IEEE 2021 NSS MIC

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Scintillation Detectors I

Session chair: Watanabe , Kenichi (Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka, Japan); Di Fulvio , Angela (University of Illinois at Urbana Champaign, Nuclear, Plasma, and Radiological Engineering, Urbana, USA)
 
Shortcut: N-16
Date: Wednesday, 20 October, 2021, 9:15 AM - 11:15 AM
Room: NSS - 4
Session type: NSS Session

Contents

Click on an contribution to preview the abstract content.

9:15 AM N-16-01

Neutron Light Output Response and Anisotropy of Deuterated Trans-stilbene (#700)

J. Zhou1, N. Gaughan1, F. Becchetti2, R. Torres-Iseab2, A. Di Fulvio1

1 University of Illinois at Urbana Champaign, Department of Nuclear, Plasma, and Radiological Engineering, Urbana, Illinois, United States of America
2 University of Michigan, Department of Physics, Ann Arbor, Michigan, United States of America

Abstract

We have characterized the neutron light output response and anisotropy of a deuterated trans‑stilbene (stilbene-d12) crystal of approximately 170 cm3 volume. We used two methods for the light output characterization: 1) the time-of-flight (TOF) method and 2) the n-d scattering method with a monoenergetic 14.1 MeV D-T source. The TOF method was used to characterize the light output response in the 0.8 – 5 MeV neutron energy range while the n-d scattering method was designed to extend the light output response from 0.5 to 14.1 MeV neutrons. The light output data measured with the two approaches are explained well by a semi‑empirical functional form based on the Birks’ light-output model. The measured detector response enabled spectroscopic measurements of 14.1 MeV DT, 2.5 MeV DD, and PuBe neutron sources. We also found that stilbene‑d12’s response is dependent on the irradiation angle, at 14.1 MeV neutrons, similarly to 1H-trans-stilbene. The response anisotropy was not detected at 2.5 MeV neutrons in stilbene‑d12. Therefore, we infer that the angular dependence of the stilbene-d12 response is energy-dependent. The crystal used in this work was grown at Lawrence Livermore National Laboratory using a solution growth method.

Acknowledgment

This work was funded in part by the Nuclear Regulatory Commission Faculty Development Grant 31310019M0011, and NRC fellowship grants NRC-HQ841560020 and NRC-31310018M0029.

Keywords: deuterated stilbene, scintillation detector, light output response, angular dependence
9:30 AM N-16-02

Development of an alpha- and beta-imaging detectorusing a thin-stilbene plate for radon-222 progeny measurements (#242)

Y. Morishita1

1 Japan Atomic Energy Agency, Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Futaba County, Japan

Abstract

Radon-222 is a naturally-occurring radioactive gas, and the measurement of this isotope and its progeny is of interest from the viewpoint of protection against internal exposure. The author has developed a new alpha/beta-imaging detector combined with a waveform digitizer capable of imaging alpha- and beta-particle locations simultaneously. A 0.9-mm-thick stilbene plate was optically coupled to a position-sensitive photomultiplier tube (PSPMT), and the analog signals from the PSPMT were transferred in parallel to the waveform digitizer. For 5.5-MeV alpha particles, the detection efficiency was 97.2 % for 2pi steradians, and the energy resolution of the 5.5 MeV alpha peak was 21.6 ± 0.18% full width at half maximum (FWHM). The imaging detector was able to discriminate between alpha and beta particles via the pulse-shape-discrimination (PSD) technique, as well as being capable of alpha- and beta-particle imaging. The imaging detector was used for 222Rn-progeny measurements. When measuring the 222Rn progeny, both 214Bi and 214Po are imaged simultaneously, and a correlation is found between the positions of 214Bi and 214Po. The developed detector will be useful as a 222Rn detector and in alpha-continuous-air monitoring for nuclear facilities.

Acknowledgment

This work was supported in-part by JSPS KAKENHI Grant Number 19K15482.

Keywords: Radon-222, Thin-stilbene plate, Alpha/beta-imaging detector, Pulse shape discrimination, Time-interval analysis
9:45 AM N-16-03

High Efficiency Compact Scintillator Detectors (#611)

L. Soundara Pandian1, J. Tower1, P. Bhattacharya1, E. van Loef1, J. Glodo1, K. Shah1

1 Radiation Monitoring Devices, Inc., Watertown, Massachusetts, United States of America

Abstract

The Tl based compounds are new scintillator materials that show high efficiency for gamma detection due to their high effective Z and density.  Tl2LiYCl6:Ce (TLYC), Tl2LaCl5:Ce (TLC) Tl2ZrCl6 (TZC) are few materials that are being developed and scaled up for large sizes at RMD.  These scintillators offer good gamma energy resolution along with neutron detection capabilities.  TLYC and TZC show a light yield of ~30,000 ph/MeV with energy resolution as good as 4.0% at 662 keV, while TLC shows a high light yield of ~60,000 ph/MeV with an excellent energy resolution of 3.0% at 662 keV.  TLYC can detect and discriminate both thermal and fast neutrons through neutron capture reactions in 6Li and 35Cl, while TZC and TLC can detect fast neutrons.

