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At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

WE-AB-BRB-09: Real Time In Vivo Scintillating Fiber Array Detector for Medical LINACS

Purpose: An in vivo transmission scintillation fiber detector was developed to monitor patient treatment in real time for the enhancement of patient safety and treatment accuracy. The detector system is capable of monitoring each pulse from a medical LINAC during treatment to determine the dose delivered as treatment progresses. Methods: The detector system consists of 60 parallel scintillating fibers coupled to fast data processing optoelectronics that can monitor the beam fluence in real time. Each 2.5mm{sup 2} square fiber is aligned with an MLC leaf pair and is long enough to capture a 40cm field. The fibers are embedded within a water equivalent polymer substrate that is secured in the LINAC accessory tray. The fibers are coupled to high speed photosensors and front end amplifiers that filter noise and pass each pulse to a high speed analog-to-digital converter. The system components are capable of detecting pulse repetition times shorter than what is delivered by a medical LINAC to ensure true real time data acquisition. Results: The system was able to capture and record the signal from each linac pulse and display the information in real time with no pulse pile up. It was found that the fiber array attenuates 2.65% of the beam which can easily be compensated for in treatment planning. The fibers responded linearly with dose, are independent of clinical beam energies, and are independent of dose rate. Calibration of the system was performed as a function of beam energy, beam size, dose rate, and monitor units to optimize beam fluence error detection. Conclusion: The detector system presented provides true real time in vivo beam monitoring to enhance patient safety and treatment delivery accuracy. Furthermore, the detector can be used for current patient specific QA.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SU-G-TeP4-12: Individual Beam QA for a Robotic Radiosurgery System Using a Scintillator Cone

Purpose: The targeting accuracy of the Cyberknife system is measured by end-to-end tests delivering multiple isocentric beams to a point in space. While the targeting accuracy of two representative beams can be determined by a Winston-Lutz-type test, no test is available today to determine the targeting accuracy of each clinical beam. We used a scintillator cone to measure the accuracy of each individual beam. Methods: The XRV-124 from Logos Systems Int’l is a scintillator cone with an imaging system that is able to measure individual beam vectors and a resulting error between planned and measured beam coordinates. We measured the targeting accuracy of isocentric and non-isocentric beams for a number of test cases using the Iris and the fixed collimator. The average difference between plan and measured beam position was 0.8–1.2mm across the collimator sizes and plans considered here. The max error for a single beam was 2.5mm for the isocentric plans, and 1.67mm for the non-isocentric plans. The standard deviation of the differences was 0.5mm or less. Conclusion: The CyberKnife System is specified to have an overall targeting accuracy for static targets of less than 0.95mm. In E2E tests using the XRV124 system we measure average beam accuracy between 0.8 to 1.23mm, with maximum of 2.5mm. We plan to investigate correlations between beam position error and robot position, and to quantify the effect of beam position errors on patient specific plans. Martina Descovich has received research support and speaker honoraria from Accuray.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

