Vulcanization of SBR in a Thermal Neutron Field

1960 ◽  
Vol 33 (4) ◽  
pp. 1083-1091
Author(s):  
Herbert R. Anderson
Keyword(s):  
Boron Nitride ◽  
Thermal Neutron ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Neutron Field ◽  
Energy Utilization ◽  
Rubber Compound ◽  
Helium Atmosphere ◽  
Residual Radioactivity

Abstract The nuclear reactions B10(n,α)Li7* and Li6(n,α)H3 can be used to generate highly ionizing particles in a pure thermal neutron field to vulcanize an otherwise transparent rubber compound. Vulcanizates have satisfactory physical properties comparable with those produced by other means of vulcanization, e.g., gamma rays and peroxides. Such vulcanizates possessed negligible residual radioactivity. The somewhat analogous initiating systems gave vastly different vulcanizates with the same parent rubber compound in a helium atmosphere, and a possible explanation is presented. The G values for lithium methoxide promotion (ca. 3) are comparable with those obtained with gamma-ray vulcanizates. Promotion is less efficient with boron nitride, the average values of G being approximately 0.9. The irradiation atmosphere has a pronounced influence on the type of vulcanizate produced and on the energy utilization. Substitution of air for helium as the irradiation atmosphere increases net crosslinking of cold rubber with boron nitride promotion, while it decreases it when lithium methoxide is used as the promoter.

Gamma-ray sensitivity and shielding of a neutron imaging plate

1999 ◽  
Vol 32 (5) ◽  
pp. 878-882 ◽  
Author(s):  
Y. Karasawa Haga ◽  
S. Kumazawa ◽  
N. Niimura
Keyword(s):  
Thermal Neutron ◽  
Energy Dependence ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Neutron Imaging ◽  
Atomic Energy ◽  
Imaging Plate ◽  
Energy Research ◽  
Experimental Hall ◽  
Lead Foil

The energy dependence of gamma-ray sensitivity of a neutron imaging plate (NIP) has been measured. The gamma-ray sensitivity is equivalent to one half that of a thermal neutron at a gamma-ray energy less than 300 keV, and 1/40 at greater than 300 keV. The shielding of the NIP, by lead, from gamma rays in the experimental hall of the reactor JRR-3M of the Japan Atomic Energy Research Institute (JAERI) was measured. It was found that lead of thickness 40 mm is sufficient to reduce the gamma-ray background to 1/10 on a normalized scale. Covering the NIP with lead foil of thickness 1 mm results in a decrease of the gamma-ray background without reduction of the neutron signal.

GAMMA-RAY ANGULAR CORRELATIONS FROM ALIGNED NUCLEI PRODUCED BY NUCLEAR REACTIONS

1961 ◽  
Vol 39 (6) ◽  
pp. 788-824 ◽  
Author(s):  
A. E. Litherland ◽  
A. J. Ferguson
Keyword(s):  
Angular Correlation ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Residual Nucleus ◽  
Incident Beam ◽  
Nuclear Spectroscopy ◽  
Population Parameters ◽  
Axially Symmetric ◽  
Angular Correlations

Two general procedures for the measurement and analysis of angular correlations of gamma radiations from nuclear reactions are described which have wide applications in nuclear spectroscopy for the determination of spins and gamma-ray multipolarities. Cases can be studied by these methods when the reaction proceeds through a compound state too complex to allow the usual analysis to be made, for example where several levels overlap or where direct interaction is dominant. The basis of these procedures is to exploit the simplifications brought about by making the reacting system axially symmetric. A sharp gamma-ray-emitting state formed in such a system can be regarded as aligned and described in terms of a relatively small number of population parameters for the magnetic substates. In the first procedure, a state Y* is prepared by a nuclear reaction X(h1h2) Y* in which h2 is unobserved. The state Y* has axial symmetry about the beam axis. From coincidence angular correlation measurements of two cascade gamma rays from Y*, the unknown population parameters for Y* together with the nuclear spins and gamma-ray multipolarities can be determined. In the second procedure, h2 is measured in a small counter at 0° or 180° relative to the incident beam. It is then shown that the quantum numbers of the magnetic substates of Y* which can be populated do not exceed the sum of the spins of X, h1, and h2. In cases where the sum of the spins does not exceed [Formula: see text], the angular correlation of the gamma rays from the aligned state depends only upon the properties of the states in the residual nucleus. Theoretical expressions for angular correlations from aligned states are given, together with a method whereby existing extensive tables of coefficients can be used to calculate them. The results of two recent experiments are discussed as examples.

