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The ANITA Experiment: Searching for UHE Neutrinos above the Antarctic Ice Shield

The ANITA experiment aims to detect ultra-high energy neutrinos (UHE ν) above the Antarctic ice shield. Neutrinos provide new information about cosmic rays and can probe the weak force at extreme energies. The experiment utilizes the Askaryan effect in ice to detect radio pulses emitted by UHE neutrino-induced showers. ANITA has undergone several flights and continues to collect data for analysis.

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The ANITA Experiment: Searching for UHE Neutrinos above the Antarctic Ice Shield

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  1. Search for UHE neutrinos high above the Antarctic Ice Shield – The ANITA experiment. Konstantin BelovUCLAUHECR, May 22, INR, Moscow 2008

  2. Why UHE ν’s ? γ attenuation length (MPc) G. Sigl 50 MPc 1 GPc ν Earth p Not to scale • Uncharged and not affected by a magnetic field • Do not attenuate • Do not decay • Point back to their sources even in early Universe • Can bring new information about UHE Cosmic Rays • No other way to probe weak force at EeV Sources of UHE ν • Exotic top-down models:Z-burstsTopological DefectsRelic ν’slarge fraction of the byproducts are UHE ν’s • GZK neutrinos K. Belov UHECR-08

  3. K. Belov UHECR-08 GZK Break is at (5.6 ± 0.5) x 1019 eV; GZK expected at 6 x 1019 eV. The break is the GZK cutoff.

  4. σνand ν flux TD GZK Fe GZK p • GZK p : Engel, Seckel, Stanev, PRD 64,093010 • GZK Fe: Ave, Busca, Olinto, Watson,Yamamoto, Astropart. Phys., 23, 19 • TD: Yoshida, Dai Jui, Sommers, Ap. J. 479, 547 σν estimates, courtesy F. Halzen and M. Block K. Belov UHECR-08

  5. K. Belov UHECR-08 Detector volume

  6. Askaryan Effect • UHE primary particle will induce e-m shower in media Askaryan – 10% excess charge MC – 20% excess charge Gurgen Askaryan (1928-1997) K. Belov UHECR-08

  7. K. Belov UHECR-08 Radio Pulse Spectrum Frank-Tamm power spectrum:

  8. K. Belov UHECR-08 SLAC experiment 2006 P. Gorham et. al., “Observations of the Askaryan Effect in Ice”, Phys. Rev. Lett. 99, 171101 (2007).

  9. Ice as the Detector Media Ice at the South Pole • Optical attenuation in ice is ~ 100 m, while radio attenuation ~ 1 km! • UHE neutrinos initiate showers with > 108 electrons within RMoliere ~ 10 cm • A radio pulse is emitted with frequency upto 1 GHz • 1 ns pulse => bandwidth ~ 1 GHz (from uncertainty principle ΔωΔt > ½ ) • Linearly polarized K. Belov UHECR-08

  10. Where to find the ice? • Antarctica has about 25 x 106 km3 of pure ice • There is NASA long duration balloon program • Flying at ~ 37 km altitude can observe ~ 3 x 106 km3 of ice. K. Belov UHECR-08

  11. K. Belov UHECR-08 ANITA-Antarctic Impulsive Transient Antenna ANITA concept

  12. K. Belov UHECR-08 ANITA collaboration University of California, Irvine Irvine, California Ohio State University Columbus, Ohio University of Kansas Lawrence, Kansas Washington University in St. Louis St. Louis, Kansas University of Delaware Newark, Delaware University of California, Los Angeles Los Angeles, California University of Hawaii at Manoa Honolulu, Hawaii National Taiwan University Taipei, Taiwan University College London London, England Jet Propulsion Laboratory Pasadena, California Stanford Linear Accelerator Center Menlo Park, CA

