2 nd tpc workshop paris, december 2004 marco zito1 a large tpc for the t2k neutrino oscillation...

2nd TPC Workshop Paris, December 2004

Marco Zito 1

A large TPC for the T2K neutrino oscillation experiment

Marco Zito

Dapnia-SPP

CEA-Saclay

Outline:•T2K project•Near detector•TPC studies


Marco Zito 2

The Tokai to Kamioka (T2K) project

Long baseline neutrino oscillation experiment with an intense (0.75 MW) beamOff-axis by 2.5° -> Eν peaks at 0.75 GeV

Eν

SKNear det.


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The J-PARC facility at Tokai

50 GeV PS : Budget 1.5 G$ over 7 yearsNeutrino beam line : 160 M$

1021 POT (130 days) = 1year

Site 60km NE of KEK


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J-PARC (Japan Proton Accelerator Reasearch Complex)


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Decay Volume Constructionviewed from downstream

3NBT


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Looking closer to the Decay Volume Construction


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The T2K schedule

Start data taking in 2009


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Precise measurement of Δm223 and θ23

Obs/expected5000 ev/year at SK105 ev/year at ND

1-sin2(2θ)

Δm2

νμ disappearance

Need flux and spectrum measurement at ND detector

P(νμ→ νμ)≈1- cos4 θ13 sin2

2θ23 sin2 (1.27 Δm2

23 L/Eν)

Eν(MeV)


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νe appearance and θ13 measurement

100 ev/5 years for sin2(2θ)=0.1, BKG 15

Need νe contamination at ND and study of other backgrounds

P(νμ→ νe)≈sin2 2θ13 sin2

(1.27 Δm213 L/Eν)


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The near detector at 280m

TargetNear detector

To SuperK

Aims of the near detector :•Measure flux and spectrum based on

the quasi-elastic CC reaction νn -> μ-p

(pμ ≈1 GeV/c, pproton ≈ 300 MeV/c)

•Control background to QE

•Measure νe contamination in beam

•Measure NC νn -> νn π° : background

to νe appearance in SK

cos

2/2

pEm

mEmE

N

Nrec


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Schematic of near detector

• 280 m from target• Measure the energy spectrum and the (flux • cross-

section)• Recycle the UA1 (and NOMAD) magnet : 0.2 T


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Schematic of near detector

• 5-10 tons active target : segmented scintillator (+water) surrounded by EM calorimeter for NC and π0 production

• Flux : active target + tracker to measure μ, p (π) based on the quasi-elastic reaction : νn -> μ-p

Target + Ecal Active target (scintillator bars)

2 or 3 TPC modules


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TPC schematic

•Readout : GEM or Micromegas. The first large surface (o(10m2)) readout based on micropattern!

2.5m

B (0.2T)

E (200V/cm)E

ν beam

HV membrane

2.5 m

30x30 cm2 RO detecteurs

1m


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Why a TPC ?

• Excellent spatial resolution• Excellent pattern • Low mass• dE/dx for e-μ id• Build on existing RD project for the LC • Bonus : few 103/year interactions in the gas

Typical design parameters :• 2.5x2.5x1 m3 per module (2 to 3 modules)

• Gas : Ar (Ne)-CO2 based mixture (low transverse diffusion)

• Drift 1.25 m with E=200V/cm (V=25kV)• Pad : 4 to 8 mm -> few 100 k to 1M channels

First estimations , design studies in progress !


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TPC view of a nu interaction

Thanks to Dean Karlen


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TPC design issues : field cage

Various design are considered : Various design are considered : ALICE, STAR, NA49ALICE, STAR, NA49

Issue : high efficiency for low energy protons. MC studies (F. Sanchez, IFAE) give indication that NA49-like design (more compact) is slightly more efficient

Study by Juergen Wendland (UBC postdoc)Study by Juergen Wendland (UBC postdoc)

E=200 V/cm V=25 kV (up to 50 kV)


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TPC design issues : gas mixture

• Low magnetic field (0.2 T) and long drift (1.25 m) → need low transverse diffusion

• CO2 is a good component. Drawback enhanced attachment on Oxygen

• Main component : Ar or Ne (closer to Oxygen in nuclear size)

