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

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

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.

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

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

shower (~10 9 e 28.5 GeV) SLAC T486: Setup in End Station A shielding block beam pipe high freq. antennas RF dipole ~45 feet target (not to scale) ~22 ft. crane (~40 dB Att., ran w/o amps)

SLAC T486: Setup in End Station A

SLAC T486: Askaryan Pulses in Ice! ➢ First pulses observed 6/19/06 ! ~10 ns Signal power vs. shower energy consistent with coherent emission. (see for videohttp://today.slac.stanford.edu/a/2006/06-29.htm of visible Cerenkov light from ice target)

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

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.

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 ongoing work... (ESS param.)

Monte Carlo Studies of Energy Resolution 1 2 3,4 5 6 ● Antenna voltages in horizontal & vertical channels give magnitude of electric field and polarization vector. Initial |E|, p

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

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

Monte Carlo Studies of Energy Resolution 1 2 3,4 5 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/ ) ● For reconstruction, D is unknown: choose mean interaction depth as guess GZK Ice attenuation

Monte Carlo Studies of Energy Resolution 1 2 3,4 5 6 J. Alvarez-Muñiz, R.A. Vázquez, E. Zas Phys.Rev. D62 (2000) astro-ph/ Estimate neutrino energy using parameterization from: Conversion to shower & neutrino energies Irreducible uncertainties: y (inelasticity), angle of observed RF relative to nominal axis of Cerenkov cone put in tex-point version of formula here

Monte Carlo Studies of Energy Resolution (E true -E rec) E true

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

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

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

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

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

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

Calibration ➢ For ANITA: expect ~120 ps ~1.5 deg., ~0.5 deg. 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 Extra slides

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