Systematic measurement of pd breakup cross section at quasi-free scattering Y. Eguchi a, K. Sagara a, S. Kuroita a, K. Yashima a, T. Shishido a, T. Yabe a, and S. Ishikawa b a Department of Physics, Kyushu University b Department of Physics, Science Research Center, Hosei University

31 August th International IUPAP Conference on Few-Body Problems in Physics 2 Discrepancies in 3N system 3N binding energy problem 1980’s  3NF(FM) was found 1998 pd capture A jj discrepancy pd breakup discrepancy  3NF ?  3NF ? Relativity ? ① Higher energy discrepancies pd elastic scatt. discrepancy ② Lower energy discrepancies Space Star Anomaly Quasi-Free Scatt. Anomaly ? ??? FM-3NF 1957 pd elastic scatt. C.S. discrepancy A y puzzle 1986 A y puzzle ??? Space Star Anomaly 1989 NN N π π NNN π ρ

Space Star (SS) Anomaly SS Anomaly was first found in 1989 in nd breakup reaction at 13 MeV. 31 August th International IUPAP Conference on Few-Body Problems in Physics 3 Space Star (c.m. system) equilateral triangle 90° nd exp. Erlangen & TUNL （ ● ） （ ○ ） nd calc. Space Star (1989) (1996) J.STRATE et al., Nucl. Phys. A501 (1989) 51 H.R.Setze et al., Physics Letters B388 (1996) 229 G.RAUPRICH et al., Nucl. Phys. A535 (1991) 313 pd exp. Koeln （ 1991 ） E N =13 MeV ~30% In Star configuration, outgoing 3 nucleons have the same energy and form an equilateral triangle. In Space Star (SS), the star plane is perpendicular to the beam axis in c.m. system.

Space Star (SS) Anomaly in pd breakup Recently pd calc. have become available (by Deltuva et al. and by Ishikawa). 31 August th International IUPAP Conference on Few-Body Problems in Physics 4 nd calc. pd calc. by Deltuva et al. (2005) pd exp. Koeln （ □ ） & KUTL （ ■ ） A.Deltuva et al., PRC72, (2005) (2002) E N =13 MeV nd exp. Erlangen & TUNL （ ● ） （ ○ ） nd calc. Space Star (1989) (1996) pd exp. Koeln （ 1991 ） E N =13 MeV ~30% ~15% At pd SS, exp. cross section is smaller than pd calc. At nd SS, exp. cross section is larger than nd calc.

Energy dependence of SS Anomaly SS Anomaly has a maximum at around E N = 13 MeV. 31 August th International IUPAP Conference on Few-Body Problems in Physics 5 Erlangen Bochum TUNL Koeln KUTL Space Star G. Rauprich et al., Nucl. Phys. A 535, 313 (1991). G. Grossmann et al., Nucl. Phys. A 603, 161 (1996). H. Patberg et al., Phys. Rev. C 53, 1497 (1996). K. Gebharbt et al., Nucl. Phys. A 561, 232 (1993). H. R. Setze et al., Phys. Lett. B 388, 229 (1996). Z. Zhou et al., Nucl. Phys. A 684, 545 (2001). M. Stephan et al., Phys. Rev. C 39, 2133 (1989). 90° p + d n + d ~30% ~15%

Off-plane Star An angle between the star plane and the beam axis in c.m. system is defined as an inclined angle α. –α = 90 deg. at Space Star 31 August th International IUPAP Conference on Few-Body Problems in Physics 6 Off-plane Star (c.m. system) Systematic measurements of pd breakup cross section have been started at Off-plane Star in 0° ≦ α ≦ 180 ° at E p = 9.5 MeV (E d = 19 MeV) and E p = 13 MeV (E d = 26 MeV). α

・ Anomaly exists at forward angles. → My talk Star Anomaly has different α dependence between 9.5 MeV and 13 MeV. → Maeda’s talk (nuclear forces session)  dependence of Star Anomaly 31 August th International IUPAP Conference on Few-Body Problems in Physics 7 Space Star (α = 90 deg.) α=144º α=124º J. Ley et al, (Koeln) PRC73 (2006) E N =13 MeV ~15%

Discrepancy at Quasi-free Scattering At forward angles, star configuration is close to Quasi-free Scattering (QFS) configuration. Cross section become several times larger than SS cross section. Therefore, the anomaly at forward angles, is considered to be QFS anomaly than Star Anomaly. 31 August th International IUPAP Conference on Few-Body Problems in Physics 8 ～ QFS EnEn Space Star (α = 90 deg.) 90° α = 0 deg.

QFS condition 31 August th International IUPAP Conference on Few-Body Problems in Physics 9 p + d → p 1 + p 2 + n QFS Star  =0° QFS We measure pd breakup C.S. at QFS configuration.

