Scintillation

About: Scintillation is a research topic. Over the lifetime, 14022 publications have been published within this topic receiving 187694 citations.

Accurate measurement of the rise and decay times of fast scintillators with solid state photon counters

Abstract: In this work we present a measurement setup for the determination of scintillation pulse shapes of fast scintillators It is based on a time-correlated single photon counting approach that utilizes the correlation between 511 keV annihilation photons to produce start and stop signals in two separate crystals The measurement is potentially cost-effective and simple to set up while maintaining an excellent system timing resolution of 125 ps As a proof-of-concept the scintillation photon arrival time histograms were recorded for two well-known, fast scintillators: LYSO:Ce and LaBr3:5%Ce The scintillation pulse shapes were modeled as a linear combination of exponentially distributed charge transfer and photon emission processes Correcting for the system timing resolution, the exponential time constants were extracted from the recorded histograms A decay time of 43 ns and a rise time of 72 ps were determined for LYSO:Ce thus demonstrating the capability of the system to accurately measure very fast rise times In the case of LaBr3:5%Ce two processes were observed to contribute to the rising edge of the scintillation pulse The faster component (270 ps) contributes with 72% to the rising edge of the scintillation pulse while the second, slower component (20 ns) contributes with 27% The decay of the LaBr3:5%Ce scintillation pulse was measured to be 154 ns with a small contribution (2%) of a component with a larger time constant (130 ns)

LiCaAlF6:Ce crystal: a new scintillator

Abstract: Scintillation properties of LiCaAlF6:Ce crystal, well known as the effective UV laser material, is reported. Ce3+ emission at 286–305 nm with a single exponential decay time of 35 ns provides a scintillation pulse. Radiation damage in pure and Ce-doped crystals is studied. In contrast to the majority of fluoride crystals, cerium is responsible for the ultradeep traps formation revealing thermostimulated luminescence. Overlapping of color center absorption and Ce3+ ion emission bands limits the scintillation efficiency of LiCaAlF6:Ce at high radiation doses.

Potentials of Digitally Sampling Scintillation Pulses in Timing Determination in PET

Abstract: We investigate the potentials of digitally sampling scintillation pulses techniques for positron emission tomography (PET) in this paper, focusing on the determination of the event time We have built, and continue building, a digital library of PET event waveforms generated with various combinations of photo-detectors and scintillator materials, with various crystal sizes Events in this digital library are obtained at a high sampling of 20 GSps (Giga-samples per second) so that their waveforms are recorded with high accuracy To explore the potential advantages of digitally sampling scintillation pulses, we employ a dataset in the above-mentioned library to evaluate two methods for digitizing the event pulses and linear interpolation techniques to analyze the resulting digital samples Our results show that the two digitization methods that we studied can yield a coincidence timing resolution of about 300 ps FWHM when applied to events generated by a pair of LSO + PMT detector units This timing resolution is comparable with that is achieved by the same detector pair with a constant fraction discriminator (CFD) As a benchmark, regular-time sampling (RTS) method, usually implemented with very fast traditional analog-to-digital converters (ADCs) for digitizing scintillation pulses, is not feasible for a multi-channel system like a PET system Digitizing scintillation pulses with multi-voltage threshold (MVT) method could be implemented at a reasonable cost for a PET system With digitized PET event samples, various digital signal processing (DSP) techniques can be implemented to determine event arrival time Our results have therefore demonstrated the promising potentials of digitally sampling scintillation pulses techniques in PET imaging

Measurement of atmospheric millimetre-wave phase scintillations in an absorption region

Abstract: A typical spectrum of differential phase scintillations measured between two frequencies near 54.5 GHz on a 4.1 km line-of-sight path is presented and the measurement system described. Results confirm the expected -8/3 dependence of the spectrum. A marked loss of spectral density at very low scintillation frequencies is observed.