WE-AB-BRB-03: Real-Time Volumetric Scintillation Dosimetry for Radiation Therapy

Despite widespread IMRT treatments at modern radiation therapy clinics, precise dosimetric commissioning of an IMRT system remains a challenge. In the most recent report from the Radiological Physics Center (RPC), nearly 20% of institutions failed an end-to-end test with an anthropomorphic head and neck phantom, a test that has rather lenient dose difference and distance-to-agreement criteria of 7% and 4 mm. The RPC report provides strong evidence that IMRT implementation is prone to error and that improved quality assurance tools are required. At the heart of radiation therapy dosimetry is the multidimensional dosimeter. However, due to the limited availability of water-equivalent dosimetry materials, research and development in this important field is challenging. In this session, we will review a few dosimeter developments that are either in the laboratory phase or in the pre-commercialization phase. 1) Radiochromic plastic. Novel formulations exhibit light absorbing optical contrast with very little scatter, enabling faster, broad beam optical CT design. 2) Storage phosphor. After irradiation, the dosimetry panels will be read out using a dedicated 2D scanning apparatus in a non-invasive, electro-optic manner and immediately restored for further use. 3) Liquid scintillator. Scintillators convert the energy from x-rays and proton beams into visible light, which can be recorded with a scientific camera (CCD or CMOS) from multiple angles. The 3D shape of the dose distribution can then be reconstructed. 4) Cherenkov emission imaging. Gated intensified imaging allows video-rate passive detection of Cherenkov emission during radiation therapy with the room lights on. Learning Objectives: To understand the physics of a variety of dosimetry techniques based upon optical imaging To investigate the strategies to overcome respective challenges and limitations To explore novel ideas of dosimeter design Supported in part by NIH Grants R01CA148853, R01CA182450, R01CA109558. Brian Pogue is founder and president of the company DoseOptics LLC, dedicated to developing and commercializing the first dedicated Cerenkov imaging camera and system for radiation dose imaging. Work reported in this talk does not involve the use of DoseOptics technology.; H. Li, this work was supported in part by NIH Grant No. R01CA148853; S. Beddar, NIH funding R01-CA182450.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Upper limit on the cross section for elastic neutralino-nucleon scattering in a neutrino experiment at the Baksan Underground Scintillator Telescope

The results of a neutrino experiment that involved 24.12 yr of live time of observation of muons from the lower Earth's hemisphere with the aid of the Baksan Underground Scintillator Telescope are presented. In the problem of searches for a signal from the annihilation of dark matter in the Sun, an upper limit on the cross section for the elastic scattering of a weakly interacting massive particle (WIMP) on a nucleon was obtained at a 90% confidence level from an analysis of data accumulated within 21.15 yr of live time of observation. A neutralino in a nonminimal supersymmetric theory was considered for a WIMP. The best limit at the Baksan Underground Scintillator Telescope on the cross section for spin-dependent neutralino interactionwith a proton corresponds to 3 Multiplication-Sign 10{sup -4} pb for the neutralino mass of 210 GeV/c{sup 2}. This limit is three orders of magnitude more stringent than similar limits obtained in experiments that detected directly WIMP scattering on target nuclei.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Performances of a large mass ZnMoO 4 scintillating bolometer for a next generation 0νDBD experiment

Here we present the performances of a 330 g zinc molybdate (ZnMoO 4 ) crystal working as scintillating bolometer as a possible candidate for a next generation experiment to search for neutrinoless double beta decay of 100 Mo. The energy resolution, evaluated at the 2615 keV γ-line of 208 Tl, is 6.3 keV FWHM. The internal radioactive contaminations of the ZnMoO 4 were evaluated as < 6 μBq/kg ( 228 Th) and 27 ± 6 μBq/kg ( 226 Ra). We also present the results of the α vs β/γ discrimination, obtained through the scintillation light as well as through the study of the shape of the thermal signal alone.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

CUPID-0: the first array of enriched scintillating bolometers for 0$\nu \beta \beta$ decay investigations

The CUPID-0 detector hosted at the Laboratori Nazionali del Gran Sasso, Italy, is the first large array of enriched scintillating cryogenic detectors for the investigation of 82 Se neutrinoless double-beta decay (0$\nu \beta \beta$). CUPID0 aims at measuring a background index in the region of interest (RoI) for 0$\nu \beta \beta$ at the level of 10 -3 counts/(keV kg years), the lowest value ever measured using cryogenic detectors. CUPID-0 operates an array of Zn 82 Se scintillating bolometers coupled with bolometric light detectors, with a state of the art technology for background suppression and thorough protocols and procedures for the detector preparation and construction. In this paper, the different phases of the detector design and construction will be presented, from the material selection (for the absorber production) to the new and innovative detector structure. The successful construction of the detector lead to promising preliminary detector performance which is discussed here.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Low energy neutrino detection with a compact water-based liquid scintillator detector

