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The scintillation response of LaBr3:Ce scintillation crystals was studied as function of temperature and Ce concentration with synchrotron X-rays between 9 keV and 100 keV. The results were analyzed using the theory of carrier transport in wide band gap semiconductors to gain new insights into charge carrier generation, diffusion, and capture mechanisms. Their influence on the efficiency of energy transfer and conversion from X-ray or γ-ray photon to optical photons and therefore on the energy resolution of lanthanum halide scintillators was studied. From this, we will propose that scattering of carriers by both the lattice phonons and by ionized impurities are key processes determining the temperature dependence of carrier mobility and ultimately the scintillation efficiency and energy resolution. When assuming about 100 ppm ionized impurity concentration in 0.2% Ce3+ doped LaBr3, mobilities are such that we can reproduce the observed temperature dependence of the energy resolution, and in particular, the minimum in resolution near room temperature is reproduced. [ABSTRACT FROM AUTHOR]

CeBr3 crystals have been studied to assess their utility as potential gamma ray spectrometers for future ESA planetary missions. Pulse height spectra, scintillation time profiles, X-ray excited emission spectra, and photoluminescence spectra have been recorded as a function of temperature between 78 and 600 K. In addition, the influence of exposing CeBr3 to various doses of gamma rays from a strong 60Co source on its scintillation performance has been investigated. [ABSTRACT FROM AUTHOR]

The effect of high dose 60Co gamma irradiation on photoelectron yield, energy resolution, optical transmission, scintillation time profiles and thermoluminescence glow curves of LaBr3:5%Ce and LaCl3:10%Ce crystals has been investigated. Both materials show lower yields and deteriorated resolutions after exposure to a strong 60Co source, however their transmission, yield proportionality, scintillation decay, and thermoluminescence remain unaffected. Initial scintillation characteristics can be retrieved neither by spontaneous recovery nor upon heating in vacuum. [ABSTRACT FROM AUTHOR]

Photoelectron yields and energy resolutions of bare and packed LaBr3:Ce crystals are determined as function of proton irradiation dose, cerium concentration and sample height from 1 mm to 2 inch. A simple model is employed to predict light yield for ⊘3′ × 3′ size crystals, and to assess the quality of packaging. The effect of proton exposure on scintillation yield and resolution of LaBr3:Ce is investigated. Intense proton irradiation does not deteriorate yield or resolution. It also does not affect thermoluminescence behavior. [ABSTRACT FROM AUTHOR]

Background: The understanding and description of forbidden decays provides interesting challenges for nuclear theory. These calculations could help to test underlying nuclear models and interpret experimental data. Purpose: Compare a direct measurement of the 138Laβ-decay Q value with the β-decay spectrum end-point energy measured by Quarati et al. using LaBr3 detectors [Appl. Radiat. Isot. 108, 30 (2016)]. Use new precise measurements of the 138Laβ-decay and electron capture (EC) Q values to improve theoretical calculations of the β-decay spectrum and EC probabilities. Method: High-precision Penning trap mass spectrometry was used to measure cyclotron frequency ratios of 138La, 138Ce, and 138Ba ions from which β-decay and EC Q values for 138La were obtained. Results: The 138Laβ-decay and EC Q values were measured to be Qβ=1052.42(41) keV and QEC=1748.41(34) keV, improving the precision compared to the values obtained in the most recent atomic mass evaluation [Wang et al., Chin. Phys. C 41, 030003 (2017)] by an order of magnitude. These results are used for improved calculations of the 138Laβ-decay shape factor and EC probabilities. New determinations for the 138Ce 2EC Q value and the atomic masses of 138La, 138Ce, and 138Ba are also reported. Conclusion: The 138Laβ-decay Q value measured by Quarati et al. is in excellent agreement with our new result, which is an order of magnitude more precise. Uncertainties in the shape factor calculations for 138Laβ decay using our new Q value are reduced by an order of magnitude. Uncertainties in the EC probability ratios are also reduced and show improved agreement with experimental data. [ABSTRACT FROM AUTHOR]

We measured with unprecedented accuracy key features of the (138)La radioactive decays as β particle energy distribution from 0.5keV to the end-point and ratios of electron capture probabilities PL/PK, PM/PK and PM/PL. This was achieved by making use of LaBr3:Ce and CeBr3 scintillator detectors. The advantage of the presented technique relies on the double role of LaBr3:Ce as source of (138)La and detector medium resulting in a relatively efficient counting statistics and unaltered β energy detection. The experimental results are compared to advanced computational techniques and significant deviation is found below 20keV with the computational spectrum showing a 5% excess of β particle relative to the experimental spectrum at 10keV., (Copyright © 2016. Published by Elsevier Ltd.)

We measured with unprecedented accuracy key features of the (138)La radioactive decays as β particle energy distribution from 0.5 keV to the end-point and ratios of electron capture probabilities PL/PK, PM/PK and PM/PL. This was achieved by making use of LaBr3:Ce and CeBr3 scintillator detectors. The advantage of the presented technique relies on the double role of LaBr3:Ce as source of (138)La and detector medium resulting in a relatively efficient counting statistics and unaltered β energy detection. The experimental results are compared to advanced computational techniques and significant deviation is found below 20 keV with the computational spectrum showing a 5% excess of β particle relative to the experimental spectrum at 10 keV., (Copyright © 2015 Elsevier Ltd. All rights reserved.)