核スペクトロスコピーー K1.8 B.S. & SKS ー

高橋　俊行KEK

J-PARC Online/DAQ W.S.

Contents

1. 核スペクトロスコピー2. 装置　 K1.8 Beamline と SKS

3. High rate での Chamber の考察4. 必要な回路のチャンネル数5. まとめ

Hypernuclear Spectroscopy

• potential in nuclei– -N interaction (S=2 Baryon-Baryon Int.)– E.O.S. of Neutron Star Core

• N-(-H) Mixing– ~28MeV difference N-– ~75MeV for -– ~300MeV for N-

実験方法• (K,K+) reaction spectroscopy

– p + K + K+

– P(K) = 1.8GeV/c measured by B.S.– P(K+) = ~1.3GeV/c measured by SKS– 23 MeV/c2(FWHM) resolution

• Target mass dependence– CH2, 12C, 28Si, 51V, ..., 208Pb

Theretical Prediction2MeV FWHM Resolution

58Ni(K,K+) 208Pb(K,K+)

FoldingWood-Saxon

V0=24MeVV0=16MeV

FoldingWood-Saxon

V0=24MeVV0=16MeV

bound region bound region

MHY-MA [MeV] MHY-MA [MeV]

Hadron Hall Layout

K1.8

Elec. HatRef. Cntrl. Hat

ES1

ES2

K1.1BR

K1.1

KL

T1

Upgraded SKS

Beam Spectrometer

MS2

FF

K1.8 Beamline50GeV-15A 30GeV-9A

Max. Mom. [GeV/c] 2.0

Length [m] 48.853

Acceptance [msr %] 1.4

K Int.@FF [ppp]

1.8GeV/c 6.6 x 106 1.0 x 106

1.1GeV/c 3.8 x 105

K/@1.8GeV/c 8 6.9

X/Y Size @FF [mm] 19.8 / 3.2

Singles Rate @FF 7.4 x 106 1.1 x 106

@MS1 4 x 107 6 x 106K +

Beam Spectrometer 上流側K decay x 3 の混入 x 2

Wire Chamber でどこまで測れるか？

M/spill46.03

100102 5

現在の K6/SKS の状況• 5mm cell size DC• 3.6M/Spill (Spill=1.4sec)• p/ ~0.1• BeamSize@DC ~10cm• drift time ~50ns• ~ 75ns

Total

/ wire

Singles Rate は？

200kHz/wire を目標にすると

3mm cell size10cm beam sizeext. time ~0.6 sec

140kHz 100/5

102.83

MHz83.24.1

)1.01(106.3

6

6

B.S.の下流側はOK

MWPC では？M/spill126.0

1

100102 5 1mm MWPC

10cm beam sizemm289.0121mm/

cluster sizeが１となれば、 rate的にも位置分解能的にも問題はない。

実際には、斜め入射や Accidental で CS が大きくなるかも？

ノイズを落とすため、時間情報も欲しい。• Trigger 前後 100ns 程度の ON/OFF 情報

１０ ns 程度の分解能で• Multi-hit TDC で L.E./T.E. を Wire 毎に記録する。

Beam Spectrometer @ K1.8BL

QQ

Q

Q

D

VI

VO

FF

MS2

• QQDQQ Spectrometer• VI->VO point to point optics

• <X|> = 0• <X|X> = -0.44• <X|> = 1.57cm/%

BC1,2

BC3,4

BH1

BH2BAC1,2

p/p ~1.4x10

x~0.2mm

Detectors of Beam SpectrometerSize [mm2] #layers #chan. #cards

BC1 200 x 100 1mm MWPC 6 1248 78

BC2 200 x 100 6 1248 78

BC3 200 x 100 3mm cell size DC

6 480 30

BC4 200 x 100 6 480 30

Size [mm2] #Seg. #PMTs

BH1 150 x 100 Plastic. 12 24

BH2 150 x 100 Plastic. 5 10

BAC 100 x 100 ２台必要 2/4

BGC 必要か？ 1

Multi-timing の MWPC encoding system か Drift Chamber 的な読出し

HR-TDC のほかにMulti-hit TDC での読出しも行いたい。（ Rate の高い Counter ）

K1.8 Spectrometer (SKS)

SKS (395A,2.7T)

New DipoleMagnet~1.5T30cm gap

=1325mm

Total Bend Angle85 degree

950 mm

DC1

DC2DC3

DC4DC5X

DC5Y

TOFAC1

AC2LC

Detectors of SKS (wire chambers )

Size [mm2] #layers #chan. #cards

DC1 250 x 200 3mm cell size DC 6 350 22

DC2 400 x 250 4 640 40

DC3 800 x 450 5mm Hex. cell DC 4/8 384/768 24/48

DC4 1000 x 700 既存 4 80 5

DC5X 1000 x 1000 既存 6 144 12

DC5Y 1000 x 1000 既存 6 144 12

read by multi-hit TDCboth Leading Edge & Trailing Edge

t~0.5ns, F.S. 2-5sec, 16depths

Detectors of SKS (PMTs)

Size [mm2] #Seg. #PMTs

TOF1 1050 x 1000 既存 15 30

AC1 1100 x 1100 既存 40

AC2 1200 x 1200 既存 40

LC 1400 x 1200 既存 14 28

Water Cerenkov 1 1400 x 1200 要検討 4 8

WC2 1500 x 1200 要検討 5 10

Read by ADC & HR-TDC (25ps/ch)

まとめ• Hypernuclear Spectroscopy @ K1.8

– Beam Spectrometer & Upgraded SKS Spectrometer

• Rate に強く、物質量の少ない位置検出器が重要– 1mm MWPC– 3mm DC– Max 200kHz に耐えうる回路（ Amp-Shaper-Discri.)

• 必要なチャンネル数– 6000 ch. for wire chamber (Multi-hit)

• 2500 for MWPC

– 200 ch. for PMTs (ADC, HR-TDC)