Results from the first fast beam test of the Energy Loss Optical Scintillation System*

The Energy Loss Optical Scintillation System (ELOSS) is a proposed high luminescence-yield gaseous detector used for atomic number identification of rare, short-lived atomic nuclei [1]. ELOSS will function as part of the focal-plane detector system of the S800 spectrograph [2] for particle identification (PID) in nuclear physics experiments at the Facility for Rare Isotope Beams (FRIB). FRIB is among the world’s premier rare-isotope beam facilities producing a majority of the isotopes that are created in the cosmos, which then decay into the elements found on Earth. State-of-the-art experimental equipment like ELOSS will tap into FRIB’s unprecedented discovery potential by studying isotopes at high beam rate and with high performance, having a broad, global impact on radiation-detection physics and technology. ELOSS also represents a prototype for the development of PID detector systems of other planned and future spectrometers, such as the High Rigidity Spectrometer at FRIB [3].

     This work will focus on the operational mechanism and performance of ELOSS, demonstrated in a fast beam (150 MeV/u) experiment with ³⁶Ar at FRIB. The initial detector response and DAQ configuration to CF4 scintillation, effective area scanning for finishing the calibration of the optical readout, comparison between primary and proportional scintillation modes and the performance as a function of beam rate are discussed.