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Saltdome Shower Array: A GZK neutrino Detector Introduction. Peter Gorham University of Hawaii at Manoa. (Ultra-)High Energy Physics of Cosmic rays & Neutrinos. 40 yrs of 10 18-20 eV CR data: Origin unknown above 10 19 eV Energy: 10 7 times Tevatron

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Saltdome Shower Array:

A GZK neutrino Detector

Introduction

Peter Gorham

University of Hawaii at Manoa

P. Gorham, SLAC SalSA workshop


Ultra high energy physics of cosmic rays neutrinos
(Ultra-)High Energy Physics of Cosmic rays & Neutrinos

40 yrs of 1018-20 eV CR data:

  • Origin unknown above 1019 eV

    • Energy: 107 times Tevatron

    • A paradox: No nearby sources, but physics excludes distant sources due to collisions with boosted (in c.m. frame) microwave background (GZK process)

  • Neutrinos at 1017-19 eV required by standard-model physics through the GZK process--observing them is crucial to resolving the GZK paradox

galactic

extragalactic

  • Observation of UHECR GZK cutoff feature by Auger still requires confirmation with GZK neutrino observations to verify GZK interactions

P. Gorham, SLAC SalSA workshop


Neutrinos the only useful messengers at pev energies
Neutrinos: The only useful messengers at >PeV energies

  • Photons lost above 30 TeV:pair production on IR & mwave background

  • Charged particles:scattered by B-fields or GZK process at all energies

  • But the source energetics extend to 109 TeV !

    Conclusion:

  • Study of the highest energy processes and particles throughout the universe requires PeV-ZeV neutrino detectors

Region not observable

In photons or

Charged particles

P. Gorham, SLAC SalSA workshop


Particle physics energy frontier neutrinos
Particle Physics: Energy Frontier & Neutrinos

  • Well-determined GZK n spectrum becomes a useful beam

    • 10-300 TeV center of momentum particle physics

    • study large extra dimensions at scales beyond reach of LHC

    • n Lorentz factors of g=1018-21!

  • Measured flavor ratios ne:nm:ntcan

    • identify non-standard physics at source

    • Longest L/E for: sterile n admixtures & anomalous n decays

Large extra

dimensions

Std. model

GZK n

Anchordoqui et al. Astro-ph/0307228

P. Gorham, SLAC SalSA workshop


Particle astrophysics cosmology
Particle Astrophysics/Cosmology

  • Cosmic ray Emax, the maximum acceleration energy

  • UHECR flux vs. redshift to z = 15-20 (eg. WMAP early bright phase, )

  • Independent sensitivity to dark energy density

  • Exotic (eg. Top-down) sources; GUT-scale decaying relics

P. Gorham, SLAC SalSA workshop


What is needed for a gzk n detector
What is needed for a GZK n detector?

  • Standard model EeV GZK n flux: <1 per km2 per day over 2p sr

    • Interaction probability per km of water = 0.2%

    • Derived rate of order 0.5 event per year per cubic km of water or ice

       A teraton (1000 km3 sr) target is required!

      Problem: how to scale up from current water Cherenkov detectors

  • One solution: exploit the Askaryan effect: coherent radio Cherenkov emission

    • Particle showers in solid dielectric media yield strong, coherent radio pulses

    • Neutrinos can shower in many radio-clear media: air, ice, rock-salt, etc.

    • Economy of scale for a radio detector (antenna array + receivers) is very competitive for giant detectors

P. Gorham, SLAC SalSA workshop


Antenna array

Saltdome Shower Array (SalSA) concept

Salt domes: found throughout the world

Qeshm Island, Hormuz strait, Iran, 7km diameter

1

2

3

Depth

(km)

4

  • Halite (rock salt)

  • La(<1GHz) > 500 m w.e.

  • Depth to >10km

  • Diameter: 3-8 km

  • Veff ~ 100-200 km3 w.e.

