MRI: Development of a Separator for Capture Reactions (SECAR) Phase 2

Michigan State University, East Lansing MI

Investigators

Abstract

It is well known that nuclei are made from protons and neutrons. One of the open questions in nuclear science, as identified by the Nuclear Science Advisory Committee, is: what is the origin of the elements? To produce nuclei having more than a few neutrons and protons requires a sequence of nuclear reactions that take place in stars. To produce nuclei heavier than iron requires a highly energetic environment, such as a supernova explosion or a neutron star merger. The equipment to be built here, the Separated Capture Reaction (SECAR) spectrometer, will enable physicists at the National Superconducting Cyclotron Laboratory (NSCL) to measure rare nuclear reactions that are necessary to understand the origin of the elements. Phase 2 of the SECAR spectrometer, planned here, will become a world-leading facility for this purpose. SECAR Phase 2 opens a wide range of science opportunities. It enables measurements of the entire range of important reactions in X-ray bursts, the most common thermonuclear explosions observed in our Galaxy. X-ray bursts occur on the surface of mass-accreting neutron stars. With the SECAR Phase 2 data, burst observations can be used to probe the properties of neutron stars and X-ray binary systems. In addition, predictions can be made of the elements created that form the crust of the neutron star and may also, in part, be ejected into space. SECAR Phase 2 will also enable predictions of the element signatures of astrophysical Nova explosions, especially unusually energetic events that may be observed with new telescopes in the near future. This will help to identify the signatures of these events in observational data, and in the composition of meteoritic grains found on earth. SECAR Phase 2 data will also help understand the production of radioactive elements in supernovae, the signatures of the most massive stars ever that existed in the early universe, the contribution of supernova neutrino winds to the origin of the elements, and help prove, or disprove, the existence of Thorne-Zytkov objects, hypothetical stellar objects that contain a neutron star as their core.