Detectors Detectors for Super-Beams for Super-Beams and Neutrino Factories and Neutrino Factories Kevin McFarland Kevin McFarland University of Rochester University of Rochester NUFACT ’03 NUFACT ’03 10 June 2003 10 June 2003
DetectorsDetectorsfor Super-Beamsfor Super-Beams
and Neutrino Factoriesand Neutrino Factories
Kevin McFarlandKevin McFarlandUniversity of RochesterUniversity of Rochester
NUFACT ’03NUFACT ’0310 June 200310 June 2003
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AcknowledgementsAcknowledgements
• This summary is greatly informed by:This summary is greatly informed by:– The recent FNAL study on neutrino detectors The recent FNAL study on neutrino detectors
for super-beams for super-beams (M. Goodman and D. Harris, chairs)(M. Goodman and D. Harris, chairs)
– J-PARC J-PARC νν studies studies– BNL oscillation LOIBNL oscillation LOI– Recent Recent Annual ReviewAnnual Review on Oscillation Physics at on Oscillation Physics at
Neutrino Factories Neutrino Factories (J.J. Gomez-Cadenas, D. Harris)(J.J. Gomez-Cadenas, D. Harris)
• Thank you!Thank you!
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Organizational Preamble…Organizational Preamble…
• This is the first of two talksThis is the first of two talksreviewing detectorsreviewing detectors– André Rubbia will cover liquid ArgonAndré Rubbia will cover liquid Argon
• The rationale, courtesy of Hugh Montgomery:The rationale, courtesy of Hugh Montgomery:
“Should we hold off for liquid Argon, or “Should we hold off for liquid Argon, or should we proceed with the should we proceed with the miserable miserable technologiestechnologies we have in hand?” we have in hand?”
Miserable Technologies Miserable Technologies for Super-Beamsfor Super-Beams
and Neutrino Factoriesand Neutrino Factories
Kevin McFarlandKevin McFarlandUniversity of RochesterUniversity of Rochester
NUFACT ’03NUFACT ’0310 June 200310 June 2003
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The Catalog of MiseryThe Catalog of Misery
• Large Large черенковчеренков (Čerenkov) detectors(Čerenkov) detectors
• Low Z Sampling CalorimetersLow Z Sampling Calorimeters
• Magnetized Fe Sampling CalorimetersMagnetized Fe Sampling Calorimeters
• And their “issues”…And their “issues”…– efficiencies and backgroundsefficiencies and backgrounds– construction and funding realitiesconstruction and funding realities
for for superbeams, superbeams,
ννμμ→ν→νe e , , accept accept ννee CC. CC.
Reject Reject ππ00
for neutrino factories, for neutrino factories, ννee→ → ννμμ (gold), (gold), ννττ (silver) (silver)
accept “wrong-sign” accept “wrong-sign”
CC.CC.
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The Ground RulesThe Ground Rules
• After the present generation of superbeams After the present generation of superbeams (NUMI, CNGS), order of magnitude increases (NUMI, CNGS), order of magnitude increases in flux appear difficultin flux appear difficult– corollary: also difficult to increase the number of corollary: also difficult to increase the number of
facilities by an order of magnitude facilities by an order of magnitude
• To reach sensitivity to CP violation in To reach sensitivity to CP violation in oscillations, we must improve detectorsoscillations, we must improve detectors– size size , signal efficiency , signal efficiency , backgrounds , backgrounds – or add new capabilities, e.g., electron charge or add new capabilities, e.g., electron charge
(André)(André)
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TeragramTeragram§§-Class Water -Class Water
ČerenkovČerenkov
• Perceived widely as a “straightforward” Perceived widely as a “straightforward” extension of existing engineeringextension of existing engineering
• No shortage of proposals, e.g., Hyper-K, No shortage of proposals, e.g., Hyper-K, UNOUNO
• No shortage of sites, e.g., DUSEL, Frejus, No shortage of sites, e.g., DUSEL, Frejus, Kamioka, etc.Kamioka, etc.