In this presentation, we report on the characterization of compact detectors constructed and fabricated at RMD using small volume crystals of TLYC, TZC, and TLC coupled to silicon photomultipliers (SiPM).  These compact detectors with excellent gamma energy resolution and high gamma efficiency with added neutron detection capability are suitable for instruments such as pagers or handhelds that require radioisotope identification and gamma-neutron discrimination.  TLYC detector constructed with a 12 mm x 12 mm x 7 mm crystal coupled to a 12 mm x 12 mm total area SiPM array shows an excellent energy resolution of ~4.3% at 662 keV along with pulse shape discrimination capability.  TZC detector constructed with a 12 mm x 12 mm x 3 mm crystal shows an energy resolution of 4.8% at 662 keV.  More results with other Tl based materials will also be presented.

AcknowledgmentThis work has been supported by the US Department of Energy, under competitively awarded contract DE-SC0015793.  This support does not constitute an express or implied endorsement on the part of the Government. 
Keywords: Tl2LiYCl6, Tl2ZrCl6, Scintillator detectors, Gamma-rays, Silicon photomultipliers
10:00 AM N-16-04

Radiation Detection Performance of 3D Printable Light-Cured Plastic Scintillators (#1008)

B. Frandsen1, M. Febbraro2, J. Bevins1

1 Air Force Institute of Technology, Department of Engineering Physics, Wright-Patterson AFB, Ohio, United States of America
2 Oak Ridge National Laboratory, Physics Division, Oak Ridge, Tennessee, United States of America

Abstract

Newly developed light-cured plastic scintillators have been designed to cure quickly so they can be used with commercial stereolithography 3D printers. Nine different scintillator formulations were produced, all of which were cured to a solid within 10-30 seconds. The relative light yield compared to EJ-276, resolution, and pulse shape discrimination figure of merit were measured for each scintillator using Na-22 and AmBe sources. The scintillators were able to produce between 49% to 75% of the light yield of EJ-276, with corresponding resolutions. All the scintillators were able to distinguish between neutrons and gamma radiation using pulse shape discrimination, with the figure of merit of events between 450-550 keVee ranging from 0.66 to 1.14 amongst the new scintillators.

Keywords: radiation detection, plastic scintillator, SLA 3D printing
10:15 AM N-16-05

Scintillating fibre based beta spectrometer: proof of concept by Monte-Carlo simulation and first experimental assessment (#499)

N. Dufour1, A. Sari1, G. Bertrand1, F. Carrel1

1 Commissariat à l'Energie Atomique et aux Energies Alternatives, Université Paris-Saclay, CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, Gif-sur-Yvette, France

Abstract

During decommissioning and dismantling (D&D) operations, radiological contaminations must be characterized. These contaminations can be comprised of mixed beta emitters. In order to separate the different contributions, we developed a new beta measurement method based on the use of scintillating fibres. Taking advantage of both their deformability capacity and their potential lengths up to a few meters, we expect that scintillating fibres will be well adapted to the radiological characterization of large areas, and suitable for deployment on uneven surfaces. Using fibres of various cladding thicknesses and core diameters, a contrast can be achieved between beta emitters characterized by various energy spectra. Physical origin of this contrast relies on the exponential evolution of the polystyrene stopping power in the 0 to 3 MeV energy range, leading to high-energy beta particles being less affected by thicker cladding than medium-energy beta particles. As a first experimental proof of concept, by using scintillating fibres with different cladding thicknesses and a deconvolution method, we were able to identify and quantify two beta contributors in a measured spectrum. We have used 36Cl and 90Sr–90Y sources, considering 36Cl as a medium-energy emitter and 90Sr-90Y as a high-energy emitter. Results obtained using scintillating fibres with a single cladding thickness showed that it is not possible to estimate both contributions correctly, with errors up to 71% of the actual activities. However, thanks to acquisitions carried out with fibres of different cladding thicknesses, we were able to estimate both contributions with an error of 26% for 36Cl and 10% for 90Sr-90Y, thereby validating the feasibility of this approach. Study of the improvement of the deconvolution is underway. The next step of this work will consist in designing a beta spectrometer based on scintillating fibres, and assess its performances in laboratory using various beta sources.

Keywords: Scintillating fibre, Deconvolution
10:30 AM N-16-06

Improvements in position resolution for 1D and 2D ZnS:Ag/6LiF Wavelength Shifting Fibre Neutron Detectors (#631)

