Light collection in MicroBooNE

Arati PrakashMassachusetts Institute of TechnologyFermi National Accelerator LaboratoryOptical System for MicroBooNE

OutlineINSS 07/20/2011Arati Prakash 2Introduction - What is MicroBooNELight in Liquid ArgonMicroBooNE PMT System DesignOutlineINSS 07/20/2011Arati Prakash 3Introduction - What is MicroBooNELight in Liquid ArgonMicroBooNE PMT System DesignMicroBooNE ExperimentINSS 07/20/2011Arati Prakash 4170 ton Liquid Argon Time Projection Chamber (LArTPC) Examine low energy neutrino cross sectionsLow energy excess observed in MiniBooNE experiment or e? Start taking data early 2014Located on axis to the ~1GeV Booster Neutrino Beamline at Fermilab (Chicago, IL)

MicroBooNE Detector DesignINSS 07/20/2011Arati Prakash 5LArTPC: 3 wire planes with 2.5m drift in 170 tons of LAr Located in a cylindrical cryostat vessel: 4m radius x 12 m length PMT system sits along the wall behind the TPCCharge drifts to the TPC planes T~msPMT scintillation light detected T ~nsSo, the PMT system in principle can trigger the TPC

OutlineINSS 07/20/2011Arati Prakash 6Introduction - What is MicroBooNELight in Liquid ArgonMicroBooNE PMT System DesignLAr Scintillation LightINSS 07/20/2011Arati Prakash 7RecombinationExcitationIonized moleculeExcited molecule IonizationArArArAr+Ar*Ar2*Ar2*Ar2+e-

128 nmPrompt component: T ~ 6 ns (25%) Delayed component: T ~1.6 us (75%)OutlineINSS 07/20/2011Arati Prakash 8Introduction - What is MicroBooNELight in Liquid ArgonMicroBooNE PMT System DesignSystem RequirementsINSS 07/20/2011Arati Prakash 9In the MicroBooNE E = 500 V/cm, we expect 24,000 photons/MeVNeed to trigger on a 40 MeV proton (~30MeV MIP particles) for MicroBooNEFurther goal: trigger on a 5 MeV electron to see supernovae eventsDesign ConstraintsINSS 07/20/2011Arati Prakash 10PMTs must work efficiently at cryogenic temp (87K)UV light does not pass through glass - Scintillation light (128nm) must be made visible to PMTsOptimize Cost vs. coverageMaintain LAr purityAllow enough space for TPCLongevity of the SystemChoice of PMTINSS 07/20/2011Arati Prakash 1130 x 8-inch, 14-stage Hamamatsu cryogenic PMT

Gain ~10^9

Actual gain of the tubes will decrease at cryogenic temperatures and at operating voltages lower than the nominal 1700 V, which are a necessary precaution in order to reduce the risk of high-voltage breakdown in the region where the cabling passes through gaseous argon. With these combined effects, gain still remains above 107.

11Wavelength shiftingINSS 07/20/2011Arati Prakash 12Scintillation light is produced in the UV ~128nm.We coat acrylic plates with TPB mixture to shift the light into the visible, ~425 nm.(Previous experiments (ICARUS) coated PMTs directly.)

ConclusionINSS 07/20/2011Arati Prakash 13MicroBooNE will hopefully provide valuable information for LArTPC detector R&D, as well as data that will be informative for understanding the MiniBooNE observed excess etc.Come see my poster!

Thank YouMicroBooNE PeopleINSS 07/20/2011Arati Prakash 14Brookhaven LabHucheng ChenJason FarrellFrancesco LanniDavid LissauerDon MakowieckiJoseph MeadSusan DuffinVeljko RadekaSergio ResciaJack SonderickerCraig ThornBo YuKuo-Chen Wu

Princeton UniversityKirk McDonaldChangguo LuQing He

Columbia UniversityLeslie CamilleriRachel CarrGary ChengGeorgia KaragiorgiCamillo MarianiBill SeligmanMike ShaevitzBill WillisBill SippachCheng-Yi Chi

Los Alamos NationalLaboratory Gerry GarveyJackie GonzalesBill LouisChris MaugerGeoff MillsZarko PavlovicRichard Van de WaterHywel White

FermilabBruce BallerCat JamesHans JostleinStephen PordesGina RameikaJennifer RaafTinjun YangBrian RebelRich SchmittDave SchmitzJin-Yuan WuSam ZellerHerb GreenleeMike Kirby

Kansas StateUniversityTim BoltonDavid McKeeGlenn Horton-Smith

MITWilliam BarlettaLen BugelJanet M. ConradChristina IgnarraBen JonesTeppei KatoriTess SmidtArati Prakash

Michigan StateUniversityCarl BrombergDan EdmundsSaint Mary'sUniversity ofMinnesotaPaul Nienaber

Syracuse UniversityMitch Soderberg

YaleBonnie T. FlemingEric ChurchRoxanne GuenetteAndrzej SzelcJosh SpitzKinga PartykaAdam PatchEllen KleinJoseph Lozier

University ofCincinnatiRandy Johnson

University of Texasat AustinSacha KoppKarol Lang