• Physics case is “broad”Physics case is “broad”– proton decay, neutrino astrophysicsproton decay, neutrino astrophysics
§§Labeling this a “Megaton” detector would be an enormous public relations Labeling this a “Megaton” detector would be an enormous public relations mistake.mistake.We need to expunge this unfortunate jargon ASAP before someone overhears We need to expunge this unfortunate jargon ASAP before someone overhears us…us…
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Teragram HTeragram H22O Č : Signatures IO Č : Signatures I• Elegant proof of e/Elegant proof of e/μμ separation from Super-Kamiokande separation from Super-Kamiokande
atmospheric neutrino resultsatmospheric neutrino results– Sub-GeV single-ring dominated: “Sharpness!”Sub-GeV single-ring dominated: “Sharpness!”
FC μ cand.
e cand.
Figures courtesy M. MessierFigures courtesy M. Messier
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Teragram HTeragram H22O Č : Signatures II O Č : Signatures II (cont’d)(cont’d)• e/e/ππ00 separation is a more subtle business separation is a more subtle business
– Multi-ring topologies more difficultMulti-ring topologies more difficult– At high energies, At high energies, ππ00→ → γγγγ more “closed” more “closed”
π0 cand. e cand.
Figures courtesy M. MessierFigures courtesy M. Messier
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Teragram HTeragram H22O Č : Signatures II O Č : Signatures II (cont’d)(cont’d)• Also, many processes contribute to single-ringAlso, many processes contribute to single-ring
– Example: K2K (broadband) beam at Super-KExample: K2K (broadband) beam at Super-K
– At EAt Eνν~3 GeV, FC 1-ring ~3 GeV, FC 1-ring μμ candidates are candidates are1/3 QE, 1/3 single 1/3 QE, 1/3 single ππ, 1/3 “DIS”, 1/3 “DIS”
Figures courtesy T. KajitaFigures courtesy T. Kajita
Best fit
Noosc.
ApparentQE νμ CCat Super-K
Notefeed-down from high Eν
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Teragram HTeragram H22O Č : Signatures II O Č : Signatures II (cont’d)(cont’d)• Can avoid problems by sticking to low energy, Can avoid problems by sticking to low energy,
quasi-elastic regime (and paying a rate price!)quasi-elastic regime (and paying a rate price!)
Flux Flux (not rate)(not rate) on and off- on and off-axisaxis
Figure courtesyFigure courtesyA. KonakaA. Konaka
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Teragram HTeragram H22O Č : Signatures II O Č : Signatures II (cont’d)(cont’d)• e/e/ππ00 separation demonstrated separation demonstrated (in low E(in low Eνν OA beam) OA beam)
– but it will be a complicated multi-variate businessbut it will be a complicated multi-variate business
Figures courtesy T. KajitaFigures courtesy T. Kajita
BG
Signal
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Teragram HTeragram H22O Č : Signatures II O Č : Signatures II (cont’d)(cont’d)• Editorial commentEditorial comment: e/: e/ππ00 separation is much tougher at high energies separation is much tougher at high energies
– BNL proposal (in my view) needs more to demonstrate feasibility of this rejectionBNL proposal (in my view) needs more to demonstrate feasibility of this rejection– Background control relies onBackground control relies on
rarity of single pions at high Erarity of single pions at high Eπ0π0
– Note that single-ring events inNote that single-ring events in this region this region are mostly are mostly inelastic! inelastic!
Single πSingle π00 background vs E background vs Eπ0π0 (M. Diwan) (M. Diwan)
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Teragram HTeragram H22O Č : TechnologyO Č : Technology
• Contained detector with instrumented wall has Contained detector with instrumented wall has been extensively studied at engineering levelbeen extensively studied at engineering level
• ““Open” technology (CNGT) historically riskyOpen” technology (CNGT) historically risky
• PhotosensorsPhotosensors– figure of merit at low E: (coverage)×(quantum eff.)figure of merit at low E: (coverage)×(quantum eff.)
– is this figure of merit identical for use of His this figure of merit identical for use of H22O Č as a O Č as a neutrino target?neutrino target?
