Spin dependent momentum distribution of proton in 3 He studied via proton induced exclusive knock-out reaction CNS, Univ. of Tokyo Y. Shimizu I.Introduction a.3N system b.Proton polarization in polarized 3 He RCNP III.Result a.Comparison with calculation IV.Summary

Collaborators CNS, Univ. of Tokyo T. Uesaka, T. Kawabata, K. Itho, Y. Sasamotno, S. Sakaguchi, T. Kawahara, H. Tokieda Univ. of Tokyo H. Sakai, K. Yako, K. Sasano Kyushu Univ. T. Noro, T. Wakasa, Y. Yamada, M. Dozono RCNP, Osaka Univ. K. Hatanaka, H. Okamura, A. Tamii, H. Matsubara CYRIC, Tohoku Univ. T. Wakui, H.P. Yoshida Univ. of Miyazaki Y. Maeda

3N system The 3N bound states have been calculated by using Faddeev equation with the modern NN potentials. Under binding problem of the 3N system  B = B 2N  B exp =  0.5 ~  1.0MeV  The solution has been included 3NF. Extensions of the 3N scattering states –p+d elastic scattering Cross sectionO.K. Spin observables???  Suggest defects in spin dependence REVISIT the 3N bound state –The structure of 3 He has not been clearly understood yet. –Spin dependent momentum distribution K. Hatanaka et al., PRC 66, (2002). NN only NN + TM3NF

3-body 2-body Spin dependent momentum distribution p d J. Golak et al., PRC 72, (2005). k w/o D-state The calculated proton polarization without D-state are differ visibly from the full calculation. full calc. The momentum distribution of the proton polarization in polarized 3 He is sensitive to the small 3 He components. For the S-state alone, the proton polarization is zero independent of proton momentum. The polarization deviate from zero due to the small components, in particular S’-state. R.G. Milner et al., PLB 379, 67 (1996). S-state only full calc.

3 He(e,e’p) The 3 He(e,e’p) experiment would require.  This experiment is very demanding. The electron target asymmetries in the 3 He(e,e’p) 2 H and 3 He(e,e’p)pn can be simply related to the proton polarization in 3 He.  The experiment was carried out at MAMI.  The measured asymmetries are well reproduced by the PWIA calculations including re-scattering.  For 3-body configuration, strong re- scattering effects are observed. To study the 3 He spin structure in more detail, the measurement of the momentum distribution of these asymmetries are required. k ~ 40 MeV/c,  E ~ 1 MeV 3-body: < 20 MeV PWIA only PWIA + re-scattering J. Golak et al., PRC 72, (2005). P. Achenbach et al., EPJ A 25, 177 (2005).

3 He(p,2p) In the PWIA, the spin correlation parameter can be related to the nucleon polarization by. – 3 He(p,pN): 200 and 290 TRIUMF – 3 He(p,pN): 197 IUCF The neuron polarization is almost one due to the S- state. The proton polarization has negative value at low momentum due to the S’-state. k recoil momentum PnPn PpPp 3 He(p,pN): 197 M.A. Miller et al., PRL (1995).  E ~ 20 MeV The poor resolution (  E~20MeV) could not allow the separation of the 2-body and 3-body contributions. To study the 3 He spin structure in more detail, the high resolution (  E~1MeV) would required

New Experiment Proton polarization in polarized 3 He –The 3 He(p,2p) reaction is a suitable tool to measure the proton polarization in polarized 3 He experimentally. –The kinematical setting satisfied that the C yy of pp elastic scattering was large and independent of momentum Minimum suppression of re-scattering effects –400 MeV proton beam  Recoiled protons have E ~ 200 MeV –Large momentum transfer : q > 500 MeV/c  The re-scattering effects are small enough to extract the proton polarization from the (p,2p) reaction. High resolution –require  E = 1 MeV to distinguish 2-body and 3-body breakup.  double arm spectrometer at RCNP

RCNP Polarized 3 He target Measurement 3 He(p,2p) 2 H, 3 He(p,2p)pn Observables Differential cross section d  /d  (k = 0 – 300 MeV/c) Spin correlation parameter C yy (k = 0, 100 MeV/c) Polarized proton Energy : 392 MeV Polarization : 50 % Intensity : 50 nA Polarized 3 He target Spin exchange method Polarization ： 8% (Max. 14 %) Monitor by AFP-NMR method Calibrated by 3 He(p,  + ) 4 He

RCNP Beam Scattered proton Knock out proton GR LAS Polarized 3 He target Diode laser Beam MWDC 100 mm

Spectra of 3 He(p,2p) The resolution of 1.1 MeV allowed a clear separation into the two final state channels. The cut for the 3-body channel was made from 2.2 to 30 MeV.

Differential cross section 2-body 3-body total The cross sections normalized by the value at 0 MeV/c are consistent with other experimental data. The ratio of the 3-body to the total increases with the proton momentum.

Proton polarization in 3 He For the 2-body, our results are in good agreement with the calculation. For the total, our results are consistent with other experimental data. For the 3-body, our results are larger and same in sign compared to the calculation. R.G. Milner et al., PLB 379, 67 (1996). 2-body 3-body total The Faddeev calculation may underestimate the S’-state. OR The re-scattering mechanisms may be taken into account.

Summary Spin dependent momentum distribution of proton in 3 He –Under biding problem of light nuclei –Spin dependences of 3NF The spin correlation parameters C yy of 3 He(p,2p) 2 H and 3 He(p,2p)pn reactions were measured at RCNP for the first time. The resolution of 1.1 MeV allowed a clear separation into the two final state channels. d  /d  : consistent with existing data P p : large discrepancy with Faddeev calculation for 3-body break-up We will measure the proton polarization at high momentum region, where the D-state contribution is dominant. In future works,

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Target Polarization 3 He polarization was monitored by AFP-NMR method. In order to calibrate the 3 He polarization, we measured the C yy of the 3 He(p,  + ) 4 He reaction. Polarization was very low because of three sources. A) Magnetic field inhomogeneity at experimental hall  Improvement in the magnetic shield of Q-magnet. B) Insufficient laser power  Combination of the two or three diode lasers. C) Short relaxation time  Fabrication of the target cell with cesium coated glass. Max. 14 % Ave. 8 %