1. J-PARC での YN 相互作用の研究 東北大学理学研究科 三輪浩司

2. Contents Physics background YN interaction Scattering experiment, spectroscopy Past experiments of YN scattering What did we learn?. What should we improve? Experiment at J-PARC LH 2, Fast IIT, Scifi-MPPC R&D of Scifi-MPPC Performance for MIP, proton e+ beam test @ LNS proton beam test @ CYRIC Outlook Trigger, Multi-channel readout

3. Nuclear force What is the origin? Color magnetic interaction meson exchange picture NN interaction  interaction Isospin 3/2 Spin 1 Quark Pauli effect Strong repulsive force More exchange mesons K K*,  To SU(3) flavor symmetry

4. Baryon-Baryon interaction NN interaction special aspect of BB interaction BB interaction Effect of new quark Different aspect of u,d quarks  N  exchange is forbidden.  N (S,T)=(1,3/2) quark Pauli effect S=0 NN(T=1) S=-1  N(T=3/2)  N-  N(T=1/2) S=-2  (T=2)  N-  -  (T=1)  N-  -  (T=0) S=-3  (T=3/2)  -  (T=1/2) S=-4  (T=1) S=0 NN(T=0) S=-1  N-  N(T=1/2) S=-2  N-  (T=1) S=-3  (T=3/2) S=-1  N(T=3/2) S=-2  N-  -  (T=1) S=-3  -  (T=1/2) S=-4  (T=0) S=-1  N-  N(T=1/2) S=-2  N-  (T=1)  N-  -  (T=0) S=-3  -  (T=1/2) S=-1  N-  N(T=1/2) S=-2  N-  (T=1)  N(T=0) S=-3  -  (T=1/2) S=-2  N-  -  (T=0)

5. Experimental investigation of YN interaction 2body interaction pp, np scattering deuteron Tensor force Spin dependent force Structure of Nuclei Large LS force Polarized pp, np scattering 2body interaction Bubble chamber Poor data SU(3) framework Spin dependent force Structure of  Hypernulei 1950 NN interaction YN interaction np  nppp  pp  p  p  p  0 p   p  + p   p   p   p  0 n   p  n At J-PARC! 70 90 ×

6. YN scattering observables Precise measurement Model selection Meson exchange model Quark model RGM-F NSC HC-D HC-F   p scattering

7. N(  N)=N(  beam)/10000 More Hyperon beam More fast imaging YN scattering experiment at KEK

8. Important parameter Production of   1cm Scifi (CH) (from free proton) 1M/spill beam KURAMA spectrometer acceptance (  ,   ) 1.8mb  9   / spill (  ,   ) 0.5mb  2   / spill Scattering of   Mean flight legth ~ 1.3cm  (   p) ~ 10mb (assumption) 1600    1   p scattering

9. Production target 2cm CH 2 + 2cm CH Free proton 54   Quasi free 118   Important parameter2 (  ,   ) (  ,   ) 1M/spill10M/spill 5M/spill50M/spill500M/spill5000M/spill  172/spill1720/spill17200/spill172000/spill  p scat 0.1/spill1/spill 10/spill100/spill We need Fast Imaging device We need high quality trigger @ 1M K 

10. R&D works for fast imaging Ieiri High-Speed Image Delay Tube Image duration  Electron drift J.K. Ahn LH2 target (No Imaging) Detect all state particle with spectrometer Miwa Scifi-MPPC readout Fast imaging + spectrometer

11. Read out system of SCIFI using MPPC’s Multi-Pixel Photon Counter (MPPC) New Si photo-diode consisted of multipixel of Avalanche Photo Diode (APD) operating in Geiger Mode 100 ～ 1600 pixels of APD in MPPC Output signal is the sum of each pixel Characteristics Fast time response ( < 10ns) It can operate in the high beam intensity Large gain (10 5  10 6 ) Possible to detect 1 photon Operation at the magnetic field IIT can not work at the magnetic field Can we use this detector for hyperon scattering experiment using a high intensity beam ? 1mm

12. At J-PARC 1 st target is   p scattering   production via (  ,   ) reaction using a 1.1GeV/c K - beam Forward spectrometer ＋ Cylindrical spectrometer Concept of whole experimental setup Zoom up

13. To be studied MIP Light yield Enough efficiency Slow proton Dynamic range Range analysis Total energy deposit     p     p