In this study, the conceptual design and physics simulations of a near-field Water-based Liquid Scintillator (WbLS) detector placed 100 m from the Akkuyu Nuclear Power Plant (ANPP), currently under construction and aiming at being Turkey’s first nuclear power plant, is presented. The ANPP is an excellent opportunity for neutrino studies and the development of an R &D program for neutrino detectors in Turkey. The Reactor Neutrino Experiments of Turkey (RNET) program includes a compact detector with a 2.5-ton volume of WbLS and a ~ 30% photo-coverage, and the program is planned to be expanded with a medium-size 30-ton detector that will be an international testbed for WbLS and new detector technologies through low energy neutrino studies. In the following, the focus will be on the smaller ~2.5 ton detector, instrumented with 8-in. high quantum efficiency PMTs and two layers of cosmic veto paddles, covering all sides of the detector, to track and veto cosmic particles. Inverse Beta Decay (IBD) events from electron anti-neutrinos generated in the reactor core are simulated using the RAT-PAC simulation package and several liquids with different percentages of Liquid Scintillator (LS) and Gadolinium (Gd) are investigated.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Measurement of proton light yield of water-based liquid scintillator

Abstract The proton light yield of liquid scintillators is an important property in the context of their use in large-scale neutrino experiments, with direct implications for neutrino-proton scattering measurements and the discrimination of fast neutrons from inverse $$\beta $$ β -decay coincidence signals. This work presents the first measurement of the proton light yield of a water-based liquid scintillator (WbLS) formulated from 5% linear alkyl benzene (LAB), at energies below 20 MeV, as well as a measurement of the proton light yield of a pure LAB + 2 g/L 2,5-diphenyloxazole (PPO) mixture (LABPPO). The measurements were performed using a double time-of-flight method and a pulsed neutron beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. The proton light yields were measured relative to that of a 477 keV electron. The relative proton light yield of WbLS was approximately 3.8% lower than that of LABPPO, itself exhibiting a relative proton light yield 15–20% higher than previous measurements of an analogous anoxic sample. The observed quenching is not compatible with the Birks model for either material, but is well described with the addition of Chou’s bimolecular quenching term.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Saturation of a Ce:Y 3 Al 5 O 12 scintillator response to ultra-short pulses of extreme ultraviolet soft X-ray and X-ray laser radiation

Investigations of radioluminescence saturation in monocrystalline cerium doped yttrium aluminum garnet (Ce:YAG) exposed to intense extreme ultraviolet (XUV), soft X-ray and X-ray radiation delivered from three free-electron lasers are described in this article. The measurements were performed with wavelengths of 98, 25.6, 13.5 and 0.15 nm. We have found that saturation of the photon yield occurs at an excitation level of 2.0 x 10 20 eV/cm 3 resulting in an emission of 1.5 x 10 18 visible photons per cubic centimeter. This number is much smaller than the concentration of Ce3+ in the scintillator that was equal to 2 x 10 20 cm –3 . Because the internal radiance efficiency η does not depend strongly on the irradiating photon energy, i.e., η ≈0.035 ± 0.015 in the range 10 to 100 000 eV, the results presented here could be used to predict saturation effects in scintillator slabs placed in imaging systems of bright XUV, X-ray and particle beams. In conclusion, the saturation of the Ce 3+ emission is explained by mutual quenching of excitons created at high densities, preceding the stage of energy transfer to the Ce 3+ ions.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Validated Models for Radiation Response and Signal Generation in Scintillators: Final Report

This Final Report presents work carried out at Pacific Northwest National Laboratory (PNNL) under the project entitled “Validated Models for Radiation Response and Signal Generation in Scintillators” (Project number: PL10-Scin-theor-PD2Jf) and led by Drs. Fei Gao and Sebastien N. Kerisit. This project was divided into four tasks: 1) Electronic response functions (ab initio data model) 2) Electron-hole yield, variance, and spatial distribution 3) Ab initio calculations of information carrier properties 4) Transport of electron-hole pairs and scintillation efficiency Detailed information on the results obtained in each of the four tasks is provided in this Final Report. Furthermore, published peer-reviewed articles based on the work carried under this project are included in Appendix. This work was supported by the National Nuclear Security Administration, Office of Nuclear Nonproliferation Research and Development (DNN R&D/NA-22), of the U.S. Department of Energy (DOE).

