PeV Cosmic Neutrinos from the Mountains

Ping Yeh (葉平 )National Taiwan University

November 15, 2002 CosPA 2003 @ NTU, Taipei

Today is the 75th Birthday of NTU!

Ultra-High Energy Cosmic Rays

Origin

D.J. Bird et al., Ap. J. 511, 738astro-ph/9806096

AGASA4% excess

M. Teshima et al.,27th ICRC p337, 2001

Anisotropy

Fly’s EyeP(fluct) < 0.07

High Energy Cosmic Neutrinos

Production presumably dominated by and e

Hadronic

Transportation & Oscillation: 1:1:1

Cosmic Rays and Neutrinos

Cosmic Ray Spectrum

Not Well Understood

CR + X e2e

UHECR + CMB N + GZK

~ 0.1 /EeV/year/km2/sr GZK Firm!

~ 1.2 x 103 /PeV/year/km2/sr

AGN ?

Observing High Energy Cosmic Neutrinos

Principle: convert neutrinos to observablesLow cross section: need large target volumeSignals development: need large detection volumeMostly use H2O as target and detection volume (Bikal, AMANDA, ANTARES, IceCube)

Energy coverage: H2O, air fluorescence, and the “hole”

Conventional Detectors: Atm/Solar

Shield from CR & Atmospheric ’s: Underground Under Water/IceVery Large Target Volume = Detection Volume

SuperK

solar deficit/ &

SNO

Conventional High Energy Detectors

Limited by Target Volume: Maximum Energy ~ 1015 eV

Deployment: 2003 - 2009

Existing

Yoshida’s talk

IceCube: 1 PeV Limit for

UHECR Detectors

Detect -induced Air ShowersConversion Efficiency in Atmosphere Small

Auger

Fluorescence Energy Threshold High > 1018 eV

Reflected

Window of Opportunity

Conventional Detector UHECR Detector?

AGN Jets, CRs and Protons?

?

Earth Skimming

Telescope

Cross SectionCross Section ~ E~ E1.41.4

Earth Skimming + Mountain PenetratingCherenkov vs. fluorescence

Sensitive to

e: electron energy mostly absorbed in mountain : no extensive air shower

appearanceexperiment!

Collaboration Italy: IASF, CNR, Palermo

– N. La Barbera, O. Catalano,G. Cusumano, T. Mineo,B. Sacco

France: Paris, France F. Vannucci, S. Bouaissi

USA: Hawaii J.G. Learned

Japan: ICRR M. Sasaki

Taiwan: – NCTS/CosPA3– G.L. Lin, H. Athar, …

NTUHEP/CosPA2PIs: W.S. Hou & Y.B. HsiungHardware Team:

K. Ueno (Faculty)Y.K. Chi (Electronics)Y.S. Velikzhanin (Electronics)M.W.C. Lin (Technician)

Simulation Team:M.Z. Wang (Faculty)P. Yeh (Faculty)H.C. Huang (Postdoc)C.C. Hsu (Ph.D. student)

NUUM.A. Huang (Faculty)

Formed in Spring 2002

Rates, Rates? Rates!

Figure of merit for the experimentDiffused source vs point source

Flux: different sources, different modelsAcceptance: Maximizing A(E) within the budget constraint is the design goal

Feasibility

Feasibility study was done in 2002 (Alfred Huang)Assume: aperture = 1 m2, light collection efficiency = 10%, ~ 40 km wide valley, ~ 2 km high mountainConclusion was O(1) events per yearDeemed feasible, more attractive with a small budget, and was funded that wayMore detailed study in 2003, will be shown

Acceptance

Figure of merit of the telescope designA = integration of detection efficiency in the phase space (x, y, theta, phi)

Detection efficiency depends on aperture & field of viewlight collection efficiencytrigger logic

Factors for Acceptance

The chain of conversions

to conversion rate: ~ O(10-5) - O(10-4)Expect O(10) /year/km2/sr flux> O(1) km2 sr acceptance desired

decay: ~ 82% branching fraction for showersLight collection (baseline design): 1 m2 aperture, 8o x 16o field of view, ~ 10% efficiencyTrigger: position dependent

The Signal and Background Pattern

Cherenkov: ns pulse, angular span ~ 1.5 degreesNight Sky Background (mean)

Measured at Lulin observatory: 2.0 x103 ph/ns/m2/srA magnitude 0 star gives 7.6 ph/m2/ns in (290,390) nm

Cosmic Ray background very small

Cluster-based trigger algorithmRandom Background with NSB flux 1 km away from a 1 PeV e- shower

Trigger Study

Background Rates vs Signal Efficiency1PeV, 30 km, normal incidence

1PeV, 30 km, 10° incidence

H-L Trigger

Single Trigger

H-H Trigger (Dual trigger)

H threshold

Tri

gg

er R

ate

(Hz)

X

Y

Local coincidence necessary

to kill the background!

