The measured electron response nonproportionalities of CaF/sub 2/, BGO, and LSO

Abstract

To study the light yield nonproportionality and intrinsic energy resolution of inorganic scintillators, a Compton coincidence technique was previously designed, implemented and benchmarked. This technique provides the ability to accurately measure the electron response of scintillation materials and thus provides an accurate means of studying these characteristics. In this study, the electron responses of two "classic" scintillators (CaF,(Eu) and Bi,Ge,012 (BGO)) and a newer scintillator (Lu,Si0,:Ce3+ (LSO)) have been measured over the energy range from 5 keV to approximately 450 keV using this technique. Electron responses for all three scintillation materials are observed to increase monotonically with electron energy. BGO is observed to have the least nonproportionality, with its electron response varying about 20% over this energy range. Conversely the LSO electron response is observed to vary about 50% over this energy range and thus exhibits the largest nonproportionality.

Energy resolution and non-proportionality of scintillation detectors – new observations

“…Development of the Compton Coincidence Technique by Valentine and Rooney allowed an accurate characterization of the electron response for a number of scintillators (Valentine and Rooney, 1994;Taulbee et al, 1997;Mengesha et al, 1998;Valentine et al, 1998). For the first time the true response for electrons was measured using a method not affected by the surface effects in scintillators.…”

“…Numerous studies have characterized the non-proportional response and a contribution of scintillators to the energy resolution of new Ce-doped crystals (Moszyń ski, 2003;Dorenbos et al, 1995;Taulbee et al, 1997;Mengesha et al, 1998;Valentine et al, 1998;Balcerzyk et al, 2000;Kapusta et al, 1999), heavy oxide crystals (Moszyń ski et al, 2004(Moszyń ski et al, , 2005a and undoped NaI and CsI at liquid nitrogen temperature (Moszyń ski et al, 2003b(Moszyń ski et al, , 2005c.…”

Energy nonlinearity in radiation detection materials: Causes and consequences

“…Alkaline earth dihalides CaF 2 (Eu) [23] and BaF 2 [7] as well as some complex oxides including CdWO 4 [7], Gd 2 SiO 5 (Ce) [7], Lu 3 Al 5 O 12 (Sc) [7], Lu 2 SiO 5 (Ce) [25], Y 2 SiO 5 (Ce) [26] and bismuth germanate (Bi 4 Ge 3 O 12 ) [27] show a different nonlinear behavior: the specific light output rises by some 20-30% with increasing energy from around 10 to 100 keV, then levels out and remains approximately constant without decreasing again up to the highest published energy values. (Some of these materials also show a decrease of specific light output with increasing energy at very low energies, passing through a minumum near 8 keV.)…”

“…In contrast to the relative ubiquity of gamma response measurements, however, electron response functions have been determined for relatively few detector materials. The Compton coincidence technique [5,[41][42][43][44] in particular has provided a potent tool for measurement of response to energy-tagged secondary electrons generated essentially uniformly throughout a detector's active volume. To date, the electron responses of NaI(Tl) [42], CaF 2 (Eu), Bi 4-Ge 3 O 12 , and Lu 2 SiO 5 (Ce) [43], CsI(Tl), CsI(Na) and YAlO 3 (Ce) [24], Gd 2 SiO 5 (Ce) and BaF 2 [45], and LaCl 3 (Ce) [46] have been determined by this method.…”

Studies of Non-Proportionality in Alkali Halide and Strontium Iodide Scintillators Using SLYNCI

“…To measure this proportionality, a collaboration of LLNL and LBNL has constructed a second generation Compton coincidence instrument known as SLYNCI (Scintillator Light-Yield Non-proportionality Characterization Instrument) [1][2][3]. This instrument has over a 30 times higher data collection rate than previous devices, [7][8][9] enabling a complete non-proportionality measurement in less than 24 hours. This increase throughput makes it more straight forward to make systematic studies of scintillator and non-proportionality.…”