Measurement of intrinsic radioactivity in a GSO crystal

Abstract

Scintillating crystal detectors offer potential advantages in low-energy low-background experiments for particle physics and astrophysics. The GSO crystal is an interesting detector to explore for future neutrino physics experiments. The contributions to background due to the various channels of intrinsic radio-isotopes from the 232 Th and 238 U series are identified and studied with time-correlation analysis and detailed fits to the spectral shape. Good agreement is achieved between measured and simulated spectra, indicating background suppression factors to the 10 −2 − 10 −3 level are possible. The procedures can be adopted for background understanding and suppression in other low-count-rate experiments where the dominant source of background is from internal radioactivity. Based on 1656 hours of data taking, limits on the double beta decay half-life for the various channels in 160 Gd are derived. The limits for the neutrinoless and the Majoron modes are > 3.0(1.9) × 10 19 y, respectively, at 68(90)% confidence level.

Measurement of the intrinsic radiopurity of 137Cs/235U/238U/232Th in CsI(Tl) crystal scintillators

“…Our work complements and extends the scope of those previous efforts on this [8,9] and other crystal scintillators: NaI(Tl) [11,12,13], CdWO 4 [14], GSO(Ce) [15], CeF 3 [16], BaF 2 [17] and CaF 2 (Eu) [18]. The achieved sensitivities match the best among these results as well as those from massive liquid scintillator facility [19].…”

Significantly different pulse shapes for γ- and α-rays in Gd3Al2Ga3O12:Ce3+ scintillating crystals

“…Nonetheless, there are not many efficient scintillators containing Gd in the hosts. Several experiments [2][3][4] on the neutrinoless double beta decay have been performed with Gd 2 SiO 5 (GSO):Ce scintillating crystals as a unified target and a detector material. To improve the sensitivity of the experiments, it is of vital importance to reduce the background that comes from the a decays of heavy radioisotope impurities of 232 Th-, 238 U-and 235 U-series in the scintillators.…”

Alpha–gamma pulse-shape discrimination in Gd3Al2Ga3O12 (GAGG):Ce3+ crystal scintillator using shape indicator

“…The two peaks observed in the 550-650 keV range were attributed to the α-emitting impurities of the U and Th series. Such impurities were shown to exist in similar Gd containing heavy oxide crystals Gd 2 SiO 5 [14,15]. Their origins include raw materials Gd 2 O 3 [16].…”