The T2K Near Detector Tracker - University of Victoriakarlen/talks/t2k/lblt2k.pdfzThe J-PARC 50 GeV proton accelerator at Tokai, currently under construction, will be the highest intensity

The T2K Near Detector TrackerThe T2K Near Detector Tracker

Dean Karlen / U. Victoria & TRIUMFDean Karlen / U. Victoria & TRIUMFLBNL RPMLBNL RPM

November 4, 2004November 4, 2004

November 4, 2004November 4, 2004 The T2K TPC / Dean Karlen, U. Victoria & TRIUMFThe T2K TPC / Dean Karlen, U. Victoria & TRIUMF 22

OutlineOutlineBrief reminder of neutrino oscillation physicsBrief reminder of neutrino oscillation physics

Introduction to the T2K experiment and its Introduction to the T2K experiment and its physics programphysics program

Near detector concept for the T2K experimentNear detector concept for the T2K experimentfocus on the tracker focus on the tracker –– builds upon the ILC TPC R&Dbuilds upon the ILC TPC R&D

T2K schedule and prospectsT2K schedule and prospects


Progress in neutrino physicsProgress in neutrino physicsCompared to the generally slow, but steady, Compared to the generally slow, but steady, progress towards greater understanding in progress towards greater understanding in particle physics as a whole, progress in the particle physics as a whole, progress in the neutrino sector has been remarkably rapid:neutrino sector has been remarkably rapid:

15 years ago we were just discovering that there were 15 years ago we were just discovering that there were only 3 flavours of light neutrinos at SLC and LEPonly 3 flavours of light neutrinos at SLC and LEP

We now understand that the three neutrinos have We now understand that the three neutrinos have mass, and that their weak and mass mass, and that their weak and mass eigenstateseigenstates are are exceedingly different exceedingly different –– thanks to measurements by thanks to measurements by SuperKamiokandeSuperKamiokande, Sudbury Neutrino Observatory, , Sudbury Neutrino Observatory, KamlandKamland, and many others, and many others


Current understanding…Current understanding…The weak The weak eigenstateseigenstates are a mixture of the mass are a mixture of the mass eigenstateseigenstates::

analogous to the mixing of the weak and flavour analogous to the mixing of the weak and flavour eigenstateseigenstates in the quark sectorin the quark sectorthe states produced through weak interactions do not the states produced through weak interactions do not maintain their identity as they propagatemaintain their identity as they propagate

or in other words, they oscillate (or as W says: “flipor in other words, they oscillate (or as W says: “flip--flop”)flop”)

=

3

2

1

321

321

321

ννν

ννν

τττ

µµµ

τ

µ

UUUUUUUUU eeee


Current understanding…Current understanding…The probability for a neutrino to be detected as a The probability for a neutrino to be detected as a particular flavour depends on the mixing angles particular flavour depends on the mixing angles and the relative phases of the corresponding and the relative phases of the corresponding mass mass eigenstateseigenstates::

The phase terms are given byThe phase terms are given by

∆∆mm22 –– difference in the squared masses of the mass difference in the squared masses of the mass eigenstateseigenstates (in eV(in eV22))LL –– distance the neutrino has travelled (in km)distance the neutrino has travelled (in km)EE –– the energy of the neutrino (in the energy of the neutrino (in GeVGeV))

∆E

Lm 27.1sin2

2


Current understanding…Current understanding…Mass hierarchy:Mass hierarchy:


Current understanding…Current understanding…Neutrino mixing matrixNeutrino mixing matrix


Long baseline neutrino programsLong baseline neutrino programsDirect a beam of neutrinos of a fixed energy at a Direct a beam of neutrinos of a fixed energy at a large target far enough away to reach the first large target far enough away to reach the first oscillation maximumoscillation maximum

maximize the oscillation effectmaximize the oscillation effect

First generation program: K2K First generation program: K2K from KEK to from KEK to SuperKamiokandeSuperKamiokandeconfirmed atmospheric resultsconfirmed atmospheric results