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Teragram HTeragram H22O Č : Technology O Č : Technology (cont’d)(cont’d)
• Some UNO details:Some UNO details:– depth reduced by “sideways” topologydepth reduced by “sideways” topology– two photocathode density zones to lower two photocathode density zones to lower
sensor costssensor costs• middle zone is highmiddle zone is high
density for nucleon decaydensity for nucleon decayand solar and solar νν
• edge zones loweredge zones lowerdensity: suitable for density: suitable for atmospheric and beam atmospheric and beam νν
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Teragram HTeragram H22O Č : Technology O Č : Technology (cont’d)(cont’d)
• Some Hyper-K details:Some Hyper-K details:– sideways cylinder limits depth, simplifies sideways cylinder limits depth, simplifies
geometry with beamgeometry with beam– copiouscopious
segmentationsegmentation(10 modules)(10 modules)
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Teragram HTeragram H22O Č : Technology O Č : Technology (cont’d)(cont’d)
• Photosensor R&D: can one drive down Photosensor R&D: can one drive down cost?cost?
5 inch HPD prototype5 inch HPD prototype(Shiozawa, NP02)(Shiozawa, NP02)
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Low-Z Sampling CalorimetryLow-Z Sampling Calorimetry• The concept in a nutshell:The concept in a nutshell:
– Low Z absorber in a calorimeter Low Z absorber in a calorimeter X X00 increases increases for fixed massfor fixed mass• improved resolution for electromagnetic showersimproved resolution for electromagnetic showers
– key for key for ππ00/e separation/e separation
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Low-Z Sampling Calorimetry Low-Z Sampling Calorimetry (cont’d)(cont’d)
• Issues: coping with increased size per unit Issues: coping with increased size per unit massmass– Construction/building issuesConstruction/building issues– Structural issues of absorberStructural issues of absorber– Increased number of ionization sensors Increased number of ionization sensors
• All lead to a new generation of All lead to a new generation of requirements of industrial capability for requirements of industrial capability for detector constructiondetector construction
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Low-Z: Signatures Low-Z: Signatures (cont’d)(cont’d)
In theory…In theory…
• With long XWith long X0,0, two photons two photons should rarely be should rarely be degeneratedegenerate
• Other final state Other final state particles well particles well separatedseparated
π+
e-
π0
figures courtesy A. figures courtesy A. ParaPara
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Low-Z: Signatures Low-Z: Signatures (cont’d)(cont’d)
• Preliminary efficiency and backgrounds…Preliminary efficiency and backgrounds…– with realistic detector,with realistic detector,
see see εε~10~10-3-3, few×10, few×10-4-4 for forNC, CC, respectivelyNC, CC, respectively
– maintain ~40% efficiencymaintain ~40% efficiencyfor signalfor signal
• For P(νFor P(νμμ→→ννee), see high), see high(S/√B)~40(S/√B)~40– δδmm22=2.4×10=2.4×10-3-3,,
sinsin22θθ1313=0.1, 200kTon-yr,=0.1, 200kTon-yr,4×104×102020 POT/yr NUMI POT/yr NUMI
figures courtesy L. figures courtesy L. CamilleriCamilleri
osc νe
νμ NC
“y”
hits
track h
its
track a
ng
le
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Low-Z: TechnologiesLow-Z: Technologies
• First things first… can we afford absorber?First things first… can we afford absorber?– visions of walnut shells, cracked corn, “all liquid”…visions of walnut shells, cracked corn, “all liquid”…
• Real question: can we afford Real question: can we afford structuralstructural absorberabsorber– one idea: Particle board (wood scrap + glue)one idea: Particle board (wood scrap + glue)
• very strong against compression along boardvery strong against compression along board
• laminations of sheets provide sound 3D structureslaminations of sheets provide sound 3D structures– 50 kTon of particle board is two weeks of production at one 50 kTon of particle board is two weeks of production at one
northern Minnesota plant; cost is ~15 MUSD cut & deliverednorthern Minnesota plant; cost is ~15 MUSD cut & delivered
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Low-Z: Technologies Low-Z: Technologies (cont’d)(cont’d)
• ““Containerization” and modular Containerization” and modular constructionconstruction– shipping containers (J. Cooper) appear to be a shipping containers (J. Cooper) appear to be a
cost-effective way to house modulescost-effective way to house modules
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Low-Z: Technologies Low-Z: Technologies (cont’d)(cont’d)
• Containing the container…Containing the container…
Size of 50kTon of
low-Z calorimeter
figures courtesy J. figures courtesy J. CooperCooper
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Low-Z: Technologies Low-Z: Technologies (cont’d)(cont’d)
• Ionization sensors: scintillator+WLS fiberIonization sensors: scintillator+WLS fiber– extrapolation from successful MINOS extrapolation from successful MINOS
experienceexperience– new construction facility at FNAL Lab 5:new construction facility at FNAL Lab 5:
continuous inline extrusion process continuous inline extrusion process
figures courtesy A. figures courtesy A. BrossBross
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Low-Z: Technologies Low-Z: Technologies (cont’d)(cont’d)
• New and old photosensors:New and old photosensors:– new: VLPCsnew: VLPCs
• very high QEvery high QE
• success at D0success at D0
• R&D going on nowR&D going on nowto lower costs. Enough?to lower costs. Enough?