Environmental Molecular Sciences Laboratory↗
DOE OSTI2015

Preliminary study of the inclusion of Water-based Liquid Scintillator in the WATCHMAN Detector

This note summarizes an effort to characterize the effects of adding water-based liquid scintillator to the WATCHMAN detector. A detector model was built in the Geant4 Monte Carlo toolkit, and the position reconstruction of positrons within the detector was compared with and without scintillator. This study highlights the need for further modeling studies and small-scale experimental studies before inclusion into a large-scale detector, as the benefits compared to the associated costs are unclear.

47 OTHER INSTRUMENTATION↗
DOE OSTI2015

Low-Afterglow Scintillators for High-Rate Radiation Detection

The present work reports on the development of two types of metal-loaded plastic scintillators that seek to improve the decay kinetics and light-yield properties of existing materials used for high count-rate radiation detection. The strategy followed in this work involves the addition of an organometallic iridium or organometallic tin compound to reduce the extent of deleterious delayed luminescence following exposure to ionizing radiation. Key results include a seven times greater light yield compared to existing high-rate scintillators (i.e. BC422Q plastic, stilbene-doped bizenzyl crystal), while achieving comparable or even faster decay characteristics than these benchmark materials.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Final report for the DOE/NA22 project, Physics of Scintillator Nonproportionality

The energy resolution of current scintillators is known to be limited by the adverse impact of light yield nonproportionality. This effort aims to advance the understanding of the physics underlying nonproportionality sufficiently to enable breakthrough performance, by achieving energy resolution beyond the present limit of 2.5% at 662 keV. While we have formulated several mechanistic frameworks that quantitatively describe the basic processes and are able to deduce the impact on resolution (Figure 1), we are in the midst of developing theoretical means of knowing a priori which material properties mediate these intrinsic mechanisms. Addressing the experimental and theoretical challenges of elucidating these mechanisms, we aim to develop and apply a predictive model guiding the improvement of scintillator performance.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Multiple Phase Screen Scintillation Modeling Code

This document describes the underlying theory and use of a computer code written to simulate scintillation effects on propagating electromagnetic (EM) signals. The Multiple Phase Screen (MPS) technique [1, 2, 3, 4] is employed to model the effects of scintillation on EM signals as they travel through the earth’s ionosphere.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Performance of BaFCl:Eu2+ scintillating composites for X-ray imaging screens

A cost-effective solution for improving X-ray imaging detectors is presented through the use of a translucent scintillating composite and pixelated screen structure. A large quantity of BaFCl:Eu 2+ polycrystalline scintillator powder was synthesized via flux growth and its optical properties characterized through photoluminescence (PL) and absolute quantum yield (QY). UV-curable composites containing the BaFCl:Eu 2+ material were fabricated with differing amounts of NOA1665 and NOA170 optical adhesives. It was determined that, when the two resins were combined, the translucency of the resulting composite could be enhanced. The BaFCl:Eu 2+ composite was also cast into a pixelated glass screen containing an array of 160 μm x 160 μm holes by two separate methods: composite paste application and powder-resin application. Based on visual inspection, using a composite paste to fill the apertures proved to be more effective in creating a uniform packing.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Toward A Precision Era Of Neutrino Oscillation Physics: Liquid Argon Scintillation Detector Development for DUNE and Neutrino Oscillation Studies with NOvA

