1. Pion productions in mass asymmetric 28 Si+In reactions at 400, 600, 800 MeV/nucleon Tetsuya MURAKAMI Department of Physics Kyoto University Based on Mr. Sako-kun’s upcoming PhD thesis Work 2015/6/291NuSYM15@Krakow

2. Tsang et al. Phys. Rev. C 86, 015803 (2012) RIBF HI Collisions 132 50 Sn 82 (n-rich) @200~300 MeV 124 50 Sn 74 High-density (participant region) Why  - /  + ratio ?  /  0 ~(  +1) 2.3 @ 300 MeV/nucleon

3. The symmetry pressure in high density region of neutron- rich system expels neutrons and attracts protons. 2015/6/29 3 NuSYM15@Krakow Bao-An Li et al., Phys. Rev. C 71, 014608 (2005) Suppress Y(n)/Y(p), Y(  - )/Y(  + ), etc. Prediction of transport theory

4. 2015/6/29 4 NuSYM15@Krakow NN Inelastic Scattering Most dominant channel for pion production Threshold energy ~ 290 MeV in laboratory pp  - /  + =(5 Ｎ 2 +NZ)/(5Z 2 +NZ)~(N/Z) 2 (  dominance model) Cycle of pion recreation NN→NN NN→N  N  →NN  →N  N  →    Total     production ratio as a function of asymmetric parameter 

5. Au+Au Z. Xiao et al., PRL 102 (2009) 625 J. Xie et al., PLB 718 (2013) 1510 J. Xu et al., PRC 87 (2013) 067601 G. Ferini et al., PRL 97 (2006) 202301 Z.Q.Feng and G.-M. Jin, PLB 683 (2010) 140 J.Hong, P. Danielewicz, PRC 90 (2014) 024605 2015/6/29 5 NuSYM15@Krakow Need more information on various observables

6. Japanese sub-group started pion experiments using HIMAC from 2007. RI-beam >> require large acceptance Usual beam >> small acceptance may be usable 2015/6/29 6 NuSYM15@Krakow

7. Using mass-symmetric collisions so far (N/Z) participant ≈(N/Z) proj ≈(N/Z) targ Over-simplified the situation Impossible to distinguish different moving source frames, like NN cm, participant cm, nucleus-nucleus cm etc. Better study mass-asymmetric collisions 2015/6/29 7 NuSYM15@Krakow

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9. 50cm θ lab Beam Target Range Counter Multiplicity Array Ion Chamber Target Multiplicity Array 27-58 deg. Air Vacuum Target : In ~ 390 mg/cm 2 Typical Intensity : ~ 10 7 ppp Range Counter : 14 layers (+2) of Sci. measured angle (θlab) : 30, 45, 60, 75, 90, 120 degree solid angle : 10 msr Target : In ~ 390 mg/cm 2 Typical Intensity : ~ 10 7 ppp Range Counter : 14 layers (+2) of Sci. measured angle (θlab) : 30, 45, 60, 75, 90, 120 degree solid angle : 10 msr Beam 28 Si 132 Xe Energy(AMeV)400, 600, 800 400 2015/6/29 9 NuSYM15@Krakow

10. #0~7Hit#8~13 No Hit STOP 01 23 4 counter # 5 6 7 8 9 ・・・ 12 STOP CONDITION  + →  + + μ ・ π + decay to μ + ・ μ + : Energy ~ 4 MeV : Range ~ 1 ㎜ Double pulse in one layer 10 NuSYM15@Krakow ～ 400MeV/u Pion’s are rare less than 1/100 of protons 2015/6/29

11. Counter #8 STOP Condition + #8 Double Hit ＜ π+ events ＞ 2 nd Hit – 1 st Hit time (nsec) Fit the Histogram “2 nd Hit Time -1 st Hit Time” by Cexp(- t /τ) ⇒ τ = 26.0±0.6 nsec ch7 ch8 Successfully select  + 2 nd Hit Time – 1 st Hit Time of ch8 stop events Fit curve : C*exp(- t /τ) 2015/6/29 11 NuSYM15@Krakow

12. 2015/6/29 12 NuSYM15@Krakow Using other functional form one couldn’t fit data so well so far……..

13. E bea m (MeV/nucleon)  mov (c) E 0 (MeV)N-N- N+N+ P 4000.20(0.05)37.0(4.3)13.7(2.1)0.19(0.05)0.91(0.07) 6000.19(0.04)44.1(5.0)22.6(2.9)0.63(0.13)0.75(0.05) 8000.22(0.04)51.8(5.1)26.8(2.6)1.44(0.12)0.59(0.04) 2015/6/29 13 NuSYM15@Krakow E bea m (MeV/nucleon)  exp (  + )  exp (   )  JQMD (  + )  JQMD (   ) 4000.330.630.280.38 6000.871.370.901.12 8001.412.101.682.01

14. 2015/6/29 14 NuSYM15@Krakow At 400MeV/nucleon

15. 2015/6/29 15 NuSYM15@Krakow 400 MeV/nucleon 600 MeV/nucleon 800 MeV/nucleon Simple Coulomb effect? Ratio alone can be fitted by functional form of Maheswari et al. (NP A628 (1998) 669), but differential cross sections seem to be imposible.

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18. 2015/6/29 18 NuSYM15@Krakow 400 MeV/nucleon800 MeV/nucleon

19. 2015/6/29 19 NuSYM15@Krakow Semi-analytic formula.

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21. Normalization constant: 2.02, 1.68, and 1.43 2015/6/29 21 NuSYM15@Krakow

22. 2015/6/29 22 NuSYM15@Krakow  + associated multiplicity High multiplicity event/total event

23. 2015/6/29 23 NuSYM15@Krakow E bea m (MeV/nucleon)  exp (  + )  exp (   )  JQMD (  + )  JQMD (   ) 4000.330.630.280.38 6000.871.370.901.12 8001.412.101.682.01 E bea m (MeV/nucleon)  mov (c)  JQMD (c)  CM (c)  part (c)  mid (c) 4000.20(0.05)0.31(0.02)0.180.340.42 6000.19(0.04)0.34(0.04)0.220.410.49 8000.22(0.04)0.35(0.06)0.260.460.55

24. Measured doubly differential cross sections of  + and  - for the 28 Si + In reactions at 400, 600 and 800 MeV/nucleons. They are emitted isotropically from the single moving source, whose velocity is quite slower than the mid rapidity. The differential pion ratios represented in such moving frames overlap each other at each incident energy. PHITS fails to reproduce the observed absolute cross section, the angular dependence of the cross sections and the charged pion ratio. 2015/6/29 24 NuSYM15@Krakow

25. 2015/6/29NuSYM15@Krakow 25 M, Sako1;2, T, Murakami1;2, Y, Nakai2, Y. Ichikawa1, K. Ieki3, S. Imajo1, T. Isobe2, M. Matsushita3, J. Murata3, S. Nishimura2, H. Sakurai2, R.D. Sameshima1, E. Takada4, Collaborator 1.Kyoto University 2.Riken 3.Rikkyo University 4.NIRS

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