Follow up program: T2KFollow up program: T2Kfrom the new Jfrom the new J--PARC accelerator in Tokai to PARC accelerator in Tokai to SuperKamiokandeSuperKamiokande


T2K neutrino projectT2K neutrino projectThe JThe J--PARC 50 PARC 50 GeVGeV proton accelerator at proton accelerator at Tokai, currently under construction, will be the Tokai, currently under construction, will be the highest intensity proton beamhighest intensity proton beam

beam power = 0.75 MWbeam power = 0.75 MW$1.5 B budget over 7 years for phase 1$1.5 B budget over 7 years for phase 1

A neutrino A neutrino beamlinebeamline directed towards the Super directed towards the Super KamiokandeKamiokande detector was approved by the detector was approved by the Japanese government in December 2003.Japanese government in December 2003.

$160 M budget$160 M budget


JJ--PARC facility constructionPARC facility construction

Phase 1

Phase 2

Linac(Normal Conducting)

50 GeV PS

Neutrinos toSuperKamiokande

50 GeV PSExperimental Area3 GeV PS

(25Hz)

R&D for NuclearTransmutation

Linac(Superconducting)

3 GeV PSExperimental Area

11February, 2004

Linac area 3 GeV area

50 GeV area

Feb 2004


T2K collaborationT2K collaborationJanuary 2004: First official collaboration meeting January 2004: First official collaboration meeting at KEKat KEK


Geography Geography –– Off axis beamOff axis beamFor the 300 km baseline, the first neutrino For the 300 km baseline, the first neutrino oscillation maximum occurs at Eoscillation maximum occurs at Eνν ~ 0.7 ~ 0.7 GeVGeV

an off axis angle of about 2.5an off axis angle of about 2.5°° gives a narrow band gives a narrow band beam with peak energy ~ 0.7 beam with peak energy ~ 0.7 GeVGeV


Neutrino energy reconstructionNeutrino energy reconstructionUse the quasiUse the quasi--elastic charged current processelastic charged current process

dominates the cross section for low Edominates the cross section for low Eνν

SuperKSuperK detector measures detector measures muonmuon only: proton is only: proton is below below CherenkovCherenkov thresholdthreshold


MuonMuon neutrino disappearanceneutrino disappearancePrecise measurementsPrecise measurementsof of θθ2323, , ∆∆mm2323

Is sinIs sin2222θθ2323 = 1?= 1?


Electron neutrino appearanceElectron neutrino appearanceObserve Observe ννee events at SK (single electrons)events at SK (single electrons)Sensitive to Sensitive to θθ1313


The challenge…The challenge…A wide range of neutrino interactions must be A wide range of neutrino interactions must be understood in the SK detectorunderstood in the SK detector

0. 1. 2. 3. 4. 5. 6. 7. 8.neutrino energy (GeV)

0. 1. 2. 3. 4. 5. 6. 7. 8.neutrino energy (GeV)

50

100

150

200

250

300

350

250

500

750

1000

1250

1500

1750

2000

2250


The Near DetectorThe Near DetectorLocated 280 m Located 280 m downstream of thedownstream of theproduction targetproduction targetPurpose:Purpose:

measure energy spectrummeasure energy spectrumand flux and flux ×× cross cross ––sections for sections for ννµµ reactionsreactionson Oxygenon OxygenImportant processes:Important processes:

X n n

X p n 0πνν

µν

µµ

µ

→

→


Near Detector conceptNear Detector conceptWill use the UA1 magnet… most recently used Will use the UA1 magnet… most recently used for the NOMAD experimentfor the NOMAD experiment

7 m 7 m ×× 3.5 m 3.5 m ×× 3.5 m interior volume3.5 m interior volume0.2 T 0.2 T →→ 600 kW600 kW


Near Detector ConceptNear Detector ConceptNeutral current section:Neutral current section:

Use ~10 Ton of segmented Use ~10 Ton of segmented scintillatorscintillator, surrounded by , surrounded by EMEM--calorimeter to measure calorimeter to measure ππ00 productionproduction

Charged current section:Charged current section:Use active target (Use active target (scintillatorscintillator or or scintillator+waterscintillator+water) with ) with a charged particle detector toa charged particle detector tomeasure measure µµ momentum and momentum and other reaction productsother reaction products


