Long range neutron-gamma point source detection and imaging using unique rotating detector

Seeds of Tillandsia fasciculata var. fasciculata were treated with gamma radiation, gamma and thermal neutron radiations, or ethyl methanesulfonate (EMS) and grown in vitro. Observed chlorophyll deficient phenotypes included yellowish-green, yellow, variegated and albino. The highest combined percentages of chlorophyll deficient phenotypes was 8.7% for the gamma radiation treatment (2.7 krad), 4.6% for the gamma and thermal neutron radiations treatments (combined dose of 2.7 krad at a gamma to thermal neutron ratio of 7.4:1.0), and 10.8% for the EMS treatment (0.4% EMS × 5 h). Some yellowish-green and yellow seedlings multiplied in half strength MS medium with 0.3 or 0.5 μM BA and IBA and the newly formed shoots retained their respective mutant phenotypes. However, the variegated seedlings were sectoral or mericlinal chimeras and when they multiplied, the newly formed shoots were not variegated. The chlorophyll a/chlorophyll b ratio of the wild type seedling was 1.1 whereas that of the yellowish-green and the yellow seedlings was 2.0. Electron micrographs showed that compared to the wild type chloroplasts, the chloroplasts of the yellowish-green and yellow seedlings had fewer grana and fewer thylakoids within each granum.

Selene’s Explorer for Roughness, Regolith, Resources, Neutrons and Elements (SER3NE) is a lunar orbiter mission designed to map the topmost composition of the lunar surface, including elemental composition and water abundance. Planned instruments include a Gamma Ray and Neutron Spectrometer (GRNS) for elemental composition, including hydrogen indicating water, a Laser Altimeter (LA) for surface roughness and albedo observations, and a near-infrared spectrometer (LIPS) to determine water forms.The GRNS detector is designed for both in situ utilization as well as remote sensing. It has a core of CLLBC and LaBr3 crystal scintillators in a chessboard pattern for high-resolution gamma-ray detection (30 keV-8MeV) and thermal to epithermal neutron sensitivity. Gd foil on CLLBC allows separation of thermal and epithermal neutrons, while LaB3 and CLLBC enable advanced neutron detection analysis. Encapsulated by EJ-248M plastic scintillators, the detector includes anti-coincidence detector for charged particle rejection. With gamma-ray spectroscopy, rock-forming elements as well as KREEP and trace elements can be detected in the shallow surface of the moon. The local count rates of thermal and epithermal neutrons allow for the analysis of the distribution of hydrogen on the lunar surface, as well as for estimation of neutron lifetime from the lunar orbit.A demonstrator of the GRNS instrument has been successfully tested in the lab. A prototype of this lunar GRNS instrument will fly on the CENSSat-1 Bifrost CubeSat mission, scheduled for launch 2027.In this presentation, the GRNS instrument concept will be presented, focusing on the detector design and suitability for elemental composition analysis on a lunar orbiter.

Although there have been anecdotal accounts of people sensing high levels of radiation (e.g. having a metallic taste or tingling skin) there is no scientific support for these accounts; to the best of our knowledge humans lack the ability to sense ionizing radiation. Thus, radiation detection instruments are the only reliable way that we have to indicate the presence of radiation or radioactivity and the level of risk that they pose. However, not all radiation detectors are capable of detecting all forms of radiation, conducting the different types of surveys that might be called for, or obtaining a reading under all conditions. As one example, radiation detectors made of sodium iodide are excellent for detecting gamma radiation, but are not at all sensitive to alpha particles; a policeman carrying a sodium iodide detector would be utterly unaware of the presence of even very high levels of Po-210, such as that used to assassinate Alexander Litvenenko. By the same token, the zinc sulfide crystals used to detect alpha radiation are not sensitive to gamma radiation. There are numerous examples of radiation instruments being used incorrectly or inappropriately, even by seasoned professionals.

