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The neutral particle analyzer (NPA) is one of the crucial diagnostic devices in a Tokamak facility. The stripping unit is one of the main parts of the NPA. A windowless gas-stripping room with two differential pipes has been constructed in a parallel electric and magnetic fields (E//B) NPA. The pressure distributions in the stripping chamber are simulated by ANSYS Fluent together with MolFlow+. Based on the pressure distributions obtained from the simulation, the stripping efficiency of the E//B NPA is studied using GEANT4. Hadron reaction physics is modified to track the charge state of each particle in a cross-section-based method in GEANT4. The transmission rates (R) and stripping efficiencies $$f_{+1}$$ are examined for particle energies ranging from 20 to 200 keV with the input pressure ( $$P_0$$ ), ranging from 20 to 400 Pa. According to the combined global efficiency, $$R \times f_{+1}$$ , $$P_0$$ = 240 Pa is obtained as the optimum pressure for the maximum global efficiency in the incident energy range investigated.

Hamamatsu R1924A is one of the most widely used photomultiplier tubes (PMTs) in nuclear physics. Since the active base suitable for R1924A is still not available in market, an active base is designed for Hamamatsu R1924A PMT, and the test results at high counting rates are presented. The active bases with two different sets of resistor chains were tested and compared by a frequency-controlled green straw hat LED light. A stable signal output up to 100 kHz is achieved using frequency-controlled LED pulsed light. The temperature of bases, which reflects the power consumption and is crucial for applications in vacuum, is also monitored with the same LED pulsed light. The temperature of the active base with smaller resistances reaches about twice of that of the active base with larger resistances in the resistor chain. For the applications in vacuum, the active base with resistance between the two sets of resistor chains may be preferable.

In this report, a kinematical focusing technique will be briefly described, and using this technique, the primary hot isotope yields from the multiplicities of evaporated light particles, associated with isotopically identified intermediate mass fragments, are reconstructed. Symmetry energy and characteristic properties of the fragmenting source at the time of the intermediate mass fragment formation are extracted from these reconstructed primary isotope yields using a self-consistent manner. The extracted density-dependent symmetry energy is further compared with those experimentally extracted from other heavy-ion reactions in literatures. A direct connection between the freeze-out concept and transport model simulations in a multifragmenting regime of heavy-ion collisions is also demonstrated quantitatively in the present work.