Tracker design criteriaTracker design criteriaDesign criteria for the tracker:Design criteria for the tracker:

Good point resolutionGood point resolutiongood good muonmuon momentum resolution:momentum resolution:

goal: better than 10% at ~ 1 goal: better than 10% at ~ 1 GeVGeV, since Fermi motion , since Fermi motion limits Elimits Eνν resolution in CCQE events to that levelresolution in CCQE events to that level

Good two particle resolutionGood two particle resolutionbetter pattern recognition for more complicated eventsbetter pattern recognition for more complicated events

Good particle identificationGood particle identificationseparate electron, separate electron, ππ//µµ, proton , proton

Low massLow massto reduce multiple scattering to reduce multiple scattering –– better momentum resolutionbetter momentum resolution

Simple, proven designSimple, proven designto be built in timely manner to be built in timely manner –– there is little time for R&Dthere is little time for R&D


TPC is baseline technology choiceTPC is baseline technology choiceExcellent resolutionExcellent resolution

need low diffusion gas (include COneed low diffusion gas (include CO22, for example), for example)

Fine granularityFine granularityLow massLow massProven technologyProven technologyThe TPC gas itself can be used as an additional The TPC gas itself can be used as an additional oxygen rich target:oxygen rich target:

egeg. 2.5 m . 2.5 m ×× 2.5 m 2.5 m ×× 1 m volume of CO1 m volume of CO22 = 12.5 kg= 12.5 kg3 such modules (35 kg) would provide about 3500 3 such modules (35 kg) would provide about 3500 events per year, with very fine granularityevents per year, with very fine granularity

similar statistics as SKsimilar statistics as SK


ArAr COCO22 gas propertiesgas propertiesvery slow at low fieldsvery slow at low fields very low diffusionvery low diffusion

E (V/cm) E (V/cm)

Tran

sver

se D

iffus

ion

µm

/ √(

d [c

m])

Drif

t vel

ocity

(c

m /

µs)


TPC with COTPC with CO22

For modest fields: 200For modest fields: 200--400 V/cm (125 cm drift)400 V/cm (125 cm drift)~ 25~ 25--50 kV maximum potential 50 kV maximum potential –– no problemno problemv ~ 2 mm/v ~ 2 mm/µµs s →→ ~0.6 ms maximum drift time~0.6 ms maximum drift time

no problem given the beam spill interval (seconds)no problem given the beam spill interval (seconds)electronics can be electronics can be ““slowslow”” (cheaper, less noise)(cheaper, less noise)very small very small lorentzlorentz angleangle

minimum ionizing minimum ionizing electonelecton--ion pairs: ~91/cmion pairs: ~91/cmdiffusion: ~ 150 diffusion: ~ 150 µµm / m / √√cm cm →→ 1.7 mm max 1.7 mm max σσ

diffusion limits space resolution to ~0.3 mm per 4 mm samplediffusion limits space resolution to ~0.3 mm per 4 mm sample

gain: lower, but probably acceptablegain: lower, but probably acceptablevery sensitive to Overy sensitive to O22 contamination (electron attachment) contamination (electron attachment)

need to keep this to ~ 0.1 need to keep this to ~ 0.1 ppmppm for pure COfor pure CO22 –– a real challengea real challenge


Initial T2K TPC design ideasInitial T2K TPC design ideasGiven limited timescale Given limited timescale –– follow existing designsfollow existing designs

Gas containment and field cage: start with ALICEGas containment and field cage: start with ALICE

Outer Wall (30 mm)CO2 envelope (75 mm)

Inner Wall (30 mm)Field cage (30 mm from inner wall)

CO2 envelope provides:• electrical insulation from central cathode• thermal insulation• additional O2 barrier from drift volume


Initial T2K TPC design ideasInitial T2K TPC design ideasGas amplification:Gas amplification:

Gas electron multipliers have been shown to improve Gas electron multipliers have been shown to improve TPC performance in several small prototypes TPC performance in several small prototypes developed for the International Linear Colliderdeveloped for the International Linear Collider

reliable and easy to work withreliable and easy to work withwires require more tension and are prone to breakagewires require more tension and are prone to breakage