NOvA is an accelerator-based high-energy particle physics experiment that studies oscillations in a beam of mostly muon (anti-)neutrinos, looking for the disappearance of muon (anti-)neutrinos and appearance of electron (anti-)neutrinos. This search is sensitive to several key neutrino oscillation parameters. After the completion of NOvA, DUNE will continue to study neutrino oscillations with a liquid argon time-projection chamber, which provides finer granularity of tracking than NOvA. Furthermore, the beam will be more powerful, the detector fiducial volume is approximately 3 times larger than the full NOvA detector, and the detector will be situated underground. DUNE is therefore expected to usher in a precision era of long-baseline neutrino oscillation physics. While the main signal from a liquid argon time-projection chamber is the ionization signal produced by the passage of charged particles, argon is also a copious source of scintillation. This light is useful for pro viding a precise event time. Scintillation light is potentially especially useful in non-beam studies in DUNE, such as atmospheric neutrinos, supernova neutrinos, and potential nucleon decay. In this dissertation, I will discuss both projects. In addition to a study of the drift in NOvA’s energy calibration, recent oscillation analysis is discussed, which finds a best fit at $\sin^2\theta_{23}=0.56^{+0.04}_{-0.03}$, $\Delta m^{2}_{32}=2.48^{+0.11}_{-0.06}\times10^{-3}\text{eV}^2$, $\delta_{CP}/\pi=0.0^{+1.3}_{-0.4}$, and prefers normal ordering at 1.9$\sigma$. Contributions to NOvA analysis will also be highlighted, especially methods used to perform separation of neutrinos and antineutrinos in the predominantly antineutrino beam for study. This wrong-sign component is initially used to provide further understanding of the beam components. Furthermore, characterization and prototype testing of photon detectors for DUNE is discussed. Finally, a study is performed with wrong-s ign separation techniques applied to the appearance signal i! n both NOvA and DUNE to create two samples: one enriched in signal and the other enriched in the wrong-sign oscillation appearance. Wrong-sign in the oscillation diminishes the sensitivity of the analysis, so this study aimed to determine if such a separation would enhance the sensitivity of the oscillation. Little benefit was found at the ultimate exposure with NOvA with the techniques currently available, but the study showed potential promise when applied to DUNE.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

(U) Endpoint Energy and Scintillator Geometry Effects on the Swank Factor, Quantum Efficiency, and DQE(0) for High-Energy Radiography

High-energy radiography is used to image imploding materials to better understand weapon design and performance. The Enhanced Capabilities for Subcritical Experiments (ECSE) is a new facility proposal that aims to collect radiographic images of nuclear material. As part of the facility design, we aim to optimize data quality and radiographic performance by investigating different detector designs. We addressed design decisions by simulating different scintillator designs using M CNP6 and calculated the quantum efficiency, Swank factor, and detective quantum efficiency at zero-frequency (DQE(O)). First, we investigated the effects of the x-ray endpoint energy on the detector response. We generated three x-ray spectra with endpoint energies of 20 MeV, 22 MeV, and 24 MeV. The three raw spectra were filtered using the Dual-Axis Radiographic Hydrodynamic Test facility (DARHT) line-of-sight materials along with 1) flat field filtration using 7 cm tungsten alloy in the bullnose and 2) an FTO with 4 plates. The scatter-to-direct radiation ratio was much larger for FTO with 4 plates (50-60%) compared to the flat field with 7 cm of bullnose material (8%). We used these filtered spectra to calculate the detector response for the original DARHT segmented scintillator design. We found that the endpoint energy and filtration had a negligible effect on the detector response. The quantum efficiency was 0.63, the Swank factor was 0.84, and the DQE(O) was 0.53 for all six spectra.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Linearity for Ca 2+ -Doped CeBr 3 Scintillating Materials [Slides]

This project seeks to develop low-cost, high-resolution gamma scintillators based on new fracture-resistant alloys of cerium bromide. These alloys will eliminate limitations imposed by self-activity and fracture of currently available lanthanum-based scintillators.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