Discrepancy in pd Breakup Reaction at Ep = 13 MeV K. Sagara, M. Tomiyama, S. Shimomoto, T. Ishida, T. Kudoh, S. Kuroita, T. Morikawa, M. Shiota, H. Ohira, *H. Kamada and **H. Witala Dept. of Physics, Kyushu University, Fukuoka, Japan *Dept. of Physics, Kyushu Institute of Technology, Kita-Kyushu, Japan, **Dept. of Physics, Jagiellonian University, Cracow, Poland

Backgrounds: Ay puzzle in pd and nd scattering exists at 0 < Ep and En < 30 MeV. Space Star (SS) anomaly in nd breakup is most prominent at En=13 MeV. 2  3NF effects are too small to explain these discrepancies. Questions: Does SS anomaly appear also in pd breakup at 13 MeV? Are there further discrepancies in pd breakup at 13 MeV? Experiments: We made three measurements at Ep =13 MeV 1) D(p,pp)n experiment at pp FSI 2) D(p,p)pn experiment at  p =10deg ~60 deg 3) D(p,pp)n experiment at many angle pairs around SS A new method to estimate Coulomb effects: Watson&Migdal-Faddeev approximation for pd breakup cross section is compared with pd calculation by Deltuva et al. Outlook

Ay puzzle: Systematic measurement of pd scattering Ay at Ep =2-18 MeV at Kyushu University (1994) Tornow talked about nd Ay puzzle on Monday. Ay puzzle is still an open problem since 1986.

Space Star anomaly nd exp. Erlangen & TUNL pd exp. Koeln nd calc. D(n,nn)p at En =13 MeV D(p,pp)n at Ep =13 MeV

Energy Dependence of SS

Questions: Does SS anomaly exist also in pd breakup at 13 MeV? Are there other discrepancies in pd breakup at 13 MeV? We made three experiments at 13 MeV: 1)D(p,pp)n experiment at pp FSI to study the treatment of Coulomb effects 2) D(p,p)pn experiment at  p = 10deg ~60 deg to see global feature of breakup cross section 3) D(p,pp)n experiment at wide angular range around SS to see angular dependence of SS anomaly

 1 =  2 = 20 deg. : φ 12 = 16.3 deg. θ 1 =θ 2 = 30 deg.: φ 12 = 11.2 deg. θ 1 =θ 2 = 40 deg.: φ 12 = 8.7 deg. Experiment (1) Ep =13 MeV D(p,p 1 p 2 )n near pp-FSI

D(p,p 1 p 2 )n E p =13MeV data E1 vs. E2 S-curve FSI E1 vs. E2 back ground (TOF gated) 20 deg. ΔT1-ΔT2 vs. ΔT(E1,E2) (Energy gated)

Comparison with nd-Faddeev calc. Watson-Migdal pp FSI calc. Faddeev calc. by H. Kamada D(p,pp)n at 13 MeV

Watson-Migdal FSI Formula Scattering length Effective range Coulomb penetration factor Sommerfeld parameter Slowly varying function nd breakup nn-FSI pd breakup pp-FSI

F(nd) = f(n 1 n 2 ) + f(n 1 p) + f(n 2 p) F(pd) ≈ f(n 1 n 2 )x(WM pp /WM nn ) + f(n 1 p) + f(n 2 p) WM nn (E nn ) WM pp (E pp ) (WM pp /WM nn ) E NN (MeV) 2

n+n+p calculation ↓ p+p+n calculation

WM-Faddeev calculation gives nearly the same results as pd calculation by Deltuva et al. WM-Faddeev calculation Calc. by Deltuva et al

Experiment (2): D(p,p)pn cross section at  p = 10~60 deg at Ep = 13 MeV 13 MeV p D 2 gas / vacuum 13 MeV p D 2 gas / vacuum / H 2 gas 4  m Al foil 2.2  m Havar foil For 20degree <  p For  p ≤ 20degree

D(p,p)pn at 10 degree D 2 target vacuum target H 2 target – vacuum target Ep (channel)

WM+Faddeev Deltuva etal.

Preliminary data Tentative conclusion: In D(p,p)pn inclusive cross section at  p = 10 ~ 60 degree, no discrepancy has been found. 15 degree 20 degree 10 degree

Experiment (3): D(p,pp)n cross section at around Space Star at Ep = 13 MeV p n p  1 =50.5   2 =50.5   12 =120  CM system Lab. system

D(p,pp)n cross section was measured at 23 angle pairs around SS configuration (  1 =50.5 ,  2 =50.5 ,  12 =120  )

Present data and Koeln data at SS agree well. Calc. by Deltuva nd calc pd calc

space star

 1+  2 11 22 averaged cross section There is a discrepancy in pd breakup cross section around the space star. Calc. by Deltuva

Summary Three experiments have been made on 1) D(p,pp)n cross section at pp FSI 2) D(p,p)pn cross section at  p =10deg ~60 deg 3) D(p,pp)n cross section at around the space star Cross section around pp-FSI and D(p,p)pn inclusive cross section are well reproduced by pd calculation by Deltuva et al. There is a discrepancy (10%-15%) in the cross section around the space star. Watson&Migdal-Faddeev approximation was found to be a simple and effective method to estimate pd breakup cross section.