Helium-3 Scattering at Bates Large Acceptance Spectrometer Toroid (BLAST)

United States Naval Academy- Do Not Use, Annapolis MD

Investigators

Abstract

The study of helium-3 through electron scattering attempts to expose nuclear physics and its underlying forces by breaking apart one of the simplest nuclei, a bound state of one neutron and two protons, also known as helium-3. The lowest bound nuclei are hydrogen, deuterium ( a bound neutron and proton), tritium (one proton and two neutrons) and then helium-3. Because deuterium has only two nucleons, it is an odd nucleus and does not represent standard nuclear material well. Tritium is a difficult to work with, leaving helium-3 as the simplest nucleus that has sufficiently interesting dynamics that are believed to exist in larger nuclei. By breaking apart these nuclei using an electron beam, the nucleus can be reconstructed from data taken and then tested against leading theories in the field. By working in two locations, the United States Naval Academy (USNA) and MIT, students can be trained in the handling of the helium-3 nuclei at USNA, and then later complete their education by working at the MIT-Bates laboratory during the Summer months. The BLAST (Bates Large Acceptance Spectrometer Toroid) experiment provides these students the chance to participate on a world-class experiment while exposing them to new concepts and instrumentation. The facilities to perform experiements of this caliber are unique and only a handful are in operation around the world. The specialized features of the experiment BLAST are that the electron beam and helium-3 targets are both polarized in a magnetic field such that new information about the nucleus is revealed. One particular quantity sought after is the electric moment of the neutron, dubbed G_E_n, which describes how the neutron begins to appear as an electric moment as higher and higher energies come to bear on the neutron. For this purpose, the BLAST experiment will use both deuterium as well as helium-3 as targets for the electrons to strike the neutrons held within the nuclei.