scholarly journals Measurements of short-lived fission product yields using monoenergetic neutron and photon beams

2020 ◽  
Vol 242 ◽  
pp. 01004
Author(s):  
Sean Finch ◽  
Matthew Gooden ◽  
Chris Hagmann ◽  
Calvin Howell ◽  
Vanessa Linero ◽  
...  
Keyword(s):  
Fission Product ◽  
Fission Products ◽  
Product Yield ◽  
Transfer System ◽  
Photon Beams ◽  
Product Yields ◽  
Transit Times ◽  
Hpge Detectors ◽  
Fission Product Yields ◽  
Pu Isotopes

A joint TUNL-LLNL-LANL collaboration was formed to measure the absolute fission product yields from the 235 U, 238 U, and 239 Pu isotopes. Our goal is to study the energy evolution of fission products using monoenergetic beams. In order to extend our successful fission product-yield studies to include products with shorter half-lives, a RApid Belt-driven Irradiated Target Transfer System, named RABITTS, was constructed. This system allows us to perform cyclic activation and quantify fission products with γ-ray spectroscopy using HPGe detectors. Both a 1 meter and 10 meter transfer system have been developed, with transit times of 0.4 and 1.1 seconds, respectively. Using these systems, we have measured sub-second half-lives. Our goal is to measure fission product yields from neutron-induced fission with En = 0.5 − 14.8 MeV and photofission with Eγ = 8 − 15 MeV. A detailed characterization of the system’s performance is presented, including preliminary fission product measurements, and the expected sensitivity.

scholarly journals Comparing fission-product yields from photon-induced fission of 240Pu and neutron-induced fission of 239Pu as a test of the Bohr hypothesis in nuclear fission

2020 ◽  
Vol 242 ◽  
pp. 01008
Author(s):  
Jack Silano ◽  
Anton Tonchev ◽  
Roger Henderson ◽  
Nicolas Schunck ◽  
Werner Tornow ◽  
...  
Keyword(s):  
Fission Product ◽  
Excitation Energy ◽  
Compound Nucleus ◽  
Nuclear Fission ◽  
Photon Beams ◽  
Fission Process ◽  
Product Yields ◽  
Fission Product Yields ◽  
Induced Fission ◽  
First Time

Fission product yields (FPYs) are a uniquely sensitive probe of the fission process, with well established dependence on the species of nucleus undergoing fission, its excitation energy and spin. Thus FPYs are well suited for testing Bohr’s hypothesis in the context of nuclear fission, which states that the decay of a compound nucleus with a given excitation energy, spin and parity is independent of its formation. Using FPYs, we have performed a new highprecision test of the combined effects of the entrance channel, spin and parity on the fission process from two of the most commonly used particles to induce fission neutrons and photons. The 239 Pu(n,f) reaction at En = 4.6 MeV and the 240 Pu(γ,f) reaction at Eγ = 11.2 MeV were used to produce a 240 Pu∗ compound nucleus with the same excitation energy. The FPYs from these two reactions were measured using quasimonoenergetic neutron beams from the TUNL’s FN tandem Van de Graaff accelerator and quasimonenergetic photon beams from the High Intensity γ-ray Source (HIγS) facility. The FPYs from these two reactions are compared quantitatively for the first time.

scholarly journals Employing FREYA for fission product yield evaluations

2020 ◽  
Vol 242 ◽  
pp. 03002
Author(s):  
R. Vogt ◽  
J. Randrup ◽  
N. Vassh ◽  
T. Sprouse ◽  
R. Surman
Keyword(s):  
Fission Product ◽  
Product Yield ◽  
Fission Yield ◽  
Fission Reaction ◽  
Product Yields ◽  
Large Samples ◽  
Reaction Event ◽  
Fission Product Yields ◽  
The Future ◽  
Fission Product Yield

The fast event-by-event fission code FREYA (Fission Reaction Event Yield Algorithm) generates large samples of complete fission events while employing only a few physics-based parameters. Not only is FREYA fast, it is also flexible, able to employ a variety of input formats to test the implications of various fission yield evaluations on neutron and photon observables. We describe how FREYA was applied to the neutron-rich nuclei needed for r-process nucleosynthesis calculations as an example of this flexibility. Finally, we discuss how we plan to make use of this flexibility to extend FREYA to calculations of cumulative fission product yields to aid evaluations of these yields in the future.

scholarly journals New Fission Product Yield Measurements at Oregon State University