• Various mixtures with 5 – 10 % CO2 are under study• Example : Ar-Methane-CO2 (85-10-5)• v(drift)= 2.7 cm/μs; Diffusion (T) = 230 μm/sqrt(cm); Diffusion (L) =

270μm/sqrt(cm); • Spatial resolution (diffusion term) = 420 μm (at 1.2 m drift, for 4mm

pad) • σ(pt)/pt = 4 % (for 60 cm track measurement, at 1 GeV)• Gas studies just started, will continue next year


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TPC design issues : gas amplification

GEM

OR

MICROMEGAS

Both concepts have been built and proven to work (COMPASS) Minor advantages/drawbacks each : •GEM : multistage, industrialization•Micromegas : sparks, charge spread (resistive foil ?)Both need to tackle the large surface, multidetectors problem (dead zones, mechanics, etc) !


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TPC design issues : pad geometry

Pad 8x8 mm2: CCQE at drift=60 cm, D = 300 mm/Pad 8x8 mm2: CCQE at drift=60 cm, D = 300 mm/cmcmStudy by Dean Karlen

Error budget pt / pt <10 %

pt / pt vs pt

pt / pt vs pt < 0.8 GeV/cpt / pt

pt (GeV/c)


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68 Channels

SCA

Digital Processor

(FPGA/DSP)

N x 68 channels

M x Mbits switches

600 Kchannels

Dig

itize

r

SyncTrigger1 chip

• How to build the whole system.

• How to transfer the whole set of data

TPC electronicsFirst ideas presented by F. Druillole (Saclay)

ASIC


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PAC Filters

Sampler control

Discri + decoder (selection of read part)

SCA(512 cells)

Tr

= 1

00n

s

Tsh

ap

ing

2

00n

s 2

µs Fs 1MHz to 10MHz

Anti-aliasing

Shaper

Low noise preamp

Options twoOptions two

x n

Column selector

Slow control

ADC

seri

aliz

er

ADC freq : 20MHz

50MHzOne integrated ADC/channel

TPC electronicsF. Druillole (Saclay)


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Timeline-Organisation

• Groups involved : Saclay, TRIUMF, Victoria U., Geneva U., Italy (Bari, Roma,…), Spain (Barcelona,…)

• Draft « Conceptual Design Report » : march 2005• Detector study and design : 2005• Ready to take data : 2009

• Next meeting 7-12 march 2005 at KEK• Lot of studies and prototype activity next year at

TRIUMF, CERN (Harp TPC) and Saclay


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The Saclay TPC prototype

SC magnet from NMR, field up to 2T

Thanks to Paul Colas, Vincent Lepeltier, Mike Ronan

TPC prototype with Micromegas r/o for LC, now being also used for T2K studies


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2x10 mm2 pads

1024 pads

1x10 mm2 pads

Readout anode pad plane

Berkeley Saclay OrsayChamber

diameter 50 cm length 50 cm

Copper mesh

50 m pitch

50 m gap

The TPC The TPC prototypeprototypeThe TPC The TPC

prototypeprototype

STAR electronics


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Example of Ne-CO2 (10%)Cosmic ray trackNovember 2004


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Conclusions

• The first large scale TPC based on micropattern techniques !

• Timescale : start data taking in 2009 • Plenty of opportunity to test technical solutions in a real-

size detector


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Backup slides


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Neutrino Facility overview

ND280mAug.2004 version

3NBT

Nowunder construction


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• Specification:

• Drift Time = 51 µs to 512µs• Number of cells : 512• Samples frequency : 1MHz to 10MHz• Anti-aliasing filter : 2µs• shaping time : 200ns to 2µs (discrete values)• Estimated dimension = 30mm² à 50mm²• Number of channel : 68 (Useable : 64)• Dynamic range = 10 bits• resolution : <10 bits• Input noise level < to be defined (relative to the detector gain)

The electronic must be able to adapt the signal processing in function of the gas inside the detector.

Asic cost will be negligible in the total electronic system.

Electronics specifications

2 nd tpc workshop paris, december 2004 marco zito1 a large tpc for the t2k neutrino oscillation...

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