140 µm

50 µm


Initial T2K TPC design ideasInitial T2K TPC design ideasPossible TPC layoutPossible TPC layoutusing the largest availableusing the largest availableGEM foils (30 cm GEM foils (30 cm ×× 30 cm)30 cm)

2500.0

0 m

m


Experience with GEM Experience with GEM TPCsTPCsPrototype GEM Prototype GEM TPCsTPCs with with GEMsGEMs (developed for (developed for ILC) have shown exceptional performance:ILC) have shown exceptional performance:

For example, the University of Victoria TPCFor example, the University of Victoria TPC30 cm drift volume30 cm drift volumeDouble GEM gas amplificationDouble GEM gas amplification2 mm x 7 mm pads arranged in 8 rows2 mm x 7 mm pads arranged in 8 rows


Experience with GEM Experience with GEM TPCsTPCsExample cosmic ray events with P5 gas, 25 cm Example cosmic ray events with P5 gas, 25 cm drift distance, in a magnetic field:drift distance, in a magnetic field:

transverse diffusion reduced with increasing B fieldtransverse diffusion reduced with increasing B field

B=0T B=0.9T B=2.5T B=4.5T


Expected resolution for T2K TPCExpected resolution for T2K TPCCOCO22 transverse diffusion: ~150 transverse diffusion: ~150 µµm/m/√√cmcm

trans

vers

e re

solu

tion

(mm

)

drift time (50 ns bins) 300 mm30 mm

B = 0, Dt = 700 µm/√cm

B = 0.9 T, Dt = 170 µm/√cm

B = 1.5 T, Dt = 110 µm/√cm

projectionfor 1250 mm

target = 0.3 mm

P5 gas• solid: data• open: MC


Two track separation powerTwo track separation powerDouble laser studies done to measure the Double laser studies done to measure the degradation of resolution as two tracks are degradation of resolution as two tracks are brought close brought close together together

Track Separation [mm]

Sin

gle

Row

Res

olut

ion

[µm

]

Track Separation [mm]

Sin

gle

Row

Res

olut

ion

[µm

]


Pads for the T2K TPCPads for the T2K TPCUse 4mm square pads: many large angle tracksUse 4mm square pads: many large angle tracks

simulation of minimum ionizing tracks in COsimulation of minimum ionizing tracks in CO22

Drift distance: 10 - 50 cm

Drift distance: 130 cm

only 25 cm sectionsof tracks are shown


Expected performanceExpected performanceFor 4 mm samples, we expect to be able to For 4 mm samples, we expect to be able to achieve 300 achieve 300 –– 400 400 µµm space point resolution per m space point resolution per sample:sample:

Measure 60 cm path length in a single TPC module:Measure 60 cm path length in a single TPC module:For a 1 For a 1 GeV/cGeV/c pptt muonmuon, 150 space points gives momentum , 150 space points gives momentum resolution contributions:resolution contributions:

~4% from space point resolution~4% from space point resolution~4% from multiple scattering~4% from multiple scattering

muonmuon charge determined to better than 3charge determined to better than 3σσ for pfor ptt < 8 < 8 GeV/cGeV/c

The TPC concept meets the initial goals for the near The TPC concept meets the initial goals for the near detector trackerdetector tracker


Neutrino events in gas targetNeutrino events in gas targetTo see what events in the gas target look like, a To see what events in the gas target look like, a sample of neutrino events were generated sample of neutrino events were generated randomly in the gas volume with the NEUT randomly in the gas volume with the NEUT Monte Carlo programMonte Carlo program

following images show some of the first 10 events in a following images show some of the first 10 events in a small gas volume, 25 cm small gas volume, 25 cm ×× 25 cm 25 cm ×× 140 cm140 cmGEANT was used to generate GEANT was used to generate dEdE in 1 mm steps, in 1 mm steps, insert the produced electrons into GEMinsert the produced electrons into GEM--TPC TPC simulation packagesimulation packageCharge collected by 4 mm Charge collected by 4 mm ×× 4 mm pads4 mm pads


