Measurements of Ay for the pd breakup reaction at 250MeV Yukie Maeda (CNS, Univ. of Tokyo) T. Uesaka, T. Kawabata, K. Suda, S. Sakaguchi, Y. Sasamoto (CNS, Univ. of Tokyo) H. Sakai, K. Yako, M. Sasano, S. Noji (Dep. of Physics, Univ. of Tokyo) K. Hatanaka, Y. Sakemi, A. Tamii, Y. Shimizu, Y. Tameshige, T. Matsubara, M. Takechi (RCNP) T. Sagara, T. Wakasa, M. Dozono, E. Ihara (Dep. of Physics, Kyushu Univ.) K. Sekiguchi (RIKEN) SPIN2006, October 2, 2006, Kyoto

1 Introduction; Three Nucleon Force (3NF) Study of 3NF effects Nuclear force (2NF,3NF) input Faddeev equation numerical results experimental results of 3NS TM-3NF Urbana IX-3NF CDBonn, AV18, Nijmegen I/II/93 Cross Section Spin Observables Binding Energy of 3 H, 3 He N+d scattering at intermediate energy region is good probe for 3NF effects. 135MeV/A : DCS & A y data are well reproduced by introducing 3NF!!

2 N+d elastic scattering at 250MeV p+d (K. Hatanaka et.al, PRC66(2002)044002) & n+d (Y. Maeda PhD thesis) measurements at RCNP ● pd : NN only : NN with TM-3NF : AV18+UrbanaIX- 3NF : CD-Bonn+TM’-3NF Calculations by Prof. Kamada

3 Relativistic effects Fully relativistic calculations by Witała et al. Non-Rel. Rel. NN potential Lorentz boosted potential Approx. １ Approx. ２ Relativistic effect is limited to the very backward angles. Large discrepancy indicates that we need other types of 3NF (?) More studies of 3NF at 250 MeV are important to understand this discrepancy.

4 pd breakup reaction Why are Nd breakup reactions good at this energy? E1 E2  tot  breakup  ela Cross section becomes relatively large. J. Kuroś et al., PRC66 (2002) Elastic scattering  Integration of all p Breakup reaction  Select a point on the S-curve It is important to select good kinematical configuration to search the detail of 3NF effect.

5 Analyzing powers Around the final state interaction (FSI) configuration at 200MeV J. Kuroś, Doctoral Dissertation (2002) : NN only : NN with TM-3NF : AV18+UrIX-3NF : CD-Bonn +TM’-3NF  12 =  1   2 Measurements along the S-curve around the FSI configuration (  1 =  2,  12 =0) is good probe to make a discrimination between the present 3NF models !! We chose the configuration of  p1 =  n to avoid the Coulomb force acting between two nucleons in FSI.

6 Experiment at RCNP p+d  250MeV ; Differential cross sections & A y Two protons  Detected by using double-arm spectrometer Neutron in FSI  Not detected p p n

7 Experimental procedure Configuration: (  p1 =  n = 40 deg,  1n = 0 deg)  (  p1 = 40 deg,  p2 ～ 67 deg,  12 = 180 deg) polarized proton beam E p = 250 MeV B.I. = 50 nA polarization ~ 70 %  LAS = 40deg E p1 = 50 ~ 115 MeV  GR ~ 67 deg E p2 = 116 ~ 120 MeV CD 2 target Liq D 2 target S-curve S=0[MeV]

8 Liquid deuteron target Target thickness about 30 ｍｇ / ｃｍ 2 Thickness of aramid foils 12  m Monitoring of the target thickness by the measurement of pd elastic scattering  θ p = θ d = 50.8deg (LAB) Calibration of the absolute values of the data Deuterated polyethylene （ CD2) ５ 0 ｍｇ / ｃｍ 2 Graphite

9 Missing Mass & S-curve

10 Results Vector analyzing powers   S = 7 MeV-bin  Statistical errors  Ay < 0.02 Differential cross sections  The analysis is in progress. dp breakup at 250MeV dp breakup at 200MeV Preliminary

11 Summary 250 MeV pd breakup measurements were performed at RCNP.   p1 =  n = 40 deg,  1n = 0 deg configurations were measured by detecting two protons.  S = 30 – 125 MeV range including FSI. Results  Vector analyzing powers were obtained with  Ay <  Data will be compared with the theoretical predictions with/without 3NF.  The results of the differential cross sections are coming soon.

12 Thank you for your attention.

13 Results

14 Our proposal To search the detail of the 3NF effects and make a discrimination between 3NF models, we propose to perform p+d  (p+n)+p break up measurement at …  E p = 250 MeV  Observable: A y  Configuration: (  p1 =  n = 40 deg,  1n = 0 deg)  (  p1 = 40 deg,  p2 ~ 67 deg,  12 = 180 deg) Large 3NF effects Difference between 3NF models S-curve S=0[MeV] Experiments at RCNP 250MeV d(p,p)pn ; Cross section & Ay 100MeV/A p+d  (pn)1So + p ; Cross section, Ay, Ayy, Axx, Axz

15 Kinematics  1,  n = 29 – 31 deg (dashed lines) S = 80 – 170 MeV ; E 1 = 115 – 50 MeV Data points  A y ; 7 points,  A y = 0.01 – 0.02  K y y’ ; 2 points,  K y y’ = 0.04

16 Coulomb interaction It is difficult to include Coulomb force into the Faddeev calculations.  Comparison between d+n Faddeev calculations and d+p data. How large is the Coulomb effect in the intermediate energy region?  Calculation including Coulomb force approximately.  Data is well reproduced by including the Coulomb force at the forward angular region.  Large difference between calculations with/without Coulomb interaction. NN:AV14 calculations by Prof. Koike

17 2  -exchange 3NF models 3NF modelabcd FM TM Urbana IX TM’ p-wave s-wave b, d a c