Gamma Rays: Applications in Environmental Gamma Dosimetry and Determination Samples Gamma-Activities Induced by Neutrons (original) (raw)
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Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1990
A versatile PC computer code has been developed to he used in neutron activation analysis to determine the self-absorption fractions of gamma-rays in high-Z materials. The interactive code can he employed for different geometrical configurations for radioactive counting. The input data only requires the sample geometry, length and diameter of the sample, mass of the sample, the number of major constituents, the associated Z values and weight fraction of each element.
Study for the long-lived gamma background due to neutron emitting calibration reactions
EPJ Web of Conferences
In this article, a detailed theoretical investigation has been done on the long-lived gamma background due to neutron emitting reactions. It mainly focused on the experiments that will be used to calibrate energy with the terminal voltage of an upcoming Facility for Research in Experimental Nuclear Astrophysics (FRENA). Many reactions like (p, n), (p, γ) have been utilized in various accelerator facilities around the globe for energy calibration purposes. Neutron emitting reactions like 7Li(p, n), 13C(p, n), 19F(p, n), 27Al(p, n), etc. have been very commonly used. For such reactions, a significant number of neutrons produced from such experiments can interact with surrounding elements like copper, tantalum, stainless steel (SS304 and SS316), concrete materials,etc. These interactions may create long-lived gamma activity in the vicinity of the accelerator and detection area. Background gammas from these radioactive isotopes can interfere with gamma measurements in future experiments...
Encyclopedia of Scientific Dating Methods, 2014
Neutron activation analysis is a chemical analysis technique that may be used to determine the average (bulk) concentrations of major, minor, and trace elements in a sample. It may be used to measure the concentration of a single element or, more often, to measure the concentrations of many elements, as part of a chemical characterization of a set of samples to determine chemical similarities or differences. Samples may be liquid (aqueous or organic) or solid (e.g.The most common form of neutron activation analysis is instrumental neutron activation analysis. In this, a suitably encapsulated, weighed amount of the sample to be analyzed is sent, pneumatically or manually, into an irradiation site of a research nuclear reactor, and is bombarded by neutrons with a broad range of energies that the reactor produces.
Utilization of prompt gamma rays in gamma irradiation experiments
Academia Letters, 2021
A new technique was introduced in this study to utilize the prompt gamma rays, that generated from the fission process, in gamma irradiation experiments. The method de- pends on utilizing the difference of the attenuation effect of water on neutrons from that of gamma rays The core of 22 MW power is submerged in the water of open pool type reactor and the theoretical and experimental studies have illustrated that the influence of water in attenuating the prompt neutrons is higher than the prompt gamma rays. Based on this phenomena, the dose rate distributions for the prompt neutrons and the prompt gamma rays were studied in the water volume that surrounding the core during reactor operation. Then, the proper position, that achieves the considerable gamma dose rate as well as the minimum neutron dose rate, could be determined. An irradiation device was developed to contain the samples during the gamma irradiation process. The irradiation device would be located in the proper position that was chosen depending on the previous conditions. MAVRIC code was used to determine the dose rate distributions in the water surrounding the reactor core.
Investigation of long lived activity produced due to neutron emitting reactions
2022
In this article, a detailed investigation has been done for the long lived gamma activity due to neutron emitting experiments. These calculations mainly focused on the experiments used for energy calibration purposes. Calibrated energy is one of the most essential features of any accelerator facility. Several experiments have been used for this purpose. Generally, experiments having sharp curvature change in cross section of yield are used. Neutron emitting experiments are one of such. Around the globe reactions like 7 Li(p, n), 13 C(p, n), 19 F(p, n), 27 Al(p, n) etc. are used to calibrate energy of the beam with accelerator terminal voltage. Neutrons coming from these experiments can interact with surrounding elements. These interactions with neutrons can create long lived gamma activity which may interfere with future measurements. The present study has been done keeping in mind the new Facility for Research in Experimental Nuclear Astrophysics (FRENA) at Saha Institute of Nuclear Physics. It is a 3MV tandetron low energy high current machine.
