Speaker
Description
A large-area detector system has been developed for measuring coincident fission fragments in experiments with reaccelerated rare isotope beams. The system consists of two 30 x 40 cm2 position-sensitive detectors based on the Multi-Mesh Thick Gas Electron Multipliers (MM-THGEM) and one 10 x 10 cm2 position-sensitive Multi-Wire Proportional Counter (MWPC). All detectors are operated in low pressure isobutane and are equipped with delay-line readout for precise x and y coordinate reconstruction. Additionally, the double Time-of-Flight (ToF) method is employed to reconstruct the mass and angle of the binary reaction products. The MWPC in-beam transmission detector, located before a reaction target, is used as the start timing signal for the ToF measurement, with the MM-THGEM detectors providing the stop timing signal. The 1 ns ToF resolution and 1 mm position resolution ensure a mass reconstruction of 3 a.m.u. for the binary fragments.
The full system has been successfully commissioned with a stable 16O beam elastically scattered on 208Pb and 197Au targets and has begun operations in measuring fission fragments formed in the 34Si + 232Th reaction at the ReA6 reaccelerated facility of the Facility for Rare Isotope Beams (FRIB). I will report on the design and performance of the individual detectors and of the overall system.
Acknowledgement: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and user resources of the Facility for Rare Isotope Beams (FRIB) Operations, which is a DOE Office of Science User Facility under Award Number DE-SC0023633. This project is also supported by the U.S. Department of Energy (DOE) under Award Number DE-SC0021938 and by Australian Research Council Grant DE230100197. The authors acknowledge the facilities, and the scientific and technical assistance provided by Heavy Ion Accelerators (HIA). HIA is supported by the Australian Government through the National Collaborative Research Infrastructure Strategy (NCRIS) program.