Search

Application of CaMoO4 as a scintillation target in cryogenic rare event searches relies on the understanding of scintillation properties of the material at the temperatures at which these detectors operate. We devised and implemented a detection module with a low-temperature photomultiplier from Hamamatsu (model R8520-06) powered by a Cockcroft-Walton generator. The detector module containing the CaMoO4 crystal was placed in a ³He/4He dilution refrigerator and used to measure scintillation characteristics of CaMoO4 in the millikelvin temperature range. At the lowest temperature achieved, the energy resolution of CaMoO4 for 122 keV γ from a 57Co source is found to be 30%, and the fast and slow decay constants are 40.6±0.8 μs and 3410±50 μs, respectively. The temperature variation of the CaMoO4 decay kinetics is discussed in terms of a three-level model of the emission center. [ABSTRACT FROM AUTHOR]

Scintillation materials based on polystyrene (PS) have been investigated. Para-terphenyl was employed as a fluorescent molecule (fluor) that functions as a wavelength shifter. A clear increase in photon yield of the scintillation materials relative to the pure PS was observed, which cannot be explained by the conventional theory of scintillation mechanism. Furthermore, the photon yield increased with flour concentration in accordance with a power-law. Here we reveal the emergence of a luminescence of PS-based scintillation materials and demonstrate that their photon yields can be controlled by the fluor concentration. [ABSTRACT FROM AUTHOR]

A new scintillator material consisting of a methanol adduct of cerium trichloride with the composition CeCl3(CH3OH)4 has been discovered and crystallized in the form of large single crystals by solution growth in methanol. The peak emission of the x-ray-excited luminescence spectrum occurs at ∼364 nm. A light yield of up to ∼16 600 photons/MeV and an energy resolution of 11.4% were obtained using 662 keV gamma-ray photons. The scintillator decay time for 662 keV gamma-ray excitation was measured using the time-correlated, single-photon-counting method, and a nominal value of 64.4 ns was obtained. The molecular adduct CeCl3(CH3OH)4 represents the first example of a rare-earth, metal-organic scintillator that is applicable to gamma ray, x ray, and neutron detection. [ABSTRACT FROM AUTHOR]