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Radio detection of high energy Radio detection of high energy particles in dense media, & particles in dense media, & ANITAANITA

Peter GorhamUniversity of Hawaii Manoa Department of Physics & Astronomy

Co-Is: S. Barwick, UCI; J. Beatty, OSU, W. Binns, M. Israel, Wash. U. St. Louis, M. DuVernois, U. Minn., K. Liewer & C. Naudet, JPL/NASA; D. Saltzberg, UCLA, G. Varner, UH Manoa

P. Gorham, Granlibakken 2007

Science roots: the 60’s…+Science roots: the 60’s…+++

1962: G. Askaryan predicts coherent radio Cherenkov from particle showers in solid dielectrics– His applications? Ultra-high energy cosmic rays

& neutrinos

– Mid-60’s: Jelley & collaborators see radio impulses from high energy cosmic ray air showers – -- from geo-sychrotron emission, not radio

Cherenkov, false alarm!

– 1970-2000: Askaryan’s hypothesis remained unconfirmed

– 2000-2001: Argonne & SLAC beamtests confirm strong radio Cherenkov from showers in silica sand

– 2004-2006, salt & ice also tested, all confirmed

Saltzberg, et al PRL 2001

Goprham, et al PRD 2004

P. Gorham, Granlibakken 2007 3 of 21

Measurements for Cosmic rays Measurements for Cosmic rays predict predict NeutrinosNeutrinos

Neither origin nor acceleration mechanism known for cosmic rays above 1019 eV, after 40 years!A paradox:

No nearby sources observed distant sources excluded

due to collisions with microwave bkg

Neutrinos at 1017-19 eV required by standard-model physics

Lack of neutrinos: UHECRs not hadrons?! Lorentz invariance

wrong?! New physics?

galactic

Extra-galactic

“GZK cutoff ” process

p, + pions, e+e- GZK neutrinos

P. Gorham, Granlibakken 2007 4 of 21

Neutrinos: The only long-range messengers Neutrinos: The only long-range messengers

at ultra-high energiesat ultra-high energiesPhotons lost above 30 TeV: pair production on IR & 3K wave background

Charged particles: scattered by B-fields or 3K bkg photons at all energies

But we know there are sources up to at least 1020

eV

Ergo: Study of the highest energy processes and particles throughout the universe requires ultra-high energy neutrino detectors

Region not observableIn photons orCharged particles

P. Gorham, Granlibakken 2007 5 of 21

How to detect UHE neutrinos? How to detect UHE neutrinos?

Ice RF clarity:1.2 km(!) attenuationlength

Effective “telescope” aperture: • ~250 km3 sr @ 1018.5 eV• ~104 @ km3 sr 1019 eV

(Area of Antarctica ~ area of Moon)

~4km deep ice!

Typical balloonfield of regard

P. Gorham, Granlibakken 2007 6 of 21

ANITAGondola &

Payload

Antenna array

Overall height ~8m

Solarpanels

Antarctic Impulsive Transient Antenna--Antarctic Impulsive Transient Antenna--ANITAANITA

NASA start in 2003, first LDB launch in ‘06-07, 10 day baseline mission

Ultra-broadband antenna array, views large portion of ice sheet looking for Askaryan impulses

Instantaneous balloon field of view

~320ps

Measured impulse response

Quad-ridged-horn dual-pol antenna

(lower panels removed here)

DAQ & flight computer

P. Gorham, Granlibakken 2007 7 of 21

ANITA as a neutrino telescopeANITA as a neutrino telescope

ANITA sees a band of sky just below the “visible” horizonThe band is different for different longitudes of the balloon

Pulse-phase interferometer (150ps timing) gives intrinsic resolution of <0.5o elevation by ~1o azimuth for arrival direction of radio pulse

Neutrino direction constrained to ~<2o in elevation by earth absorption, and by ~3-5o in azimuth by polarization angle

P. Gorham, Granlibakken 2007 8 of 21

ANITA-lite Prototype flight 2004ANITA-lite Prototype flight 2004

Piggyback Mission of Opportunity on the 03-04 TIGER* flight, completed mid-January 04

ANITA prototypes & off-the-shelf hardware used 2 dual-pol. ANITA antennas w/ low-noise

amps 4 channels at 1 GHz RF bandwidth, 2 GHz

sampling

18.4 days flight time, set the best current limits on UHE neutrino fluxesPaved the way for a full-scale ANITA payload