14. Performance check for MIP LNS-Tohoku, test beam line With 450MeV Positron beam 2007/Jan 20ch MPPC readout

15. Performance for MIP particle Prototype of Scifi-MPPC system Readout of 20ch MPPC e+ beam 1mmx1mm Fiber 20 ch Scinti. Fiber MPPC Connection between Fiber and MPPC MPPC Fiber

16. Photon number for MIP Identification of beam Required hits of upstream and downstream fibers Required these hits  two photon Check the photon number

17. Performance for proton Tohoku Univ. CYRIC 80MeV proton beam 2008/June 50ch readout

18. Purpose of this experiment Response of Scifi-MPPC system for proton Light yield Momentum resolution from Range Radiation hardness Momentum range of proton in YN scattering exp. Total 0~1.2GeV/c Stop in Scifi 0~0.4GeV/c This momentum range is accessible in CYRIC (80MeV proton)

19. Experimental setup Primary Proton beam Ekin = 77.52 MeV 1~5nA Secondary proton beam pp scattering (11~42MeV) Primary target CH 2 30, 100, 300  m Fiber bundle 5segment x 10 layer 1mmx1mm Vacuum chamber 10 -3 Pa 77.52MeV p p p’ Trigger counter 12cm from target Entrance  3mm Fiber 5segment x 10layer 20cm from target

20. Data List  (deg) trigger  ’(deg) fiber Ekin(M eV) Range (mm) 236711.31 276314.32 30.558.518.84 35.555235 385227.47.3 39.549.530.08 45 34.711 504042.116 CH 2 target p p Scif i Trigger counter p beam 77MeV Angle scan pp scattering Momentum selected proton beam to Scifi

21. Signal of proton Raw signal Proton ~250mV 1p.e. ~4mV Dynamic range (400pixel) 1p.e. (1pixel) ~ 10ch 34MeV proton ~ 120pixel Stopping proton ~ 300pixel Trigger selection Proton  OK Stopping proton  OK MIP region Proton stop Proton pass through ~250mV (single photon ~ 4mV) 40ns

22. Stop layer and Total energy deposit Stop layer Total energy

23. Trigger possibility Identify of scattering proton Total Energy deposit 1 scattering / 100 cut events ( >22MeV) Number of particle + each energy deposit     p Detect 3 particles with counter 2 particles  Counter 1 stopping particle  Energy deposit

24. Multi-channel readout Total channel of MPPC ~5000 ch We have to serialize the readout (like SSD). Serializing chip  Flash ADC Requirement of serialize Fast time response 10MHz Trigger generation Chip VA chip? (slow?) APV25 (50ns peaking time)

25. Summary We want to reveal new aspects of B.B. interaction  N,  N,  N We need high intensity beam   ~10MHz,   ~ 100MHz We have to develop high speed imaging device Fast image delay tube MPPC readout MIP mean photon number ~6 photon Proton Dynamic range is enough. Works well as range counter. Stopping proton can be triggered easily. Further works Trigger possibility Multi-channel read out

26. Typical image (Ekin=30MeV)

27. YN scattering experiment at KEK Scintillation fiber and IIT- CCD KEK-PS E289, E452  p,   p,   p elastic scattering Feasibility of SCIFI active target reaction Event number E289 pp 31 pp 30 pp ---- E452 pp 113 Problem IIT-CCD is slow There are overlaps of image @ beam intensity > 300kHz Detection of all particles in the final state is difficult

28. Experimental investigation of YN interaction Hyperon-Nucleon Scattering Difficult due to short lifetime of hyperon Poor data compared to NN scattering Structure of  hypernuclei High resolution magnetic spectrometer Gamma-ray spectroscopy using Ge detector Problem Derive two body force from complex many body system  N interaction,  N interaction ？ np  nppp  pp  p  p  p  0 p   p  + p   p   p   p  0 n   p  n

29. 大きさについて

30. Advantage of detecting all particles in the final state Remove the quasi free scattering SCIFI consists of CH Quasi-free scattering with proton in carbon nuclei should be separated from the scattering with free proton.    Scattered p  + from  n from   pp Scat’  : Momentum Scat’ angle Proton: Mom, Angle Prediction Proton: Mom, Angle Measurement Consistency check Remove quasi free  Momentum proton (GeV/c)  (degree) Free proton Quasi free scattering

31. Photon number for MIP Mean photon number ~6 photon Efficiency ( > 2 photon) ~ 95% Mean photon number > 1photon > 2photon

32. Operation in Magnetic Field Photon number with magnetic field Photon number Gain e + beam Magnet Fiber B Field Do NOT change due to the magnetic field We can use this Scifi-MPPC system as an imaging detector inside the magnetic spectrometer