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Systematic experiment on Star anomaly in pd break up at E / A = 9.5 MeV

Systematic experiment on Star anomaly in pd break up at E / A = 9.5 MeV. K. Ishibashi, K. Sagara S. Kimura, S. Tanaka, T. Yabe, S. Kuroita, T. Tamura, M. Okamoto, Y. Maeda 1) , Y. Ooishi 2) , Y. Ishibashi 2) , A. Ozawa 2) , Y. Tagishi 2) and T. Komatsubara 2).

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Systematic experiment on Star anomaly in pd break up at E / A = 9.5 MeV

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  1. Systematic experiment on Star anomaly in pd break up at E/A = 9.5 MeV K. Ishibashi, K. Sagara S. Kimura, S. Tanaka, T. Yabe, S. Kuroita, T. Tamura, M. Okamoto, Y. Maeda1), Y. Ooishi2), Y. Ishibashi2), A. Ozawa2), Y. Tagishi2) and T. Komatsubara2) Department of Physics, Kyushu University, 1)Department of Applied Physics, Miyazaki University 2)Department of Physics, Tsukuba University, Tsukuba, APFB2011

  2. Discrepancies in p+d reactions Discrepancies Candidate origins At high energy s, Aｙ,A ij Elastic scattering ππ3NF πρ3NF ρρ3NF relativity Breakup s, Aｙ Capture A jj At low energy Aｙ Elastic scattering 3NF? or else? Breakup s exp. on Space Star anomaly exp. on QFS anomaly Kimura’s talk (Tue.) This talk APFB2011

  3. Finding of Space Star anomaly Space Star cross section at EN=13MeV n+d→n+n+p Erlangen (1989) TUNL (1996) Koeln (1991) nd+Δ nd pd+Δ c.m. system pd Calc by A.Deltuva (2005) At Space Star configuration, three outgoing nucleons form an equilateral triangle, which is perpendicular to the beam axis p+d→p+p+n Space Star nd exp >nd calc pdexp <pd calc C.S.B. lab system Δ effects is very small Coulomb effects is small APFB2011

  4. Space Star Anomaly is a severe problem. Anomaly in cross section, that is Anomaly in a basic scalar observable. Space Star Anomaly is a difficult problem. Origin is not known. No theoretical guesses, so far. n+d→n+n+p Erlangen (1989) TUNL (1996) Koeln (1991) Calc by A.Deltuva p+d→p+p+n Space Star Our strategy Systematicexperiments on pd Star cross section. (pd data are more reliable than nd data)  Compare the pd data with pd calculations. (Reliable pd calculations by Deltuva et al since 2005)  Find characteristic features of pd Star Anomaly.  Find origin of pd Star Anomaly. APFB2011

  5. #1: First experiment around Space Star at Kyushu (2002) p+d p1+p2+nEp=13 MeV f12=120° θ2 θ１ Space Star exp/calc ratio is obtained Calc by A.Deltuva Anomaly exists not only space star but also around Space Star APFB2011

  6. #2: Second experiment on inclined Star at Koeln Ed=19MeV (=9.5MeV/A) Definition of inclination angle α α=124° Inclined Star α=144° c.m. system Inclined Star Star at α=90ºis called “Space Star” Large Anomaly, different from Space Star Anomaly, was reported by Koeln group (2005). APFB2011

  7. (#1 & #2) : α-dependence of Star Anomaly E/A = 9.5 MeV (Ed=19 MeV) E/A = 13 MeV 15% 25% KUTL #1 Koeln #2 Space Star Space Star Star Anomaly seems to occur in a wide angular region. Is it true? APFB2011

  8. #3 : Exp. on full α-distribution of Star Anomaly at 13 MeV E/A = 9.5 MeV (Ed=19 MeV) E/A = 13 MeV (Ed=26 MeV) exp./ calc. of cross section KUTL #1 Koeln #2 KUTL #3 RCNP #3 Koeln At 13 MeV, Star Anomaly occurs only around a = 90º. Is Star Anomaly different at 9.5 MeV and at13 MeV? APFB2011

