Download or read book Beta Decays and Delayed Gammas from Fission Fragments written by James Griffin and published by . This book was released on 1963 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Novel Gamma ray Detection System for Decay Data Measurement and Beta delayed Spectroscopy of Primary Fission Fragments at N 82 written by Robert Shearman and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Four Parameter Measurements of Delayed Gamma Rays from Spontaneous Fission of Cf written by Frank Walton Guy and published by . This book was released on 1970 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Other Details of Post fission Beta Decay written by James J. Griffin and published by . This book was released on 1964 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Deposition in the Atmosphere by Delayed Gammas from Fission written by E. W. Bennett and published by . This book was released on 1964 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements from the Prompt and Delayed Radiation of Fission Fragments written by Nathan T. Brewer and published by . This book was released on 2013 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling the Production of Beta Delayed Gamma Rays for the Detection of Special Nuclear Materials written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this LDRD project was to develop one or more models for the production of [beta]-delayed [gamma] rays following neutron-induced fission of a special nuclear material (SNM) and to define a standardized formatting scheme which will allow them to be incorporated into some of the modern, general-purpose Monte Carlo transport codes currently being used to simulate inspection techniques proposed for detecting fissionable material hidden in sea-going cargo containers. In this report, we will describe a Monte Carlo model for [beta]-delayed [gamma]-ray emission following the fission of SNM that can accommodate arbitrary time-dependent fission rates and photon collection histories. The model involves direct sampling of the independent fission yield distributions of the system, the branching ratios for decay of individual fission products and spectral distributions representing photon emission from each fission product and for each decay mode. While computationally intensive, it will be shown that this model can provide reasonably detailed estimates of the spectra that would be recorded by an arbitrary spectrometer and may prove quite useful in assessing the quality of evaluated data libraries and identifying gaps in the libraries. The accuracy of the model will be illustrated by comparing calculated and experimental spectra from the decay of short-lived fission products following the reactions [sup 235]U(n[sub th], f) and [sup 239]Pu(n[sub th], f). For general-purpose transport calculations, where a detailed consideration of the large number of individual [gamma]-ray transitions in a spectrum may not be necessary, it will be shown that a simple parameterization of the [gamma]-ray source function can be defined which provides high-quality average spectral distributions that should suffice for calculations describing photons being transported through thick attenuating media. Finally, a proposal for ENDF-compatible formats that describe each of the models and allow for their straightforward use in Monte Carlo codes will be presented.
Download or read book A Review of Information on the Gamma Energy Radiation Rate from Fission Products and Its Significance for Studies of Radioactive Fallout written by Harold A. Knapp and published by . This book was released on 1959 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fisica della spettroscopia NMR in biologia e medicina written by and published by . This book was released on 1988 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Delayed Beta and Gamma ray Production Due to Thermal neutron Fission of 235U Spectral Distributions for Times After Fission Between 2 and 14000 Sec written by Oak Ridge National Laboratory. Neutron Physics Division and published by . This book was released on 1978 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monte Carlo Models for the Production of Beta delayed Gamma Rays Following Fission of Special Nuclear Materials written by and published by . This book was released on 2004 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Monte Carlo method for the estimation of [beta]-delayed [gamma]-ray spectra following fission is described that can accommodate an arbitrary time-dependent fission rate and photon collection history. The method invokes direct sampling of the independent fission yield distributions of the fissioning system, the branching ratios for decay of individual fission products and the spectral distributions for photon emission for each decay mode. Though computationally intensive, the method can provide a detailed estimate of the spectrum that would be recorded by an arbitrary spectrometer, and can prove useful in assessing the quality of evaluated data libraries, for identifying gaps in these libraries, etc. The method is illustrated by a first comparison of calculated and experimental spectra from decay of short-lived fission products following the reactions 235U(n{sub th}, f) and 239Pu(n{sub th}, f). For general purpose transport calculations, where detailed consideration of the large number of individual [gamma]-ray transitions in a spectrum may be unnecessary, it is shown that an accurate and simple parameterization of a [gamma]-ray source function can be obtained. These parametrizations should provide high-quality average spectral distributions that should prove useful in calculations describing photons escaping from thick attenuating media.
