1. Next Generation neutrino detector in the South Pole Hagar Landsman, University of Wisconsin, Madison Askaryan Under-Ice Radio Array

2. Outline Askaryan Effect and neutrino detection Why Ice? Why Radio? Radio detection Experiment Design and prospective A skaryan U nder ice R adio A rray

3. Tribute to ATLAS@LHC.CERN 45 m 25 m Ice Cube ~ 1km The Future: Hybrid Detector ~10 km

4. Quest for UHE neutrinos GZK Cut-off p+  CMB –No cosmic rays from proton above 10 20 eV –As a by-product – neutrino flux –A non detection will be even more exciting Point Sources of neutrinos Dark matter

5. Why so big? To detect 10 GZK events/year, a detection volume of 100 km 3 ice is needed. A larger detector requires a more efficient and less costly technology. Alternative options include radio and acoustic detection.

6. Neutrino interact in ice  showers Charge asymmetry: 20%-30% more electrons than positrons. Moliere Radius in Ice ~ 10 cm: This is a characteristic transverse dimension of EM showers. <<R Moliere (optical), random phases  P  N >>R Moliere (RF), coherent  P  N 2 Hadronic (initiated by all flavors) EM (initiated by an electron, from e ) Askaryan effect Vast majority of shower particles are in the low E regime dominates by EM interaction with matter Less Positrons: Positron in shower annihilate with electrons in matter e + +e -   Positron in shower Bhabha scattered on electrons in matter e + e -  e + e - More electrons: Gammas in shower Compton scattered on electron in matter e - +   e - +   Many e -,e +,   Interact with matter  Excess of electrons  Cherenkov radiation  Coherent for wavelength larger than shower dimensions

7. As the energy increases, the multiplicity of the shower increases and the charge asymmetry increases.  As the energy increases, mean free path of electrons is larger then atomic spacing (~1 PeV) (LPM effect).  Cross section for pair production and bremsstrahlung decreases  longer, lower multiplicity showers The Neutrino Energy threshold for LPM is different for Hadronic and for EM showers  Large multiplicity of hadronic showers. Showers from EeV hadrons have high multiplicity ~50-100 particles.  Photons from short lived hadrons  Very few E>100 EeV neutrinos that initiate Hadronic showers will have LPM LPM effect Landau- Pomeranchuk- Migdal  In high energy, Hadronic showers dominate  Some flavor identification ability

8. Measurements of the Askaryan effect Typical pulse profile Strong <1ns pulse 200 V/m Simulated curve normalized to experimental results Expected shower profiled verified Expected polarization verified (100% linear) Coherence verified. New Results, for ANITA calibration – in Ice Salt Ice D.Salzberg, P. Gorham et al. Were preformed at SLAC (Saltzberg, Gorham et al. 2000-2006) on variety of mediums (sand, salt, ice) 3 Gev photons are dumped into target and produce EM showers. Array of antennas surrounding the target Measures the RF output Results: RF pulses were correlated with presence of shower

9. Why Ice? Why Radio? -Long attenuation - Radio ~1km -Optical attenuation in ice 100m -No scattering for Radio In ice. -A lot of it. -Free to use. -South pole is isolated. RF quiet. -Antennas are cheaper and more robust than PMTs. -No need to drill wide holes lower drilling cost of deployment w.r.t optical detectors 10 16 - ~10 23 eV optical Radio Acoustic Ice, no bubbles (1.5-2.5 km) Ice, bubbles (0.9 km) Water (Baikal 1km) Effective Volume per Module (Km 3 ) Energy (eV) 10 12 10 13 10 14 10 15 10 16 Astro-ph/9510119 P.B.Price 1995 10 17 Effective volume per detector element for e induced cascades

10. IceCube Pressure vessel Connectors Mainboard DAQ Cables Holes ANITA LABRADOR chip: low power consumption low deadtime large bandwidth cold rated RICE Antennas Data analysis Electronics and control KU University of Maryland University of Delaware University of Hawaii Kansas University University of Wisconsin - Madison Penn State University

