In/On-ice Cosmic Ray radio detection -Some history RAND, RAMAND -Present efforts: ARIANNA, ARA

Transcription

1 In/On-ice Cosmic Ray radio detection -Some history RAND, RAMAND -Present efforts: ARIANNA, ARA -Comparison of the two experiments (based on publications and personal communications, with no attempt on my part to 'vet')

2 In the beginning... RAMAND: Follows 1983 proposal by Markov and Zheleznykh to instrument surface array at Vostok Aside: Vostok deeper (x1.4) than South Pole Colder than South Pole (surface temp~5o C colder) Firn layer 90 m vs. 150 m at South Pole Institute of Nuclear Research, Moscow (Zheleznykh and Provorov) Tests at station Vostok by Provorov, $1M rubles promised to continue research by CCCP on August 18,

3 Kravchenko et al, ARENA 2010 Proceedings Side Note: Hydra antennas same as used for Barwick et al 2004 measurement of Latten at South Pole

4 On the second day ( )... RAND (South Pole):

5 On the second day... The Smoot Group has performed two preliminary tests of the feasibility of using the Antarctic Ice for radio detection in trips to the South Pole in 1989 and The December January 1992 expedition, under the acronym A.R.C.N.O. (Antarctic Radio Cherenkov Neutrino Observatory), utilized three broad-band receivers singly and in coincidence on the surface. These tests indicated that there was no insurmountable background to the radio detection. However, a surface array is not optimal for radio detector, as the earth is fairly opaque to very ultra-high energies and total internal reflection in the top layer of ice both limit the available observation solid angle. angle.

6 RICE: 20-ch dipole array: (200m) parasitic* operation vis-a-vis AMANDA / IceCube... Limits on neutrino fluxes: as in bloodsucking... *

7 8 LPDA Rx 110 MHz+ All HPOL! Air showers?

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9 E/E=2.4 for reflected events / angular resolution in ~2.5o (simulation) (Flux convolved with detector response) (Earth absorption at high energies)

10 Latten~400 m

11 ARIANNA Hexagonal Array-2012 Funded by OPP, MEP, and MRI within NSF ($900K MRI funding as of Sept. 2011) 3 year development and deployment: 3 x 8-ch stations in 2012/ stations in 13/14 1 km Deployed Future Premium on LOW-Power w/ wireless comms ARIANNA Station 2012

12 2011/2012 Season Deployed 1 station with new DAQ technology Second generation ATWD, chip used by IceCube Pattern trigger to reduce thermal trigger rate (aside: in development for ARA by ALH+student) Deployed 1 km from first prototype station, commissioned in 2009 and still in operation

13 ATWD-based DAQ

14 Power Budget: Total~12 W/8-ch station: (accept hit in slightly higher threshold) Number Total Power Draw LNA's 8 1W Readout 8 3W Wireless comms W comms+gps+ heartbeat 1 3W Control+digitizer 1 4W Note: NO CPU: use on-board micro-controller only!

15 Power System Wind Gen 30W Solar Panels

16 2012 Station Operation: R~0.1 Hz Most recent 100 runs Automated file transfer and monitoring.

17 Sensitivity with 961-station (7000 channel) array (961-station array) ARA-37: ESS01: 50 evts/yr

18 ARA Australia (UNSW, Adelaide), Belgium (ULB), Germany (Wuppertal, Aachen, Bonn), Israel (Weizmann), Japan (Chiba), Taiwan (NTU), UK (UCL), US (Bartol, Hawaii, Maryland, OSU, Wisconsin, UNL, KU), France (Nancay/CODALEMA) ~$10 M USD ($3M already committed from non-us participants; $7M proposal approved for science (12Oct11; logistics impact review/co-funding with EPP panel: Feb 2012) Phase 1: km2 footprint Establish cosmogenic flux, observe first GZK neutrinos Phase 2: km2 footprint: statistical studies of neutrinos

19 ARA:, radioglaciology, air showers Now an umbrella effort, in addition to primary neutrino-detection experiment, comprises: The Experiment Formerly Known as RICE, now: ([affectionate] diminutive form:) RICE-ARA-ONI The Experiment Formerly Known as AURA, now: AUARA The Experiment Formerly Known as SATRA, now: SATRARA The Experiment We Hope Will Be Known As RASTA, now: RASTARA

20 Footprint (NB: local power=> >2km spacing!)

21 Station concept =4 vertical holes, 10 m apart laterally, 200 m deep Each can independently image a neutrino event in-ice 4 Rx (2 Hpol + 2 Vpol)/hole; 5-m vertical spacing resolution via 4 Gsa/s 2 GHz BW digitizer 4 Hpol surface antennas-independent trigger Prototype with testbed (2010-) NOT ideal: only meters deep; Only 2 Hpol surface antennas Only 4 in-ice Vpol have been fully calibrated & are useful for reconstruction Limited bandwidth and throughput DAQ Provide a lower limit for estimating individual station performance

