Gamma-Ray, Neutrino & Gravitational Wave Detection

arXiv:0801.3886v2[astro-ph]25Jan200830THINTERNATIONALCOSMICRAYCONFERENCEGamma-Ray,Neutrino&GravitationalWaveDetection:OG2.5,2.6,2.7RapporteurG.ROWELLSchoolofChemistry&Physics,UniversityofAdelaide,Adelaide5005,[e-mail]:Thisreportisbasedonarapporteurtalkpresentedatthe30thInternationalCosmicRayConferenceheldinMerida,Mexico(July2007),andcoversthreeoftheOGsessionsdevotedtoneutrino,gravitationalwave,andγ-raydetection.Introduction&OverviewSummarisedherearekeyresultsfrompapersandposterspresentedinthesessionsOG2.5(neutrinodetection),2.6(gravitationalwavedetection),and2.7(γ-raydetection).Thenumberofpresentationsineachsessionwas75(OG2.7),19(OG2.5)and2(OG2.6),withγ-raydetectionclearlydominating.OG2.5wasdevotedtoneutrino/γ-rayconnectionsandrelatedexperimentalandtheoreticalissuesandcontainsoverlapswiththeHE2session.AmoredetailedsummaryofneutrinodetectorsandrelatedastrophysicaltheorycanbefoundintheHE2rap-porteurbyTomGaisser[69].Here,summariesofeachsessionsareorderedaccordingtothenumberofcontributions.IhavekepttocitingonlyICRCpresentations/posterssinceinmostcasesadetailedlistofreferencesmaybefoundtherein.OG2.7:Gamma-RayDetectionThisγ-raydetectionsessionencompassedtechni-calstatusreportsfromspaceandgroundγ-rayin-struments,summariesoftheiranalysistechniquesandperformance,andplansforfutureinstruments.Resultsfromγ-rayinstruments(sessionsOG2.1to2.4)aresummarisedbyJimHinton[68]andIwillonlytouchonafewkeyrelevantresults.Ground-Basedγ-RayDetectors:Current&FundedGround-basedγ-raydetectorscanbebroadlysplitintothreecamps:(i)TelescopesemployingtheImagingAtmosphericCherenkovTechnique(IACT)includingthosewith≥2telescopesoper-atingasstereoscopicarrays,(ii)WaterCherenkovdetectors,and(iii)Groundarrays.IACTDetectors/ArraysTherearefourmajorIACTdetectors/arraysinop-erationtoday,andstatusreportspresentedatthisconferenceonthetwomostrecentlycommissionedsystems—VERITASandMAGIC/MAGIC-II,weredominantinnumber.BothH.E.S.S.andCANGAROO-IIIhavebeeninfulloperationsince∼2004andmuchoftheirtechnicaldetailshavebeenpresentedatpreviousICRCs,althoughanupdatedstatusofCANGAROO-IIIwaspresentedhere.Aftermany(non-scientific)delays,VERITAS[65]achievedfirstlightwithfourtelescopesinApril2007.[39]presentedanoverviewoftheVERI-TASarraywhichcomprises4×106m2telescopessituatedattheBasecampatFredLawrenceWhip-pleObservatory,Mt.Hopkins,Arizona(Fig1).TheopticsofeachtelescopecomprisesaDavies-Cottondishwith345mirrorsegments[48].Mir-rormis-alignmentduetodishdeformationvs.el-evationhasbeensuccessfullycorrectedusingaRAPPORTEUROG2.5,2.6,2.7laseralignmentsystem[56].Thetelescopes’cam-erascomprisea499photomultiplier(PhillipsXP2970/02PMT)pixelarray[45],providinga∼3.5◦fieldofview(FoV).Thesize(diameter)ofeachpixelis0.15◦.Thetriggersystemisbasedonthreelevels:L1-pixel;L2-camerapixelpat-tern;L3-arraytrigger[61].Apixeltriggerof4–5pe.(photoelectrons)isfirstapplied.Thecam-eraistriggeredwhen(presently)3adjacentpixelswithinapre-definedgrouparetriggeredwithin6ns(see[62]fordetails).Thispatternlogicgreatlyreducesaccidentaltriggersduetoskynoise.Theinter-telescopearraytrigger(L3)ismetwhenever≥2telescopestriggerwithinatimewindowupto125ns,dependingonthezenithandazimuthangleofobservations.The3-telescopearraytriggerrateis∼220Hzwitha10%deadtime.PMTpulsesaredigitisedusing500MHz(VME-based)flashADCs(FADCs)[27].SeveralmethodsbasedonFADCsamplingandfilteringtoextracttheCherenkovpulsearrivaltimewereevaluatedby[12],withacombinationofresamplingandlinearinterpola-tionyieldinga∼0.2nstimeresolution.Cali-brationissuesencompassingtheuseofsingle-peruns,muonringdataandflatfieldingweresum-marisedby[26].[32]alsodiscussedtheuseoflasershotsasawaytocorrectforlocalatmo-spherics.Adataanalysischainoutlinedby[17]focusedonthespecificeventdisplayandVEGAS[13]packages.Togethertheyhandletheimagefor-mation(fromFADCs),imagecalibration,cleaning(employingawell-knownpicture/boundaryphilos-ophy)andstereoreconstructionofeventdirection.Asforanynewinstrumentsuchasthis,observa-tionsoftheCrabprovidethefirstrealtestandre-sultshaveclearlymetexpectationsgleanedfromearlierMonte-Carlo(MC)studies[40](seeFig.1).OveralltheVERITASarrayprovidesaneventwiseangularresolutionbetterthan0.14◦anda5σde-tectionofa10%Crabfluxinunder1hour.Withalloftheseresults,it’snowclearthatVERITASisfullyfunctioningandweeagerlyawaitthenewhighenergyastrophysicstocome(see[68]forasummaryoffirstVERITASresults).TheMAGICtelescope[66]hasbeeninfulloper-ationsince2004andresultshaveflowedsteadilysince.Technicalissuespresentedatthisconfer-enceweredevotedtoupdatesoftheMAGICcam-era&electronics,improvementstodataanaly-Figure1:Top:ViewoftheVERITAS4-telescopeIACTarray[39];Bottom:VERITASfluxsensitiv-ity(Crabunits)oftheVERITASarrayforseveraltelescope(T1,T2,etc..)combinations[40].sis,andthestatusofphaseII(MAGIC-II)oftheprojectinwhichasecondtelescopewillsoonbeoperational.AnoverviewofMAGIC/MAGIC-IIwaspresentedby[21].MAGICisasinglelarge(236m2)telescopesituatedatthe2200ma.s.lontheCanaryIslandofLaPalma.TheMAGICteamhaveemphasisedtheuseofnewtechnologysuchaslightweightconstruction(forfas