*Trans-Iron Galactic Element Recorder

P. Gorham, Granlibakken 2007 9 of 21

June 2006, SLAC T486: “Little June 2006, SLAC T486: “Little Antarctica” Antarctica”

Stanford Linear acceleratorParticle (e-) bunches with composite energy same as UHE neutrinosBest possible calibration for ANITA

P. Gorham, Granlibakken 2007 10 of 21

ANITA & Askaryan effect in iceANITA & Askaryan effect in ice

Impulses are band-limited, highly polarized, as expected

Very strong--need 20dB ‘pads’ on inputs--signals are +95dB compared to Antarctic neutrino signals, since we are much closer 10 ns

P. Gorham, Granlibakken 2007 11 of 21

Nov. 2006, Antarctica: Putting it Nov. 2006, Antarctica: Putting it together together

The Long Duration Balloon Base at Williams field ~7 miles out on Ross Ice shelf, smooth, flat ice, 80m deep

a first-class field operation, run by NASA’s Columbia Scientific Balloon Facility (Palestine Texas)

P. Gorham, Granlibakken 2007 12 of 21

ANITA “hangtest,” ANITA “hangtest,” Sunday 12/3/06Sunday 12/3/06

Final pre-flight checkoutPayload is ready for launch

P. Gorham, Granlibakken 2007 13 of 21

Launch: December 15, 2007Launch: December 15, 2007

ANITA at float (123Kft) See through amateur

telescope from the South Pole

Size of the Rose Bowl!

(thanks to James Roth)

P. Gorham, Granlibakken 2007 14 of 21

Landing…~360 miles from S.PoleLanding…~360 miles from S.Pole

Ouch!What a drag…But instrument & data OK

P. Gorham, Granlibakken 2007 15 of 21

ANITA flight pathANITA flight path

35 days, 3.5 orbitsAnomalous Polar Vortex conditionsStayed much further “west” than averageIn view of stations (Pole & MCM) ~30% of time

P. Gorham, Granlibakken 2007 16 of 21

Flight sensitivity snapshot Flight sensitivity snapshot (preliminary)(preliminary)

ANITA sensitivity floor defined by thermal (kT) noise from ice + sky

Thermal noise floor seen throughout most of flight—but punctuated by station & satellite noise

Significant fraction (>40%) of time with pristine conditions

T~ 50K (Sun+Gal. Center)

<Tant>~ 200K

•T anti-correlated to altitude: • higher altitude at higher sun angle• sun+GC higher farther off main antenna beam

P. Gorham, Granlibakken 2007 17 of 21

Validation data: borehole pulserValidation data: borehole pulser

RF Impulses from borehole antenna at Williams field

Detected at payload out to 300-400 km, consistent with expected sensitivity

Will allow trigger & pointing calibration

P. Gorham, Granlibakken 2007 18 of 21

Trigger pattern, borehole pulserTrigger pattern, borehole pulser

Trigger pattern requires >3 antennas (9 of 24 signal channels) in both upper and lower 16-antenna ringsNegligible accidentals, but ~4-5Hz from thermal noise

But Thermal noise is incoherent in spatial & temporal character

P. Gorham, Granlibakken 2007 19 of 21

99.99+% of triggers: incoherent thermal 99.99+% of triggers: incoherent thermal noisenoise

P. Gorham, Granlibakken 2007 20 of 21

ANITA’s potential science impact ANITA’s potential science impact

ANITA-lite: 18.4 days of data, net 40% livetime with 60% analysis efficiency for detection

Z-burst UHECR model ( annihilation -->hadrons) excluded:

expect 6-50 events, see none Highest Toplogical defect

models also excluded

ANITA projected sensitivity (3 flights):

e included, full-mixing assumed

45 days exposure at 67% efficiency assumed

We are roughly within a factor of 2 with 1st flightStrongest limits: all radio

’06-07 flight (preliminary)

P. Gorham, Granlibakken 2007 21 of 21

Summary & PlansSummary & PlansANITA may have first glimpse of the ultra-high energy neutrino universe already on disk

Data disks returned from Antarctica a couple of weeks ago

Two independent blind analyses just getting started

Preliminary results by late summer?

ANITA II proposed to fly in 2008