Nuclear medicine imaging consists of planar scintigraphy (2D gamma-ray projection imaging) and emission computed tomography (ECT) (or 3D tomographic imaging). ECT includes two modalities: single-photon emission computed tomography (SPECT) and positron emission tomography (PET). The field of nuclear medicine, in general, consists of imaging physics and instrumentation, radiopharmaceutical sciences and radiotracer methodologies, image processing, reconstruction, and quantitative analysis, physiological modeling and kinetic analysis, and applications to biomedical research and clinical practice. In this broad spectrum of interdisciplinary fields related to nuclear medicine, this chapter focuses on radiation detection in SPECT and PET. Major historic developments are briefly reviewed first. Current state-of-the-art technologies in radiation detection routinely used in clinical applications are then discussed. Some of the recent advances in radiation detectors and detection techniques associated with PET and SPECT are surveyed. Finally, future trends and directions in adapting novel radiation detection technologies in nuclear medicine, especially in PET and SPECT, are projected and delineated.

Journal Article Dose Equivalent Measurement for Thermal Neutrons and Gamma Rays with a Small BGO Scintillator Connected to an Optical Fibre Get access T. Matsumoto T. Matsumoto Search for other works by this author on: Oxford Academic PubMed Google Scholar Radiation Protection Dosimetry, Volume 35, Issue 4, 1 April 1991, Pages 241–245, https://doi.org/10.1093/oxfordjournals.rpd.a080954 Published: 01 April 1991

This report provides the technical justification for locating a large detector underground in a US based Deep Underground Science and Engineering Laboratory. A large detector with a fiducial mass greater than 100 kTon will most likely be a multipurpose facility. The main physics justification for such a device is detection of accelerator generated neutrinos, nucleon decay, and natural sources of neutrinos such as solar, atmospheric and supernova neutrinos. The requirement on the depth of this detector will be guided by the rate of signals from these sources and the rate of backgrounds from cosmic rays over a very wide range of energies (from solar neutrino energies of 5 MeV to high energies in the range of tens of GeV). For the present report, we have examined the depth requirement for a large water Cherenkov detector and a liquid argon time projection chamber. There has been extensive previous experience with underground water Cherenkov detectors such as IMB, Kamioka, and most recently, Super-Kamiokande which has a fiducial mass of 22 kTon and a total mass of 50 kTon at a depth of 2700 meters-water-equivalent. Projections for signal and background capability for a larger and deeper (or shallower) detectors of this type can be scaled from these previous detectors. The liquid argon time projection chamber has the advantage of being a very fine-grained tracking detector, which provides enhanced capability for background rejection. In the current work we have taken the approach that the depth should be sufficient to suppress the cosmogenic background below predicted signal rates for either of the above two technologies. Nevertheless, it is also clear that the underground facility that we are examining must have a long life and will most likely be used either for future novel uses of the currently planned detectors or new technologies. Therefore the depth requirement also needs to be made on the basis of sound judgment regarding possible future use. In particular, the depth should be sufficient for any possible future use of these cavities or the level which will be developed for these large structures. Along with these physics justifications there are practical issues regarding the existing infrastructure at Homestake and also the stress characteristics of the Homestake rock formations. In this report we will examine the various depth choices at Homestake from the point of view of the particle and nuclear physics signatures of interest. We also have sufficient information about the existing infrastructure and the rock characteristics to narrow the choice of levels for the development of large cavities with long lifetimes. We make general remarks on desirable ground conditions for such large cavities and then make recommendations on how to start examining these levels to make a final choice. In the appendix we have outlined the initial requirements for the detectors. These requirements will undergo refinement during the course of the design. Finally, we strongly recommend that the geotechnical studies be commenced at the 4850 ft level, which we find to be the most suitable, in a timely manner.

