Experimental and Monte Carlo investigation of the light collection efficiency of heterogeneous scintillation flow cell detectors

Experiments were conducted and then modeled with Monte Carlo methods to evaluate the impact of optical and geometrical properties on light collection efficiency of heterogeneous scintillation flow-cell detectors. Light collection measurements were made by placing a photon source, ZnS(Ag) scintillator attached to an ²⁴¹Am alpha point source, at a fixed distance from a photomultiplier tube (PMT). Non-scintillating glass beads, contained in a mobile phase to simulate a flow-cell detector, were positioned between the photon source and the PMT. The index of refraction, n, of the mobile phase, and the number of layers of glass beads were investigated. The three mobile phases chosen were air (n=1), water (n=1.33) and methylnaphthalene (n=1.62); and the diameter of the glass beads (n=1.5) was 115 μm. Results showed that the light collection efficiency decreased with increasing number of bead layers Comparisons between the experimental and Monte Carlo model results are presented.