The γ-γ fast-timing technique and the EXILL&FATIMA campaign

At the Institut Laue-Langevin in Grenoble, germanium-gated γ-γ fast-timing lifetime measurements of nuclear excited states in neutron-rich nuclei have been performed within a prompt γ-ray spectroscopy experimental campaign. We report on results obtained from the cold-neutron induced fission of 235U. The excited secondary fission products were stopped almost instantaneously within the thick target and the γ rays emitted were collected triggerlessly using the EXILL&FATIMA mixed array of HPGe and LaBr3(Ce) detectors. Precise lifetimes could be determined by analysing the γ-γ time difference spectra using the generalized centroid difference method. This picosecondsensitive method provides many advantages and is briefly explained. Still, the major source of systematic errors is related to the contribution of time-correlated Compton background. The EXILL&FATIMA results are discussed with respect to the typical energy-dependent timing behaviour of the background. According to the time response of the background, appropriate methods and a time correction for the sub-nanosecond regime are proposed.

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Recoil studies of some light-mass products from the proton-induced fission of 238U at intermediate energies

Canadian Journal of Chemistry ◽

10.1139/v69-100 ◽

1969 ◽

Vol 47 (4) ◽

pp. 655-662 ◽

Cited By ~ 3

Author(s):

G. B. Saha ◽

L. Yaffe

Keyword(s):

Kinetic Energy ◽

Energy Region ◽

Fission Products ◽

Thick Target ◽

Average Kinetic Energy ◽

Intermediate Energies ◽

Energy Relationships ◽

Kinetic Release ◽

Induced Fission ◽

Bombarding Energy

The recoil properties of 66Ni, 67Cu, and 72Zn produced in the fission of 238U by protons of 40–85 MeV energy have been studied radiochemically by the thick target – thick catcher technique. The average kinetic energy of each product has been calculated from the ranges by use of known range–energy relationships. The calculated impact velocity vll shows that these fission products are formed predominantly via a compound nucleus mechanism in this energy region. The average total kinetic release in fission is found to be insensitive to the bombarding energy.

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High resolution gamma-ray spectroscopy of fast-neutron induced fission

EPJ Web of Conferences ◽

10.1051/epjconf/202125600019 ◽

2021 ◽

Vol 256 ◽

pp. 00019

Author(s):

Jonathan Wilson ◽

Damien Thisse ◽

Matthieu Lebois ◽

Nikola Jovancevic ◽

Rhiann Canavan ◽

...

Keyword(s):

Fast Neutron ◽

Gamma Ray ◽

Precision Spectroscopy ◽

Fast Timing ◽

Experimental Campaign ◽

Γ Rays ◽

Fission Neutrons ◽

Induced Fission ◽

Multiplicity Distributions ◽

Prompt Fission

Experiments to perform precision spectroscopy of fast neutron induced fission were carried out during the ν-Ball experimental campaign at the ALTO facility of IJC Laboratory Orsay. Low energy fission of 232Th(n,f), 238U(n,f) and spontaneous fission of 252Cf were studied using this hybrid highresolution spectrometer and calorimeter. New observables such as γ-ray multiplicity distributions correlated with specific fission fragments are presented and discussed. A new method using fast-timing techniques to detect prompt fission neutrons in coincidence with prompt fission γ-rays is described.

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

EPJ Web of Conferences ◽

10.1051/epjconf/202023903001 ◽

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.

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From fission yield measurements to evaluation: status on statistical methodology for the covariance question

EPJ Nuclear Sciences & Technologies ◽

10.1051/epjn/2018030 ◽

2018 ◽

Vol 4 ◽

pp. 26 ◽

Cited By ~ 1

Author(s):

Brieuc Voirin ◽

Grégoire Kessedjian ◽

Abdelaziz Chebboubi ◽

Sylvain Julien-Laferrière ◽

Olivier Serot

Keyword(s):

Statistical Tests ◽

Fission Products ◽

Experimental Program ◽

Mass Yield ◽

Statistical Methodology ◽

Fission Yield ◽

Fission Process ◽

Induced Fission ◽

Entropy Criterion ◽

Fission Yields

Studies on fission yields have a major impact on the characterization and the understanding of the fission process and are mandatory for reactor applications. Fission yield evaluation represents the synthesis of experimental and theoretical knowledge to perform the best estimation of mass, isotopic and isomeric yields. Today, the output of fission yield evaluation is available as a function of isotopic yields. Without the explicitness of evaluation covariance data, mass yield uncertainties are greater than those of isotopic yields. This is in contradiction with experimental knowledge where the abundance of mass yield measurements is dominant. These last years, different covariance matrices have been suggested but the experimental part of those are neglected. The collaboration between the LPSC Grenoble and the CEA Cadarache starts a new program in the field of the evaluation of fission products in addition to the current experimental program at Institut Laue-Langevin. The goal is to define a new methodology of evaluation based on statistical tests to define the different experimental sets in agreement, giving different solutions for different analysis choices. This study deals with the thermal neutron induced fission of 235U. The mix of data is non-unique and this topic will be discussed using the Shannon entropy criterion in the framework of the statistical methodology proposed.