Measurements of thermal neutrons and gamma rays using multiple Cs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> LiYCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> : Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> (CLYC) crystals with photomultiplier tube (PMT) and silicon photomultiplier (SiPM) are compared. The first set of measurements used three single-sided crystals (two made from 95% enriched <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> Li and one made with 99% enriched <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> Li) mated with the PMT and SiPM to compare the energy resolutions and figures of merit (FOM) for the pulse shape discrimination of gamma rays and neutrons. All crystals and photomultipliers were able to resolve full-energy photopeaks for <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">137</sup> Cs and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60</sup> Co and distinguish gamma-ray interactions from neutron interactions (FOM > 1 in all cases) while operating in a thermal neutron environment. Measurements made with the PMT had better energy resolution, and switching to the SiPM degraded the energy resolution by an average of 34.0 ± 0.7% (at 662 keV). The second set of measurements used a CLYC crystal with two optical windows to enable simultaneous measurements with the PMT and SiPM. Once again, both photomultipliers were able to distinguish gamma rays from neutrons, and the PMT had the best energy resolution. However, in this case, the SiPM was not able to resolve the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">137</sup> Cs full-energy photopeak, and neither photomultiplier could resolve any photopeaks if <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60</sup> Co was used simultaneously. The degradation in energy resolution was due to the relative splitting of scintillation light intensity between each photomultiplier depending on the position of the interaction site within the crystal. Each pair of waveforms recorded from the PMT and SiPM, corresponding to a single interaction within the double-sided crystal, were combined to improve the energy resolution at 662 keV from 15.9 ± 0.9% to 12.7 ± 0.3% and the FOM from 1.850±0.004 to 2.117±0.003 when compared to the data just from the PMT.

In this study, the neutron and gamma radiation-shielding properties of serpentinites from the Guleman ophiolite complex were investigated, and results were evaluated in comparison with rare earth element (REE) content. The linear and mass attenuation coefficients (LAC and MAC), half-value layer (HVL), mean free path (MFP), and effective atomic numbers (Zeff) of serpentinite samples were experimentally measured in the energy range of 80.99–383.85 keV. Theoretical MAC values were calculated. Additionally, fast neutron removal cross-sections, as well as thermal and fast neutron macroscopic cross-sections, were theoretically determined. The absorbed equivalent dose rates of serpentinite samples were also measured. The radiation protection efficiency (RPE) for gamma rays and neutrons were determined. It was observed that the presence of rare earth elements within serpentinite structure has a significant impact on thermal neutron cross-sections, while crystalline water content (LOI) plays an influential role in fast neutron cross-sections. Moreover, it has been observed that the concentration of gadolinium exerts a more substantial influence on the macroscopic cross-sections of thermal neutrons than on those of fast neutrons. The research results reveal the mineralogical, geochemical, morphological and radiation-shielding properties of serpentinite rocks contribute significantly to new visions for the use of this naturally occurring rock as a geological repository for nuclear waste or as a wall-covering material in radiotherapy centers and nuclear facilities instead of concrete.

The most serious terrorist threat we face today may come from radiological dispersion devices and unsecured nuclear weapons. It is imperative for national security that we develop and implement radiation detection technology capable of locating and tracking nuclear material moving across and within our borders. Many radionuclides emit gamma rays in the 0.2 -- 3 MeV range. Unfortunately, current gamma ray detection technology is inadequate for providing precise and efficient measurements of localized radioactive sources. Common detectors available today suffer from large background rates and have only minimal ability to localize the position of the source without the use of mechanical collimators, which reduces efficiency. Imaging detectors using the Compton scattering process have the potential to provide greatly improved sensitivity through their ability to reject off-source background. We are developing a prototype device to demonstrate the Compton imaging technology. The detector consists of several layers of pixelated silicon detectors followed by an array of CsI crystals coupled to photodiodes. Here we present the concept of our detector design and results from Monte Carlo simulations of our prototype detector.

Liquefied-noble-gas (LNG) detectors offer, in principle, very good energy resolution for both neutrons and gamma rays, fast response time (hence high-count-rate capabilities), excellent discrimination between neutrons and gamma rays, and scalability to large volumes. They do, however, need cryogenics. LNG detectors in sizes of interest for fissionable material detection in cargo are reaching a certain level of maturity because of the ongoing extensive R&}D effort in high-energy physics regarding their use in the search for dark matter and neutrinoless double beta decay. The unique properties of LNG detectors, especially those using Liquid Argon (LAr) and Liquid Xenon (LXe), call for a study to determine their suitability for Non-Intrusive Inspection (NII) for Special Nuclear Materials (SNM) and possibly for other threats in cargo.Rapiscan Systems Laboratory, Yale University Physics Department, and Adelphi Technology are collaborating in the investigation of the suitability of LAr as a scintillation material for large size inspection systems for air and maritime containers and trucks. This program studies their suitability for NII, determines their potential uses, determines what improvements in performance they offer and recommends changes to their design to further enhance their suitability. An existing 3.1 liter LAr detector (microCLEAN) at Yale University, developed for R&}D on the detection of weakly interacting massive particles (WIMPs) was employed for testing. A larger version of this detector (15 liters), more suitable for the detection of higher energy gamma rays and neutrons is being built for experimental evaluation. Results of measurements and simulations of gamma ray and neutron detection in microCLEAN and a larger detector (326 liter CL38) are presented.

