He scattering at 70 MeV

Three-nucleon forces (3NFs) are essentially important in clarifying various nuclear phenomena. With the aim of exploring the properties of the 3NFs in four-nucleon scattering systems we are planning the measurement of p−³He scattering with the polarized ³He target at intermediate energies (E/A ≥ 65 MeV).

We developed the polarized ³He target for the measurement of ³He analyzing power. Polarized ³He was produced by the spin-exchange optical pumping method. To measure ³He polarizations and control ³He spin directions, we used the adiabatic fast passage–NMR method. We obtained the absolute values of ³He polarizations by the electron spin resonance measurement. ³He polarizations were about 50 %.

Using the polarized ³He target, we performed the measurement of ³He analyzing power with 70 MeV proton beams at the Cyclotron and Radioisotope Center, Tohoku University. Measured angles were from 35◦ to 125◦ in the laboratory system (47◦ − 141◦ in the center of mass system). We extracted ³He analyzing power by measuring the asymmetry of elastically scattered protons from the polarized ³He target.

In the conference we will report results of this experiment.