Event 1Event 1

ν

E = 742 MeV π+

p⊥ = 547 MeV/c

pp⊥ = 248 MeV/c

µ−

p⊥ = 85 MeV/c

pp⊥ = 150 MeV/c

4 mm x 4 mm padscolor: relative signalamplitude:


Event 2Event 2

ν

E = 352 MeV

pp⊥ = 211 MeV/c

µ−

p⊥ = 159 MeV/c

pp⊥ = 415 MeV/c


Event 4Event 4

ν

E = 2727 MeV

pp⊥ = 280 MeV/c

µ−

p⊥ = 2636 MeV/c


Event 6Event 6

ν

E = 6572 MeV

π+

p⊥ = 170 MeV/c

pp⊥ = 50 MeV/c

µ−

p⊥ = 5846 MeV/c

pp⊥ = 1048 MeV/c

protonstops


Event 7Event 7

ν

E = 722 MeV

pp⊥ = 650 MeV/c

µ−

p⊥ = 492 MeV/c


Electronics considerationsElectronics considerationsAt most, 1 million pads (4mm x 4mm) needed to At most, 1 million pads (4mm x 4mm) needed to instrument all 3 TPC modules (both sides).instrument all 3 TPC modules (both sides).

Need to keep electronics cost and power Need to keep electronics cost and power consumption under control:consumption under control:

Use slow shaping & sampling times:Use slow shaping & sampling times:1 1 µµs sampling s sampling →→ 1 mm resolution in drift direction per sample1 mm resolution in drift direction per sample

more than adequatemore than adequateUse faster ADCs to sample many pads without analog memoryUse faster ADCs to sample many pads without analog memory

ieie. multiplex in the time domain. multiplex in the time domain

Develop an ASIC solution?Develop an ASIC solution?


MultiplexingMultiplexingTo reduce the number of A/D elements, To reduce the number of A/D elements, multiplex in time:multiplex in time:

Put as much on back of readout pad board as possiblePut as much on back of readout pad board as possiblebring out data on optical linksbring out data on optical links

preamp + sample & hold

switch

ADC

1 MHz

n MHz

n pads

ASIC

control, 0 supp, encoding

FADC

FPGA


R&D underway: proof of conceptR&D underway: proof of conceptPrototype gas containment and field cage in design Prototype gas containment and field cage in design

125 cm drift, 60 cm x 30 cm125 cm drift, 60 cm x 30 cmtest field cage design, look for attachmenttest field cage design, look for attachmentuse high density, slow electronicsuse high density, slow electronics

discrete components to prove multiplex concept for ASIC designdiscrete components to prove multiplex concept for ASIC designdemonstrate space point resolution in test beamdemonstrate space point resolution in test beam


Near detector organizationNear detector organizationLed by Tsuyoshi Led by Tsuyoshi NakayaNakaya (Kyoto) with working groups:(Kyoto) with working groups:

Tracking groupTracking group (mainly (mainly TPC+Magnet+FGDTPC+Magnet+FGD))convener: Akira convener: Akira KonakaKonaka (TRIUMF, CANADA)(TRIUMF, CANADA)deputydeputy--convener: Pier convener: Pier LoverreLoverre (Rome, Italy)(Rome, Italy)

EM groupEM group (mainly EM cal, side MRD, (mainly EM cal, side MRD, ππ00 detector)detector)convener: Kevin McFarland (Rochester, USA)convener: Kevin McFarland (Rochester, USA)deputydeputy--convener: Dave convener: Dave WarkWark (Imperial, UK)(Imperial, UK)

Neutrino Beam Monitor groupNeutrino Beam Monitor group (on(on--axis axis detdet., ., muonmuon monitor)monitor)convener: Tsuyoshi NAKAYA (Kyoto, Japan)convener: Tsuyoshi NAKAYA (Kyoto, Japan)

Software/Physics simulation groupSoftware/Physics simulation groupconvener: Federico Sanchez (Barcelona, Spain)convener: Federico Sanchez (Barcelona, Spain)deputydeputy--convener: Clark McGrew (Stony Brook, USA)convener: Clark McGrew (Stony Brook, USA)


