24th European Conference on Few-Body Problems in Physics

Measurement of 3He analyzing power for p−3He scattering using the polarized 3He target

3 Sept 2019, 15:20

20m

University of Surrey

Talk Nuclei Parallel Session Tuesday: Few-Nucleon Systems

Speaker

Mr Atomu Watanabe (Tohoku University)

Description

The three-nucleon force (3NF) is essentially important to clarify various nuclear phenomena, such as the binding energy of light mass nuclei [1], the equation of state of nuclear matter [2] and few-nucleon scattering systems [3]. The isospin $T=3/2$ components of the 3NF also play an important role in many-nucleon systems especially for neutron-rich nuclei as well as neutron matter properties. The $p{-}^3$He scattering is one of the simplest prove for studying the $T=3/2$ components of the 3NF. With the aim of exploring the properties of the 3NF we are planning the measurement of ${}^3$He analyzing power for $p{-}^3$He scattering with the polarized ${}^3$He target at intermediate energies ($E/A\ge 65\mathrm{M}\mathrm{e}\mathrm{V}$). Polarized ${}^3$He was produced by the alkali-hybrid spin-exchange optical pumping method. To measure the ${}^3$He polarization and control ${}^3$He spin directions, we used the adiabatic fast passage-NMR method. We obtained the absolute value of the ${}^3$He polarization and calibrated the NMR signal by the electron spin resonance measurement of Rb. The maximum ${}^3$He polarization was $\sim 50\mathrm{\%}$ in our system.

Using the polarized ${}^3$He target, we performed the measurement of ${}^3$He analyzing power at CYRIC ($E_p=70\mathrm{M}\mathrm{e}\mathrm{V}$) and RCNP ($E_p=100\mathrm{M}\mathrm{e}\mathrm{V}$) in Japan. Measured angles were ${\theta }_{\mathrm{l}\mathrm{a}\mathrm{b}.}={35}^{\circ }-{125}^{\circ }$ (${\theta }_{\mathrm{c}.\mathrm{m}.}={46}^{\circ }-{141}^{\circ }$) at CYRIC and ${\theta }_{\mathrm{l}\mathrm{a}\mathrm{b}.}={35}^{\circ }-{135}^{\circ }$ (${\theta }_{\mathrm{c}.\mathrm{m}.}={47}^{\circ }-{149}^{\circ }$) at RCNP respectively. Proton beams were injected to the target, and scattered protons were detected by using $E-\mathrm{\Delta }E$ detectors which consisted of plastic and NaI(Tl) scintillators. During the experiment, we measured the ${}^3$He polarization and flipped the spin directions of ${}^3$He nucleus by using the AFP-NMR method. We extracted ${}^3$He analyzing power by measuring the asymmetry of elastically scattered protons from the polarized ${}^3$He target. In the conference we report recently results of the experimental data.

[1] S. C. Pieper $\mathit{e}\mathit{t}\mathit{a}\mathit{l}\mathit{.}$, Phys. Rev. C $\mathbf{64}$, 014001 (2001).
[2] A. Akmal $\mathit{e}\mathit{t}\mathit{a}\mathit{l}\mathit{.}$, Phys. Rev. C $\mathbf{58}$, 1804 (1998).
[3] N. Kalantar-Nayestanaki $\mathit{e}\mathit{t}\mathit{a}\mathit{l}\mathit{.}$, Rep. Prog. Phys. $\mathbf{75}$, 016301 (2012).