  • No known background

  • >2p steradians possible

5

Isacksen salt dome, Elf Ringnes Island, Canada 8 by 5km

6

7

  • Rock salt can have extremely low RF loss:  as radio-clear as Antarctic ice

  • ~2.4 times as dense as ice

  • typical:50-100 km3 water equivalent in top ~3km ==>300-500km3 sr possible

P. Gorham, SLAC SalSA workshop


U s gulf coast salt domes
U.S Gulf coast salt domes

  • Salt dome demographics:

  • Several hundred known—some are good source of oil

  • Typical ~3-5 km diameters, 5-15 km deep

  • ~200 km3 water equiv. in top 3-5 km for many domes

Hockley dome/mine

Houston

New Orleans

P. Gorham, SLAC SalSA workshop


Gulf coast salt domes
Gulf coast salt domes

  • Texas, Louisiana, Mississippi all have dozens or even hundreds of domes

  • 3-4 km diameters, 5-10 km depths typical

  • Often explored for oil that is trapped on flanks

P. Gorham, SLAC SalSA workshop


Tehuantepec mexico
Tehuantepec, Mexico

  • These salt domes have similar ages, structure, composition, to Louisana/Texas domes

  • Several are very large

    • 7 by 4 km

    • 6 by 5 km

  • Probably there are many more than shown here

P. Gorham, SLAC SalSA workshop


Utah colorado salt structures
Utah/Colorado salt structures

  • Utah, Colorado contains a region of salt diapirs

  • Many “anticlines”, several domes

  • Beds are relatively shallow, salt formations are young

  • Salt is relatively impure with more clay & brine entrained

P. Gorham, SLAC SalSA workshop


In situ salt dome examples of attenuation
In situ salt dome examples of attenuation

P. Gorham, SLAC SalSA workshop


Borehole radar on dome flank
Borehole radar on dome flank

  • Pine Prairie dome, LA northern extreme of Louisiana salt dome region

  • Holser et al 1972 used dipole & helix antennas at 230MHz in a 5” diameter sonde to map the flank of the dome (1 microsec pulses)

  • Most data within 150m of edge of dome (anhydrite content usually increases)

  • Saw attenuation lengths of 60-220m, ~100m on average

  • Flank location confirmed by retrieved samples when flank was intercepted

P. Gorham, SLAC SalSA workshop


Humble dome oil rich caprock
Humble dome: oil-rich caprock

  • 4.8 km wide, salt level begins at 600m depth, thick caprock

  • Town of Humble is centered on dome!

  • Humble Oil--now known at Exxon!!

P. Gorham, SLAC SalSA workshop


Examples of salt dome halite purity
Examples of salt dome halite purity

P. Gorham, SLAC SalSA workshop


Salsa simulations
SalSA simulations

  • A 2.5 km3 array with 225 m spacing, 122=144 strings, 123=1728 antenna nodes, 12 antennas per node, dual polarization ==> 290 km3 sr at 1 EeV

  • Threshold 1017 eV, few 100s antennas hit at 1 EeV, >1000 hits at 10 EeV

  • Rate: at least 10 events per year from rock-bottom minimal GZK predictions

P. Gorham, SLAC SalSA workshop


Existing neutrino limits and potential future sensitivity
Existing Neutrino Limits and Potential Future Sensitivity

  • RICE limits for 3500 hours livetime

  • GLUE limits~120 hours livetime

  • ANITA sensitivity, 3 flights:

    • nm & neincluded, full-mixing parameterized

    • ~8 to 30 GZK neutrinos

  • IceCube

  • Auger

  • SalSA sensitivity, 3 yrs live

    • Similar to ANITA calcs

    • 70-230 GZK neutrino events!!

P. Gorham, SLAC SalSA workshop


Roadmap to a gzk neutrino detector
Roadmap to a GZK neutrino detector

  • Site investigations: needed now

  • Site surveys: core samples on select domes (within 1 year)

  • Prototype arrays (3-4 strings) in 2 or more domes to test propagation (next 2 years)

  • Final site selection & construction timed to begin with announcements by ANITA,IceCube, Auger of GZK neutrinos, 2007-2008!

P. Gorham, SLAC SalSA workshop


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