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A new detector system for the measurement of high-energy prompt γ-rays for low-energy neutron induced fission

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment ◽

10.1016/j.nima.2018.07.055 ◽

2018 ◽

Vol 906 ◽

pp. 88-96 ◽

Cited By ~ 4

Author(s):

H. Makii ◽

K. Nishio ◽

K. Hirose ◽

R. Orlandi ◽

R. Léguillon ◽

...

Keyword(s):

High Energy ◽

Low Energy ◽

Detector System ◽

Energy Neutron ◽

Γ Rays ◽

Induced Fission

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Fission Product Yield Measurements from Neutron-Induced Fission of 235,238 U and 239Pu

EPJ Web of Conferences ◽

10.1051/epjconf/202023203006 ◽

2020 ◽

Vol 232 ◽

pp. 03006

Author(s):

M. A. Stoyer ◽

A. P. Tonchev ◽

J. A. Silano ◽

M. E. Gooden ◽

J. B. Wilhelmy ◽

...

Keyword(s):

Fission Product ◽

Nuclear Physics ◽

Fission Products ◽

Product Yield ◽

Tandem Accelerator ◽

Precision Data ◽

High Precision Data ◽

Induced Fission ◽

The Impact ◽

Fission Yields

Fission product yields (FPY) are one of the most fundamental quantities that can be measured for a fissioning nucleus and are important for basic and applied nuclear physics. Recent measurements using mono-energetic and pulsed neutron beams generated using Triangle Universities Nuclear Laboratory’s tandem accelerator and employing a dual fission chamber setup have produced self-consistent, high-precision data critical for testing fission models for the neutron-induced fission of 235,238U and 239Pu between neutron energies of 0.5 to 15.0 MeV. These data have elucidated a low-energy dependence of FPY for several fission products using irradiations of varying lengths and neutron energies. This paper will discuss new measurements just beginning utilizing a RApid Belt-driven Irradiated Target Transfer System (RABITTS) to measure shorterlived fission products and the time dependence of fission yields, expanding the measurements from cumulative towards independent fission yields. The uniqueness of these FPY data and the impact on the development of fission theory will be discussed.

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The Electron Injection Function and Energy‐dependent Delays in Thick‐Target Hard X‐Rays

The Astrophysical Journal ◽

10.1086/306522 ◽

1998 ◽

Vol 509 (2) ◽

pp. 911-917 ◽

Cited By ~ 36

Author(s):

John C. Brown ◽

Andrew J. Conway ◽

Markus J. Aschwanden

Keyword(s):

Electron Injection ◽

Thick Target ◽

X Rays ◽

Energy Dependent ◽

Injection Function

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Fission fragment yields and total kinetic energy release in neutron-induced fission of235,238U,and239Pu

EPJ Web of Conferences ◽

10.1051/epjconf/201816900024 ◽

2018 ◽

Vol 169 ◽

pp. 00024 ◽

Cited By ~ 1

Author(s):

F. Tovesson ◽

D. Duke ◽

V. Geppert-Kleinrath ◽

B. Manning ◽

D. Mayorov ◽

...

Keyword(s):

Kinetic Energy ◽

Kinetic Energy Release ◽

Nuclear Fission ◽

Total Kinetic Energy ◽

Experimental Techniques ◽

Science Center ◽

Fission Process ◽

Induced Fission ◽

Time Projection ◽

Energy Dependent

Different aspects of the nuclear fission process have been studied at Los Alamos Neutron Science Center (LANSCE) using various instruments and experimental techniques. Properties of the fragments emitted in fission have been investigated using Frisch-grid ionization chambers, a Time Projection Chamber (TPC), and the SPIDER instrument which employs the 2v-2E method. These instruments and experimental techniques have been used to determine fission product mass yields, the energy dependent total kinetic energy (TKE) release, and anisotropy in neutron-induced fission of U-235, U-238 and Pu-239.

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A CALORIMETRIC DETERMINATION OF THE AVERAGE KINETIC ENERGY OF THE FRAGMENTS FROM U235 FISSION

Canadian Journal of Physics ◽

10.1139/p55-042 ◽

1955 ◽

Vol 33 (7) ◽

pp. 357-363 ◽

Cited By ~ 15

Author(s):

R. B. Leachman ◽

W. D. Schafer

Keyword(s):

Kinetic Energy ◽

Average Energy ◽

Fission Products ◽

Average Kinetic Energy ◽

U235 Fission ◽

Induced Fission ◽

Differential Calorimeter ◽

Calorimetric Determination ◽

Good Agreement

The average heat of thermal-neutron induced fission of U235 has been measured by a differential calorimeter. The average energy per fission observed by the calorimeter was 170.1 ± 1.2 Mev. On the basis of the thicknesses of the calorimeter materials and the theoretical energy loss equation, the β energy per fission observed by the calorimeter is 3.0 ± 1 Mev. and, on the same basis, the γ and neutron energy observed is negligible. The resulting 167.1 ± 1.6 Mev. for the average kinetic energy of the fission products is shown to be in good agreement with less direct determinations of this quantity.

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