Experiment (pp-QFS) p-beam : E p =9.5 MeV, 13 MeV (~150 KUTL Target : CD2 foil (thickness : ~0.3mg/cm 2 ) Detector : Si-SSD (solid angle : ~0.4 msr) Observable : cross section Target thickness was monitored by using pd elastic scattering. We used accurate pd elastic C.S. to obtain absolute pd breakup C.S.. 31 August th International IUPAP Conference on Few-Body Problems in Physics 10 p-beam F.C. Si-SSD CD 2 foil CD 2 foil (Rotary target) M Monitor K. Sagara et al., Phys. Rev. C 50, 576 (1994)

Data analysis We measure Energy and Time of Flight of 2 proton. 31 August th International IUPAP Conference on Few-Body Problems in Physics 11 TOF gate background TOF gate E1 vs. E2 ΔT2-ΔT1 vs. ΔT (E2,E1) E1 vs. E2 background E1 vs. E2 B.G. subtracted S curve Raw data TOF data

Result (pp-QFS) 31 August th International IUPAP Conference on Few-Body Problems in Physics 12 QFS E p = 9.5 MeV E p = 13 MeV QFS ~10% smaller ~13% smaller

Energy dependence of QFS Anomaly 31 August th International IUPAP Conference on Few-Body Problems in Physics 13 E p = 9.5 MeV E p = 13 MeV QFS KUTL Bochum ( 1992 ) ( ) 10 ~ 13% p + d n + d ~10% ~13%

Energy dependence of QFS Anomaly 31 August th International IUPAP Conference on Few-Body Problems in Physics 14 A. Siepe et al., Phys. Rev. C 65, (2002) X. C. Ruan et al., Phys. Rev. C 75, (2007) Bonn univ. （ 2002 ） E n =26 MeV CIAE （ 2007 ） E n =25 MeV ～ 18% θ 1 = θ 2 = 42 deg. θ 1 = θ 2 = 42.2 deg. ～ 16% QFS KUTL Bochum ( 1992 ) ( ) 10 ~ 13% p + d n + d 16 ~ 18%

Energy dependence of QFS Anomaly 31 August th International IUPAP Conference on Few-Body Problems in Physics 15 ~30% ~15% Space Star 90° p + d n + d QFS KUTL Bochum ( 1992 ) ( ) 10 ~ 13% p + d n + d 16 ~ 18% Large charge asymmetry

Systematic measurement of C.S. at around QFS 31 August th International IUPAP Conference on Few-Body Problems in Physics 16 QFS E p = 9.5 MeVE p = 13 MeV θ 1 = θ 2 Star α=0 QFS Star α=0 p + d → p 1 + p 2 + n

Angle dependence of QFS Anomaly 31 August th International IUPAP Conference on Few-Body Problems in Physics 17 ① ② ③ ④ ⑤ ⑥ ⑦ E p = 9.5 MeV E p = 13 MeV ① ② ③ QFS (9.5 MeV) θ 1 = θ 2 (9.5 MeV) QFS 13 MeV θ 1 = θ 2 13 MeV ~10 % ~ 15%

Summary We performed systematic measurement of pd breakup cross section at around Quasi-free Scattering (QFS). Those experimental results were compared with the calculation included coulomb force by Deltuva et al.. Both at 9.5 MeV and 13 MeV, pd experimental data are smaller than pd calculation generally. Large charge asymmetry was found both in SS Anomaly and in QFS Anomaly; experiment > calculation at nd breakup and experiment < calculation at pd breakup. We will continue systematic experiment of pd breakup cross section to find the origin of Star Anomaly and QFS Anomaly. 31 August th International IUPAP Conference on Few-Body Problems in Physics 18

31 August th International IUPAP Conference on Few-Body Problems in Physics 19

31 August th International IUPAP Conference on Few-Body Problems in Physics 20 Discrepancies in 3N system 3N binding energy problem 1980’s  3NF(FM) was found 1998 pd capture A jj discrepancy pd breakup discrepancy  3NF ?  3NF ? Relativity ? ① Higher energy discrepancies pd elastic scatt. discrepancy ② Lower energy discrepancies Space Star Anomaly Quasi-Free Scatt. Anomaly ??? FM-3NF 1957 pd elastic scatt. C.S. discrepancy A y puzzle 1986 A y puzzle ??? Space Star Anomaly 1989 NN N π π NNN π ρ

Space Star (SS) In Star configuration, outgoing 3 nucleons have the same energy and form an equilateral triangle. In Space Star (SS), the star plane is perpendicular to the beam axis in c.m. system. Star configuration is most far from Final State Interaction (FSI) configuration. –In FSI configuration, one of relative energy = 0. –FSI enhances Cross Section. It is expected that small effects are seen in Star configuration. 31 August th International IUPAP Conference on Few-Body Problems in Physics 21 Space Star (c.m. system) equilateral triangle 90° FSI p d Relative energy = 0