Download or read book Signatures of Special Nuclear Material written by and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since September 11, 2001, much effort has been devoted to the development of new and improved means for the detection and prevention of the clandestine transport of special nuclear material (SNM, i.e. 235U or 239Pu) and other materials for producing weapons of mass destruction. In a recent Brief Communication, Borozdin et al. showed that cosmic-ray muons could be used to image dense objects inside containers. Here we describe a method for unequivocally identifying SNM in large seagoing containers. Our method is based on the fact that neutron-induced fission of 235U or 239Pu is followed by [beta] decays of short-lived fission fragments during which large numbers of high-energy [gamma] rays (above 3000 keV) are emitted. These [gamma] rays have energies above those of natural [gamma] background, are emitted with significantly greater intensity per fission than [beta]-delayed neutrons, have much higher probabilities of escaping hydrogenous cargo loadings than neutrons, and their energy spectra and time dependencies provide a unique signature of SNM. To demonstrate the main properties of high-energy delayed [gamma] rays, we produced neutrons by bombarding a 1-inch thick water-cooled Be target with 16-MeV deuterons from Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. Neutrons were moderated using steel and polyethylene. We employed a pneumatic transfer system to shuttle targets from the irradiation location inside the polyethylene moderator to a remote shielded counting station. We irradiated 235U (93% isotopic content), 239Pu (95% isotopic content), wood, polyethylene, aluminum, sandstone, and steel targets for 30 seconds (in a thermal-neutron flux of 1.5 x 106/cm2-sec) and acquired 10 sequential [gamma]-ray spectra, each of 3 sec. duration starting 3 sec. after the end of bombardment. We used an 80% relative efficiency coaxial germanium detector and a 30-cm x 30-cm x 10-cm plastic scintillator to detect [gamma] rays and acquired data using ORTEC PC-based electronics and software. The qualitative difference in the spectra from SNM versus that of any other material is illustrated in Figure 1, where we show the results obtained following the irradiations of 0.568 grams of 239Pu and 115 grams of steel. From the steel target, we observed a small number of low-energy [gamma] rays produced by the decays of long-lived isotopes such as {sup 56M}n (t12 = 2.58 hours). Similar results were obtained for all other non-SNM targets. However, we observed a large number of high-energy [gamma] rays produced by the decays of short-lived fission fragments from the 239Pu target. Thermal-neutron fission of 235U produces about 3 times as many delayed high-energy [gamma] rays as from 239Pu. We concluded that a sensitive method to identify SNM is simply to integrate the total number of events in a wide energy interval. The results of this type of analysis for two energy intervals, (3000-4000 keV) and (4000-8000 keV), are shown. The integrated numbers of events from irradiated SNM decay with a short effective half-life of approximately 25 seconds, whereas those from all other materials tested showed much longer decay times. These two features--large numbers of high-energy [gamma] rays decaying with a short effective half-life--provide a unique signature of SNM. Because of the high-density of [gamma]-ray lines produced by the decays of fission fragments, a practical system for interrogating large objects would not require high resolution detectors. In fact, we obtained the same results using the low-resolution plastic scintillator as we did with the germanium detector. Based on our measurements, we have estimated the response of a full-scale system employing a 14-MeV neutron generator producing 1011 neutrons per second and an array of scintillator detectors surrounding a standard cargo container in which a 5-cm diameter sphere of 239Pu was hidden inside a load of wood. Neutron irradiation of this container for 30 seconds would result in about 350 detected [gamma]-ray events above 3000 keV in 30 seconds (for 235U the detected yield would be approximately 1000 events). Thus an entire cargo container could be scanned for SNM in about 1 minute. This system could be combined with a radiographic imaging system for rapid identification of SNM in a wide range of applications.
Download or read book Delayed Fission Neutrons written by International Atomic Energy Agency and published by . This book was released on 1968 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Beta Decay of 79 80 81Zn and Nuclear Structure Around the N written by Stephen William Padgett and published by . This book was released on 2011 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation reports on new information in the [beta minus] decay of the neutron-rich nucleus 81Zn, which populates states in its daughter nucleus 81Ga. This includes new [gamma]-ray transitions in the daughter nucleus, 81Ga, as well as a [beta]-delayed neutron branching ratio. This isotope was produced at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory through the Isotope Separation Online technique. They are fission fragments from proton-induced fission on a uranium carbide target. These fission fragments are ionized and both mass and isotopically separated before arriving at the Low Energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS). The [gamma]-ray and [beta] electron emissions from the decays are measured and analyzed in this work. A new [beta]-delayed neutron branching ratio is reported for this decay, which is in agreement with recent theoretical values. The core excited states in the daughter nucleus, 81Ga, populated through allowed Gamow-Teller decays are analyzed. A trend in core excited states with other N=50 isotones indicates an increasing gap between a deeply bound neutron hole and the valence neutron above the N=50 gap upon moving towards doubly magic 78Ni. This dissertation also reports on additions to the decay schemes of 79Zn and 80Zn decays. Their decay level schemes have been expanded upon and an improved picture of the total allowed Gamow-Teller decay strength is known from 79Zn to 81Zn. This work presents an improved, albeit still incomplete, picture of the energy of states populated through Gamow-Teller decays from below to above the N=50 shell gap in zinc isotopes.
Download or read book Beta and Gamma Decay Heat Measurements Between 0 1s 50 000s for Neutron Fission of 235U 238U and 239Pu Progress Report June 1 1992 February 28 1993 written by and published by . This book was released on 1993 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: A helium-jet/tape-transport system is employed in the study of beta-particle and gamma-ray energy spectra of aggregate fission products as a function of time after fission. During the initial nine months of this project we have investigated the following areas: Design, assembly and characterization of a beta-particle spectrometer; Measurement of 235U(n{sub th}ff) beta spectra for delay times 0.2 s to 12,000 s; Assembly and characterization of a 5 x 5 Nal(Tl) gamma-ray spectrometer; Measurement of 235U(n{sub th}ff) gamma-ray spectra for delay times 0.2s to 1 5,500s; Assembly and characterization of HPGe gamma-ray spectrometer with a Nal(Tl) Compton-and-background-suppression annulus; Measurement of 235U(n {sub th}, ff) high-resolution gamma-ray spectra for delay times 0.6 s to over 100,000 s; Comparison of individual gamma-line intensities with ENDF/B-VI; Adaptation to our computer of unfolding program FERDO for beta and gamma aggregate fission-product energy spectra and development of a spectrum-stripping program for analysis of HPGe gamma-ray spectra; Study of the helium-jet fission-fragment elemental transfer efficiency. This work has resulted in the publication of twelve BAPS abstracts of presentations at scientific meetings. There are currently four Ph. D. and two M.S. candidates working on dissertations associated with the project.
Download or read book Decay Heat and Beta delayed Neutron Emission from Fission Products written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