  13. K. Belov UHECR-08 ANITA timeline Dec 03 - Jan 04: ANITA-lite flight June 2006: ANITA-I beamtest (SLAC) Dec 06 - Jan 07: ANITA-I flight • Winter - Spring 2008: Instrument upgrades rebuild gondola • Spring 2008: Vacuum testing, EMI testing June - July 2008: Integration and hang test at CSBF facility in Palestine, TX November 2008: Final integration in Antarctica December 2008: ANITA-II launch

  14. K. Belov UHECR-08 Real Face of ANITA is quad-horn!

  15. K. Belov UHECR-08 Pumping in

  16. K. Belov UHECR-08 Ready for the launch.

  17. K. Belov UHECR-08 Over the south pole. Picture by James Roth

  18. Flight 2006-2007 • Launched 15 December 2006 from McMurdo • “Landed” January 19, 2007 • Fully recovered – thanks to NSF and CSBF Plot by K. Palladino K. Belov UHECR-08

  19. K. Belov UHECR-08 Perfect landing! Picture by Dana Braun

  20. Extreme working conditions! K. Belov UHECR-08

  21. K. Belov UHECR-08 ANITA-I • 32 quad-horn antennas sensitive to V and H polarization • L1 trigger:- 4 frequency bands in both LCP and RCP for trigger- 3/8 channels to form L1 trigger • L2 trigger 2/3 adjacent antennas • Upper and lower ring to form L3 trigger

  22. K. Belov UHECR-08 Calibration V peak-to-peak of signals at the payload Dotted black: 1/r fit Red: 1/r * Fresnel fit Courtesy Stephen Hoover • Calibration signals • Surface & Borehole • McMurdo & Field camp • Signals used for • Calibration • Instrument health • Tests of analysis methods By Christian Miki

  23. K. Belov UHECR-08 ANITA data analysis in progress V-pol • We are looking for a short broadband pulse of non-anthropogenic origin • Check the for the pulse origin on the ice surface • Is there a CW ? • Polarization? H-pol

  24. K. Belov UHECR-08 Direction errors

  25. K. Belov UHECR-08 260 MHz source S.Hoover

  26. K. Belov UHECR-08 Radio image Summed cross-correlations, vertical polarization Summed cross-correlations, horizontal polarization S.Hoover

  27. K. Belov UHECR-08 260 MHz waveform Ev# 1330900Coherently Summed Waveform, v-pol, az 167.7 degrees, el -1.18:Pick a direction. Add the waveforms of the nearest 10 antennas, shifting each waveform for the relative time delay for signals from that direction. S.Hoover

  28. K. Belov UHECR-08 ANITA-II • Change L1 trigger – only trigger on V-pol signal, 3 narrow-band channels + 1 full band channel, 3 out of 4 channels to trigger • Move the first stage preamps to the antenna (-20K) • New preamps (-20K) • New front end filters (-20K) • Faster CPU • New GPS Trigger module New preamp. New front end filter

  29. ANITA-II – more antennas • 8 new drop down antennas (better sensitivity, better angular resolution in elevation) Drawing by M. Rosen K. Belov UHECR-08

  30. K. Belov UHECR-08 Better flight path ANITA-I flight path (from K. Palladino) Typical Long Duration Balloon paths

  31. K. Belov UHECR-08 EMI test To test e-m compatibility of ANITA with SIP – NASA flight control equipment.

  32. EMI test • Parasitic signals are generated by local TV stations and the SIP equipment K. Belov UHECR-08

  33. K. Belov UHECR-08 Current Limits and ANITA II RICE ANITA-lite AMANDA GLUE ANITA TD FORTE Z-burst GZK Fe GZK p GZK Neutrinos: Theoretical fluxes & Current Limits (Dotted grey line is a projected limit for ANITA with 45 days of livetime)

  34. Conclusion • ANITA II flight is approved • EMI test conducted at University of Hawaii in May • Hang test at CSBF facility at Palestine, TX starting June • Launch is scheduled for December 2008 from McMurdo

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