Neutron flux analysis plays a crucial role in various nuclear research studies and sample analysis in research reactors. Accurate knowledge of the neutron flux spectrum and the ratio of thermal to epithermal neutrons is essential in these applications. In recent years, the newly k₀ method has been utilized to determine thermal and epithermal neutron flux. This method involves the irradiation of two monitors, typically gold and zirconium, followed by the counting of emitted gamma rays using suitable detectors like HpGe. By analyzing the photonic peak area of the collected gamma-ray spectrum from the monitors, the thermal and epithermal neutron flux at the irradiation site can be calculated. In this study, the k₀ method was employed to determine the thermal and epithermal neutron flux of Miniature Neutron Source Reactors (MNSRs).The method involved the irradiation of gold and zirconium monitors, followed by the measurement of emitted gamma rays. The photonic peak area of the gamma-ray spectrum obtained from the monitors was utilized to calculate the thermal and epithermal neutron flux. The research achieved a calculated error of 4 percent in determining the neutron flux. The k₀ method, using gold and zirconium monitors, proved to be an effective approach for determining the thermal and epithermal neutron flux in the Isfahan's MNSR. The use of zirconium, with its suitable neutron absorption cross-sections, along with cadmium calculations, contributed to the accuracy of the flux determination. It is recommended to apply the k₀ method in neutron and boron therapies and perform simulations using popular computational codes alongside the dual metal (gold and zirconium) measurement. This would enhance the accuracy of dosimetry calculations for absorbed doses resulting from neutron therapy.

Absolute yields have been determined for 105 gamma rays emitted in the decay of 95 fission products representing 54 mass chains created during thermal-neutron fission of /sup 245/Cm. These results include 17 mass chains for which no prior yield data exist. Using a Ge(Li) detector, spectra were obtained of gamma rays between 30 sec and 0.3 yr after very short irradiations of thermal neutrons on a 1 ..mu..g sample of /sup 245/Cm. On the basis of measured gamma-ray yields and known nuclear data, total chain mass yields and relative uncertainties were obtained for 51 masses between 84 and 156. The absolute overall normalization uncertainty is <8%. The measured A-chain cumulative yields make up 81% of the total light mass (A< or =121) yield and 92% of the total heavy mass yield. The results are compared with fission-product yields previously measured with generally good agreement. The mass-yield data have been compared with those for thermal-neutron fission of /sup 239/Pu and for /sup 252/Cf(s.f.); the influences of the closed shells Z=50, N=82 are not as marked as for thermal-neutron fission of /sup 239/Pu but much more apparent than for /sup 252/Cf(s.f.). Information on the charge distribution along several isobaric mass chains wasmore » obtained by determining fractional yields for 12 fission products. The charge distribution width parameter, based upon data for the heavy masses, A=128 to 140, is independent of mass to within the uncertainties of the measurements. Gamma-ray assignments were made for decay of short-lived fission products for which absolute gamma-ray transition probabilities are either not known or in doubt. Absolute gamma-ray transition probabilities were determined as (51 +- 8)% for the 374-keV gamma ray from decay of /sup 110/Rh, (35 +- 7)% for the 1096-keV gamma ray from decay of /sup 133/Sb, and (21.2 +- 1.2)% for the 255-keV gamma ray from decay of /sup 142/Ba.« less

We are working on a revolutionary scintillating plastic material in the form of a fused fiber structure. The material has different responses to fast neutrons, gamma rays and thermal neutrons. Energy deposited in 3-D voxels will be recorded using SiPM technology. This material development is directed towards the urgent need for high resolution imaging of both fast fission neutrons and gamma rays, and detection of thermal neutrons. This multi-functionality is driven by the demanding needs to detect various types of special nuclear material (SNM). This unique scintillating material is the basis for an imaging camera capable of performing, for the first time, all three of the above fundamental measurements for passive detection of SNM and RDDs. It does this with increased signal/background by order of magnitude or more. A Nanoptics, Inc. patent application is being submitted for the unique material and structure of the camera.