Acceptance Determination

Integration of efficiencies in phase space

Three independent methods for cross-checking

Results are consistent with each other!

Method Efficiency Integration Investigator

MIR Range determined fromSimulation

Monte Carlo Alfred

MIME Modelled Curve Monte Carlo Minzu

NISE Detailed Simulation Numerical Ping

Acceptance Curve

Estimated with an idealistic vertical plane mountain surface

Acceptance starts at E ~ 1 PeV

Gradually levels off near 1 EeV ( decay length = 50 km @ 1 EeV)

Preliminary Reconstruction

Reconstruction: Minimize 2 for x,y,,,

and E– Two Detectors Separated by a few 100m

E, x, y, ,

1 2

N1, T1

, x1 , y1, 1, 1

N2, T2

, x2 , y2, 2, 2

Reconstruction Error

Possible to Reconstruct Events

– Angular Error within 1°– Energy Error ~ 40%– Reconstruction Efficiency 30% ~ 70%

Sensitivity

Sensitivity :

1 event/year/decade

of energy Great Chance to See

from– AGN– TD– GC

Attenuation is an Issue

Requirements on the Instrument

Find signal on top of background!Rate >= 0.5 events/year

aperture, light collection efficiency, triggerAngular resolution: 0.5 degrees or smallerTiming (ns pulse)Low budget

Prototype Telescope

Purpose:– Proof of Concept– Measure Background

Telescope– Commercial Fresnel Lens

(NTK-F300, f30cm, size=30cm,

pitch=0.5mm, PMMA UV),

– UV Filter (BG3)

– Hamamatsu 4x4 (H6568) MAPMT

– Readout Electronics: Preamp, Receiver,

Trigger, ADC and DAQ

Field Test at Lulin Observatory (2900m)

E

玉山(Mt. Jade)

0°3°7°

15°Sirius

3 elevation angles: 3°, 7°, 15°2 conditions: w/o BG3 filter

Cosmic Rays

CR tracks seen by prototype telescope– System functions

properly Potential Use:

– Monitor System Health– Calibration by CR events

The Optics

Want to utilize existing mirrors or lensesFirst concept: EUSO-type Fresnel lens

Note that EUSO is years away

Timely readiness and cost!

The Optics - revised Current direction: ASHRA-type Mirror + correction len

s Photon Sensor: Multi-Anode Photomultiplier Don’t need arc-min resolution: optics is basically read

y NOW

Sasaki’s talk

The Electronics

Dynamic Range x4

Schematics of the Electronics

PMT Preamp.

UV filter

Hamamatsu8x8 MPMT

16-channelspreamplifier

DAQ

PMT Preamp.

UV filter

TriggerDetector pair

Start readout

32 – channels DCM(Data Collection Module) in cPCI

10 bit x40 MHzPipelinedADC

16 RAM x 256 x 16 per 8 channels

Mirror

Trigger FPGA

FADC

bufferRAM

ADC controlFPGA (x4)

To/fromAnother DCM

Trigger

cycleRAM

Start readout10 bit x40 MHzPipelinedADC

FADC

bufferRAM DAQ

cycleRAM

To/fromAnother DCM

Signal-sharing plate

Front-end electronics box 8x8 pixels(1 MPMT, 1 SSP, 4 preamplifiers)

Calibration: Pointing

Crab Nebula as the standard candleCan we see it?

d J / d E = 0.28 * ( E / 1TeV ) -2.6 km-2 s-1 TeV-1

Integrated flux is not small: 0.3 /km2 /sRandom background > 10 times higher in “stary stary nights” Use neutral density filter + tighter trigger

Acceptance to the Crab Acceptance ~ around O(0.1) km2 sr Rate ~ 6 events/hr Exposure of several nights would be useful

Photon density (1/m2

)

1 TeV gamma

Distance (m) log E (TeV)

Trigger Range (m)

Site Primary Site: Mt. Hualalai looking at Mauna Loa

– Good weather condition, less background, GC in FOV

– No electricity, no water, no communication Prototype Site: Mauna Loa looking at Mauna Kea

– Infrastructure ready, on-site help from CosPA1!

– No GC observation

Mt. Hualalai

Mauna Kea Mauna Loa

Still looking for

possible sites!

Schedule

Detector Design

Construct1024 Ch. Prototype

2003 2004 2005

Prototype Operation

Construct Full-size Telescope

Site Survey / Preparation

Installation & Calibration

Full Telescope Operation

Crab’s itinerary dictates October - December

Conclusion NuTel is the first experiment dedicated to Earth skim

ming / mountaing watching The PeV cosmic rate is a few events/year

The cost is low: O(1) million US dollars to build it The time is short: prototype deployment in 2004 The window of opportunity is good, both in energy an

d time (Hmm… the uncertainty principle?)

Ashra is a natural continuation for NuTel– Site coincides

– Physics complimentary

– Schedule looks promising