| Summary: | The SEparator for CApture Reactions (SECAR) is currently being developed at the National Superconducting Cyclotron Laboratory (NSCL) and the future Facility for Rare Isotope Beams (FRIB) for measurements of nuclear reactions critical for understanding energy generation and element synthesis in stellar explosions. SECAR is an electromagnetic recoil separator designed for sensitive measurements of radiative capture reactions using beams of proton-rich, short-lived isotopes at the energies relevant for explosive environments such as Type I X-ray bursts and classical novae. SECAR is designed to efficiently separate capture reaction products of interest from the incident beam by up to a factor of 10^17 by use of the separator and detection systems together.
This thesis focuses on the initial design of the focal plane for SECAR, including a preliminary suite of detectors and the supporting infrastructure. The recoils from capture reactions that reach SECARs focal plane can be discriminated from scattered beam by velocity (via time-of-flight), trajectory, total energy, and relative energy-loss measurements. The initial instruments include a pair of transmission detectors based on metal-foil, micro-channel plates that are separated by a drift length to provide an accurate time-of-flight measurement and discriminate recoils from the generally higher velocity scattered beam. The recoils are ultimately stopped, and their full energy measured, in either a silicon (Si) strip detector or gas-filled ionization chamber. At higher energies, the gas-filled ionization chamber provides selective determination of the atomic number via a relative energy-loss measurement. An ionization chamber for implementation into the SECAR focal plane that augments the traditional relative energy-loss measurement with a position-sensitive capability has been designed and constructed. The effectiveness of the different techniques varies; at lower energies (below about 0.5 MeV/A) relative energy loss becomes less effective and a full energy measurement with a silicon strip detector provides better resolution. A flexible infrastructure was designed using the CAD software Autodesk Inventor to allow the focal plane configuration to be optimized for the best performance for each experiment given the wide range of beam conditions expected in the scientific program that is envisioned with SECAR.
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