutrino enters ice

RICE-AMANDA-SPASE (South Pole)

RICERICE

SPASE

17 in-ice half-wave ‘fat’ dipole antennas (400 MHz)

Effective Volume Systematics:

Signal Strength

Transfer Function

Re(epsilon) (=n)

Im(epsilon) (=Latt)

Birefringence

System Total Gain

Livetime

Software Cuts

Diffuse Neutrino Search (1999-2005)

Phys.Rev. D73 (2006) 082002

No UHE neutrinos yet observed compare

with theoretical predictions for how

many neutrinos RICE should have observed,

given sensitivity of experiment and radio

transmission properties of ice

GZK nu models

Diffuse GRB flux

Two representative models: ESS/WB. Both bootstrap from observed charged CR spectrum and estimate neutrino flux (WB assumes all UHECR’s from GRB’s)

Caution on presentation

• RICE uses a 95% CL upper limit convention– (vs. conventional 90% CL upper limit convention)

• ESS GZK-flux depends on several parameters– RICE upper limits based on most conservative (I.e., lowest flux –

not typical)

• Upper limits as a function of energy are largely for presentation only – sans energy resolution, only integral matters!

Volumosity? Voluminosity? Your model x our exposure

During RICE livetime, approximately 120 GRB’s in southern hemisphere w/ `nearly’ complete info. Only 5 with redshift information:

Astro-ph/0605480 (accepted Astropart. Phys.)

RICE acceptance favors neutrinos incident along horizon at near-glancing angles

From photon flux to neutrino flux

• Assume photon flux from decay; relate photon flux to neutrino flux (from + decay) via Waxman-Bahcall.

Note: Limits generally weak (preferentially high-redshift sample)

The future VISION

• South Polar ice is unique!– Optical clarityIceCube (TeV threshold)

– Radio clarityRICE (10 PeV threshold)

– Purest water on planet & high hydrostatic pressureno impurities or defects in ice latticeclear propagation of acoustic wavesacoustic detection of sound wave produced by neutrino interactions! (EeV threshold)

• South Pole is only place that can support all three neutrino detection technologies

• 2006-2010: During bulk of IceCube hole drilling, co-deploy radio & acoustic modules into IceCube holes– 1 km deployment scale x10 over current RICE

• >2010: Dedicated hole-drilling (much cheaper holes!) for acoustic&radio over 10 km deployment scale

GZK detections / hybrid dector (c. 2010)

KU

The Askaryan UnderIce Radio Array = THE BRIGHT, SHINING FUTURE!

•Develop technology for larger radio array

•Further map out the radio properties of South Pole Ice

•Build intermediate detector with improved effective volume over RICE

06-07: codeploy with IceCube in 3-4 holes.

•spare attachment points on IceCube cable (1450m, 2450m, center of the string, an additional breakout could be added a 1400m for minimal cost) could accommodate a “DRM”

•additional connectors added to pressure sphere would connect each of four antennas to form a cluster

•grouping antennas in clusters at 10m separation, gives enough timing difference to distinguish backgrounds, thereby allowing a drop in thresholds

•antenna calibration unit provided calibration and ice property studies

•signal conditioning and amplification happen at the front end, signal is digitized and triggers formed in DRM

Separate cable taped to IceCube cable would allow deployment at shallow depths where rf tranparency is highest

Same paradigm as 05-06 deployment--shown to work

Search for highly ionizing magnetic monopoles in Antarctic ice (Daniel Hogan, KU UG)

• Relativistic magnetic monopole generates photon swarm.

• Weizsäcker-Williams energy spectrum:

Jackson, 1963, etc.

Energy Loss in Earth: ionization+brem+pair production+ photonuclear

Razzaque et al., 2002

3/1

242 183ln

137

4

ZA

rzZNE

dx

dE eo

rad

1

2ln4

22222

I

mvzmcr

A

ZN

dx

dEeo

ion

Check total energy loss against mmc package (dima chirkin) and also seckel, weiler&wick calculation

Energy Loss in Earth

• Chord Length through Earth:

• Loses energy as z=1/(2α) electric charge

sin

2sin rl

r

θ

lr

Preliminary monopole flux limits (+/- x2)