Cs2LiYCl6:Ce (CLYC) has been demonstrated to be sensitive to thermal neutrons via the 6Li(n, α)t reaction, and recently to fast neutrons via the 35Cl(n,p) reaction. The scintillation properties of ...CLYC have been investigated in more detail to further understand its capabilities. Pulses from thermal neutron, fast neutron, and γ-ray induced excitations were captured, digitized over a 16μs time range, and analyzed to identify the scintillation mechanisms responsible for the observed shapes. Additionally, the timing resolutions of CLYC crystals of different sizes were measured in coincidence with a fast CeBr3 scintillator. The effect of high count rates on fast neutron energy resolution and pulse-shape discrimination was investigated up to 45kHz.
Optimizing Cs2LiYCl6 for fast neutron spectroscopy D'Olympia, N.; Chowdhury, P.; Guess, C.J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2012, Letnik:
694
Journal Article
Recenzirano
Cs2LiYCl6 (CLYC) has generated recent interest as a thermal neutron detector due to its excellent n/γ-ray pulse-shape discrimination and energy resolution. Here, the capabilities of CLYC as a fast ...neutron detector and spectrometer are reported. A 1in.×1in. CLYC detector was used to measure the response of mono-energetic neutrons over a range of 0.8–2.0MeV produced via the 7Li(p,n) reaction at the University of Massachusetts Lowell 5.5MV Van de Graaff accelerator. A broad continuum from the 6Li(n, α) reaction was observed, as well as additional peaks below the thermal capture peak. Based on possible reactions in CLYC, the additional peaks are determined to be due to the 35Cl(n,p)35S reaction, with a Q-value of +615keV, and corroborated in simulations using MCNPX. The average resolution of 9% for these peaks makes CLYC a promising candidate for a fast neutron spectrometer.
Fast-rotating N=151 isotones 245Pu, 247Cm and 249Cf have been studied through inelastic excitation and transfer reactions with radioactive targets. While all have a ground-state band built on a ...νj15/27349/2− Nilsson configuration, new excited bands have also been observed in each isotone. These odd-N excited bands allow a comparison of the alignment behavior for two different configurations, where the νj15/2 alignment is either blocked or allowed. The effect of higher order deformations is explored through cranking calculations, which help clarify the elusive nature of νj15/2 alignments.
We are exploring a novel time- and cost-efficient approach to produce robust, large-volume polycrystalline lanthanide halide scintillators using a hot wall evaporation (HWE) technique. To date, we ...have fabricated LaBr
3:Ce and LaCl
3:Ce films (slabs) measuring up to 7
cm in diameter and 7+
mm in thickness (20–25
cm
3 in volume) on quartz substrates. These polycrystalline scintillators exhibit very bright emissions approaching those exhibited by their melt-grown crystal counterparts. Scanning electron micrographs (SEMs) and X-ray diffraction analysis confirm polycrystalline growth with columnar structures, both of which help in light piping, thereby contributing to the observed high light yields. The new scintillators also exhibit good energy resolution for γ-rays over the tested range of 60
keV (
241Am) to 662
keV (
137Cs), although they have not yet reached that of the corresponding crystals. The measured response linearity over the same energy range is comparable for both our HWE synthesized films and melt-grown commercially-available reference crystals. Similar consistency in response is also observed in terms of their decay time and afterglow behaviors. The data collected so far demonstrate that our HWE technique permits the rapid creation of scintillators with desired structural and compositional characteristics, without the introduction of appreciable defects, and yields material performance equivalent to or approaching that of crystals. Consequently, the deposition parameters may be manipulated to tailor the physical and scintillation performance of the resulting structures, while achieving a cost per unit volume that is substantially lower than that of crystals. In turn, this promises to allow the use of these novel scintillation materials in such applications as SPECT, PET, room-temperature radioisotope identification and homeland security, where large volumes of materials in a wide variety of shapes and sizes are needed. This paper describes our growth and testing of polycrystalline LaBr
3:Ce scintillators and provides comparative characterizations of their performance with crystals.
In recent years, a number of materials from the elpasolite crystal family have been under development for either or both gamma ray and neutron detection. The scintillators show good energy resolution ...and thermal neutron detection efficiency. The latter is achieved due to the fact, that the selected compositions contain Li-6 ions. In order to effectively and reliably register both types of radiation, it is necessary to separate them through particle identification schemes. This can be accomplished using either pulse height or/and pulse shape discrimination, with the latter being more reliable. In this paper, we summarize our work and provide current status of pulse shape discrimination in the selected elpasolite scintillators. These include Cs 2 LiYCl 6 (CLYC), Cs 2 LiLaCl 6 (CLLC), Cs 2 LiLaBr 6 (CLLB), and Cs 2 LiYBr 6 (CLYB).
The scintillation properties of a novel plastic scintillator loaded with an organolead compound are presented. Under X-ray and gamma-ray excitation, emission is observed peaking at 435nm. The ...scintillation light output is 9000ph/MeV. An energy resolution (full width at half maximum over the peak position) of about 16% was observed for the 662keV full absorption peak. Excellent pulse shape discrimination between neutrons and gamma-rays with a Figure of Merit of 2.6 at 1MeVee was observed.
New generation of plastic scintillators have been developed at RMD for fast neutron detection technology. These plastics have peak emission wavelength ~ 440 nm, fast scintillation decay <; 10 ns, ...light output ~ 13,000 photons/MeV, and excellent Pulse Shape Discrimination (PSD) between gamma rays and neutrons. We have achieved a Figure-of-Merit (FOM) of 2.3 at 1.0 MeVee electron energy threshold for a 2 inch diameter right cylinder sample. At RMD, comparative measurements were made between the plastic scintillator and Eljen liquid scintillator EJ309 both 1 inch diameter × 1 inch length. RMD plastic showed competitive performance. Additionally, in an experiment performed at the University of Kentucky 7 MV Van De Graaff accelerator, RMD plastic scintillator was irradiated with mono-energetic fast neutron beam energies up to 20.8 MeV. The results from this experiment confirm fast neutron spectroscopy capabilities. These results and effects of different electronic systems on the PSD measurements are discussed in this paper.
A promising composition, Ce doped Cs 2 LiYBr 6 (CLYB) originally introduced by van Loef et al. has been investigated recently as a gamma-ray and neutron detector. It belongs to the elpasolite family ...and has a cubic structure. A single crystal of this material has been grown using the vertical Bridgman method. Scintillation properties such as energy resolution, emission, light yield, non-proportionality, and decay times are discussed in this paper. It can be used effectively to discriminate between the gamma and neutron events using pulse-shape discrimination (PSD) technique.
Recently a number of alkaline earth halide scintillators doped with Eu 2+ have been reported on. They are characterized by very good proportionality, high up to 100,000 photons/MeV light yield, and ...very good energy resolution, as low as 2.8% at 662 keV. Yet, one of the issues facing these materials is radiation trapping. Radiation trapping results from a small Stokes shift that creates considerable overlap between emission and absorption bands. As a result the scintillation light is absorbed and emitted multiple times, leading to a prolongation of the scintillation decay, potential light losses and degradation of energy resolution. Spectroscopic properties of various Eu 2+ doped alkaline earth halides are presented. Materials studied include: SrI 2 , BaI 2 , BaBrI and other compounds. It appears that some compositions are less affected by radiation trapping.
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