EAPSI: Testing and development of a time projection chamber to study neutron stars

Barney Jonathan E, Lansing MI

Investigators

Abstract

A current problem in nuclear physics is determining the nuclear equation of state. In particular, part of that equation is the symmetry energy term, which is important for the understanding of everything from the physics of nuclei to neutron stars. Neutron stars are extremely dense: a teaspoon of neutron star matter would weigh about 2 billion tons on earth. The only way that we can simulate such dense systems in the laboratory is by colliding nuclei with many neutrons together. A new magnet chamber has been created at the RI Beam factory at RIKEN in Japan which is ideally suited for studying the symmetry energy. A new Time Projection Chamber (TPC) has been created specifically for this magnet chamber, and must be tested inside the chamber before experiments can be run. The TPC takes a snapshot of what happens during each collision, revealing what types of particles are created and how many, allowing us to study the forces in dense neutron systems. This research will be conducted under the sponsorship of Dr. Hiroyoshi Sakurai at RIKEN. The SAMURAI spectrometer is a high resolution spectrometer which, in conjunction with the newly developed SPiRIT TPC, will allow analysis of pion production ratios. Pion production ratios have been suggested as a probe of symmetry energy, and the SAMURAI setup will give the resolution to test the symmetry energy with this probe with a high angular acceptance. The beams available at the RI Beam factory will allow to constrain the symmetry energy to twice saturation density. Since the setup is new, it must be tested before it is used with actual beam time. In this study, safe and efficient procedures for setup and installation of the TPC in the spectrometer will be prepared and tested, and the readout electronics and gas system will be checked to ensure the functionality of the detector. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.