1. Proposal for Experiment at RCNP Measurement of Proton-Induced Subthreshold Pion Pair Production ( p+A    +  +X ) Atsushi Sakaguchi (Osaka Univ.)

2. 5 August, 2004RCNP B-PAC 2 Physics Motivation L QCD and strong interaction Chiral symmetry is broken dynamically Origin of constituent quark mass Pion as Goldstone boson Gap: QCD and low energy phenomena

3. 5 August, 2004RCNP B-PAC 3 How can we prove it to be true ? Phase transition broken  conserved High temperature (T>200MeV) High baryon density (>10 0 ) Transient phenomena, dynamical effects Partial restoration of symmetry Precursor of phase transition Nuclei as static environment with finite baryon density (0<< 0 ) 

4. 5 August, 2004RCNP B-PAC 4 Meson productions in nuclei  meson (two pions) CHAOS :   +A    +  +X Crystal Ball:   +A    +  +X TAPS : +A    +  +X // mesons KEK-E325 : p+A  e + +e  +X Still not clear Drastic effect, elementary proc., absorption    

5. 5 August, 2004RCNP B-PAC 5 CHAOS Drastic change in     channel Spike in M  <300 MeV/c 2 Elementary process seems to be not simple (pion induced)

6. 5 August, 2004RCNP B-PAC 6 TAPS R Pb/C has spike in M  <300 MeV/c 2 Elementary process seems to be simple ( induced)

7. 5 August, 2004RCNP B-PAC 7 Proposed Experiment p+A  +  +X Subthreshold Sensitive to low M  component Cross section enhancement Modification of M  shape Target mass dependence (future) Subthreshold CERSIUS PRL 88 (2002) 192301

8. 5 August, 2004RCNP B-PAC 8 Cross section Simple model calculation Realistic Fermi motion Experimental pp    pp cross section Target nucleon binding effect MC calculation   1nb/nucleon (@416MeV) Strong T beam dependence 1.34nb 0.74nb 0.38nb

9. 5 August, 2004RCNP B-PAC 9 Existing Setup Ohsho spectrometer at WSS Large acceptance Efficient   trigger Improve   /p ratio 2.5 orders About 4M   /day

10. 5 August, 2004RCNP B-PAC 10 Preliminary spectrum Search for     like pairs Byproduct of R&D for pnp experiment T Beam =392MeV 8 hours run with Cu target (2.7 h live time) One   and another h + Sensitivity down to 0.1nb/nucleon

11. 5 August, 2004RCNP B-PAC 11 New Experiment Proposal About 100 times larger yield Establish     measurement Present yield is too few Discuss     production more clearly M , p  and   distributions First step to measure A-dependence At least 2 more targets

12. 5 August, 2004RCNP B-PAC 12 System Update DAQ Decrease dead time Optimize DAQ sequence VME+FASTBUS Double memory buffer in VME High statistics Beamtime Beam energy 10 (8h80h) 3 (0.4nb1.3nb)

13. 5 August, 2004RCNP B-PAC 13 New trigger Two track trigger 2 cluster in Outer hodoscope (available) 2 cluster in CDC hits (need update) Combination of Outer and CDC hits Trigger system w/ ULM (FPGA based)

14. 5 August, 2004RCNP B-PAC 14 CDC-Outer trigger Offline analysis results

15. 5 August, 2004RCNP B-PAC 15 Requests Beam time Trigger study: 1 day Detector tuning: 1 day Physics run: 4 days Budget ULM: 600,000 yen Cables: 200,000+150,000 yen

16. 5 August, 2004RCNP B-PAC 16 Accidental Coincidence Next Bunch Next Bunch 1%1%

17. 5 August, 2004RCNP B-PAC 17  opening angle (MC) 70