K1.8BR beamline の 円筒型検出器群 (CDS) の Commissioning について

1. K1.8BR beamlineの円筒型検出器群 (CDS)のCommissioningについて Y.Sada (Kyoto-u) 2010/12/03 @KEK 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. neutron K-pp cluster p L p- p Experiments of K1.8BR 3He E15 experiment • Search for K-pp bounded state by using In-flight 3He(K-,n) Reaction K- Missing-Mass of neutron Measuring the reaction from produce to decay of K-pp cluster Invariant mass of Decayed particles (L+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 3He Target from KEK Now we ready cooling test of 3He CDS/3He Target Beam line • beamline detecoters Ready! • Beam Hodoscope(BHD,PA),Chamber(PDC,BLC) etc • Slit (MS etc) /kick angle (ESI) study O.K!

5. CDS Commissioning

6. Cylindrical Detector System 6 • Expected mass resolution : • - s ~ 3.0 MeV/c2 for L • - s ~ 13 MeV/c2 for K-pp • ( scdc = 200 mm / Field : 0.5 T) Detectors to measure the decayed particles from 3HeTarget,And get invariant mass

7. Cylindrical Drift Chamber(CDC) 7 • 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)

8. Plan of CDS commissioning • Commissioning by using Cosmic Ray • Test of Solenoid Magnet • Test of CDC in Magnetic Field • Momentum Reconstruction • Efficiency, Resolution • dPt/Pt • Commissioning by Secondly beam • pp elactic scattering (monochromatic beam) • Check of Pt Resolution by defined momentum • Invariant mass of K0s and L • 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) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Achieved Design value ! (max field : 0.7T) Field strength [T] 0 200 400 600 800 1000 Current [A]

10. CDC Efficiency Achieved Average 99% over! 1.0 0.8 0.6 0.4 0.2 0 Efficiency 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 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)

12. 400 300 200 100 0 Residual [mm] Axial Stereo Axial Stereo Axial 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Layer Residual of Hit Position Residual (Layer1) s=209mm • Achived 200~350mm • To get Intrinsic resolution, Need to comparie with Simulation Residual [mm] Result of liner track

13. Data with Secondly beam Secondly beam • 2010/10/22~10/24 • p +beam (0.9GeV/c) for pp elastic scattering • K-beam (0.9GeV/c) for Invariant mass of L and K0s Set up • Target

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

15. Other Result ( Very Preliminary ) Vertex Point Z Invariant mass(Pp-) ~4300 L ~40cm 10cm Cu (1mm) CH2 (5mm) C (5mm)

16. Summary • We got the data for CDS Commissioning (Cosmic ray and p/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, 044005 (2002). A. Dote, H. Horiuchi, Y. Akaishi, and T. Yamazaki., Phys. Rev. C70, 044313 (2004).

19. Purpose of Commissioning with Cosmic Ray • To Get the resolution of Pt • sP=√2Pdown-Pup/(Pdown+Pup) Pup Pdown KEK B-factory CDC : Nuclear Instruments and Methods in Physics Research A 455 (2000) 294-304

20. dPt/Pt

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

25. 1.0 0.8 0.6 0.4 0.2 0 Efficiency 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 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 • πelastic scattering 9.5 x 102 events/shift (cosqp ~ 0.42) • 4.7 x 103 K0s’s/shift • 4.6 x 103L’s/shift (include all reactions)

29. CDC test with cosmic ray 29 meson2010 10-15 June 2010 Intrinsic resolution Residual cosmic ray s=206 mm Check the performance of CDC with cosmic ray By comparing with a simulation,Intrinsic resolution ~ 200 mm.

30. 磁場 30 Design value (max field : 0.7T) を達成！ 性能 Field strength of Z dependence Characteristic curve (B vs A) 0.5 0.4 0.3 0.2 0.1 0 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Field strength [T] Field strength [T] Field strength : 0.5 T(maximum field : 0.7 T) Aperture : 1.2 m Length : 1.2 m -20 0 20 40 60 80 100 120 Z [cm] 0 200 400 600 800 1000 Current [A]

31. 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- 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

32. Cylindrical Detector Hodoscope (CDH) 32 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