Large solubility of lithium carboxylates reaching high rates of 6Li incorporation in polystyrene-based plastic scintillators for fast/thermal neutron and gamma ray detection

2019 ◽  
Vol 3 (8) ◽  
pp. 1626-1631 ◽  
Author(s):  
Camille Frangville ◽  
Matthieu Hamel ◽  
Guillaume H. V. Bertrand ◽  
Eva Montbarbon ◽  
Amélie Grabowski ◽  
...  
Keyword(s):  
Thermal Neutron ◽  
Homeland Security ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Thermal Neutrons ◽  
Plastic Scintillators

6Li-Doped plastic scintillators (PSs) have been optimized as radioluminescent sensors for detection of fast/thermal neutrons and gamma rays for several purposes such as homeland security.

scholarly journals Gamma-Ray Lines from Solar Flares

1975 ◽  
Vol 68 ◽  
pp. 363-383 ◽  
Author(s):  
R. Ramaty ◽  
R. E. Lingenfelter
Keyword(s):  
Gamma Rays ◽  
Solar Flares ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
The Other ◽  
Line Production ◽  
Absolute Intensities ◽  
Flare Region ◽  
Accelerated Particles

We have treated in detail the theory of gamma-ray line production in solar flares. The strongest line, both predicted theoretically and detected observationally at 2.2 MeV, is due to neutron capture by protons in the photosphere. The neutrons are produced in nuclear reactions of flare accelerated particles which also produce positrons and prompt nuclear gamma rays. From the comparison of the observed and calculated intensities of the lines at 4.4 or 6.1 MeV to that of the 2.2 MeV line it is possible to deduce the spectrum of accelerated nuclei in the flare region; and from the absolute intensities of these lines it is possible to obtain the total number of accelerated nuclei at the Sun. The study of the 2.2 MeV line also gives information on the amount of He3 in the photosphere. The study of the line at 0.51 MeV resulting from positron annihilation complements the data obtained from the other lines; in addition it gives information on the temperature and density in the annihilation region and on the anisotropy of the accelerated electron beam which produces continuum gamma rays at energies greater than about 1 MeV.

scholarly journals TANGRA multidetector systems for investigation of neutron-nuclear reactions at the JINR Frank Laboratory of Neutron Physics

2021 ◽  
Vol 256 ◽  
pp. 00014
Author(s):  
Ivan Ruskov ◽  
Yury Kopach ◽  
Vyacheslav Bystritsky ◽  
Vadim Skoy ◽  
Dimitar Grozdanov ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Nuclear Research ◽  
Gamma Ray Spectrometry ◽  
Reaction Products ◽  
Science And Engineering ◽  
Neutron Physics ◽  
Gamma Ray Spectrometer ◽  
Crystal Scintillation

In the framework of TANGRA-project at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear research in Dubna (Russia), two experimental setups (Fig. 1) have been designed and tested for investigation of 14-MeV neutron-induced nuclear reactions on a number of important for nuclear science and engineering isotopes. As a source of 14-MeV “tagged” neutrons we are using the VNIIA ING-27 steady-state portable neutron generator with embedded in its vacuum tube 64-pixel charge-particle detector. The “Romashka” system is an array of up-to 24 hexagonal NaI(Tl)-crystal scintillation probes, while the “Romasha” array consists of 18 cylindrical BGO-crystal detectors of neutrons and gamma-rays. In addition to these detectors there is a HPGe gamma-ray spectrometer and a number of Stilbene detectors that can be added for high-resolution gamma-ray spectrometry and neutron-gamma detection. The main characteristics of the neutron-induced nuclear reaction products can be investigated by commissioning the detectors in suitable for these experiments’ geometries. Both setups can be used for doing basic and applied scientific research, because they permit simultaneously to measure the energy, angle and multiplicity distributions of gamma-rays and neutrons, produced in the competitive neutron-induced nuclear reactions (n, n’γ), (n,2n), (n, xnγ) and (n, f) in pure or complex substances.

scholarly journals First in-core gamma spectroscopy experiments in a zero power reactor

2021 ◽  
Vol 253 ◽  
pp. 04022
Author(s):  
Oskari Pakari ◽  
Vincent Lamirand ◽  
Tom Mager ◽  
Axel Laureau ◽  
Pavel Frajtag ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Power Reactor ◽  
Gamma Spectroscopy ◽  
Reactor Core ◽  
Pulse Height ◽  
Nuclear Data ◽  
Federal Institute ◽  
Institute Of Technology

