ARIANNA - A New Concept for Neutrino Detection Steve Barwick, UC IrvineMadison, Aug ARIANNA Institutions: UCI, UCLA, UH, OSU,UCollege-London

The Energy Gap There is a gap in the Energy response of current detectors between x10 18 eV GAP

ARIANNA is designed to span the gap ARIANNA rates (6 month) ESSFe-only ~40few (20,500 hrs)

Neutrino Cross-Section  ] = 0.24 If N ev = 400 If   =0.5 o If  =2  GQRS 2 parameter fit: Normalization cross-section ARIANNA - 10 years GQR S

ARIANNA Concept 100 x 100 station array, ~1/2 Teraton ~300m Ross Ice Shelf, Antarctica

Satellite Image of Victoria Land and Ross Ice Shelf Ross Island 2 Dry Valleys ARIANNA south Minna Bluff ~150 km 30x30 km 2 Ice Thickness ~500m

Reflected and Direct Events ignore ice Direct Reflected (much greater solid angle) S. Barwick, 3rd NOVE Workshop (Venice, 2006)

Reflection loss: Ross Ice Shelf 150 Regions of smoother than normal ice-water interface ~0 dB 1 C.S. Neal, J. Glaciology, 24(1979)295 south Ross Ice Shelf

Reflection properties of the Ross Ice Shelf ~0 dB south

Basal Smoothness of Ross Ice Shelf from C.S. Neal, Ann. Glaciology 3(1982)216. LocationSurface RMS height (m) 77 o 25’S, 171 o 38’E (good reflection coef) 84 o 24’S, 163 o 43’W (known poor refl. coef) MHz, 60ns radio echo pulse

Corroborating Evidence for Smooth Surfaces from K. W. Nicholls, et al., Geophy. Res. Lett 33(2006)L <8mm!Flow trace Sonar map of surface beneath Fimbul Ice Shelf Conclusion: In regions outside of Flow Traces, surface variation is <8 mm!

Event Reconstruction Preliminary studies show that the radio path ambiguity (direct or reflected) is manageable. –  ~ 1 deg –  E/E ~ 1

Detector Response Simulations assume 100x100 square array, 300m separation, 500m thick ice, all v-flavors(1:1:1), firn layer, 2 Quad-ridge horns per station, 3-station multiplicity, 2/4 rms, depth dependent attenuation, 3dB reflection loss, standard model  Preliminary studies show that ARIANNA is sensitive over all angles. Direct & Reflected Reflect only

ARIANNA Configurations Configurations in Study 1: 1-Quad, 1/2 chan 2: 2-Quad, 2/4 chan 3: 1-Quad, 1 dipole, 1/3 chan 4: 5-Quad-closed, 2/10 chan 5: 5-Quad-spread, 2/10 chan 6: 5 -Quad-spread, 2/10 chan 1 station only Baseline Note: Channel threshold =2.3V rms, 3 stations in Trig, unless otherwise stated

Ice Property Systematics Index of refraction of firn ice Effective Attenuation length Reflection Coef. Scattering from Ice-Water

ARIANNA Config. Systematics Separation between stations Channel Threshold Stations in Trigger Channel Multiplicity

ARIANNA Advantages Near McMurdo, logistics manageable Site likely has good reflection and absorption properties Site protected from RF interference, and likely to stay that way Borrow technologies from Auger, ANITA Deployment straightforward and stations serviceable Design relatively insensitive to many imprecisely known ice properties (eg, localized patches of bad ice, strong scattering, reflection) Negligible environmental impact –stations removable when project ends 24/7/(365/2)

Protostation Block Diagram of Electronics

Outlook With AMANDA-II, the requisite tools to inaugurate multi-messenger astronomy are available -> IceCube continues this technique. To probe the neutrino fluxes and physics at highest energies, new techniques are being developed based on radio cherenkov detection. ANITA extends search volume to 10 6 km 3 –McMurdo launch expected Dec 2006 ARIANNA spans the impending energy gap –Awaiting further ice studies in Nov’ 06 (A-127M, if you want to track our progress), and not the only contender (SALSA, superRICE, acoustic detection) –Development continues at a feverish rate

ARIANNA Spec Sheet ~0.5 Teraton, 30km x 30km, 100x100 array Resides on Ross Ice Shelf, near McMurdo Angular Resolution  <1 deg 2  view of sky Energy Resolution  E/E ~ 1 Energy interval = 5x10 17 eV eV GZK Event Rate ~40 events/6 mo. (ESS) Few/6 mo if Fe only

Station Configurations top side 2m “2 Quad” top side “5 Quad, Closed” 2m 5 Quad, Spread has 5m spacing

Block Diagram of ARIANNA Station Electronics

Ice Thickness Map for ARIANNA McMurdo ARIANNA 170 km 50 km 1 2 south

Antarctic Traverse Route Use part of traverse infrastructure to access ARIANNA? Hillary Route - ‘57

UCI/UCLA Simulation Comparison UCLA UCI Direct: N>3 direct rays Reflect: N>3 reflected rays Combo: N<3 for both direct and ref. Both: N>3 direct, N>3 reflect

PHOTONS : not deflected, but: reprocessed in sources, absorbed in IR (100 TeV), and CBR PROTONS : deflection in magnetic fields, GZK cutoff NEUTRINOS : not absorbed or deflected, hard to see

ANITA-GZK  ~100  sm For GZK E CC  sm (Anchordoqui, et al, hep-ph/ ) EHE Neutrinos Explore Higher Dimensions

Ice transparency Loss tangent a strong function of temperature For cold ice, UHF (0.1- 1GHz) best Antarctic data approaches pure ice values L  =  [  n (  ’’ /  ’ )] –1 ~ 6 km at 300 MHz & -60C (pure ice, theory) Matsuoka et al. 1996

The Energy Gap and ARIANNA [ Antarctic Ross Iceshelf ANtenna Neutrino Array ]