Scintillators for neutron and gamma detection
Structured LiNaI:Eu Scintillators for Neutron Radiography and Tomography (#3056)
M. J. More1, S. Miller1, S. Waterman1, J. Crespi1, M. Marshall1, H. Bhandari1, P. Nickerson1, V. Nagarkar1
1 RMD, Waterwown, MA, United States of America
We have developed a novel neutron scintillator material, LiNaI:Eu that is fabricated in microcolumnar format using the physical vapor deposition (PVD) method. Such structured scintillators mitigate the conventional trade-off between spatial resolution and detection efficiency by channeling the scintillation light towards the detector while minimizing lateral spread in the film. Consequently, high resolution and high contrast neutron images can be acquired in a time efficient manner. In this paper, we present recent imaging results with the LNI films measured at HFIR, ORNL. The films were lens-coupled to a CCD camera and phantom images were acquired. Finally, tomographic imaging of a cockroach specimen (Blaptica dubia) was also performed.
Keywords: neutron radiography, neutron tomography, Lithium Sodium Iodide, microcolumnar scintillators
Towards an advanced characterization of the n/gamma detection properties of the new CLLB elpasolite crystal (#2258)
G. Hull1, F. Camera2, 3, M. Josselin1, I. Matea1
1 Institut de Physique Nucleaire, CNRS-IN2P3, Université Paris-Sud, Université Paris-Saclay, Orsay, France
In this work we will present the study of the neutron and gamma detection performances of two CLLB crystals, with different sizes, to evaluate the effect of the increasing volume in the crystal detection performances.
As a matter of fact, in these latest years the elpasolite crystals imposed their presence in the scintillator materials field due to their good gamma detection property, associated to a remarkable n/gamma pulse shape discrimination capability. Anyway, while the CLYC as been extensively studied, the other elpasolite crystals, such as CLLB, CLLC or CLLBC, still remains less explored alternatives.
In this communication we will present the study of two cylindrical Cs2LiLaBr6:Ce optics by Saint Gobain, with dimensions of 1” diam x 1” and 2” diam x 2”, respectively, when irradiated with gamma rays and thermalized neutrons.
In particular we measured the light yield and energy resolution with gamma rays emitting sources in the energy range between 81 keV and 3.2 MeV and up to 9 MeV with an AmBe(Ni) source, and we compared the results with a standard LaBr3:Ce crystal. We investigated the effect of the 138La internal activity on the neutron detection and we evaluated the crystal n/gamma PSD, in comparison with a CLYC scintillator. Finally we performed a scan along the x, y and z axes, using a collimated 137Cs source, to evaluate the crystal response as a function of the interaction point.
Keywords: elpasolite crystals, PSD, CLLB
High-Performance Composite Scintillators for Gamma-Neutron Detection (#2275)
S. Lam1, J. Fiala1, S. Motakef1
1 CapeSym, Inc., Natick, Massachusetts, United States of America
Composite scintillators hold the promise of high-performance, low-cost gamma-neutron detectors in sizes that would be otherwise prohibitively expensive or impossible to produce. For example, the excellent scintillation performance of SrI2:Eu and the dual mode detection capability of CLYC:Ce make these halide crystals ideal candidates for nuclear radiation detection, but these detectors become expensive at large diameters (e.g. at 3-inches) due to decreased crystal growth yield. Fortunately, the cost of embedding small diameter crystals into a large plastic matrix such as polyvinyltoluene (PVT) is low, and the plastic matrix can even be shaped to improve light collection. This presentation will discuss the design, fabrication, and performance of our CLYC-PVT and SrI2-PVT composite scintillators. Fabrication of these composites were guided by Geant4 simulations to characterize the generation, transport, and collection of photons, and their dependence on surface conditions and index of refraction. Our first 2-inch diameter CLYC-PVT achieved an energy resolution of 4.4% at 662 keV and a PSD of 3.2. More recently, we demonstrated the feasibility of 5-inch diameter composite fabrication. We will also present on SrI2-PVT composites. Other important considerations for composite fabrication will be discussed.
Keywords: Scintillator, Composites, Dual-mode detection, Neutron detection, Plastic scintillator, CLYC, SrI2
New Plastic Scintillators for Gamma Spectroscopy, Neutron Detection and Imaging (#3635)
N. Cherepy1, H. P. Martinez1, R. Sanner1, P. Beck1, E. Swanberg1, S. Payne1, C. Hurlbut2, B. Morris2
1 Lawrence Livermore National Laboratory (LLNL), Livermore, United States of America
We are working on scale up of several new plastic scintillator compositions. One composition uses Iridium complex fluors to obtain up to 3x higher light yields for improved particle (alpha, neutron, fission product) detection and imaging. Other compositions include high loading of Bismuth for gamma spectroscopy and with Lithium for neutron detection. Plastics containing 21 wt% elemental Bismuth and an Ir fluor provide strong photopeaks and R(662 keV) ~9%. When activated with standard organic fluors, 10 in3 plastic scintillators containing 8 wt% Bismuth provide a strong photopeak with R(662 keV)~ 19%. A 5 in3 plastic formulation including 1 wt% Lithium-6 provides a neutron capture peak at 350 keVee, with 11% resolution for the capture peak.
Keywords: plastic scintillators, imaging, gamma spectroscopy, neutron detection
Neutron and Gamma Ray Pulse Shape Discrimination with EJ-270 Lithium-loaded Plastic Scintillator (#2346)
M. Ellis1, C. Hurlbut2, C. Allwork1, B. Morris2
1 AWE Aldermaston, Detection Science, Reading, United Kingdom of Great Britain and Northern Ireland
Eljen have developed the new EJ-270 plastic scintillator, which contains the element lithium-6 at an isotopic enrichment of 95.5 atomic percent. This material is based on research carried out at Lawrence Livermore National Laboratory where the scintillator was developed. The material is formulated to provide Pulse Shape Discrimination (PSD) of scintillation pulses from thermal neutrons, fast neutrons and gamma rays. Pulse shape discrimination measurements and analysis are made on an early EJ-270 sample measuring 51 x 51 mm (diameter x length) with a lithium-6 loading level of 0.5% by weight. Results are presented on the optimisation of PSD algorithm parameters for this new material along with a quantification of the separation that can be achieved between the three particle detection modes. Direct comparisons are also made with other PSD-capable plastics.
Keywords: Pulse Shape Discrimination, PSD, Scintillator, EJ-270, lithium-loaded
Lithium-loaded scintillators coupled to a custom-designed silicon photomultiplier array for neutron and gamma-ray detection (#1528)
F. Liang1, H. Brands1, L. Hoy1, J. Preston2, J. Smith1
1 FLIR Systems Inc., Oak Ridge, Tennessee, United States of America
Scintillators capable of detecting both neutron and gamma-ray have generated considerable interest. In particular, the use of such scintillators with silicon photomultipliers (SiPMs) enables low-power and compact-geometry applications. Three Li-loaded scintillators, CLYC, CLLB, and NaIL, have been tested with a
Keywords: silicon photomultiplier, neutron detection, CLYC, CLLB, NaIL