  9. #4 : Exp. on Star Anomaly at Ep=9.5 MeV at KUTL E/A = 13 MeV (Ed=26 MeV) E/A = 9.5 MeV (Ed=19 MeV) exp./ calc. of cross section Koeln #2 KUTL #1 KUTL #4 KUTL #3 RCNP #3 New #5 Also at 9.5MeV,Star Anomaly occurs around a= 90º. Koeln data are out of systematic a-dependence. We started #5 experiment to confirm a-dependence. APFB2011

  10. Present Experiment (#5) Beam ：19 MeV d-beam, un-polarized Observable：only Cross Section 120º ≦ a ≦ 180º Target：CH2 foil（rotary target） Detector：Si-SSD Set up of exp. p1 p2 d-beam APFB2011

  11. Methods forprecise measurements of cross section A)Use an un-polarized beam, and measure only cross section. Polarized beam is not suitable for cross section measurement. B) Low counting rate  dead time <8%  precise dead time correction C) Well defined aperture for SSD precise estimation of solid angle Well-defined edge by electric discharge machining. Ordinary aperture edge by mechanical machining. D) Rotary CH2 (CD2) foil target  nearly constant target thickness E) Use of precise p+d scattering s to monitor beam x target. 11 APFB2011

  12. Remove back ground Raw data １ ２ True + B.G. Ｅ2[MeV] True +B.G. gate Ｓcurve Ｅ2[MeV] Ｓcurve Ｅ１[MeV] True + B.G. S=0 B.G. B.G. only gate Remove B.G. Ｅ１[MeV] B.G. only T(E1)-T(E2)[ns] Ｓcurve Ｅ2[MeV] T1-T2[ns] true mp :proton mass Ei :energy of detected proton Li :length between target and detector Ｅ１[MeV] Break up event

  13. Decide absolute value transform true pd break up Cross Section pd break up Events α=140° 0.8MeV Geometrical Measured ・length (between target and SSD) ・aperture size Fit from experimental data (K.Sagara et al (1994)) monitor

  14. Experimental Results present data Ed=19MeV (E/A=9.5 MeV) calc. by Deltuva (2005) α=180° α=160° Star Star α=120° Star α=140° Star Systematic error :5% Present data agree well with calculation. No anomaly was found at backward a. APFB2011

  15. present data Koeln data α=162.3° α=160° calc. by Deltuva (2005) α=140° α=144° α=120° α=124° APFB2011

  16. Present results(#5 experiment) Ed =19 MeV (E/A=9.5 MeV ) present data Koeln data space star exp. #5 No anomaly was seen at 120º ≦ a≦ 180º Anomaly is only seen at Space Star (a=90º) APFB2011

  17. Why the two experimental results disagree? APFB2011

  18. Conclusion from present experiment and previous experiments space star space star present data a) Star Anomaly does exist in pd breakup reaction. b) Star Anomaly occurs only around a= 90º (Space Star). c) Star Anomaly occurs similarly at E/A = 9.5 MeV and 13 MeV. APFB2011

  19. Conclusion We precisely measured pd breakup Star cross section at α =120°~180° at Ed=19 MeV (E/A =9.5 MeV). Our experimental data agree with pd calculation, contrary to Koeln data. Star Anomaly occurs only around a=90º. Only Space Star Anomaly exists Space Star Anomaly varies smoothly with energy. Our next job is to investigate origin of Space Star Anomaly. APFB2011

  20. Future Study Why anomaly occurs in the plane perpendicular (a=90) to the beam axis? In the perpendicular plane, does anomaly occuralso at FSI and/or collinear configurations? Anomaly ?? Anomaly exist Anomaly ?? APFB2011

  21. APFB2011

  22. a dependence of Cross Section APFB2011

  23. Systematic error APFB2011

  24. Energy dependence of Cross Section at Space Star APFB2011

  25. Ｓcurve １ ２ Sdefine:the length from S=0 Ｓ curve Ｓ curve Ｅ2[MeV] S=0 Ｅ１[MeV] Kinematical

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