The National Superconducting Cyclotron Laboratory (NSCL) is the nation's premier facility to accelerate nuclei with the purpose of studying nuclear structure. NSCL has developed world-unique new experimental capabilities with reaccelerated rare-isotope beams, ensuring a continued leadership role in rare-isotope physics worldwide. With the recent expansion of research capabilities at NSCL, demand for these beams to be used in nuclear physics experiments has never been higher. The instrument proposed here, called a Helium-Jet Ion Gas System (HJ-IGS) will allow for commensal running of two experiments simultaneously, each using different detector systems at NSCL, which will expand the number of experiments and hence help to meet the demand for experiments that increase our understanding of nuclei.
Helium-Jet Ion Sources have been used for harvesting isotopes in the past, but the idea to use such a system to harvest some of the rarest isotopes available to researchers in a projectile fragmentation facility is novel. Rare isotopes that are bent out of the central beam path during the purification process of the primary rare-isotope beam are stopped and collected in a high-pressure cell filled with Helium saturated with aerosols to which the stopped isotopes will attach. With a high-pressure differential, the collected isotopes are quickly transported through a 40 meter-long capillary to an ion source that injects the isotopes, after purification, into a beam line that can feed one of several stations not used in the primary experiment. This allows two experiments to be performed at the same time: an experiment using a fast rare isotope beam directly produced in projectile fragmentation and an experiment with stopped or reaccelerated beams using the harvested, transported, ionized and purified isotopes in the HJ-IGS. State-of-the-art experiments that are in high demand in the fields of nuclear structure and nuclear astrophysics, as well as fundamental interactions and symmetries, and include such diverse techniques as high-precision mass measurements in atom traps, in-beam laser spectroscopy and polarization, nuclear decay spectroscopy, and low-energy reaction studies with an active-target time projection chamber.
