![]() ![]() Our results demonstrate that the use of this high resolution gamma-gamma-gamma coincidence technique can provide important, previously inaccessible data on fission. ![]() Subatomic Physics Identifiers URN: urn:nbn:se:kth:diva-289052 DOI: 10.1103/PhysRevC.102.064610 ISI: 000597812500003 Scopus ID: 2-s2.0-85105693548 OAI: oai:DiVA.= Pd were identified. The 0, 8, and the new 10 neutron emission yields for Mo-Ba are significantly larger than those reported previously for total sup 252Cf spontaneous fission. 102, no 6, article id 064610 National Category Place, publisher, year, edition, pagesAmerican Physical Society (APS), 2020. The new results highlight the need of a new evaluation of the prompt-fission multiplicity for U-225(n(th), f). Conclusions: This work clearly proves the lack of accurate correlation between fission fragment and neutron data even in the best-studied reactions. Finally, the neutron spectrum in the center-of-mass system was derived and plotted as a function of fragment mass. For Cf-252(sf) a slope value of partial derivative(TKE) over bar/partial derivative(nu) over bar = (-12.9 f 0.2) MeV/n was obtained. The experimental results on (nu) over bar (TKE) are also in agreement with the data at epithermal energies. For U-235(n(th), f), the (nu) over bar (A) data is very similar to the data obtained with SCINTIA, and therefore we verify these disclosed discrepancies to earlier thermal data and to the Wahl evaluation. Results: The experimental results on (nu) over bar (A) are in good agreement with earlier data for Cf-252(sf). Detailed Fluka simulations were performed to calculate the fraction of thermal neutron-induced fission, which was estimated to be about 98%. However, the effect is small for the estimated resolutions of this work. The simulation results also revealed that the partial derivative(nu) over bar/partial derivative A and partial derivative(TKE) over bar/partial derivative(nu) over bar are affected by the mass and energy resolution. Comprehensive simulations were performed to verify the methodology and to investigate the role of the mass and energy resolution on measured (nu) over bar (A) and (nu) over bar (TKE) values. 3.1 of the decays are spontaneous fission (SF) events in which Cfemits 3,757 neutrons. Digital data acquisition systems were utilized. EXAMPLE 6.1 Find the neutron emission rate per gram of Cf-252. Mannhart, PTB Braunschweig, Federal Republic of Germany, is documented. The neutrons were thermalized by a 12 cm thick block of paraffin. The californium-252 spontaneous fission neutron spectrum evaluated by W. A neutron beam with an average energy of 0.5 MeV was produced via the Li-7(p,n) reaction. Methods: The experiments were conducted at the former 7 MV Van de Graaff facility in JRC-Geel, using a Twin Frisch-Grid Ionization Chamber and two liquid scintillation detectors. Another goal was to validate the analysis methods, and prepare for planned investigations at excitation energies up to 5.5 MeV. Purpose: The purpose was to perform measurements of the prompt-fission neutron multiplicity, as a function of fragment mass and total kinetic energy (TKE), in U-235(n(th), f) and Cf-252(sf), to verify and extend the SCINTIA results. Despite numerous detailed studies, recent measurements done at JRC-Geel with the SCINTIA array in the epithermal region show surprisingly strong discrepancies to earlier thermal fission data and the Wahl systematics. These are vital benchmark data for both fission and nuclear deexcitation models, putting constrains on the fragment excitation energy and hence on the competing prompt neutron/gamma-ray emission. Not only is the spectrum itself of interest, but neutron detectors often use the spectrum for calibration, and other prompt fission neutron spectra are measured as a ratio to Cf 252. Their neutron spectra are similar to that of a fission reactor. 27 Each fission event typically results in the emission of 2 to 4 neutrons. One way to address this is by studying prompt-fission neutron multiplicities as a function of other fission observables such as the mass, (nu) over bar (A). The prompt fission neutron spectrum from spontaneous fission of Cf 252 is an integral part of several aspects of nuclear data. Spontaneous Fission Sources General A number of high mass even-even alpha emitting radionuclides (e.g., Pu-238, Cm-242, Cm-244, Cf-252) also undergo spontaneous fission. 102, no 6, article id 064610 Article in journal (Refereed) Published Abstract īackground: The sharing of excitation energy between the fission fragments is one of the key issues in studying nuclear fission. Show others and affiliations 2020 (English) In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. Furthermore, a liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a 252 Cf, a 0.84 g 240 Pu eff metal, and a 1.63 g 240 Pu eff metal sample. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |