Energy Resolution & Calibration of the ANITA Detector

Transcription

1 Energy Resolution & Calibration of the ANITA Detector TeV Particle Astrophysics II August 2006 D. Goldstein, UC Irvine for the ANITA Collaboration

2 Why ANITA? ν ~1.1 M km2 Enormous detector volume Radio transparent ~Background free environment Trigger threshold limited by thermal noise. field of view

3 SLAC T486 SLAC joins the ANITA collaboration: Test beam experiment T486 Askaryan in ice. Proposal: Direct 28.5 GeV electron beam to large ice target in End Station A. Attempt to observe Askaryan pulses in ice for the first time. Record signals for calibration and full system tests of the ANITA instrument.

4 ANITA Collaboration University of Hawaii, Manoa P. Gorham, J. Kowalski, J. Learned, C. Miki, P. Miocinovic, A. Romero Wolfe, M. Rosen, G. Varner University of California, Irvine S. Barwick, K. Dookayka, D. Goldstein, J. Nam, A. Silvestri, A. Simons, F. Wu University of California, Los Angeles A. Connolly, A. Goodhue, S. Hoover, D. Saltzberg The Ohio State University J. Beatty, B. Mercurio, R. Nichol, K. Palladino Washington University in St. Louis B. Binns, P. Dowkontt, M. Israel Jet Propulsion Laboratory K. Liewer, C. Naudet University of Minnesota M. Duvernois, B. Lusczek University of Kansas D. Besson Bartol Research Institute, University of Delaware J. Clem, S. Hussain, D. Seckel Stanford Linear Accelerator Center P. Chen, K. Reil

5 SLAC T486: Ice Target Construction ~ 10 Tons high quality carving ice Volume ~ 5m x 2m x 1.5m Top surface slope (~6 deg.) chipped by hand... Surface temp. held at ~5 degrees F

6 SLAC T486: Setup in End Station A (not to scale) (~40 db Att., ran w/o amps) crane near field antennas shielding block beam pipe target dipole RF ~45 feet shower (~ GeV) ~22 ft.

7 SLAC T486: Setup in End Station A

8 SLAC T486: Askaryan Pulses in Ice! ~10 ns First pulses observed 6/19/06! (see 29.htm for video of visible Cerenkov light from ice target) Signal power vs. shower energy consistent with coherent emission.

9 ANITA Hang Test LDB Milestone New PV cells a success (21+% efficient) Array developed ~ Watts Total payload weight OK (~ 3,970 lbs.) LOS communications functional NO TRIP TO PALESTINE, TX REQUIRED

10 Calibration Pulser data runs taken during each access period. Analysis of beam data in progress... more complicated due to accelerator instability (100+ degree temps during much of T486 scheduled beam time). Calibration goals: Characterize timing, amplitude, phase, polarization & spectral response of antenna array.

11 Monte Carlo Studies of Energy Resolution ANITA designed for discovery of UHE 's Event by event approach Tune & verify at specific energies Apply to GZK input spectrum (ESS param.) ongoing work...

12 Monte Carlo Studies of Energy Resolution Initial E, p 5 3, Antenna voltages in horizontal & vertical channels give magnitude of electric field and polarization vector.

13 Monte Carlo Studies of Energy Resolution Payload > ice distance 5 3,4 6 Timing > azimuthal & elevation angles. Ice intercept position calculated using Bedmap surface model, geoid Earth shape. Arrival times & payload position smeared. 2 1

14 Monte Carlo Studies of Energy Resolution Fresnel effects 5 3,4 6 Angle of incidence & pol. vector give Fresnel coefficents. Two Fresnel zones (air firn) and (firn ice) interfaces. 2 1

15 Monte Carlo Studies of Energy Resolution Ice attenuation 5 2 3,4 1 6 Attenuation length calculations based on measurements made near the south pole. In MC: Calculate avg. attenuation length for specific path, E > E*exp( D/<L>) For reconstruction, D is unknown: choose mean interaction depth as guess Mean Interaction Depth vs. Energy Depth [m] E+019 GZK 3.16E E E+020 Neutrino Energy [ev] 1.00E E+021

16 Monte Carlo Studies of Energy Resolution Conversion to shower & neutrino energies 5 3, Irreducible uncertainties: y (inelasticity), angle of observed RF relative to nominal axis of Cerenkov cone Estimate neutrino energy using parameterization from: J. Alvarez Muñiz, R.A. Vázquez, E. Zas Phys.Rev. D62 (2000) astro ph/ put in tex point version of formula here Mean factor for y, off axis, etc Column

17 Monte Carlo Studies of Energy Resolution (Etrue Erec) Etrue

18 Monte Carlo Studies of Energy Resolution weighted distribution many events > 0.6 many events < 10 5

19 Monte Carlo Studies of Energy Resolution Scale is linear! Resolution dominated by physics (y, off axis) Monte Carlo continuously being improved...

20 Austral Summer 2006: ANITA payload currently en route to Antarctica. Launch from McMurdo Station, December Two circuits approved by NASA ==> ~30 day flight Third circuit possible, weather permitting! Payload recovery in early 2007?

21 Extra slides Askaryan Pulses in Sand SLAC T444 (2000): 3.6 tons silica sand Bremsstrahlung photons

22 Extra slides Askaryan Pulses in Sand Paving the way for ANITA... 2 GHz data Reflection from side wall In proper plane 100% polarized Simulated shower curve (EGS) 8 orders of mag. dynamic range! Sub ns pulse, Ep p ~200 V/m!

23 Extra slides Detector volume a challenge! Why ANITA? Radio dominates above ~10 PeV

24 Calibration Extra slides Results from ANITA Lite prototype payload (18 day flight in December 2003) Detected signals from ground based pulser system Timing resolution ~160 ps ~2.3 deg. 2 antennas (22.5 deg. separation) Electronics For ANITA: expect T ~120 ps ~1.5 deg., ~0.5 deg.

25 Extra slides Pointing Resolution deg. and ~0.5 deg. constrains RF arrival direction ~1.5 Direction of incident constrained to ~2 deg. in elevation by earth absorption, and ~6 deg. in azimuth by polarization angle ~2o ~6o