Near detector scheduleNear detector scheduleDecember 6December 6--8, 20048, 2004

Near Detector meeting in RomeNear Detector meeting in Romefinalize conceptual design of near detectorfinalize conceptual design of near detector

March 6March 6--12, 200512, 2005Near Detector and Collaboration meeting at KEKNear Detector and Collaboration meeting at KEKfinalize “technical design report” of near detectorfinalize “technical design report” of near detector

……

April, 2009April, 2009start data taking! start data taking!


T2K scheduleT2K schedule

Beam Test

0.2

0.0

MW

1.0

0.8

0.6

0.4

JFY2007

平成23年度平成24年度平成19年度平成20年度平成21年度平成22年度

Usage for Experiments

Usage for Experiments

Usage for Experiment

3 GeVNeutron and Muon Construction

Construction

Construction

KEK PSPower

Completion of200 MeV Linac

400 MeV Linac Construction

200 MeVon Day 1

Expected Beam Power at 3 GeV

400 MeVon Day 1

400 MeV installationin 2008-2010

JFY2008 JFY2009 JFY2010 JFY2011 JFY2012

Completionof T2K

50 GeVNuclear - Particle

T 2 K Experiment

100× K2K

10× K2K


Prospects for 2014…Prospects for 2014…Assuming the data from the near detector is Assuming the data from the near detector is sufficient to keep the sufficient to keep the systematicssystematics of the of the measurements at SK below the level of the measurements at SK below the level of the statistical uncertainties:statistical uncertainties:

After 5 years of operation (5 After 5 years of operation (5 ×× 10102121 p.o.tp.o.t), the T2K ), the T2K experiment expects to improve the precision of the experiment expects to improve the precision of the neutrino oscillation parameters, from neutrino oscillation parameters, from ννµµdisappearance:disappearance:

0.1 0.1 ×× 1010−−330.6 0.6 ×× 1010−−332.5 2.5 ×× 1010−−33∆∆mm222323 (eV(eV22))

0.010.010.10.111sinsin2222θθ2323

T2KT2KUncertaintyUncertainty

CurrentCurrentUncertaintyUncertainty

ValueValueParameterParameter


Prospects for 2014…Prospects for 2014…From From ννee appearance, sinappearance, sin2222θθ1313 can be measured. can be measured. If it is small… the sensitivity depends on If it is small… the sensitivity depends on ∆∆mm22

1313


Prospects for 2014…Prospects for 2014…Comparison by P. Huber, et al. hepComparison by P. Huber, et al. hep--ph/0403068:ph/0403068:

due primarily to correlation with due primarily to correlation with δδCPCP since since ννee appearance appearance depends on both sindepends on both sin2222θθ1313 & & sinsinδδCPCP

disentangle sindisentangle sin2222θθ1313 & & sinsinδδCPCP by operating with by operating with ννµ µ ((sinsinδδCPCP term term changes sign) and by comparing with reactor experiment changes sign) and by comparing with reactor experiment

Expectedsensitivity in2014, usingcurrent centralvalues for theother oscillationparameters


SummarySummaryNeutrino physics is making very rapid progressNeutrino physics is making very rapid progress

The T2K project has an exciting physics The T2K project has an exciting physics program that gets underway very soonprogram that gets underway very soon

Interesting detector challengesInteresting detector challengesegeg. large tracking system using GEM . large tracking system using GEM TPCsTPCs

Opportunities for new collaboratorsOpportunities for new collaborators


Extra slidesExtra slides


Comparison to NovaComparison to Nova

From K.B. McConnel andM.H. Shaevitz, hep-ex/0409028

Assumes:

95.02sin

05.02sin

eV 105.2

232

132

23213

=

=

×=∆ −

θ

θ

m

Documents

The T2K Near Detector Tracker - University of Victoriakarlen/talks/t2k/lblt2k.pdfzThe J-PARC 50 GeV proton accelerator at Tokai, currently under construction, will be the highest intensity