J-PARC E15 実験に用いる 円筒形検出器群のコミッショニング 2010/9/12 秋季物理学会 佐田優太（京都大学） For the E15 Collaboration

Contents Introduction CDS Commissioning計画 Summary K中間子原子核 E15実験 CDS 励磁試験と磁場中の宇宙線のdata Magnetic Field Momentum Reconstruction Efficiency Resolution Summary

K中間子原子核 強い相互作用で反K中間子と 原子核が束縛した状態 赤石-山崎の理論計算 →少数系K中間子原子核で B.E.～100MeV →その後様々な理論計算 強い束縛により高密度？ →低温超高密度物質？？ T. Yamazaki and Y. Akaishi., Phys .Rev. C65, 044005 (2002). A. Dote, H. Horiuchi, Y. Akaishi, and T. Yamazaki., Phys. Rev. C70, 044313 (2004).

J-PARC E15実験 L neutron 3He K- p p- In-flight 3He(K-,n)反応を測定することによるK-pp束縛状態の探索 K-pp cluster neutron K- 3He 散乱中性子のMissing-Mass L p p- 生成から崩壊までの一連の反応を測定 崩壊粒子(L+p)の不変質量

J-PARC K1.8BRの現状 CDS/3He Target 3He TargetがKEKより 移送完了 現在、E17に向け準備中 5 J-PARC K1.8BRの現状 CDS/3He Target 3He TargetがKEKより 　移送完了 現在、E17に向け準備中 Beam line beamline detecoters Ready! Beam Hodoscope(BHD,PA),Chamber(PDC,BLC)等 Slit (MS etc) /kick angle (ESI) study O.K! →詳細は康君の発表にて 5

CDS Commissioning

Cylindrical Detector System 7 Cylindrical Detector System 3HeTargetからの崩壊粒子を測定しinvariant mass を求めるための検出器群 Expected mass resolution : - s ~ 3.0 MeV/c2 for L - s ~ 13 MeV/c2 for K-pp ( scdc = 200 mm / Field : 0.5 T)

CDS commissioning計画 宇宙線を使ったcommissioning BeamによるCommissioning Solenoid 磁石の性能テスト 磁場中でのCDCの性能テスト Momentum Reconstruction Efficiency Resolution dPt/Pt BeamによるCommissioning Invariant mass of K0s and L →今年10月の遅い取り出しのK－　Beam（0.9GeV/c) 　 を使用する予定 今回のTalk

Characteristic curve (B vs A) Solenoid磁石の励磁試験 Solenoid 磁石の励磁試験を行い 宇宙線のdataを得た 宇宙線data(+ beam direction) 磁場 -0.5T 5/20~5/28 　　35時間相当 ~500,000 event 磁場 +0.5T 8/30~9/4 　　　25時間相当 　　~400,000 event Characteristic curve (B vs A) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Design value (max field : 0.7T) を達成！ Field strength [T] 0 200 400 600 800 1000 Current [A]

Momentum Reconstruction Helix FittingによるMomentum Reconstructionに成功 Green up 0.517GeV/C Blue down　　0.523GeV/C Y Y X Z CDS XY Plane [cm] Z (beam direction) CDS YZ Plane [cm]

CDC Efficiency Average 99.1%を達成 定義 1.0 0.8 0.6 0.4 0.2 Average 　99.1%を達成 Efficiency 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Layer 定義 Eff= 対象LayerのHit数　　　/　　ReconstructできたTrack数 　　（trackからCell size以内の距離）　　　　　　　（対象Layerを外す）

Position Resolution Axial Layerで200~250mmを達成 Residual s=209mm 400 300 200 100 Residual [mm] Axial Layerで200~250mmを達成 Intrinsic resolutionを出すには Simulationとの比較必要 Resolution [mm] Axial Stereo Axial Stereo Axial 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Layer

Summary and future plan Solenoid磁石を励磁し、磁場中での宇宙線のdataを得た 　→その解析から、以下をほぼ期待通りに求めることができた Momentum Reconstruction Efficiency Position Resolution 以降、さらに解析を進め、１０月のBeamでのcommissioningに備える 　→E15実験に向け、CDSをReadyに

京大理，理研A，KEK B，東大理C，東大教養D，東工大理E，阪大RCNP F， 阪大理G，大阪電通大H，INFN-Torino I，INFN-LNF J，SMI K，ソウル国立大L， ミュンヘン工大M，Torino 大N，Victoria 大O 佐田優太，永江知文，平岩聡彦，藤岡宏之，飯尾雅実A，板橋健太A，岩崎雅彦A， 應田治彦A，大西宏明A，佐久間史典A，友野大A，塚田暁A，山崎敏光A，石元茂B， 岩井正明B，鈴木祥仁B，関本美知子B，豊田晃久B，石川隆C，佐藤将春C，鈴木隆敏C， 竜野秀行C，橋本直C，早野龍五C，藤原裕也C，松田恭幸D，康寛史E，徳田真E， 福田芳之E，味村周平F，井上謙太郎F，榎本瞬F，野海博之F，阪口篤志G，福田共和H， 溝井浩H，D. Faso I，O. Morra I， M. Bragadireanu J，C. Curceanu J，C. Guaraldo J， M. Iliescu J，岡田信二J，D. Pietreanu J，P. Behler K， M. Cargnelli K，石渡智一K，J. Marton K，鈴木謙K，E. Widmann K，J. Zmeskal K， H. Bhang L，S. Choi L，H. Yim L， P. Kienle M，L. Busso N，G. Beer O

