Composition of CeF 3 -based crystals for a composite scintillator with a polystyrene matrix
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ICAL PROPERTIES OF CRYSTALS In memory of V.G. Vasil’chenko
Composition of CeF3Based Crystals for a Composite Scintillator with a Polystyrene Matrix B. P. Soboleva, T. M. Glushkovab, E. A. Krivandinaa, and Z. I. Zhmurovaa a
Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninskii pr. 59, Moscow, 119333 Russia email: [email protected] b Moscow State University, Moscow, Russia Received December 9, 2011
Abstract—The dependences of the refractive indices of solid solutions based on cerium fluoride (Ce1 – ySryF3 – y and Ce1 – yBayF3 – y) on their composition have been studied. It is shown that at a light wavelength λ = 0.589 µm crystals of the Ce0.925Sr0.075F2.925 and Ce0.875Ba0.125F2.875 compositions have an average refractive index nav coinciding with the refractive index of polystyrene (n = 1.5975 ± 0.001) at this wavelength and can thus be used as fillers for ceriumcontaining composite scintillators based on polystyrene. DOI: 10.1134/S1063774512060156
INTRODUCTION The development of newgeneration particle accelerators called for newgeneration scintillators characterized by high time resolution, absorptivity, radiation hardness, and energy resolution. Total absorption electromagnetic calorimeters are used to detect products of interaction of accelerated particles. Single crystals of inorganic compounds are most often used as a scintillating medium in these devices. Growth of single crystals and their treatment increase significantly the cost of calorimeters. Therefore, attempts are made to use scintillators of other types, which would retain good spectroscopic characteristics and high absorptivity but would not require the growth of large crystals. When newgeneration scintillators for highenergy physics were sought, cerium fluoride (CeF3) crystals were considered on the whole among most promising [1–4]. PbWO4 was chosen as a scintillator material for the Large Hadron Collider instead of CeF3 in many respects because of the problems related to growing CeF3 single crystals of the necessary size and purity, whereas large PbWO4 crystals had been commercially produced by that time. One of the ways to reduce the cost of scintillating materials without a significant deterioration of their characteristics is the use of composites instead of sin gle crystals. Lowmelting inorganic salts and plastics of differ ent compositions can be used as matrices for compos ites [5]. A necessary condition for preserving a high specific light yield of scintillating filler is the decrease in diffuse light scattering from its particles. This is obtained by choosing similar refractive indices of the matrix and filler in the desired wavelength range.
Since the composite has a high transparency, the empirical relation between the refractive indices of the filler (nsc) and matrix (nmat) must be satisfied: Δn = |nmat – nsc | Δn (0.01–0.02) [6]. In [7] the choice of the polystyrene–CeF3 combi nation was substantiated by the proximity of their refractive indices. The value Δn ~ 0.02 for this pair (the discr
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