PeV Cosmic Neutrinos from the MountainsPing Yeh ()National Taiwan University November 15, 2002 CosPA 2003 @ NTU, TaipeiToday is the 75th Birthday of NTU!

Ultra-High Energy Cosmic RaysOriginD.J. Bird et al., Ap. J. 511, 738 astro-ph/9806096AGASA4% excessM. Teshima et al., 27th ICRC p337, 2001AnisotropyFlys EyeP(fluct) < 0.07

High Energy Cosmic NeutrinosProduction presumably dominated by nm and neHadronic

Transportation & Oscillation: 1:1:1

Cosmic Rays and NeutrinosCosmic Ray Spectrum Not Well UnderstoodCR + X e2e~ 0.1 /EeV/year/km2/srGZK Firm!~ 1.2 x 103 /PeV/year/km2/srAGN ?

Observing High Energy Cosmic NeutrinosPrinciple: 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 n Detectors: Atm/SolarShield from CR & Atmospheric s: Underground Under Water/IceVery Large Target Volume = Detection VolumeSuperKsolar deficit/ & SNO

Conventional High Energy n DetectorsLimited by Target Volume: Maximum Energy ~ 1015 eVDeployment: 2003 - 2009ExistingYoshidas talk

IceCube: 1 PeV Limit for nt

UHECR DetectorsDetect -induced Air ShowersConversion Efficiency in Atmosphere Small AugerFluorescence Energy Threshold High > 1018 eVReflected

Window of OpportunityConventional n DetectorUHECR n Detector?

AGN Jets, CRs and Protons??

Earth SkimmingEarth Skimming + Mountain PenetratingCherenkov vs. fluorescenceTelescopeCross Section ~ E1.4Sensitive to nt ne: electron energy mostly absorbed in mountain nm: no extensive air shower t appearance experiment!

CollaborationItaly: IASF, CNR, PalermoN. La Barbera, O. Catalano, G. Cusumano, T. Mineo, B. SaccoFrance: Paris, France F. Vannucci, S. BouaissiUSA: Hawaii J.G. LearnedJapan: ICRR M. SasakiTaiwan: 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

FeasibilityFeasibility 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

AcceptanceFigure 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 AcceptanceThe chain of conversions

nt to t conversion rate: ~ O(10-5) - O(10-4)Expect O(10) /year/km2/sr t flux> O(1) km2 sr acceptance desired t 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 PatternCherenkov: 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) nmCosmic Ray background very small

Cluster-based trigger algorithmRandom Background with NSB flux1 km away from a 1 PeV e- shower

Trigger StudyBackground Rates vs Signal Efficiency1PeV, 30 km, normal incidence1PeV, 30 km, 10 incidenceH-L TriggerSingle TriggerH-H Trigger (Dual trigger)H threshold Trigger Rate (Hz)XYLocal coincidence necessaryto kill the background!

Acceptance DeterminationIntegration of efficiencies in phase space Three independent methods for cross-checking

Results are consistent with each other!

Method

Efficiency

Integration

Investigator

MIR

Range determined from Simulation

Monte Carlo

Alfred

MIME

Modelled Curve

Monte Carlo

Minzu

NISE

Detailed Simulation

Numerical

Ping

Acceptance CurveEstimated with an idealistic vertical plane mountain surfaceAcceptance starts at Et ~ 1 PeVGradually levels off near 1 EeV (t decay length = 50 km @ 1 EeV)

Preliminary ReconstructionReconstruction: Minimize 2 for x,y,,, and ETwo Detectors Separated by a few 100m

Reconstruction ErrorPossible to Reconstruct Events Angular Error within 1Energy Error ~ 40%Reconstruction Efficiency 30% ~ 70%

SensitivitySensitivity : 1 event/year/decade of energyGreat Chance to See fromAGNTDGC Attenuation is an Issue

Requirements on the InstrumentFind signal on top of background!Rate >= 0.5 events/yearaperture, light collection efficiency, triggerAngular resolution: 0.5 degrees or smallerTiming (ns pulse)Low budget

Prototype TelescopePurpose:Proof of ConceptMeasure BackgroundTelescopeCommercial Fresnel Lens (NTK-F300, f30cm, size=30cm, pitch=0.5mm, PMMA UV), UV Filter (BG3)Hamamatsu 4x4 (H6568) MAPMTReadout Electronics: Preamp, Receiver, Trigger, ADC and DAQ

Field Test at Lulin Observatory (2900m)E (Mt. Jade)03715Sirius3 elevation angles: 3, 7, 152 conditions: w/o BG3 filter

Cosmic RaysCR tracks seen by prototype telescopeSystem functions properlyPotential Use: Monitor System HealthCalibration by CR events

SiriusStudy:Effective field of viewLens transmittance as function of off-axis angle.In the future, Calibrate the pointing accuracyMonitoring telescope health

The OpticsWant to utilize existing mirrors or lensesFirst concept: EUSO-type Fresnel lensNote that EUSO is years awayTimely readiness and cost!

The Optics - revisedCurrent direction: ASHRA-type Mirror + correction lensPhoton Sensor: Multi-Anode PhotomultiplierDont need arc-min resolution: optics is basically ready NOWSasakis talk

The ElectronicsDynamic Range x4

Schematics of the ElectronicsUV filterHamamatsu8x8 MPMT16-channelspreamplifierUV filterDetector pairStart readout32 channels DCM(Data Collection Module) in cPCI10 bit x40 MHzPipelinedADC16 RAM x 256 x 16 per 8 channelsMirrorTrigger FPGAADC controlFPGA (x4)To/fromAnother DCMStart readout10 bit x40 MHzPipelinedADCTo/fromAnother DCMSignal-sharing plateFront-end electronics box 8x8 pixels(1 MPMT, 1 SSP, 4 preamplifiers)

Calibration: PointingCrab 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 CrabAcceptance ~ around O(0.1) km2 srRate ~ 6 events/hrExposure of several nights would be usefulPhoton density (1/m2 )log E (TeV) Trigger Range (m)

SitePrimary Site: Mt. Hualalai looking at Mauna LoaGood weather condition, less background, GC in FOVNo electricity, no water, no communicationPrototype Site: Mauna Loa looking at Mauna KeaInfrastructure ready, on-site help from CosPA1!No GC observationMt. HualalaiMauna KeaMauna LoaStill looking forpossible sites!

ScheduleDetector DesignConstruct1024 Ch. Prototype200320042005Prototype OperationConstruct Full-size TelescopeSite Survey / PreparationInstallation & CalibrationFull Telescope OperationCrabs itinerary dictates October - December

ConclusionNuTel is the first experiment dedicated to Earth skimming / mountaing watchingThe PeV cosmic nt rate is a few events/yearThe cost is low: O(1) million US dollars to build itThe time is short: prototype deployment in 2004The window of opportunity is good, both in energy and time (Hmm the uncertainty principle?) Ashra is a natural continuation for NuTelSite coincidesPhysics complimentarySchedule looks promising