Next Generation neutrino detector in the South Pole

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

Outline Askaryan Effect and neutrino detection Under ice Why Ice? Why Radio? Radio detection Array Experiment Design and prospective

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

Quest for UHE neutrinos • GZK Cut-off p+g. CMB – No cosmic rays from proton above 1020 e. V – As a by-product – neutrino flux – A non detection will be even more exciting • Point Sources of neutrinos • Dark matter

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.

Askaryan effect Neutrino interact in ice showers Many e-, e+, g Interact with matter Excess of electrons Cherenkov radiation Coherent for wavelength larger than shower dimensions Moliere Radius in Ice ~ 10 cm: This is a characteristic transverse dimension of EM showers. <>RMoliere (RF), coherent P N 2 Hadronic (initiated by all n flavors) EM (initiated by an electron, from ne) 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- gg 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- + g e- +g Charge asymmetry: 20%-30% more electrons than positrons.

LPM effect Landau-Pomeranchuk-Migdal 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 Pe. V) (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 Ee. V hadrons have high multiplicity ~50 -100 particles. Photons from short lived hadrons Very few E>100 Ee. V neutrinos that initiate Hadronic showers will have LPM Ø In high energy, Hadronic showers dominate Ø Some flavor identification ability

Measurements of the Askaryan effect • 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 ü RF pulses were correlated with presence of shower Salt Ice ü Expected shower profiled verified ü Expected polarization verified (100% linear) ü Coherence verified. üNew Results, for ANITA calibration – in Ice Typical pulse profile Strong <1 ns pulse 200 V/m Simulated curve normalized to experimental results D. Salzberg, P. Gorham et al. Results:

Optical attenuation in ice 100 m 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 1016 - ~1023 e. V . 5 -2 5 k . (1 s le bb no e, Ic bu r e at ) km 1 al optic ik Ba ( W (0. 9 bbles al c - Ac ou sti - Long attenuation - Radio ~1 km dio a ) m R km) u Ice, b 1012 1013 1014 1015 1016 Energy (e. V) Effective volume per detector element for ne induced cascades Astro-ph/9510119 P. B. Price 1995 - Effective Volume per Module (Km 3) Why Ice? Why Radio? 1017

Ice. Cube ANITA • Pressure vessel • Connectors • Mainboard • DAQ • Cables • Holes 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 Penn State University of Wisconsin - Madison

surface junction box Counting house Deployment in the coming season 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 Ice. Cube 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 ~400 nm Not to scale! RF attenuation is longer at colder ice

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

Radio Module (DRM) Digital Optical Module (DOM) 6 Penetrators: To ce rfa su To antenna an To ten na 4 Antennas 1 Surface cable 1 Calibration unit TRACR Board Trigger Reduction and Comm for Radio Data processing, reduction, interface to MB MB (Mainboard) Communication, timing, connection to IC DAQ infrastructure, Shielding separates noisy components ROBUST Board Cal To ibr a un tion it To antenna a To na n nte Read. Out Board UHF Sampling and Triggering Digitizer card SHORT Boards Surf High Occupancy RF Trigger banding

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

Dipole Antennas 17 cm Antennas Ice. Cube DOM ROBUST TRACR DOM-MB Metal Plate DRM electronics Ice. Cube DOM

DAQ layout DRM DRM Decrease rates to fit surface cable: L 0 - Single frequency band trigger (SHORT, ROBUST) L 1 – Multiple bands and multiple antennas (ROBUST) L 2 – Higher level analysis filter-FFT (TRACR) Decrease rates to fit data storage/satellite volume L 3 - Data quality on surface (HUB) L 4 - Send over satellite? Save to tapes? e tim 3. 5 Kbytes 25 Hz HUB 3. 5 Kbytes 25 Hz Time Calibration QA Monitoring Control Time order Sat. Da ta Offline processor ta Da Event Trigger Analysis

Our Mission: • Build intermediate detector with improved effective volume over RICE, using Ice. Cube infrastructure • Experiment new Antenna and electronic design • Further map the south pole ice radio properties • Check interference between Ice. Cube 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

Picture by Mark Krasberg

Backup Slides

Askaryan Signal Electric Field angular distribution Astro-ph/9901278 Alvarez-Muniz, Vazquez, Zas 1999 Cherenkov angle=55. 8 o Electric Field frequency spectrum

Askaryan Signal Electric Field angular distribution Astro-ph/9901278 Alvarez-Muniz, Vazquez, Zas 1999 Cherenkov angle=55. 8 o Electric Field frequency spectrum

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

• 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 e. V • set limits on low scale gravity, magnetic monopoles and other exotica Note: RICE uses a 95% C. L. upper limit a larger, more technologically sophisticated array is needed for a neutrino observation… current hardware too expensive to scale up See latest results astro-ph/0601148 19 channels in depths 100 m - 300 m

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

Measurements of the Askaryan effect SLAC T 444 (2000) in sand Sand Filed strength measure by…. E= prop to shower E