J-PARC ハイパー核実験でのビーム Tracking 　 Detector

高橋俊行（ KEK ）

•　 J-PARC 施設の概要•　実験方法•　考えうる検出器

•　 0.5mm spacing MWPC• Silicon Strip Detector

• まとめ

J-PARC Facility

Linac(350m)

3 GeV Synchrotron(25 Hz, 1MW)

50 GeV Synchrotron(0.75 MW)

Neutrino to Kamiokande

Nuclear and ParticleExperimental Facility

(HD-Hall)Materials and Life ScienceExperimental Facility

Nuclear Transmutation

J-PARC = Japan Proton Accelerator Research Complex

Phase 1 & Phase 2

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

30 GeV – 9A50 GeV – 15A

HDHall@Phase 1

K1.8K1.8BR

K1.1/0.8

T1

Primary Beam• 30GeV-9A

(180MeV LINAC)• 30GeV-15A

(400MeV LINAC) flat-top 0.7sec duration 3.64sec

Phase2• 50GeV-15A flat-top 0.7sec duration 3.52sec

Experimental Method

Beam Spectrometer

Target

Scattered ParticleSpectrometer

Decay ParticleDetectors (Opt.)

Measure trajectories, mom. of beam & scattered particles event by event.• Missing Mass (Hypernulcear states)

tracking detectors

Single Reaction SpectroscopyCoincidense with DPD

tagging hypernuclear states

Position resolution 200m – 1mm

SecondaryBeam

, K

(K,K+) -hypernuclei(K,) -hypernuclei

Beam Intensity (30GeV-9A)

K1.8 K1.8BR K1.1/0.8

Max. Mom. [GeV/c] 2.2 1.1 1.1

K Intensity [ppp]

1.8 GeV/c

1.1 GeV/c

0.8 GeV/c

2.0x106

1.0x105 2.0x106

4.0x105

2.0x106

4.0x105

K/ 2.6 (1.8GeV/c) 12 (1.1GeV/c) 4.7 (1.1GeV/c)

Beam Rate [/sec] 4.6x106 3.6x106 4.0x106

PS-K6 Beam Chamber• 5mm spacing DC• 2.4mm between anode wires

and cathode planes • Ar:iso-C4H10 = 80:20• 2.5mm drift length• <100ns drift time• Single-hit TDC• ~250m

K6 beam• 3.3x106 [/pulse]• 1.7sec flat top• ~2.0x106 [/sec]• 2-10cm @DC

J-PARC Phase1 では、充分使える。 Multi-hit TDC

upgrade of pre-amp. & discriminator

Beam Intensity (50GeV-15A)

K1.8 K1.8BR K1.1/0.8

Max. Mom. [GeV/c] 2.2 1.1 1.1

K Intensity [ppp]

1.8 GeV/c

1.1 GeV/c

0.8 GeV/c

9.6x106

6.0x105 9.1x106

1.7x105

9.1x106

1.7x106

K/ 2.3 (1.8GeV/c) 10 (1.1GeV/c) 4.3 (1.1GeV/c)

Beam Rate [/sec] 2.3x107 1.7x107 2.0x107

High rate への対応• Fine spacing wire chamber

– 0.5mm MWPC

• Semiconductor device– Silicon Strip Detector

• Fine segment scintillator hodoscope

Channel 当たりの計数率を下げる。Channel 数の増大低コスト化

0.5mm-Spacing MWPC(1998 東北大）

incident angle 10 deg.

Efficiency

Anode 12m 1.7mm

0.5mm

2600 36003200

50mm x 50mm

ClusterSize=2/CS=1

Ar:iso-C4H10=7:3　　　 Plateau: 3.3-3.4kV CS2/CS1: 120%

Cathode

0.5mm MWPC – effect of freon -

3200

3400

3600

3800

4000

0 0.5 1 1.5 2 2.5 3

[%]

[V]

CBrF3

C2H6

not fullefficiency

Plateau 特性 Ar:iso-C4H10=7:3

0

25

50

75

100

125

0 0.5 1 1.5 2 2.5 3

[%]

CS2

/CS1

[%

]

CBrF3

C2H6

0 deg.

10 deg.

Cluster Size

CBrF3 1.5% で（安定）動作　 Plateau 幅 300V Cluster Size も許容範囲

製造中止代替 Freon Gas の必要

SSD as focal plane detectorat J-Lab E89-009

scattered electron spectrometer of (e,e’K+) experiment

2x108 electrons /sec /10 SSDs’ 0.5mm pitchSingle-sided 144 strips/board

50mm x 74mm

t~300mbinary readout withmulti-hit TDC 2x10-7 /sec/20mm は充分可能

Double-sided structure を２面以上　　　　－＞　 Track 再構成可能

Radiation Damage ?

bulk conversion 1012 p/cm2

物質量と分解能への影響[g/cm2] X0 unit E [MeV] 0 [mrad]

Gas Chamber

Ar 30cm

Al 0.02mm

5.1 x 10

5.4 x 10

1.05 x 10

2.6 x 10

2.3 x 10

5 x 10 0.021 0.125

SSD Si

0.5mm x 2 2.33 x 10 1.1 x 10 0.47 0.68

Pla. Scin. Hodoscope 2cm 2.06 4.7 x 10 4.13 1.5

Eneagy loss stragling ~1/10 of EPosition resolution 0.3mm

Pla. Scin. Hodo は分解能の必要な実験には向かない。

まとめ• 東海に建設中の J-PARC で K ビームを利用した

ハイパー核の実験が計画されている。• Phase1 でのビーム強度では、既存の技術で対応

可能。• Phase2 のフル性能では、新たな技術が必要。

– Fine spacing wire chamber (0.5mm MWPC)• CBrF3 に代わる Freon Gas, さらなる R&D

– Semiconductor Device ( SSD )• 物質量と放射線耐性

回路系の低コスト化が必要