DOE Germantown, June 23, 2005 1 of 25

Saltdome Shower Array (SalSA)

A GZK Neutrino Detector For High Energy Physics & Particle Astrophysics

David Saltzberg (UCLA)

Peter Gorham (University of Hawaii at Manoa)

Gary Varner (University of Hawaii at Manoa)

representing the SalSA collaboration

DOE Germantown, June 23, 2005 2 of 25

SALSA Collaboration

Kernfysisch Versneller Instituut (Netherlands)

Deutsches Elektronen Synchrotron (Germany)

Louisiana State University

University of Kansas

University of Utah Endeavour Corporation

University of Delaware University of Hawaii U.C.L.A. S.L.A.C. and Stanford University

Ohio State Univesity UC Irvine

UC Berkeleyand LBNL

University of Minnesota

UT Austin

Washington University

DOE Germantown, June 23, 2005 3 of 25

Livingston (via Panofsky) Plot

UHE Cosmic Rays don’t go on plot because cross-section already saturated

UHE neutrino cross section is 10-7 protons room for new physics enhancements

LHC

SalSA (ECM~100 TeV)

2010

1 PeV

1 EeV

ILC

How do weenter this region?

DOE Germantown, June 23, 2005 4 of 25

Particle Physics at the Energy Frontier

High energy can be a energy-frontier beam:

15-150 TeV center of momentum particle physics

Beyond LHC search for large extra dimensions micro-black-hole production TeV strings

Std. model

Large extradimensions

Anchordoqui et al. Astro-ph/0307228

GZK

DOE Germantown, June 23, 2005 5 of 25

A “GZK neutrino beam”must be available

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

Whatever Auger finds, GZK neutrinos must be there.

sees cutoffour standard flux calculationdoes not see cutoff sources are local, probably even more neutrinos (possibly, topological defects!)It’s iron Neutrinos from spallation neutrons must be there.

galactic

extragalactic

DOE Germantown, June 23, 2005 6 of 25

Where we might be in just 5 years…

ANITA:Discovery of ~10 GZK

neutrinos

IceCubeDiscovery of bottom-up sourcesDiscovery of ~ 3 GZK neutrinos

AugerDiscovery of a few GZK neutrinos ?

DOE Germantown, June 23, 2005 7 of 25

!

Why we are here today

Auger: Tau neutrino decay events ~1 GZK event per year?

SalSA sensitivity, 3 yrs live 70-230 GZK neutrino events

ANITA sensitivity, 45 days total:~5 to 30 GZK neutrinos

IceCube: high energy cascades ~1.5-3 GZK events in 3 years

A large sample of GZK neutrinos using radio antennas in a 12£ 12 array of boreholes natural Salt Domes

DOE Germantown, June 23, 2005 8 of 25

Probing an extreme regimefor particle physics

l,

p

nucleon

xp

Extreme regime: More likely to scatter off of bottom sea than down valence.

GZK

This is not HERAHERA tests proton structure to x~10-4 (& only 10-2 at “high” Q2)UHE probe proton structure to x~10-8 at high Q2

DOE Germantown, June 23, 2005 9 of 25

Measuring cross sectionup to ECM=150 TeV

30% Cross Section measurement with SalSA easily achievable using Earth as a filter near horizon

Not dependent on GZK shape or absolute intensity

Angular resolution even for non-contained events is sufficient.

Anomalous cross sections from large extra dimensions etc. at Ecm=150 TeV would be clearly visible.

