Reflectivity quenching of ESR multilayer polymer film reflector in optically bonded scintillator arrays

Loignon-Houle, Francis; Pépin, C.; Charlebois, Serge A.; Lecomte, Roger

doi:10.1016/j.nima.2017.01.051

Cited by 23 publications

(10 citation statements)

References 22 publications

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“…Because the fission spectrum motivates the lowest possible detection threshold, we chose EJ-204 over EJ-230 for this particular application. The coupling of Teflon and ESR performed similarly in the case of EJ-204, however the difficulties associated with wrapping ESR in a uniform fashion for a 64-bar system, along with optical crosstalk concerns [20], motivated the use of Teflon.…”

Section: Timing Response With 90 Srmentioning

confidence: 99%

Interaction position, time, and energy resolution in organic scintillator bars with dual-ended readout

Sweany

Galindo-Tellez

Brown

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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Section: Timing Response With 90 Srmentioning

confidence: 99%

Interaction position, time, and energy resolution in organic scintillator bars with dual-ended readout

Sweany

Galindo-Tellez

Brown

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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“…Indeed, as shown in Figure 4, the efficiency of the system is quickly reduced when the crystal size becomes comparable to the size of the coating due to the reduced packing fraction (ratio of crystal cross-section without coating to cross-section with coating). This geometric effect can be mitigated by changing the scattering behavior and resorting to other materials such as the Enhanced Specular Reflector (ESR) [14], which features a typical thickness of 65 µm; its analysis is reported in [15]. The ESR is a film of dielectric material (Figure 3 right) with high reflectivity over a very large spectrum, and represents the current gold standard when reflective coatings are applied on scintillator surfaces.…”

Section: Light Extraction Techniques: State-of-the-art 21 Conventional Light Extraction Enhancement Techniquesmentioning

confidence: 99%

Light Extraction Enhancement Techniques for Inorganic Scintillators

et al. 2021

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Scintillators play a key role in the detection chain of several applications which rely on the use of ionizing radiation, and it is often mandatory to extract and detect the generated scintillation light as efficiently as possible. Typical inorganic scintillators do however feature a high index of refraction, which impacts light extraction efficiency in a negative way. Furthermore, several applications such as preclinical Positron Emission Tomography (PET) rely on pixelated scintillators with small pitch. In this case, applying reflectors on the crystal pixel surface, as done conventionally, can have a dramatic impact of the packing fraction and thus the overall system sensitivity. This paper presents a study on light extraction techniques, as well as combinations thereof, for two of the most used inorganic scintillators (LYSO and BGO). Novel approaches, employing Distributed Bragg Reflectors (DBRs), metal coatings, and a modified Photonic Crystal (PhC) structure, are described in detail and compared with commonly used techniques. The nanostructure of the PhC is surrounded by a hybrid organic/inorganic silica sol-gel buffer layer which ensures robustness while maintaining its performance unchanged. We observed in particular a maximum light gain of about 41% on light extraction and 21% on energy resolution for BGO, a scintillator which has gained interest in the recent past due to its prompt Cherenkov component and lower cost.

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“…At incident photon angles over 50 • , TiO 2 paint transitions into a hybrid of a specular reflector and Lambertian reflector [31]. ESR film has a significant reduction in reflectivity for wavelengths below 395 nm [32,33]. This was not included in the LUT for ESR.…”

Section: Effect Of Reflectormentioning

confidence: 99%

Model-based design evaluation of a compact, high-efficiency neutron scatter camera

Weinfurther

Mattingly

Brubaker

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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This paper presents the model-based design and evaluation of an instrument that estimates incident neutron direction using the kinematics of neutron scattering by hydrogen-1 nuclei in an organic scintillator. The instrument design uses a single, nearly contiguous volume of organic scintillator that is internally subdivided only as necessary to create optically isolated pillars, i.e., long, narrow parallelepipeds of organic scintillator. Scintillation light emitted in a given pillar is confined to that pillar by a combination of total internal reflection and a specular reflector applied to the four sides of the pillar transverse to its long axis. The scintillation light is collected at each end of the pillar using a photodetector, e.g., a microchannel plate photomultiplier (MCP-PM) or a silicon photomultiplier (SiPM). In this optically segmented design, the (x, y) position of scintillation light emission (where the x and y coordinates are transverse to the long axis of the pillars) is estimated as the pillar's (x, y) position in the scintillator "block", and the z-position (the position along the pillar's long axis) is estimated from the amplitude and relative timing of the signals produced by the photodetectors at each end of the pillar. The neutron's incident direction and energy is estimated from the (x, y, z)-positions of two sequential neutron-proton scattering interactions in the scintillator block using elastic scatter kinematics. For proton recoils greater than 1 MeV, we show that the (x, y, z)-position of neutron-proton scattering can be estimated with < 1 cm root-mean-squared [RMS] error and the proton recoil energy can be estimated with < 50 keV RMS error by fitting the photodetectors' response time history to models of optical photon transport within the scintillator pillars. Finally, we evaluate several alternative designs of this proposed single-volume scatter camera made of pillars of plastic scintillator (SVSC-PiPS), studying the effect of pillar dimensions, scintillator material (EJ-204, EJ-232Q and stilbene), and photodetector (MCP-PM vs. SiPM) response vs. time. We demonstrate that the most precise estimates of incident neutron direction and energy can be obtained using a combination of scintillator material with high luminosity and a photodetector with a narrow impulse response. Specifically, we conclude that an SVSC-PiPS constructed using EJ-204 (a high luminosity plastic scintillator) and an MCP-PM will produce the most precise estimates of incident neutron direction and energy.

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Reflectivity quenching of ESR multilayer polymer film reflector in optically bonded scintillator arrays

Cited by 23 publications

References 22 publications

Interaction position, time, and energy resolution in organic scintillator bars with dual-ended readout

Interaction position, time, and energy resolution in organic scintillator bars with dual-ended readout

Light Extraction Enhancement Techniques for Inorganic Scintillators

Model-based design evaluation of a compact, high-efficiency neutron scatter camera

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