2020 ◽  
Vol 242 ◽  
pp. 01010
Author(s):  
Aaron Tamashiro ◽  
Jason Burke ◽  
Stephen Padgett ◽  
Sean Burcher ◽  
Todd Palmer ◽  
...  
Keyword(s):  
Fission Product ◽  
Branching Ratio ◽  
Nuclear Research ◽  
Product Yield ◽  
State University ◽  
Product Yields ◽  
Fission Product Yields ◽  
Training Research ◽  
Γ Rays ◽  
Oregon State University

Cumulative fast fission product yields for 235 U and 238 U were measured at Godiva-IV in burst mode. Data was collected starting 45 minutes after the prompt irradiation. Data analysis codes were developed to analyze gammarays and calculate fission product yields with their respective uncertainties. Due to uncertainties in the branching ratios, different γ-rays from the same isotope led to different fission yield. This led to an effort at Oregon State University (OSU) to utilize the Rabbit facility at their 1 MegaWatt Training, Research, Isotopes, General Atomics (TRIGA) nuclear research reactor. The new experimental setup will allow us to measure branching ratio data and short-lived fission product yields starting seconds after a prompt irradiation.

scholarly journals Validating the Bohr hypothesis: Comparing fission-product yields from photon-induced fission of 240Pu and neutron-induced fission of Pu

2020 ◽  
Vol 239 ◽  
pp. 03004
Author(s):  
Jack Silano ◽  
Anton Tonchev ◽  
Roger Henderson ◽  
Nicolas Schunck ◽  
Werner Tornow ◽  
...  
Keyword(s):  
Fission Product ◽  
Excitation Energy ◽  
Nuclear Fission ◽  
Photon Beams ◽  
Fission Process ◽  
Product Yields ◽  
Fission Product Yields ◽  
Consistent Manner ◽  
First Results ◽  
Induced Fission

The Bohr hypothesis, one of the most fundamental assumptions in nuclear fission theory, states that the decay of a compound nucleus with a given excitation energy, spin and parity is independent of its formation. Using fission product yields (FPYs) as a sensitive probe, we have performed new high precision test of the combined effects of the entrance channel, spin and parity on the fission process. Two different reactions were used in a self-consistent manner to produce a compound 240Pu nucleus with the same excitation energy: neutron induced fission of 239Pu at En = 4.6 MeV and photon-induced fission of 240Pu at Eγ = 11.2 MeV. The FPYs from these two reactions were measured using quasimonoenergetic neutron beams from the TUNL's FN tandem Van de Graaff accelerator and quasimonenergetic photon beams from the High Intensity γ-ray Source (HlγS) facility. The first results comparing the FPYs from these two reactions will be presented. Implications for validating the Bohr hypothesis will be discussed.

scholarly journals Using CGMF to estimate corrections for fission yields measured via γ-ray spectroscopy

2020 ◽  
Vol 242 ◽  
pp. 03003
Author(s):  
P. Jaffke ◽  
P. Talou ◽  
M. Devlin ◽  
N. Fotiades
Keyword(s):  
Fission Product ◽  
Nuclear Structure ◽  
Fission Products ◽  
Spin Distribution ◽  
Product Yields ◽  
Fission Fragments ◽  
Fission Product Yields ◽  
Γ Ray ◽  
The Impact ◽  
Fission Yields

Fission product yields have been inferred using γ-ray spectroscopy for several decades. Typically, these efforts have focused on even-Z even-A fission products as their nuclear structure are less complicated. To further simplify the situation, it is often assumed that no side-feeding to the ground-state occurs and multiplicity cuts have a negligible effect on the inferred yields. Using CGMF, a Hauser-Feshbach statistical decay model for the primary fission fragments, we estimate the impact of these assumptions and determine corrections for specific fission product yields. We report on these corrections and investigate their sensitivity to various nuclear parameters, specifically the spin distribution of the fission fragments and the assumed nuclear structure. Our results indicate that even in the simplest of cases, say the 2+ → 0+ transitions in even-Z even-A fragments, average level corrections are on the order of 75%.

scholarly journals Toward short-lived and energy-dependent fission product yields from neutron-induced fission

2020 ◽  
Vol 239 ◽  
pp. 03001
Author(s):  
Anton P Tonchev ◽  
Jack A Silano ◽  
Chris Hagmann ◽  
Roger Henderson ◽  
Mark A Stoyer ◽  
...  
Keyword(s):  
Fission Product ◽  
Fission Products ◽  
Incident Neutron ◽  
Tandem Accelerator ◽  
Precision Data ◽  
Product Yields ◽  
Fission Product Yields ◽  
Induced Fission ◽  
Energy Dependent ◽  
Fission Yields

