Author: T. ElevantPublisher:
ISBN:
Category : Plasma (Ionized gases)
Languages : en
Pages :
Book Description
Measurements of Fusion Neutron Energy Spectra at JET by Means of Time-of-flight Techniques
Author: T. ElevantPublisher:
ISBN:
Category : Plasma (Ionized gases)
Languages : en
Pages :
Book Description
Measurements of Fusion Neutron Energy Spectra at JET by Meansof Time-of-flight Techniques
Author: P. van BelleMeasurements of Fusion Neutron Energy Spectra at JET by Menas of Time-of-flight Techniques
Author: Summary of Neutron Measurement Methods
Author: Herman Lunden MillerPublisher:
ISBN:
Category : Gamma rays
Languages : en
Pages : 28
Book Description
Time-of-flight Measurements Made with Neutrons from Nuclear Explosions in Space
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
During the 1962 high altitude test series, measurements of the energy spectra of the neutrons from three devices were made by the space physics group of the Los Alamos Scientific Laboratory. The explosions occurred at high altitudes, above the atmosphere, and near Johnston Island. The measurements were made with detectors flown from Kauai, Hawaii to above the atmosphere, on two-stage Nike-Apache rockets. The range between the explosion and the detector packages was about 1300 km. For each of the tests, two moderated fission detectors and two plastic fluor detectors were flown, except that on the third test, an extra fluor detector which had been recovered from the ocean, was also flown. Useful records were obtained for every rocket flown, which makes thirteen neutron spectrum measurements recovered out of thirteen attempts. Although the prime objective of the experiments was to measure the neutron energy spectra, a secondary objective was accomplished in the field of time-of-flight measurements on the resonance structure of various nuclides. Since the experiments were not designed specifically to make cross section measurements, the results are not as detailed as they could be, but some useful results were obtained.
Measurement of Neutron Flux and Spectra for Physical and Biological Applications
Author: National Committee on Radiation Protection and Measurements (U.S.)Publisher:
ISBN:
Category : Neutrons
Languages : en
Pages : 104
Book Description
The Two-plate Method of Measuring Fast Neutron Energy Spectra when the Direction of the Incident Neutrons Cannot be Determined
Author: John E. EvansPublisher:
ISBN:
Category : Fast neutrons
Languages : en
Pages : 56
Book Description
Neutron and Gamma Time-of-flight Measurements in Inertial Confinement Fusion Experiments
Author: Zaarah L. MohamedPublisher:
ISBN:
Category :
Languages : en
Pages : 143
Book Description
"This work includes the study of various nuclear processes relevant to inertial confinement fusion (ICF) plasmas and big bang nucleosynthesis via experiments performed at the OMEGA laser facility. Neutron and gamma time-of-flight detectors were used to determine various quantities of interest in cryogenic and room temperature implosions. In particular, xylene neutron time-of-flight (nTOF) detectors were used to determine areal densities from backscattered neutrons for OMEGA cryogenic experiments using a forward fit analysis. This analysis was extended to a recently deployed second nTOF line of sight (LOS) on OMEGA. The presence of two nTOF LOS enables a comparison of two measurements to study implosion symmetry, however, these two measurements still leave a lack of coverage around the target chamber which makes it difficult to infer the 3D shape of the areal density. This analysis can easily be extended to additional nTOF lines of sight in the future. The original xylene nTOF detector was also used to infer properties of the 5He ground state and first excited state via a simple wave-function amplitude analysis of neutron spectra from warm TT implosions. These quantities are particularly interesting because of their relationship to the gamma spectrum produced by DT fusion and additionally because the TT neutron spectrum is a background observed in the neutron spectra produced on cryogenic implosions. The ground state mass inferred via forward fit agrees with the accepted value [Audi et al., Nucl. Phys. A 729 (2003)], but the lifetime inferred here is about 70% longer than the accepted value [Wong, Anderson, & McClure, Nucl. Phys. 71 (1965)]. The mass and width of the first excited state were also inferred and compared to previously reported values, though there is a wide spread in the previously reported values. Cherenkov detectors were used to study gamma rays from the reactions D(T,5He)[gamma], H(D,3He)[gamma], and H(T,4He)[gamma] at low energies. The measurements detailed in this work result in a DT gamma-to-neutron branching ratio of (8.42 ł 2.84) × 10-5 measured at a center-of-mass (CM) energy of 19 ł 2 keV. This branching ratio is a factor of 2 larger than the branching ratio previously inferred on an ICF platform [Kim et al., Phys. Rev. C 85 (2012)], however, the error bars on the two measurements overlap. Considering a recent measurement of the DT gamma spectrum [Horsfield et al., Phys. Rev. C. 104 (2021)], the branching ratio measurement detailed in this work also appears to be in agreement with accelerator measurements [Cecil & Wilkinson, Phys. Rev. Lett. 53 (1984); Morgan et al., Phys. Rev. C. 33 (1986)] that isolated the ground state DT gamma. S factors for H(D,3He)[gamma] and H(T,4He)[gamma] were determined at low energies (ECM=16-37 keV). The inferred H(D,3He)[gamma] S factor appears to agree with accelerator data. The H(T,4He)[gamma] S factor inferred from one detector with a relatively high gamma energy threshold appears to be 25-70% larger than an evaluated S factor determined by including accelerator data at higher CM energies [Canon et al., Phys. Rev. C 65 (2002)], however, only two accelerator data points currently exist for comparison at these low energies and these two accelerator data points are in reasonable agreement with the S factors inferred using the high threshold detector as detailed in this work. Another detector with a very low minimum gamma energy threshold was also used to study the H(T,4He)[gamma] S factor. This detector inferred significantly higher values for the H(T,4He)[gamma] S factor, but this particular measurement is thought to be contaminated by detection of neutron-induced gammas from remaining shell material. These time-of-flight gamma measurements require some assumptions concerning the gamma spectrum from each reaction in order to infer branching ratios or S factors. This is not ideal, however, traditional pulse height gamma detection cannot be used for detection of fusion gammas in ICF experiments due to the short time scales involved. Two potential designs are discussed for a true gamma spectrometer intended for operation at ICF facilities"--Pages ix-x.
Simultaneous Determination of Fast-Neutron Spectra by Time-of-Flight and Pulse-Height Unfolding Techniques
Author: E. A. StrakerPublisher:
ISBN:
Category :
Languages : en
Pages : 20
Book Description
Proton-recoil spectrometers have frequently been used in the past few years to measure spectra for neutron energies greater than approximately 1 MeV with the results depending strongly on the adequacy of the response matrix used in unfolding pulse-height spectra. By simultaneously measuring a fast-neutron spectrum by time-of-flight and by pulse-height unfolding, the adequacy of the response matrix and unfolding code could be determined. Spectra of several shapes and measurements with different time-of-flight resolution were used to validate the spectra obtained by unfolding the pulse-height spectrum. (Author).
Author: R. S. Stone