ipenInstituto de Pesquisas Energéticas e Nucleares
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DEPARTAMENTO DE FftlCA E QUÍMICA NUCLEARES CNEN/SP INSTITUTO DE PESQUISAS ENERGÉTICAS E NUCLEARES SAO PAULO-BRASIL Série PUBLICAÇÃO IPEN IN IS Categories and Descriptors A34.10 CAPTURE NEUTRON REACTIONS NICKEL 58 TARGET IPEN -Doc -3052 Publicsçfo aprovada pala CNEN am 09/11187 Nota: A radaçfo, ortografia, eoocalto» a rtvttio final ifo da rsiponiabilldada doll* autortatl.
Dosimetry in mixed neutron-gamma fields
1998
The gamma field accompanying neutrons may, in certain circumstances, play an important role in the analysis of neutron dosimetry and even in the interpretation of radiation induced steel embrittlement. At the figh Flux Isotope Reactor pressure vessel the gamma-induced reactions dominate the responses of ' W p and 238u dosimeters, and9Be helium accumulation fluence monitors. The gamma induced atom displacement rate in steel is higher than corresponding neutron rate, and is the cause of "accelerated embrittlement" of HFIR materials. In a large body of water, adjacent to a fission plate, photofissions contribute significantly to the responses of fission monitors and need to be taken into account if the measurements are used for the qualification ofthe transport codes and cross-section libraries.
Prompt Gamma Activation Analysis with the Texas Cold Neutron Source
Journal of Radioanalytical and Nuclear Chemistry Articles, 1995
(TCNS). The TCNS consists of a cold source cryostat and a curved neutron guide. The use of a guided focused cold-neutron beam will provide a high capture reaction rate and low background. The UT-PGAA facility will be used in the nondestructive determination of B, Cd, Gd and S in biological and environmental samples. Beams of neutrons produced by nuclear research reactors are used in condensed matter research to study the arrangement and interactions of atoms in materials. Thermal neutrons examine matter at the atomic scale in a way unmatched by other techniques because of their favorable wavelength to energy ratio. Using cold neutrons it is possible to probe deep within materials to characterize micropores, microcracks, small precipitates, polymers, biological macromolecules, etc. In many applications, the structural information provided by neutrons cannot be obtained in any other way. 1 A neutron beam can also be used for analytical elemental analysis by neutron-capture gamma-ray spectroscopy. Concentrations of various elements in a sample can be determined from the measured emission rates of characteristic prompt gamma rays produced by neutron capture; this is called Prompt Gamma Activation Analysis (PGAA). While Neutron Activation Analysis is more sensitive for the determination of most elements, it cannot be used for some elements which can be analyzed by PGAA. The above research applications can be enhanced in some way by using subthermal, "cold," neutrons. Cold neutrons can be defined as neutrons with energies below 10 meV, an energy which corresponds to velocity and wavelength values of 1400 m/s and 3 A, respectively. The average kinetic energy of a neutron beam can be lowered by passing it through a moderator which is cooled. Cold neutrons have longer wavelengths and lower kinetic energies on the average than thermal neutrons, which comprise the majority of the neutrons normally present in neutron beams from nuclear research reactors. Neutrons with sufficiently long wavelengths can be reflected from some surfaces in the same way light can be reflected from the interface between two transparent media. Cold neutrons, then, can be guided down cylindrical wave guides without the normal 1/r 2 attenuation and can be bent out of the line-of-sight paths followed by other radiation. The usual neutron beams from a research reactor are contaminated by fast neutrons and gamma rays that originate in the core. Filters, collimators, and shielding can reduce these undesirable components to some extent. However, cold neutron beams have a much lower gamma and fast-neutron background. Thus, detectors for capture neutron and basic physics experiments can be placed closer to the sample, increasing sensitivity and making coincidence techniques feasible in many more situations.