DOE Germantown, June 23, 2005 10 of 25

Particle Physics in Neutrino Sector

GZK neutrinos are the “longest baseline” neutrino experiment:

Longest L/E (proper time) for: extra admixtures & anomalous decays

SUN: L/E ~ 30 m/eVGZK: L/E ~ 109 m/eV

Measured flavor ratios of e::can identify non-standard physics at source

e::

! (5-6):1:1

Neutrino decay leaves a strong imprint on flavor ratios at Earth

DOE Germantown, June 23, 2005 11 of 25

Neutrinos for Astroparticle physics: The only useful messengers >100 TeV

Photons lost above 30TeV: pair production on IR & wave background Protons & Nuclei:

scattered by B-fields or GZK process at all energiesBut the sources extend to 109 TeV

If not particle physicists, who? 7 orders of magnitude of energy will remain unexplored.

at

tenu

atio

n le

ngth

(M

egap

arse

cs)

scale size of Local Group

Every new energy band yields major discoveries

domain of neutrinodominance

IR,CMB,URB ! e+ + e-

DOE Germantown, June 23, 2005 12 of 25

How to go beyond km3

Neutrinos by cosmic accelerators: IceCube et al.Volume £ solid-angle ~ 10 km3-sr~3 GZK neutrino events over lifetimeSize determined by atten ~ 100m and cost.

GZK neutrinosEssentially guaranteed to be thereNeed Volume £ solid-angle approaching 1000 km3-sr (Teraton) Need a detection with atten~500m (w.e.)

DOE Germantown, June 23, 2005 13 of 25

The Askaryan Effect

UHE event will induce an e/ shower:

In electron-gamma shower in matter, there will be ~20% more electrons than positrons.

Compton scattering: + e-(at rest) + e-

Positron annihilation: e+ + e-(at rest) +

lead

e-

dddPCR In solid material RMoliere~ 10cm.

>>RMoliere (microwaves), coherent P N2

DOE Germantown, June 23, 2005 14 of 25

Heritage of PIs’ Related Experiments

GLUEGoldstone, radio telescopes and the Moonfirst limits on >100 EeV neutrinospublished Phys. Rev. Lett. (2004)

FORTESatellite observations of Greenland icepublished in Phys. Rev. D (2003)

ANITABalloon borne observations of Antarctic iceFirst data from Anita Lite (2003)Best limits on >10 EeV neutrinosto be submitted to Physical Review letters

Accelerator measurementsArgonne and SLACAttracted scientists to the techniquePublished in Phys. Rev. Lett. (2001)+to appear in Phys. Rev. D (2005)

Salt Dome Measurementsin situPublished in NIM (2002)

DOE Germantown, June 23, 2005 15 of 25

Funding Heritage

DOE Funding (1999-2005...) made GLUE, Forte, ANITA, Accelerator Experiments, and Salt Dome Measurements possible:

DOE OJI (Outstanding Jr. Investigator awards) Saltzberg and Gorham

DOE ADRP (Advanced Detector Research Program)

DOE University Programs (tasks originated with OJI’s)

NASA Research Opportunities in Space Science (for ANITA)

University intramural support (UH, UCLA, Caltech President’s Fund)

DOE Germantown, June 23, 2005 16 of 25

Accelerator Characterization of Askaryan Effect

200 cm 0 cm

DOE Germantown, June 23, 2005 17 of 25

Radio Coherence:Quadratic Growth + Absolute

Intensity

Shows amplitude expected from detailed simulations (egs/ Geant + Maxwell’s equations)

GZK

DOE Germantown, June 23, 2005 18 of 25

Ultra-wideband data on Askaryan pulse

2000 & 2002 SLAC Experiments confirm extreme coherence of Askaryan radio pulse

60 picosecond pulse widths measured for salt showers. Unique signal reduces background, simplifies triggering, excellent timing for reconstruction.

DOE Germantown, June 23, 2005 19 of 25

SalSA SimulationsCurrently on third generation of several independently developed simulations

GLUE (Goldstone)

ANITA (Antarctic Impulsive Transient Antenna)

SALSA simulations...

