Evidence for nuclear excitation by electron transition on 193Ir and its probability

Kishimoto, Shunji; Yoda, Yoshitaka; Kobayashi, Y.; Kitao, Shinji; Haruki, Rie; Seto, Makoto

doi:10.1016/j.nuclphysa.2004.10.016

Cited by 25 publications

(20 citation statements)

References 10 publications

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“…Many of those experiments yielded conflicting results and the results differed significantly from theoretical estimates. Measurements on 197 Au and 193 Ir have provided evidence of NEET occurring and the results were near theoretical estimations [2][3][4]. One candidate isotope, 235 U, has a low-lying isomeric state at 76 eV and has been studied several times over the past 40 years.…”

Section: Introductionmentioning

confidence: 79%

Nuclear excitation by electronic transition ofU235

et al. 2016

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Background: Nuclear excitation by electronic transition (NEET) is a rare nuclear excitation that can occur in isotopes containing a low-lying nuclear excited state. Over the past 40 years, several experiments have attempted to measure NEET of 235 U and those experiments have yielded conflicting results.Purpose: An experiment was performed in order to determine whether NEET of 235 U occurs, and to determine its excitation rate.Method: A pulsed Nd:YAG laser operating at 1064 nm with a pulse energy of 790 mJ and a pulse width of 9 ns was used to generate a uranium plasma. The plasma was collected on a catcher plate and electrons from the catcher plate were accelerated and focused onto a microchannel plate detector. An observation of a decay with a 26 minute half-life would suggest the creation of 235m U and the possibility that NEET of 235 U occurred.Results: A 26 minute decay consistent with the decay of 235m U was not observed and there was no evidence that NEET occurred. An upper limit for the NEET rate of 235 U was determined to be λNEET < 1.8 × 10 −4 s −1 with a confidence level of 68.3%. Conclusions:The upper limit determined from this experiment is consistent with most of the past measurements. Discrepancies between this experiment and past measurements can be explained by assuming past experiments misinterpreted the data.

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Section: Introductionmentioning

confidence: 79%

Nuclear excitation by electronic transition ofU235

et al. 2016

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“…This may significantly alter the neutron absorption rate in branching point nuclei where such rates are comparable to their beta-decay rates, leading to altered population of predicted universal isotopic abundances [233][234][235][236]. Furthermore, NEEC [237][238][239][240] and nuclear excitation by electronic transition (NEET) [241][242][243] processes can occur on the highly-excited states produced by neutron absorption reactions before gamma emission, effectively 'hijacking' an (n,γ) reaction midway through completion [244,245]. There are currently no existing capture rate measurements on plasma-excited nuclei, for any isotope.…”

Section: Compton Gamma Spectrometermentioning

confidence: 99%

Dynamic high energy density plasma environments at the National Ignition Facility for nuclear science research

Cerjan

Bernstein

Hopkins

et al. 2018

J. Phys. G: Nucl. Part. Phys.

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The generation of dynamic high energy density plasmas in the pico-to nanosecond time domain at high-energy laser facilities affords unprecedented nuclear science research possibilities. At the National Ignition Facility (NIF), the primary goal of inertial confinement fusion research has led to the synergistic development of a unique high brightness neutron source, sophisticated nuclear diagnostic instrumentation, and versatile experimental platforms. These novel experimental capabilities provide a new path to investigate nuclear processes and structural effects in the time, mass and energy density domains relevant to astrophysical phenomena in a unique terrestrial environment. Some immediate applications include neutron capture cross-section evaluation, fission fragment production, and ion energy loss measurement in

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“…The effect of high energy density plasma (HEDP) environments on astrophysical nucleosynthesis, the formation of heavy elements from pre-existing nucleons in astrophysical plasmas, is expected to play a significant role [1]. Nuclei in stellar plasmas reach a thermal population of low-lying excited nuclear states from photo-excitation, free electrons in the plasma (NEEC) [2][3][4][5], excitation from atomic transitions (NEET) [6][7][8], and inelastic electron scattering in the dense plasma. In these experiments we investigate the NEEC process in under-dense plasmas by illuminating mini hot hohlraums (400 or 600 um in diameter) with ~15 kJ of laser light at the Omega laser facility.…”

Section: Non-lte Transport and Nuclear Lifetimes (A Kritcher)mentioning

confidence: 99%