Fission product yields (FPYs) are an important source of information that are used for basic and applied physics. They are essential observables to address questions relevant to nucleosynthesis in the cosmos that created the elements from iron to uranium, for example, in energy generating processes from fission recycling in binary neutron star mergers; resolving the reactor neutrino anomaly; decay heat release in nuclear reactors; and many national security applications. While new applications will require accurate energy-dependent FPY data over a broad set of incident neutron energies, the current evaluated FPY data files contain only three energy points: thermal, fast, and 14-MeV incident energies. Recent measurements using mono-energetic and pulsed neutron beams at the Triangle Universities Nuclear Laboratory (TUNL) tandem accelerator and employing a dual fission ionization chambers setup have produced self-consistent, high-precision data critical for testing fission models for the neutron-induced fission of the major actinide nuclei. This paper will present new campaign just beginning utilizing a RApid Belt-driven Irradiated Target Transfer System (RABITTS) to measure shorter-lived fission products and the time dependence of fission yields, expanding the measurements from cumulative towards independent fission yields.

Independent fission-product yields and fast-neutron emission by fission products

1974 ◽  
Vol 17 (7) ◽  
pp. 905-910
Author(s):  
A. B. Koldobskii ◽  
V. M. Kolobashkin ◽  
A. A. Gusev
Keyword(s):  
Fission Product ◽  
Fast Neutron ◽  
Neutron Emission ◽  
Fission Products ◽  
Product Yields ◽  
Fission Product Yields

scholarly journals Transformations of actinides fission product yields due to post scission emission of nuclear particles:232Th

2021 ◽  
Author(s):  
V.T. Maslyuk ◽  
O.O. Parlag ◽  
M.I. Romanyuk ◽  
O.I. Lendyel ◽  
O.M. Pop
Keyword(s):  
Experimental Data ◽  
Fission Product ◽  
Fission Products ◽  
Product Yields ◽  
Fission Fragments ◽  
Charge Distributions ◽  
Fission Product Yields ◽  
Symmetric Fission ◽  
The Many ◽  
Theoretical Results

The "many ensembles" method was proposed to investigate the influence of nuclear particles' post-scission emission on mass and charge distributions of fission products. The post scission approximation had been used; each of these ensembles consists of the fission fragments after emission of chains of different lengths, both the beta (±β) particles and neutrons. The theory allows one to find the most probable two fragment clusters of fission products and study their evolution after the post-scission emission of nuclear particles. The isotope <sup>232</sup>Th was chosen as an example, the fission fragments of which are intensively studied in the experiment. It is shown that the post-scission emission of nuclear particles eventually leads to the convergence of the asymmetric peaks, which looks like enhanced symmetric fission mode over asymmetric one for fission product yields. A comparison of the theoretical results and experimental data for the <sup>232</sup>Th fission fragments indicates their satisfactory matching.

scholarly journals Completeness of experimental fission product yields in EXFOR database

2020 ◽  
Vol 239 ◽  
pp. 05013
Author(s):  
Takanari Fukuda ◽  
Shin Okumura ◽  
Naohiko Otuka
Keyword(s):  
Fission Product ◽  
Nuclear Reaction ◽  
Product Yield ◽  
Yield Data ◽  
Product Yields ◽  
Wide Range ◽  
Fission Product Yields ◽  
Reaction Data ◽  
Data Centres ◽  
Exfor Database

The Nuclear Reaction Data Centres (NRDC) collaborate on worldwide compilation and dissemination of experimental nuclear reaction data by developing and maintaining the EXFOR database. With the growing interests in the fission product yields of various projectiles and a wide range of energies, several evaluation activities are ongoing. In line with these activities, the IAEA conducted completeness check of fission product yield data in EXFOR against two experimental datasets developed by the ENDF and UKFY library evaluators. The present status and statistics of these datasets as well as the result of the EXFOR completeness review are presented.

Fission product yields at intermediate energy

1998 ◽  
Author(s):  
V. A. Rubchenya ◽  
J. Äystö ◽  
P. Dendooven ◽  
S. Hankonen ◽  
A. Jokinen ◽  
...  
Keyword(s):  
Fission Product ◽  
Intermediate Energy ◽  
Product Yields ◽  
Fission Product Yields
Sign in / Sign up

Export Citation Format

Share Document