DOE Germantown, June 23, 2005 20 of 25

SalSA simulations

A 2.5 km3 array with 225 m spacing, 122=144 strings, 123=1728 antenna nodes, 12 antennas per node, dual polarization ==> Veff ~400 km3 sr w.e. at 1 EeV

Threshold <1017 eV, few 100s antennas hit at 1 EeV, >1000 hits at 10 EeVRate: at least 20 events per year from rock-bottom minimal GZK predictions

DOE Germantown, June 23, 2005 21 of 25

Angular resolution

For GZK energies:0.1o achieved for contained events--inside the array1o achieved for external events 250 m outside of array

DOE Germantown, June 23, 2005 22 of 25

Cherenkov polarization tracking

Radio Cherenkov: polarization measurements are unique

•Cherenkov radiation is 100% linearly polarized

DOE Germantown, June 23, 2005 23 of 25

Neutrino Flavor/Current ID

Simulations show NC/CC and Flavor ID to be effective on large subset of SalSA events80-90% efficiency on neutral vs. charged-current selection above 1 EeV30-50% of CC events will get first-order flavor ID above 1 EeV

~2 km

1018 eV

e,, Neutral Currents (19%)

Single Deep-Inelastic Hadronic Shower

e Charged Current (27%)

EM shower at primary vertexL.P.M. elongation

Charged Current (27%)

2ndary showers: - brem & p.p. - photonuclear

Charged Current (27%)

2ndary showers: - mainly photonuclear

DOE Germantown, June 23, 2005 24 of 25

Existing Neutrino Limits and Potential Future Sensitivity

RICE limits for 3500 hours livetime

GLUE limits 123 hours livetime

ANITA sensitivity, 45 days total: ~5 to 30 GZK neutrinos

IceCube: high energy cascades ~1.5-3 GZK events in 3 years

Auger: Tau neutrino decay events ~1 GZK event per year?

SalSA sensitivity, 3 yrs live 70-230 GZK neutrino events

Salsita: 4 strings 3 events per year

Salsita 3 years

DOE Germantown, June 23, 2005 25 of 25

Plan of Attack

First Proposal (~$4M, see next half of talk)Need to confirm

O(1km w.e.) attenuation lengthlow noise environmentoperability of hardware

PlanSingle borehole in 3-4 candidate domes + analysisAdd 2 more boreholes to measure propagationFor best dome, add 4th borehole A simple 4-borehole prototype array will see 2-3 events/year from minimal GZK models

Second Proposal ($50-100M)the full 12£ 12 array; built out from the prototype.

DOE Germantown, June 23, 2005 26 of 25

continued by Gorham (Part II)...

BACKUP SLIDES FOLLOW

DOE Germantown, June 23, 2005 27 of 25

Neutrino interactions in theStandard Model

n p

e

e

n p

W

/E/E0.36

Ghandhi, Quigg, Reno, Sarcevic

DOE Germantown, June 23, 2005 28 of 25

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 (“Top-down”) sources; GUT-scale decaying particles from big-bang relics

DOE Germantown, June 23, 2005 29 of 25

Heritage from other SALSA collaborators

SALSA collaborators have a range of relevant experienceGenerally mid-career, active, accomplished, and experienced

Amanda (optical detection in Antarctic Ice) & IceCubeRICE (radio detection from within Antarctic ice)Auger (distributed cosmic-ray detectors)SAUND and other acoustic detection measurementsDecades of experience with Oil Drilling industry Several decades of balloon-borne cosmic-ray experimentsTheory and calculation of Askaryan EffectDecades of experience with Oil Drilling industryAccelerator-based, frontier particle physicsGamma-ray astronomyTwo U.S. National LabsSignificant European interest

DOE Germantown, June 23, 2005 30 of 25

Neutrinos: The only useful messengers at >PeV energies

Photons lost above 30 TeV: pair production on IR & wave background Charged particles: scattered by B-fields or GZK process at all energiesBut the sources extend to 109 TeV !

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

Region not observableIn photons orCharged particles

DOE Germantown, June 23, 2005 31 of 25

GZK neutrino sensitivity details, 1 yr

2 independent MC calculations: UCLA & UH

UCLA: Saltzberg 2002 SPIE; also 2005 Nobel symposium

Simplified 10x10 strings, 10 antenna nodes per stringDid not truncate dome, so high energies extended

UH: Gorham et al. Phys.Rev. D 2005, in press

12x12 strings, 12 nodes with realistic trigger sims, salt dome truncatedLower trigger thresholdEven 4-string array sees GZK events in 1 year!