11. Deployment in the coming season surface junction box Counting house Each unit is composed of : − 1 Digital Radio Module (DRM) – Electronics − 4 Antennas − 1 calibration units Signal conditioning and amplification happen at the front end, signal is digitized and triggers formed in DRM Co-Deployment on spare breakouts on IceCube cables (top/bottom) or on a special breakout Depth possibilities: −Top (1450 m) : Colder Ice, less volume −Bottom (2450 m) : Warmer Ice, more volume −Dust layer : less efficient spot for ~400nm RF attenuation is longer at colder ice Not to scale!

12. Deployment in the coming season Planning to deploy 4 units. with IceCube. Start mid December 2006 3 rd hole (1400m) 8 th hole (1400m) 9 th hole (250m) 10 th hole(1400m) 11 th hole(250m) spare IceCube Holes Map for 2006-2007

13. To antenna To antenna To antenna To surface To Calibration unit To antenna Shielding separates noisy components 6 Penetrators : 4 Antennas 1 Surface cable 1 Calibration unit TRACR Board Trigger Reduction and Comm for Radio Data processing, reduction, interface to MB ROBUST Board ReadOut Board UHF Sampling and Triggering Digitizer card SHORT Boards Surf High Occupancy RF Trigger Trigger banding MB (Mainboard) Communication, timing, connection to IC DAQ infrastructure, Digital Radio Module (DRM) Digital Optical Module (DOM)

14. Multiple bandwidth trigger 16 combinations of triggers: −4 antennas −4 bandwidth on each antenna −Trigger condition will be tuned to maximize data rates within the cable bandwidth. −Remove a noisy frequency

15. TRACR DOM-MB Metal Plate Antennas DRM electronics ROBUST Dipole Antennas IceCube DOM 17 cm

16. Time Calibration QA Monitoring Control Time order Event Trigger Analysis Sat. Data 3.5 Kbytes 25 Hz 3.5 Kbytes 25 Hz 3.5 Kbytes 25 Hz DRM HUB time Data Decrease rates to fit data storage/satellite volume L3 - Data quality on surface (HUB) L4 - Send over satellite? Save to tapes? Decrease rates to fit surface cable: L0 - Single frequency band trigger (SHORT, ROBUST) L1 – Multiple bands and multiple antennas (ROBUST) L2 – Higher level analysis filter-FFT (TRACR) DRM Offline processor DAQ layout

17. Our Mission: Build intermediate detector with improved effective volume over RICE, using IceCube infrastructure Experiment new Antenna and electronic design Further map the south pole ice radio properties Check interference between IceCube and AURA Adapt form factors for narrower holes drilled exclusively for radio. Correlate events with RICE On the way to a super-duper-hybrid GZK neutrino detector

18. Picture by Mark Krasberg

19. Backup Slides

20. Askaryan Signal Cherenkov angle=55.8 o Electric Field angular distributionElectric Field frequency spectrum Astro-ph/9901278 Alvarez-Muniz, Vazquez, Zas 1999

21. Askaryan Signal Cherenkov angle=55.8 o Electric Field angular distributionElectric Field frequency spectrum Astro-ph/9901278 Alvarez-Muniz, Vazquez, Zas 1999

23. Excpected Signal surface generated event as measured by RICE detectors at different depths

27. a larger, more technologically sophisticated array is needed for a neutrino observation… current hardware too expensive to scale up made surveys of rf properties of the ice at the South Pole set most stringent limits on the neutrino flux from 10^16 to 10^18 eV set limits on low scale gravity, magnetic monopoles and other exotica Note: RICE uses a 95% C.L. upper limit See latest results astro-ph/0601148 19 channels in depths 100m - 300m

29. 2 GHz Measurements of the Askaryan effect Typical pulse profile Strong <1ns pulse

30. Measurements of the Askaryan effect SLAC T444 (2000) in sand Sand Filed strength measure by…. E= prop to shower E 