Back up

Position Resolution Layer 400 300 200 100 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Layer

dPt/Pt

K0s simulation assumptions Incident momentum of K- : 900 GeV/c Target : Carbon (5mm thickness) K-p  K0s n, K0s  p-p+ ( including angular dep.) Magnetic field : 0.5 T CDC spatial resolution : 200~350 mm Nucl.Phys.B 39 (1981) 21. generated accepted

Yield estimation for K0s Yield = Nkaon x t x s x r x A x e x 1/e Nkaon : number of incident kaon per spill -> 10k/spill t : target -> 1.80 [g/cm3] / 12 [g/mol] x 6.02 x 1023 [mol-1] x 0.5 [cm] ~ 4.5 x 1022 [cm-2] s :total cross section (K-p -> K0sn) -> 7.16 x 2 [mb] r : branching ratio (K0s->p+p-) -> 0.69 A : acceptance (%) -> 14.1 [%] e : overall efficiency (trigger, detector, ana., etc)-> 0.7 1/e : vertex cut Yield ~ 1.6 x 10-1 K0s’s/spill 600 [spills/hour] x 8 [hours/shift] x 1.6 x 10-1 [K0’s/spill] ~ 7.8 x 102 K0s’s/shift

reconstructed invariant-mass reconstructed K0s -> p-p+ s = 6.1 ± 0.4 MeV/c2 ( sCDC = 200 mm )

L simulation assumptions Incident momentum of K- : 900 MeV/c Target : Carbon (5mm thickness) K-N  pL , or K-N  pS0  pgL, L  p-p ( including angular dep.) Magnetic field : 0.5 T CDC spatial resolution : 200 mm Nucl.Phys.B 115 (1976) 82. generated accepted

Yield estimation for K-np-L Yield = Nkaon x t x s x r x A x e x 1/e Nkaon : number of incident kaon per spill -> 10k/spill t : target -> 1.80 [g/cm3] / 12 [g/mol] x 6.02 x 1023 [mol-1] x 0.5 [cm] ~ 4.5 x 1022 [cm-2] s : cross section (K-n -> p-L) -> 11.3 x 2 [mb] r : branching ratio (L->p-p) -> 0.63 A : acceptance (%) -> 6.9 [%] e : overall efficiency (trigger, detector, ana., etc)-> 0.7 1/e : vertex cut Yield ~ 1.1 x 10-1 L’s/spill 600 [spills/hour] x 8 [hours/shift] x 1.1 x 10-1 [L/spill] ~ 5.5 x 102 L’s/shift Total 7.6 x 102 L’s/shift (include all reactions)

reconstructed invariant-mass reconstructed L -> p-p s = 2.1 ± 0.1 MeV/c2 ( sCDC = 200 mm )

Cylindrical Drift Chamber (CDC) 27 Cylindrical Drift Chamber (CDC) Size Inner diameter : 300 mm Outer diameter : 1060 mm Length : 950 mm Cell Hexagonal (Drift length~9mm) Layer 15 layers (7 super layers) AA’A UU’ VV’ AA’ UU’ VV’ AA’ Read out : 1816 ch Gas : Ar-C2H6 (50:50) Efficiency curve Using 90Sr Efficiency of >99% was achieved for all layers using 90Sr.

CDC test with cosmic ray 28 CDC test with cosmic ray meson2010 10-15 June 2010 Check the performance of CDC with cosmic ray By comparing with a simulation, Intrinsic resolution ~ 200 mm. Intrinsic resolution Residual cosmic ray s=206 mm

Field strength of Z dependence Characteristic curve (B vs A) 29 Design value (max field : 0.7T) を達成！ 磁場 性能 Field strength : 0.5 T (maximum field : 0.7 T) Aperture : 1.2 m Length : 1.2 m Field strength of Z dependence Characteristic curve (B vs A) 0.5 0.4 0.3 0.2 0.1 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Field strength [T] Field strength [T] -20 0 20 40 60 80 100 120 Z [cm] 0 200 400 600 800 1000 Current [A]

Setup 中性子検出器 散乱された中性子のTOFを測定する 1.0 GeV/c K- CDS K-pp→L+p の崩壊を 測定する J-PARC K1.8BR CDS　 K-pp→L+p の崩壊を 測定する (円筒形ドリフトチェンバー・ホドスコープ等) Beam sweep magnet Cylindrical Detector System Neutron TOF length 15m Beamline Spectrometer

Cylindrical Detector Hodoscope (CDH) 31 Cylindrical Detector Hodoscope (CDH) Plastic scintillation counters for trigger and PID Cosmic-ray test Size : 99 x 30 x 700 mm3 (W x T x L) Configuration : 36 modules PMT : fine-mesh type (H8409) sint = 71.1 +/- 2.9 ps Intrinsic time resolution ~ 71 ps

Experimental Setup J-PARC K1.8BR Neutron 1.0 GeV/c K- TOF length 15m 32 Experimental Setup meson2010 10-15 June 2010 J-PARC K1.8BR Neutron counter Beam sweep magnet Cylindrical Detector System Neutron 1.0 GeV/c K- TOF length 15m Beamline Spectrometer 32

Momentum Reconstruction Green up 0.342GeV/C Blue down 0.390GeV/C Z vs Y plane

Typical Event Green up 0.904GeV Blue down 1.129GeV Z vs Y plane