A study of the use of digital techniques for the real-time, fast neutron coincidence analysis of time- and space-correlated radiations emitted by californium-252 and uranium-235 is described. These radiations have been measured with detectors based on the organic liquid scintillant, EJ-309. Time-synchronized neutron and gamma-ray event-trains, separated with pulse shape discrimination, have been sampled with a field-programmable gate array programmed with an algorithm developed in this research. This approach has been used to extract the interval time distribution of this event-train, with a time resolution of 5 ns, to investigate the temporal correlation between the neutrons and/or gamma rays emitted in the spontaneous fission of californium-252. The established model for the characterization of the interval-time distributions of correlated thermal neutron events, used widely in thermal neutron coincidence assay, has been extended to fast neutrons. The influence of geometry and the surroundings on these distributions has been investigated and quantified: the temporal coefficients for the die-away of the distributions for neutrons and gamma rays are 3.18\pm0.09 ns and 1.49\pm0.06 ns, respectively. It has been observed that 99.7% of the correlated neutrons and gamma rays are detected within 27 ns and 21 ns of each other, respectively, when a low-scatter geometry is examined. The spatial distribution of fast neutrons emitted in spontaneous fission (californium-252) has also been investigated to yield the evidence for the angular distribution of higher-order, correlated neutrons presented in this thesis; this infers a dipolar trend for third (triplet) and fourth (quadruplet) neutrons consistent with that known for second (doublet) neutrons. The gamma-ray emission has been used to provide time-of-flight information and hence the neutron spectrum for fission neutrons from californium-252. A technique for the determination of the foreground and background coincidence distribution of the emitted fast neutrons and/or gamma rays for passive and active neutron coincidence counting methods has been developed. Finally, two models have been developed to correct for erroneous coincidence events which might otherwise limit the use of organic scintillators in coincident assay: one for photon breakthrough and one for detector crosstalk. These models have been validated using californium-252 indicating that photon-breakthrough constitutes a 20% increase in the neutron count rates whilst crosstalk can result in increases of 10% and 35% on first-and second-order coincident events, respectively, for the investigated geometries. The instrumentation, techniques and results reported in this thesis extend our understanding of the fundamental temporal characteristics of nuclear fission, and are of direct relevance to the application of organic scintillators with pulse shape discrimination to nuclear safeguards and non-proliferation verification.

Material analysis with prompt gamma neutron activation analysis (PGNAA) requires a proper geometrical arrangement for equipments in laboratory. Application of PGNAA in analysis of biological samples, due to small size of sample, needs attention to the dimension of neutron beam. In our work, neutron source has been made of 241Am–Be type. Activity of 241Am was 20 Ci which lead to neutron source strength of 4.4 × 107 neutrons per second. Water has been considered as the basic shielding material for the neutron source. The effect of various concentration of boric acid in the reduction of intensity of fast and thermal components of the neutron beam and gamma ray has been investigated. Gamma ray is produced by (α, n) reaction in Am–Be source (4.483 MeV), neutron capture by hydrogen (2.224 MeV), and neutron capture by boron (0.483 MeV). Various types of neutron and gamma ray dosimeters have been employed including BF3 and NE-213 detectors to detect fast and thermal neutrons. BGO scintillation detector has been used for gamma ray spectroscopy. It is shown that the gamma and neutron radiation dose due to direct beam is of the same magnitude as the dose due to radiation scattered in the laboratory ambient. It is concluded that 14 kg boric acid dissolved in 1,000 kg water is the optimum solution to surround the neutron source. The experimental results have been compared with Monte Carlo simulation.