Studies of non-proportionality in alkali halide and strontium iodide scintillators using SLYNCI (original) (raw)
Related papers
2009
Recently a collaboration of LLNL and LBNL has constructed a second generation Compton coincidence instrument to study the non-proportionality of scintillators . This device, known as SLYNCI (Scintillator Light-Yield Non-proportionality Characterization Instrument), has can completely characterize a sample with less than 24 hours of running time. Thus, SLYNCI enables a number of systematic studies of scintillators since many samples can be processed in a reasonable length of time. These studies include differences in nonproportionality between different types of scintillators, different members of the same family of scintillators, and impact of different doping levels. The results of such recent studies are presented here, including a study of various alkali halides, and the impact of europium doping level in strontium iodide. Directions of future work area also discussed.
Performance of a Facility for Measuring Scintillator Non-Proportionality
IEEE Transactions on Nuclear Science, 2008
We have constructed a second-generation Compton coincidence instrument, known as the Scintillator Light Yield Non-proportionality Characterization Instrument (SLYNCI), to characterize the electron response of scintillating materials. While the SLYNCI design includes more and higher efficiency HPGe detectors than the original apparatus (five 25%-30% detectors vs. one 10% detector), the most novel feature is that no collimator is placed in front of the HPGe detectors. Because of these improvements, the SLYNCI data collection rate is over 30 times higher than the original instrument. In this paper, we present a validation study of this instrument, reporting on the hardware implementation, calibration, and performance. We discuss the analysis method and present measurements of the electron response of NaI:Tl from two different samples. We also discuss the systematic errors of the measurement, especially those that are unique to SLYNCI. We find that the apparatus is very stable, but that careful attention must be paid to the energy calibration of the HPGe detectors.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2010
A Compton-coincidence scintillator light yield non-proportionality measurement system was constructed and tested. Improved testing procedures and timing resolution have allowed the use of significantly less active excitation sources without lengthening test times or degrading data integrity. Previous methods typically required 100mCi Cs-137 sources, but an increase in solid angle between source and sample as well as improved timing resolution have
Progress in Studying Scintillator Proportionality: Phenomenological Model
IEEE Transactions on Nuclear Science, 2009
We present a model to describe the origin of nonproportional dependence of scintillator light yield on the energy of an ionizing particle. The non-proportionality is discussed in terms of energy relaxation channels and their linear and non linear dependences on the deposited energy. In this approach, the scintillation response is described as a function of the deposited energy deposition and the kinetic rates of each relaxation channel. This mathematical framework allows both a qualitative interpretation and a quantitative fitting representation of scintillation non-proportionality response as function of kinetic rates. This method was successfully applied to thallium doped sodium iodide measured with SLYNCI, a new facility using the Compton coincidence technique. Finally, attention is given to the physical meaning of the dominant relaxation channels, and to the potential causes responsible for the scintillation nonproportionality. We find that thallium doped sodium iodide behaves as if non-proportionality is due to competition between radiative recombinations and non-radiative Auger processes.
Photodetectors for scintillator proportionality measurement
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009
We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier Page 2 tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high (~50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.
Electron response of some low-Z scintillators in wide energy range
Journal of Instrumentation, 2012
Light yield nonproportionality and the intrinsic resolution of some low atomic number scintillators were studied by means of the Wide Angle Compton Coincidence (WACC) technique. The plastic and liquid scintillator response to Compton electrons was measured in the energy range of 10 keV up to 4 MeV, whereas a CaF 2 :Eu sample was scanned from 3 keV up to 1 MeV. The nonproportionality of the CaF 2 :Eu light yield has characteristics typical for inorganic scintillators of the multivalent halides group, whereas tested organic scintillators show steeply increasing nonproportionality without saturation point. This is in contrast to the behavior of all known inorganic scintillators having their nonproportionality curves at saturation above energies between tens and several hundred keV.
Nukleonika
LaBr 3 :Ce,CeBr 3 and GAGG:Ce scintillators were investigated and the determined characteristics were compared with those obtained for the well-known and widely used CsI:Tl and NaI:Tl crystals. All the detectors were of the same size of 10 × 10 × 5 mm 3. The aim of this test study was to single out scintillation detectors most suitable for -ray spectrometry and -ray emission radial profi le measurements in high-temperature plasma experiments. Decay time, energy resolution, non-proportionality and full energy peak detection effi ciency were measured for -ray energies up to 1770 keV. Due to their good energy resolution, short decay time and high detection effi ciency for MeV gamma rays, LaBr 3 :Ce and CeBr 3 scintillators are proposed as the best candidates for use especially under conditions of high count rates, which are expected in the forthcoming DT experiments.
Journal of Astronomical Telescopes, Instruments, and Systems, 2014
Strontium iodide doped with europium (SrI 2 (Eu 2+ )) is a new scintillator material being developed as an alternative to lanthanum bromide doped with cerium (LaBr 3 (Ce 3+ )) for use in high-energy astrophysical detectors. As with all scintillators, the issue of nonproportionality is important because it affects the energy resolution of the detector. In this study, we investigate how the nonproportionality of SrI 2 (Eu 2+ ) changes as a function of temperature 16 deg. C -60 deg. C by heating the SrI 2 (Eu 2+ ) scintillator separate from the photomultiplier tube. In a separate experiment, we also investigate the nonproportionality at high energies (up to 6 MeV) of SrI 2 (Eu 2+ ) at a testing facility located at NASA Goddard Space Flight Center. We find that the nonproportionality increases nearly monotonically as the temperature of the SrI 2 (Eu 2+ ) scintillator is increased, although there is evidence of nonmonotonic behavior near 40 deg. C, perhaps due to electric charge carriers trapping in the material. We also find that within the energy range of 662keV -6.1 MeV, the change in the nonproportionality of the SrI 2 (Eu 2+ ) is about 1.5 -2%.
Growth and Evaluation of Improved CsI:Tl and NaI:Tl Scintillators
Crystals
Scintillators play an important role in radiation detection and imaging. Thallium-doped cesium iodide (CsI:Tl) and sodium iodide (NaI:Tl) are two of the major scintillators that have been used for many applications for many decades. In this paper, we will present an improved scintillation performance of Bridgman method-grown CsI(Tl) and NaI(Tl) crystals developed by Xtallized Intelligence, Inc. (XI, Inc.), and we will compare the performance with commercially available CsI:Tl and NaI:Tl. In a preliminary testing using MicroFJ−60035−TSV silicon photomultipliers (ON Semiconductor), the newly developed and improved 12.5 × 12.5 × 6 mm3 CsI:Tl crystal has shown an energy resolution of 4.8% (FWHM) at 662 keV, compared to 7.2% obtained by a commercially available CsI:Tl with a size of 12.5 × 12.5 × 25 mm3. The energy resolution of 5.4% (FWHM) at 662 keV is obtained for the newly improved NaI:Tl crystal, compared to 7% obtained by a commercially available ∅1″ × 1″ NaI(Tl). The comparison of...