Spin Correlation Coefficients Measurement in Polarized Deuteron-Polarized Proton Scattering Experiment

Few-nucleon scattering experiment is one of the adequate probes to investigate detailed characteristics of the Three Nucleon Forces (3NFs). From an extensive performance of deuteron-proton (d-p) elastic scattering at intermediate energies (70-300 MeV/nucleon) by a group in RIKEN, clear signatures of 3NF effects were confirmed in results of the cross sections, whereas deficiencies of current 3NF models were revealed by those of the spin observables.

In view of determining the 3NFs, we now plan to measure the spin correlation coefficients for polarized deuteron-polarized proton scattering at 100 MeV/nucleon. The experiment will be performed at RIKEN RIBF facility, using polarized deuteron beam provided by the polarized ion source and polarized proton target system based on the triplet-DNP method. Polarized cross sections will be measured with a detector system incorporating multi-wired drift chambers (MWDCs) and plastic scintillators. Data taken will be utilized to fix the low energy constants in chiral effective field theory.

The newly developed polarized proton target and detector system underwent a beam test at HIMAC in December 2022. The following measurements took place:

・Quantification of target’s polarization decrease from bombardment of 200 MeV proton

・Efficiency measurement of the MWDCs

・Derivation of target polarization from yield asymmetry measurement.

In this presentation, details on the planned experiment at 100 MeV/nucleon and the results from the beam test at HIMAC will be given.