DOE Germantown, June 23, 2005 32 of 25

Neutrino interactions in theStandard Model

n p

e

e

n p

W

/E/E0.36

Ghandhi, Quigg, Reno, Sarcevic

DOE Germantown, June 23, 2005 33 of 25

Topological Defects

Possible “relic” particles (dubbed X) due to symmetry breaking phase transitions in the early Universe:

Masses at the GUT scale (MX~1025 eV).

By why don’t these decay in 10-40 sec?Confine in “topological defects” stable until destroyed/ annihilate

NO COSMIC ACCELERATOR NEEDED: “top-down” scenarioX jets mesons neutrinosX leptons or even all neutrinos

DOE Germantown, June 23, 2005 34 of 25

Topological Defects

Some specific modelsBhattacharjee, Hill, Schramm PRL 69, 567, (1992)Protheroe & Stanev PRL 77,3708 (1996)Sigl, Lee, Bhattacharjee, Yoshida PRD 59,043504 (1998)Barbot, Drees, Halzen, Hooper, PLB 555, 22 (2003)

Basic ideasWere attractive to circumvent GZK cutoff for UHE cosmic rays.Topological defects could be monopoles, superconducting cosmic strings, domain wallsGenerally these models produce hard neutrino spectrum: ~ E-(1-1.5)

“bottom-up” scenarios are more steeply falling: E-2 to E-4

not ruled out by lower energy telescopesconstrained by MeV—GeV isotropic photon fluxes

Neutrino flux vs. energy sensitive to source evolution vs. z of TD’s.

DOE Germantown, June 23, 2005 35 of 25

Neutrino Telescopes for Direct Monopole Detection

Monopoles:Dirac: The presence of even one monopole explains electric charge quantizationMonopoles are typically part of GUTsMasses typically of order GUT scalebut in some models Mmp could even be as low as ~1014 eV.

Observation of monopoles would be revolutionary for HEPParker bound (10-15 cm-2 s-1 sr-1)

c.f. UHECR>1020 eV (~10-21 cm-2 s-1 sr-1)other direct MP searches barely approach Parker boundCaveat: if monopoles catalyze proton decay then (lack of) neutron star heating provides extremely strong limit.

DOE Germantown, June 23, 2005 36 of 25

Neutrino Telescopes for Direct Monopole Detection

Intergalactic magnetic fields sheets (~100 nG over 50 MPc) could accelerate monopoles to energies of ~5£1024 eVLight monopoles would be relativistic so are candidates for radio Cherenkov detectionParker bound (10-15 cm-2 s-1 sr-1)

c.f. UHECR>1020 eV (~10-21 cm-2 s-1 sr-1)other direct MP searches, generally worse than Parker bound

Relativistic monopoles mimic particle with large charge: at least Z~68produce EM showers along path by pair-production, photo-nuclearcontinuously produces shower along its path unique signature

WKW estimate F<10-18 cm-2 s-1 sr-1 for a km3 detector for 1 year.SalSA could do much better: sensitive for Mmp up to 1023 eV, far beyond production at accelerators.

Flux limit better than typical searches

DOE Germantown, June 23, 2005 37 of 25

Polarization tracking

Measured with dual-polarization embedded bowtie antenna array in salt

DOE Germantown, June 23, 2005 38 of 25

Estimated SalSA Energy threshold

Ethresh < 300 PeV (3 x 1018 eV) best for full GZK spectral measurement

Threshold depends on average distance to nearest detector and local antenna trigger voltage above thermal noise

Vnoise = k T f

Tsys = Tsalt+Tamp = 450K

f of order 200 MHz

225 m spacing gives 30 PeVMargin of at least 10£ for GZK neutrino energies