– old: IITs, APDsold: IITs, APDspotentially significantpotentially significantcost savings!cost savings!• IITs: noise? timing?IITs: noise? timing?
• APDs: noise (cooling)APDs: noise (cooling)
• being revisited inbeing revisited indesign studies for NUMIdesign studies for NUMI
figures courtesy A. Bross,figures courtesy A. Bross,J. Nelson, R. RusackJ. Nelson, R. Rusack
•+ •-
IntrinsicRegion
GainRegion
DriftRegionSpacer
Region
Photon
•e •h
Substrate
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Low-Z: Technologies Low-Z: Technologies (cont’d)(cont’d)
• Ionization sensors: RPCsIonization sensors: RPCs– inspired by recent use at B-factoriesinspired by recent use at B-factories– reliability problems at BaBar apparently reliability problems at BaBar apparently
understoodunderstood– gas system, readout under active study for gas system, readout under active study for
NUMINUMISignal pickup (x) Resistive paint
Glass plates 8 kV
Signal pickup (y) Resistive paint
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Magnetized Sampling Magnetized Sampling CalorimetersCalorimeters• Successful construction of MINOS has bolstered the Successful construction of MINOS has bolstered the
case that this is an “easy” technologycase that this is an “easy” technology– could clearly build a longer MINOScould clearly build a longer MINOS
• Precious (“golden”, “silver”) channels at a neutrino Precious (“golden”, “silver”) channels at a neutrino factory requires identifying muon charge in DIS eventsfactory requires identifying muon charge in DIS events
• Questions:Questions:– intrinsic background levelintrinsic background level– ττ identification? (“silver”) identification? (“silver”)– can low cost teragram detector compensate for available flux can low cost teragram detector compensate for available flux
at “affordable” neutrino factory?at “affordable” neutrino factory?
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Magnetized Calor.: SignaturesMagnetized Calor.: Signatures• ννee→ ν→ νμμ, ν, νττ in presence of ν in presence of νμμ, ν, νττ (or charge (or charge
conjugate)conjugate)
• Wrong-charge background for “golden” Wrong-charge background for “golden” channel?channel?(lost)
real orfake lepton
real orfake lepton
Cervera et alCervera et al
MagnetizedScint/Fe à la
MINOS
CC ν-bar
NC ν-bar
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Magnetized Calor.: TechnologyMagnetized Calor.: Technology• ττ appearance (“silver”): OPERA technique appearance (“silver”): OPERA technique
– topological tau tag to separate from topological tau tag to separate from μμ+DIS+DIS– fully tested long before fully tested long before νν factory beam is factory beam is
available…available…
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ConclusionsConclusions• ““Teragram-class” detectors will be needed to Teragram-class” detectors will be needed to
access CP violation in oscillationsaccess CP violation in oscillations
• Superbeams:Superbeams:– HH22O Č “in the bag” but difficult at higher energiesO Č “in the bag” but difficult at higher energies
• I look forward to the BNL proponents proving me wrong!I look forward to the BNL proponents proving me wrong!
– Low-Z calorimeter work (driven by NUMI OA proposal) Low-Z calorimeter work (driven by NUMI OA proposal) looks promisinglooks promising
• Neutrino factories:Neutrino factories:– extensions of MINOS (golden), OPERA (silver)extensions of MINOS (golden), OPERA (silver)
• Or should we wait for “less miserable technology”? Or should we wait for “less miserable technology”? (André)(André)