Search for nuclear excitation by electronic transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">U</mml:mi><mml:mprescripts /><mml:none /><mml:mn>235</mml:mn></mml:mmultiscripts></mml:math>

Claverie, Gérard; Aléonard, M.M.; Chemin, J. F.; Gobet, F.; Hannachi, F.; Harston, M. R.; Malka, G.; Scheurer, J. N.; Morel, Pascal; Méot, V.

doi:10.1103/physrevc.70.044303

Cited by 23 publications

(25 citation statements)

References 20 publications

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“…The most recent and reliable experimental results on NEET have been performed on 197 Au [4,19], 189 Os [20,21] and 235 U [22]. The NEET probability for the 77.351 keV 197 Au nuclear transition that corresponds to an atomic K → M transition in neutral atoms was determined to be (5.0 ± 0.6) × 10 −8 [4].…”

Section: Introductionmentioning

confidence: 99%

Overlapping resonances in nuclei coupling to the atomic shells

Arigapudi

Pálffy

2012

Phys. Rev. A

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The resonant process of nuclear excitation by electron transition (NEET) in highly charged ions is investigated. In NEET, a bound electronic decay transition occurs with the simultaneous excitation of the nucleus, provided that the energies of the atomic and nuclear transition match. By varying the atomic charge state, the atomic transition energy can be tuned to a better match of the nuclear transition energy. We propose a new way to create the atomic hole in highly charged ions by dielectronic capture of a free electron. In order to derive the cross section for the three-step process composed by dielectronic capture, nuclear excitation by electron transition, and the subsequent nuclear decay, a Feshbach projection operator formalism is developed. With the help of this formalism, the resonances in nuclei coupling to the atomic shell and the possible interference between several direct and resonant electronic and nuclear processes such as radiative recombination, dielectronic recombination and nuclear excitation by electron capture are described.

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Section: Introductionmentioning

confidence: 99%

Overlapping resonances in nuclei coupling to the atomic shells

Arigapudi

Pálffy

2012

Phys. Rev. A

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“…The second case had the NEET rate set to a value that would produce the highest number of isomers. The third case used NEET rates near the upper limit found in [8]. Table I shows the NEET rates and the predicted number of isomers produced for each case.…”

Section: Neet Theory and Simulationsmentioning

confidence: 99%

“…Due to the known problem of exoelectrons [8], two types of uranium samples were used. The two types were the null uranium samples and the enriched uranium samples.…”

Section: B Uranium Samplesmentioning

confidence: 99%

“…The NEET cross section was calculated to be σ e = 1 × 10 −32 − 1 × 10 −31 cm 2 , which is equivalent to an excitation rate of 3 × 10 −5 s −1 [18]. The most recent experiment looking for NEET of 235 U was performed by Claverie et al [8]. A 1 J Nd:YAG laser with a pulse width of 5 ns was used to irradiate a sample of 93% enriched uranium with an estimated power density on target of approximately 10 13 W/cm 2 .…”

Section: Introductionmentioning

confidence: 99%

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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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“…14 Elaborate calculations are required in order to set appropriate laser conditions so that the desired plasma is obtained. Morel,et.…”

Section: Neet In a Plasmamentioning

confidence: 99%