Search results for "fission product yield"
showing 10 items of 37 documents
Isotopic product distributions in the near symmetric mass region in proton induced fission ofU238
1994
We have studied fission product yields using 19.8 MeV proton induced fission of a thin $^{238}\mathrm{U}$ target and the on-line mass separator IGISOL. The nonselectivity of the separation method used with respect to Z has allowed accurate determination of the yields of symmetric fission for the first time. The cumulative yields for the elements from Z=40 (Zr) up to Z=47 (Ag) have been determined from the beta- and gamma-radioactivity measurements. The independent fission product yield distributions for elements Tc, Ru, and Rh are obtained from the experimental data. An improved theoretical model for calculating mass and independent yields is described and applied. It is found that the char…
ANDES Measurements for Advanced Reactor Systems
2013
Abstract A significant number of new measurements was undertaken by the ANDES “Measurements for advanced reactor systems” initiative. These new measurements include neutron inelastic scattering from 23 Na, Mo, Zr, and 238 U, neutron capture cross sections of 238 U, 241 Am, neutron induced fission cross sections of 240 Pu, 242 Pu, 241 Am, 243 Am and 245 Cm, and measurements that explore the limits of the surrogate technique. The latter study the feasibility of inferring neutron capture cross sections for Cm isotopes, the neutron-induced fission cross section of 238 Pu and fission yields and fission probabilities through full Z and A identification in inverse kinematics for isotopes of Pu, Am…
Measurement of fission yields and isomeric yield ratios at IGISOL
2018
Data on fission yields and isomeric yield ratios (IYR) are tools to study the fission process, in particular the generation of angular momentum. We use the IGISOL facility with the Penning trap JYFLTRAP in Jyväskylä, Finland, for such measurements on 232Th and natU targets. Previously published fission yield data from IGISOL concern the 232Th(p,f) and 238U(p,f) reactions at 25 and 50 MeV. Recently, a neutron source, using the Be(p,n) reaction, has been developed, installed and tested. We summarize the results for (p,f) focusing on the first measurement of IYR by direct ion counting. We also present first results for IYR and relative yields for Sn and Sb isotopes in the 128-133 mass range fr…
Characterization of a Be(p,xn) Neutron Source for Fission Yields Measurements
2013
We report on measurements performed at The Svedberg Laboratory (TSL) to characterize a proton-neutron converter for independent fission yield studies at the IGISOL-JYFLTRAP facility (Jyv\"askyl\"a, Finland). A 30 MeV proton beam impinged on a 5 mm water-cooled Beryllium target. Two independent experimental techniques have been used to measure the neutron spectrum: a Time of Flight (TOF) system used to estimate the high-energy contribution, and a Bonner Sphere Spectrometer able to provide precise results from thermal energies up to 20 MeV. An overlap between the energy regions covered by the two systems will permit a cross-check of the results from the different techniques. In this paper, th…
New Neutron-Rich Nuclei and Isomers Produced in Symmetric Fisson
1990
The novel method for rapid on-line mass separation, the IGISOL, is described. The method has been shown applicable to mass separation of short-lived proton-induced fission products without any chemical dependence on radionuclide. Recent results on isomeric states with half-lives of the order of milliseconds produced directly in proton-induced fission of 238U and separated with the IGISOL are presented. The future plans for connection of the new K-130 cyclotron of the University of Jyvaskyla with the IGISOL are reviewed.
Mechanisms Suppressing Superheavy Element Yields in Cold Fusion Reactions.
2019
Superheavy elements are formed in fusion reactions which are hindered by fast nonequilibrium processes. To quantify these, mass-angle distributions and cross sections have been measured, at beam energies from below-barrier to 25% above, for the reactions of $^{48}\mathrm{Ca}$, $^{50}\mathrm{Ti}$, and $^{54}\mathrm{Cr}$ with $^{208}\mathrm{Pb}$. Moving from $^{48}\mathrm{Ca}$ to $^{54}\mathrm{Cr}$ leads to a drastic fall in the symmetric fission yield, which is reflected in the measured mass-angle distribution by the presence of competing fast nonequilibrium deep inelastic and quasifission processes. These are responsible for reduction of the compound nucleus formation probablity ${P}_{CN}$ …
Production of neutron rich isotopes in fission. A study for RNB facilities
2002
Abstract The theoretical model for calculations of the fission product yields in the light-particle induced fission is discussed. A comparison of the production cross sections in fission of 238 U by protons, thermal and fast neutrons, and photons is presented. The results of studies of the very asymmetric fission of 238 U by protons and neutron at the moderate energy are reported.
Measurement of fission fragments energy loss
2002
Abstract The mean energy of 252 Cf fission fragments emerging from an absorber and the determination of the capture rate in the absorber itself have been measured using two independent and complementary nuclear techniques. The results can be applied to the measurement of the energy self-absorption in a non-zero thickness source and can be used to validate simulation programs.
Production of neutron-rich isotopes in fission of uranium induced by neutrons of 20 MeV average energy
2000
In the context of a parameter study conducted by several laboratories for future European radioactive beam facilities based on fast-neutron induced fission, in particular for the SPIRAL-II project at GANIL, we have measured the yields of neutron-rich isotopes in the mass range of 88 to 144. These nuclei were obtained as fission products of natural uranium bombarded by neutrons of 20 MeV average energy emitted by a thick carbon target irradiated by 50 MeV deuterons. Yields have been measured using on-line mass separation with the ion-guide method. Compared with proton-induced fission at 25 MeV the magnitude of cross-sections, except for the symmetric region, is similar. Z-distributions of is…
Production of neutron-rich nuclei in fission induced by neutrons generated by the p + 13C reaction at 55 MeV
2003
Cross-sections for the production of neutron-rich nuclei obtained by neutron-induced fission of natural uranium have been measured. The neutrons were generated by bombarding a 13C target with 55 MeV protons. The results, position of the maximum in the (Z, A)-plane, width and magnitude, are very comparable with those where the neutrons are generated by bombardment of natural 12C graphite with 50 MeV deuterons. Depending on the geometry of the converter/target assembly the isotope yields, however, are a factor of 2-3 lower due to less efficient production of neutrons per primary projectile, especially at small forward angles.