G. Mauri1, J. Sykora1, E. Schooneveld1, N. Rhodes1

1 STFC ISIS Neutron and Muon Source, Didcot, United Kingdom

Abstract

High neutron intensity, improvements in neutron delivery, and increasingly more complex experiments at neutron scattering facilities, i.e. J-PARC, SNS, ISIS, CSNS and ESS drive the development of neutron scattering instruments and their associated detectors. Several instrument upgrades including neutron reflectometers, neutron diffractometers and spin echo small angle neutron scattering are foreseen at ISIS. These instruments demand high position resolution and counting rate capability. It is particularly challenging when both performances need to be met. ZnS:Ag/6LiF scintillation detectors coupled to wavelength shifting fibre (WLSF) are currently employed on several ISIS neutron instruments. For WLSF-based scintillation detectors the position reconstruction is routinely achieved by determining the combination of fibres that absorb scintillation light. The use of position reconstruction algorithms that analyse light spread in the system leads to an improvement in position resolution. This work focuses on the development and optimisation of a Centre of Gravity (CoG) interpolation algorithm together with a non-linear binning method that is applicable to position sensitive detectors. This algorithm leads to at least a factor of two improvement in position sensitivity whilst achieving a similar counting rate capability. The proposed interpolation method can be applied to both linear and 2-Dimensional position sensitive detector designs by tuning the algorithm parameters according to the geometric properties of the detector. Results will be presented for various position sensitive detectors. Moreover, the algorithm has been implemented on a field programmable gate array (FPGA) for real-time position reconstruction. The promising results and relatively simple implementation in an FPGA make the proposed method suitable for standard operation in a variety of applications.

Keywords: High resolution, Neutron detectors, Neutron Scattering, Scintillator detectors, Wavelength Shifting fibre
10:45 AM N-16-07

InAs Quantum Dot Scintillator: High-Yield and Ultrafast Charged Particle Detection (#2)

T. Mahajan1, A. Minns1, V. Tokranov1, M. Yakimov1, P. Murat3, M. Hedges2, S. Oktyabrsky1

1 SUNY Polytechnic Institute, Albany, New York, United States of America
2 Purdue University, West Lafayette, Indiana, United States of America
3 Fermi National Accelerator Laboratory, Batavia, Illinois, United States of America

Abstract

InAs quantum dots (QDs) functioning as luminescence centers embedded in a GaAs waveguiding (WG) matrix have uniquely fast scintillation properties with high luminescence efficiency and relatively low self-absorption. QD photoluminescence measurement shows about 60% efficiency at room temperature encouraging the normal operating condition for the detector. Scintillating signals from 241Am alpha-particles were analyzed with both an external photodiode (PD) and an integrated PD which provided an improved optical coupling. Distributions of charge collected by the PD appear bi-modal corresponding to geometry of PD and the WG. The collected charge depends on the distance between the radioactive source and the detector following the alpha-particle air ionization curve. The mean charge collected by the integrated PD corresponded to 30 photoelectrons per 1 keV of deposited energy, or 13% of the theoretically achievable light yield. To measure the transient parameters of the integrated device, the integrated PD pads were wire-bonded to the input of an 8 GHz preamplifier. The scintillation response shows a fast 0.5 ns decay time and about 70 ps time resolution, limited by the system noise. The performance of integrated photodetector was analyzed with the Monte Carlo simulations, which provided design rules for optimization of PD and scintillating pixel geometry with respect to the waveguiding properties. The combined light yield and decay time makes the InAs/GaAs QD heterostructure the fastest high yield scintillation material reported making it valuable for high energy physics and medical imaging applications.

AcknowledgmentThe work was supported by the National Science Foundation under award DMR-1708637 and the U.S. Department of Energy, Office of Science under Award Number DE-SC0019031. 
Keywords: InAs Quantum Dots, Picosecond Time Resolution, Scintillation Detector
11:00 AM N-16-08

A New Experimental Setup for the Characterizationof Ultra-Fast and Low-Density Scintillators (#555)

F. Pagano1, 2, N. Kratochwil1, 3, M. Salomoni1, I. Frank1, 4, S. Gundacker1, 5, M. Pizzichemi1, 2, M. Paganoni1, 2, E. Auffray1

1 European Organisation for Nuclear Research (CERN), Geneva, Genève, Switzerland
2 University of Milano Bicocca, Milan, Italy
3 University of Vienna, Vienna, Wien, Austria
4 Ludwig Maximilian University of Munich, Munich, Bavaria, Germany
5 RWTH Aachen University, Institute for Experimental Molecular Imaging, Aachen, North Rhine-Westphalia, Germany

Abstract

The demand for detectors with time resolution <100 ps is at the center of the research in different fields, from high energy physics to medical imaging. In recent years there has been an increasing interest in nanomaterials, because of their sub-nanosecond rise-time and decay-time. However, due to the relatively low density and low effective atomic number, standard characterization methods for scintillation properties are not optimal. 
A new method for time resolution measurements of scintillating materials is illustrated to characterise scintillation properties, using a pulsed X-ray source (10-40keV) and optimized high frequency electronics. To validate this method, standard scintillators were measured and the results were compared with the deduced values from Coincidence Time Resolution (CTR) measurements under 511 keV irradiation, obtaining a good agreement. After this first stage of setting and validating the new experimental setup, this method will be extended to ultrafast and low-density materials, allowing to study the time resolution for low energy ionizing particles. Moreover, this technique opens the way to new applications where fast X-rays detectors are requested, like Time-of-Flight Computed Tomography (TOF-CT) and, more in general, X-ray imaging.

Acknowledgment

This work was carried out in the frame of the Crystal Clear Collaboration and was supported by the CERN Budget for Knowledge Transfer to Medical Applications.

Keywords: Scintillators, Time resolution, X-Ray

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