Gamma rays in nuclear reactors, arising either from nuclear reactions or decay processes, significantly contribute to the heating and dose of the reactor components. Zero power research reactors offer the possibility to measure gamma rays in a purely neutronic environment, allowing for validation experiments of dose estimates, computed spectra, and prompt to delayed gamma ratios. The resulting data can contribute to models, code validation and photo atomic/nuclear data evaluation. To date, most experiments have relied on flux measurements using TLDs, ionization chambers, or spectrometers set in low flux areas. The CROCUS reactor allows for flexible detector placement in and around the core, and has recently been outfitted with gamma detection capabilities to fulfill the need for in-core gamma spectroscopy, as opposed to flux. In this paper we report on the experiments and accompanying simulations of gamma spectrum measurements inside a zero power reactor core, CROCUS. It is a two-zone, uranium-fueled light water moderated facility operated by the Laboratory for Reactor Physics and Systems Behaviour (LRS) at the Swiss Federal Institute of Technology Lausanne (EPFL). Herein we also introduce, in detail, the new LEAF system: A Large Energy-resolving detection Array for Fission gammas. It consists of an array of four detectors – two large ø 127 254 mm Bismuth Germanate (BGO) and two smaller ø 12 50 mm Cerium Bromide (CeBr3) scintillators. We describe the calibration and characterization of LEAF followed by first in-core measurements of gamma ray spectra in a zero power reactor at different sub-critical and critical states, and different locations. The spectra are then compared to code results, namely MCNP6.2 pulse height tallies. We were able to distinguish prompt processes and delayed peaks from decay databases. We present thus experimental data from hitherto inaccessible core regions. We provide the data as validation means for codes that attempt to model these processes for energies up to 10 MeV. We finally draw conclusions and discuss the future uses of LEAF. The results indicate the possibility of isotope tracking and burn-up validation.

scholarly journals Gamma Irradiation and the Radiation Shielding Characteristics: For the Lead Oxide Doped the Crosslinked Polystyrene-b-Polyethyleneglycol Block Copolymers and the Polystyrene-b-Polyethyleneglycol-Boron Nitride Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3246
Author(s):  
Zehra Merve Cinan ◽  
Burcu Erol ◽  
Taylan Baskan ◽  
Saliha Mutlu ◽  
Sevil Savaskan Yilmaz ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Boron Nitride ◽  
Gamma Irradiation ◽  
Gamma Rays ◽  
Lead Oxide ◽  
Gamma Ray ◽  
Mean Free Path ◽  
Radiation Shielding ◽  
Polymer Mixture ◽  
Crosslinked Polystyrene

This work aimed to research the efficiency of gamma irradiation and shielding characteristics on the lead oxide (PbO) doped the crosslinked polystyrene-b-polyethyleneglycol (PS-b-PEG) block copolymers and polystyrene-b-polyethyleneglycol-boron nitride (PS-b-PEG-BN) nanocomposites materials. The crosslinked PS-b-PEG block copolymers and PS-b-PEG-BN nanocomposites mixed with different percentage rates of PbO were used to research gamma-ray shielding characteristics. The synthesis of the copolymer was done by emulsion polymerization methods. The characterization and morphological analyses of irradiated samples were explored handling with the Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), and Scanning Electron Microscope (SEM) methods. The gamma-rays that were emitted from the E 152u source were observed with a High Purity Germanium (HPGe) detector system and examined with a GammaVision computer program. Our samples, including the different percentage rates of the PS-b-PEG (1000, 1500, 10,000), BN, and PbO, were irradiated in various gamma-ray photon energy regions (from 121.78 keV to 1408.01 keV). Then, Linear-Mass Attenuation Coefficients (LACs-MACs), Half-Tenth Value Layer (HVL), Mean Free Path (MFP), and Radiation Protection Efficiency (RPE) values of the samples were calculated. Via crosschecking the acquired data from samples with and without PbO and BN, it was observed that, if the different percentage rates by weight nano-powder of PbO and BN are added in the polymer mixture, it can be used as a convenient shielding material against gamma rays.

On the possible gamma-ray source in Cygnus

1967 ◽  
Vol 31 ◽  
pp. 469-471
Author(s):  
J. G. Duthie ◽  
M. P. Savedoff ◽  
R. Cobb
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Right Ascension

A source of gamma rays has been found at right ascension 20h15m, declination +35°, with an uncertainty of 6° in each coordinate. Its flux is (1·5 ± 0·8) x 10-4photons cm-2sec-1at 100 MeV. Possible identifications are reviewed, but no conclusion is reached. The mechanism producing the radiation is also uncertain.

Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I

1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Range ◽  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Solar Neutron ◽  
Low Altitude

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.

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