22 Expected ARA-37 reconstruction Performance: Neutrino Astronomy

23 Testebed Deployed Antennas (Jan 2011); wire bicones and bicone slot-cylinders NOTE: Cable runs through center to preserve azimuthally symmetric response

24 Surface Antennas

25 Measured Noise floor=-174 dbm/hz+2 dbm/hz system (resistive losses in QSC)

26 Trigger Rates (-May 2011) Solar flare!

27 Sensitivity to RF emissions from solar flares (can be used to calibrate Rx Ampl/time)

28 Zoom on surface antennas (LP): calibrate response vis-a-vis galactic radio emissions Corrections: 70 db gain + 60 db (MHz)

29 Cross-check phase offset of galactic signal... Sidereal Variation as Surface Rx Rotate under Galactic center

30 ARA angular resolution~0.6 deg in

31 Zoom on Calibration pulser Azimuthal angular resolution

32 2) Cal pulser polar angular resolution Sub-degree angular resolution on a baseline of 15 m, in the firn 4 Rx only

33 Operating at ~4 kt

34 Practical consequences of clean environment Nearly all triggers are either: Calibration pulser triggers (1 Hz) Forced (unbiased) triggers (1 Hz) Triggers on thermal noise fluctuations (2-3 Hz) <1% of these reconstruct to a vertex with an acceptable 2 =>unlike RICE site, which must contend with large anthropogenic effects (+wind velocity correlations), remote ARA site is clean!

35 Observation of 3 km-distant pulser (in warm ice!)

36 Radioglaciology detailed map of ice RF properties: Latten OSU/UH analyses give comparable results Analyze signals from Buried Pulser: z=2450 m; r~2000 m Calculate <Latten> via: Prx=PTxGTxGRx 2 /4 r2 exp(-2r/latten); Unfold depth dependence via lab Latten(T(z)), using IceCube T(z)

37 Dec Data: broadcast over 500 m-1 km horizontal distances to probe full 3-d COF Meaning of incomprehensible table above: asymmetry in wavespeed response primarily In horizontal plane, rather than vertical vs. horizontal plane (as would be expected by lab measurements)

38 Prototyping remote power kwclass wind turbines deployed in January, Hummer didn't; Raum & Bergey still turning

39 ARA uncertainties -Ice Properties uncertainties TBD by experiment -Determination of transfer function in situ Z->Z/n needs to be verified -ARA science includes: *air shower detection (via RASTARA) + in-ice detection of impacting core, over (ultimately) 1000 km2 area, =>understanding RF transmission through surface important Also important for ANITA and modeling response of surface-reflected RF air shower signals!

40 Understanding surface roughness (js) -use ANITA data to comprehensively map surface roughness -briefly: calculate brightness of surfacereflected solar RF image relative to directly observed solar RF image; and compare (as function of frequency) with expectations for perfect surface reflector -Vpol/Hpol separately Hard part: solar reflection on surface does not directly track solar image!

41 ARA MC unc ertai nties

42 ARA uncertainties

43 ARA: campaign Deployed 16 Rx in-ice, signal over analog OF, 2 cal pulsers ~1 km Grid West of testbed Targeted z=200 m, drill problems=>80 m deployment +4 surface antennas (RASTARA) Dedicated trigger! Data transfer happening NOW Expect a neutrino flux limit later this year Testbed-yr ~ 1-2 RICE-yrs in neutrino detection TB: Lower threshold, but reduced visibility (firn) vis-a-vis RICE -ARA-2 likely to be the first true station ATRI-c trigger board + 4 Gsa/s IRS-3 digitizer 20 channels!

44 Mano-a-mano ARA ARIANNA locale SP MinnaBluff Trigger Rate 5 Hz 0.1 Hz Trigger threshold: 4 x 4 kt over 256 ns 4 x 4 kt over 60 ns Power Draw 100 W/20 Rx + 2 Tx 10 W/8 Rx + 1 Tx Frequency band 4 x MHz + 16 x MHz 8 x MHz Hpol/Vpol Yes/yes Yes/no Attenuation length 1500 m 500 m resolution 0.5o 2.5o Air shower response Yes, via RASTARA Not yet studies (AFAIK) Firn ray tracing Small (for 200 m deployment) Yes Tx calibration 1 Hz Once/run Uncertainties (Z) Hpol:VPol response in situ Antenna response nearsurface; ray-tracing to Rx Future funding $7M OPP proposal (under review) $1 M MRI (funded)

45 Asymmetries in the ice permittivity in RF Measure signal received using bistatic radar reflected off bedrock, as function of azimuthal Tx polarization t~50 ns/34000 ns travel time

46 Effect of internal layers on RF scattering? Taglines: a) synchronous at all azimuths to within 1 ns, to ns return time b) internal structure only visible over noise floor after averaging ~10K pulses

47 Aside: Amplitude variations correlate with ice flow!

48 Amplitude variation: internal layer reflections Aside aside: Use measured amplitudes of internal layers to estimate Latten dependence on depth 13.9μs 17.2μs 19.6 us 6μs 3348 m 1521 m 1514 m 9.6μs 1170 m 867 m 964 m 13.9μs 849 m 643 m