1 K1.8BR beamline の 円筒型検出器群 (CDS) の Commissioning について Y.Sada (Kyoto-u) ストレンジネス研究 会

2 Contents Introduction Experiments of K1.8BR Status of K1.8BR CDS commissioning CDS Plan of Commissioning Result Summary

3 Experiments of K1.8BR E15 experiment Search for K  pp bounded state by using In-flight 3 He(K ,n) Reaction K-K- 3 He K - pp cluster neutron  p p -- Measuring the reaction from produce to decay of K  pp cluster Missing-Mass of neutron Invariant mass of Decayed particles (+p) E15 の物理の詳細 → 平岩さん E17 実験に関して → 橋本くん E31 実験 → 次の井上くん

4 Status of J-PARC K1.8BR beamline 4 Moving of 3 He Target from KEK Now we ready cooling test of 3 He beamline detecoters Ready! Beam Hodoscope(BHD,PA),Chamber(PDC,BLC) etc Slit (MS etc) /kick angle (ESI) study O.K! CDS/ 3 He Target Beam line

5 CDS Commissioning

6 Cylindrical Detector System Detectors to measure the decayed particles from 3 HeTarget,And get invariant mass 6 Expected mass resolution :  -  ~ 3.0 MeV/c 2 for  -  ~ 13 MeV/c 2 for K - pp (  cdc = 200  m / Field : 0.5 T)

7 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-C 2 H 6 (50:50) 7

8 Plan of CDS commissioning Commissioning by using Cosmic Ray  Test of Solenoid Magnet Test of CDC in Magnetic Field  Momentum Reconstruction  Efficiency, Resolution   Pt/Pt Commissioning by Secondly beam  p elactic scattering (monochromatic beam)  Check of Pt Resolution by defined momentum Invariant mass of K 0 s and   Check of Mass resolution and peak position

9 Cosmic Ray Data Test of Solenoid magnet and taking data of Cosmic ray Amount of data  field -0.5T (+ beam direction)  2010/5/20~5/28 total 35hour ~500,000 event  filed +0.5T  2010/8/30~9/4 25hour ~400,000 event Characteristic curve (B vs A) Current [A] Field strength [T] Achieved Design value ! (max field : 0.7T)

10 CDC Efficiency Achieved Average 99% over! Efficiency Layer definition Eff= Num of Hit of the layer / Num of Reconstructed Track （ hit is in cell size) （ without the layer of measurement ）

11 XTCurve Axial Layer (Layer 1) Stereo Layer (Layer 4)

Residual [m] Layer AxialStereoAxialStereoAxial Residual of Hit Position Achived 200~350  m To get Intrinsic resolution, Need to comparie with Simulation =209m Residual (Layer1) Residual [m] Result of liner track

13 Data with Secondly beam     beam  (0.9GeV/c) for  p elastic scattering    beam  (0.9GeV/c) for Invariant mass of  and K 0 s Total time [h] Integrated Trigger Trigger  + (0.9GeV/c) ×10 6  trigger× CDH1hit K  (0.9GeV/c) ×10 6 K trigger× CDH2hit MaterialSize[mm]Thickness [mm](g/cm 2 ) Position [mm] Polyethylene500×5005.0(0.50)+420 C500×5005.0(0.90)+50 Cu300×3001.0(0.90)-50 Secondly beam Set up Target

14 Typical Event Pt=145MeV/c Pt=470MeV/c CDH Target

15 Other Result ( Very Preliminary ) Vertex Point Z CH 2 (5mm) Cu (1mm) C (5mm) ~40cm 10cm Invariant mass(P   ) ~4300 

16 Summary We got the data for CDS Commissioning (Cosmic ray and  /K beam with magnetic field) We successfully reconstructed tracks and got some result  CDC efficiency  Residual distribution etc. Analysis is currently in progress

17 Backup

18 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 崩壊幅 20~30MeV → 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, (2002). A. Dote, H. Horiuchi, Y. Akaishi, and T. Yamazaki., Phys. Rev. C70, (2004).

19 Purpose of Commissioning with Cosmic Ray To Get the resolution of Pt  P=√2 P down -P up /(P down +P up ) P down P up KEK B-factory CDC : Nuclear Instruments and Methods in Physics Research A 455 (2000)

20 dPt/Pt

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24 PID P pi+ Pi- Very preliminary (no fine tune and TOF)

Efficiency Layer

26 K Trigger K/pi Pi K

27 Finding Track Method 1. Searching CDC Hit clusters in Super layers 2. To Draw line from inner axial super layer to outer axial super layer 3. Require that a cluster in mid axial layer is in SOME distance from the line Now I set allowed distance <10cm ~ 25MeV/c 4. There are some Stereo layer’s hits crossing the line

28 Estimation using Simulation π elastic scattering 9.5 x 10 2 events/shift (cos   ~ 0.42) 4.7 x 10 3 K 0 s’s/shift 4.6 x 10 3  ’s/shift (include all reactions)

29 CDC test with cosmic ray Check the performance of CDC with cosmic ray By comparing with a simulation, Intrinsic resolution ~ 200  m June 2010meson  =206  m cosmic ray Residual Intrinsic resolution

30 磁場 Field strength : 0.5 T (maximum field : 0.7 T) Aperture : 1.2 m Length : 1.2 m 30 Characteristic curve (B vs A) 性能 Design value (max field : 0.7T) を達成！ Current [A] Field strength [T] Field strength of Z dependence Field strength [T] Z [cm]

31 CDS K  pp→  +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 ) 中性子検出器 散乱された中性 子の TOF を測定 する Setup J-PARC K1.8BR Beam sweep magnet Cylindrical Detector System Beamline Spectrom eter Neutron TOF length 15m 1.0 GeV/c K -

32 Cylindrical Detector Hodoscope (CDH) 32 Plastic scintillation counters for trigger and PID Size : 99 x 30 x 700 mm 3 (W x T x L) Configuration : 36 modules PMT : fine-mesh type (H8409) Cosmic-ray test  int = /- 2.9 ps Intrinsic time resolution ~ 71 ps