Chemical Effect on the Half-Life of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">U</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mn>3</mml:mn><mml:mn>5</mml:mn><mml:mi>m</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>

Mévergnies, M. Nève de

doi:10.1103/physrevlett.23.422

Cited by 21 publications

(17 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At the other hand, the same circumstance is the cause of appearance of QZP: it is seen from Eq. (12), that even infinitely fast falling down of the function D e (t) would not cause a freezing of decay, if q(t) had a $-like shape.…”

Section: Quantum Zeno Paradox As the Consequence Of The General Fomentioning

confidence: 97%

Quantum Zeno Effect, Nuclear Conversion and Photoionization in Solids

Панов

1996

Annals of Physics

View full text Add to dashboard Cite

Section: Quantum Zeno Paradox As the Consequence Of The General Fomentioning

confidence: 97%

Quantum Zeno Effect, Nuclear Conversion and Photoionization in Solids

Панов

1996

Annals of Physics

View full text Add to dashboard Cite

“…The isomer's half-life under IC depends on the electronegativity of the surrounding material, an effect that has been studied intensively with U-235m [1,2] and Th-229m [9,27]. Within certain limits, the half-life can thus be tuned by choice of the stopping layer material.…”

mentioning

confidence: 99%

Toward an energy measurement of the internal conversion electron in the deexcitation of the Th229 isomer

et al. 2018

View full text Add to dashboard Cite

The first excited isomeric state of Th-229 has an exceptionally low energy of only a few eV and could form the gateway to high-precision laser spectroscopy of nuclei. The excitation energy of the isomeric state has been inferred from precision gamma spectroscopy, but its uncertainty is still too large to commence laser spectroscopy. Reducing this uncertainty is one of the most pressing challenges in the field.Here we present an approach to infer the energy of the isomer from spectroscopy of the electron which is emitted when the isomer de-excites through internal conversion (IC). The experiment builds on U-233, which decays to Th-229 and populates the isomeric state with a 2% fraction. A film of U-233 is covered by a stopping layer of few-nm thickness and placed between an alpha detector and an electron detector, such that the alpha particle and the IC electron can be detected in coincidence. Retarding field electrodes allow for an energy measurement. In the present design, the signal of the Th-229m IC electrons is masked by low-energy electrons emitted from the surface of the metallic stopping layer. We perform reference measurements with U-232 and U-234 to study systematic effects, and we study various means to reduce the background of low-energy electrons. Our study gives guidelines to the design of an experiment that is capable of detecting the IC electrons and measuring the isomer energy.

show abstract

“…The half-life of the 235m U isomer is ≈ 26 min (Zhudov et al (1979) [21]). In earlier experiments the nuclei of 235m U-isomer were implanted (Mévergnies (1969) [16]) into various metallic foils. The considered cases (Mévergnies (1969) [16]) included the Au, P t, Cu, Ni, V foils.…”

mentioning

confidence: 99%

Internal conversion of nuclear transition in the 235mU–C60−nXn molecules and related compounds

Frolov

2005

Radiation Physics and Chemistry

View full text Add to dashboard Cite

The internal conversion of nuclear transition in the 235 U atom is considered. The low-energy γ−quanta (E γ ≈ 76.8 eV ) are emitted during the E3−transition from the excited state (I = ( 1 2 ) + ) of the 235 U nucleus to its ground state (I = ( 7 2 ) − ). The decay rate of this 235m U isomer (E ≈ 76.8 eV ) noticeably depends upon the chemical composition and actual physical conditions (i.e. temperature T and pressure p). By varying such a composition and physical conditions one can change the life-time of the 235m U isomer to relatively large/small values. A specific attention is given to the fullerene molecules containing the central 235 U atom. It is shown that the decay rate λ of the 235m U isomer in the 235m U @C 60−n X n molecules and related compounds can differ significantly from the values obtained for isolated 235 U atoms. Some applications of this effect are considered.As is well known the rate of nuclear reactions and processes is usually independent of the chemical background and physical conditions. In particular, the transition rate between two arbitrary nuclear states cannot depend upon the chemical environment and temperature (or pressure) of the considered experimental sample. However, in some cases the nuclear transition energies can be relatively small. If such an energy is comparable to the energy of corresponding atomic levels, then the nuclear transition can proceed by conversion of the emitted γ−quanta into electron shells of the considered atom (Akhiezer and Beresteskii (1965) [1]). Obviously, the most interesting case is the conversion of nuclear transition to the outer electron shells of atoms. In these cases one can change, in principle, the observed nuclear conversion rate by varying the chemical environment and/or physical conditions. Such a situation can be found in some heavy atoms, e.g., in the 235 U atom.This effect was already experimentally demonstrated for the 235m U-isomer (Mévergnies (1969), (1972), Zhudov et al (1979) [16], [17], [21]). The 235m U-isomer (E ≈ 76.8 eV ±0.5 eV (Zhudov et al [21])) is extensively produced by α-decay of 239 P u in the core of nuclear warheads and reactors. This isomer is the first excited state (I = ( 1 2 ) + ) of the 235 U nucleus which is only ≈ 76.8 eV above its ground state (I = ( 7 2 ) − ). The corresponding (nuclear) E3−transition to the ground state of the 235 U nucleus (Grechukhin and Soldatov (1976) [6]) usually proceeds as an internal conversion of the nuclear transition to the outer electron shells (i.e. to the 5f 5/2 , 5f 7/2 , 6s 1/2 , 6p 1/2 , 6p 3/2 , 6d 3/2 , 6d 5/2 , 7s 1/2 shells) of the 235 U atom. The half-life of the 235m U isomer is ≈ 26 min (Zhudov et al (1979) [21]). In earlier experiments the nuclei of 235m U-isomer were implanted (Mévergnies (1969) [16]) into various metallic foils. The considered cases (Mévergnies (1969) [16]) included the Au, P t, Cu, Ni, V foils. The decay rate λ of the 235m U isomer was measured in each of these cases. The maximal deviation between the results obtained with different metals was fou...

show abstract

Chemical Effect on the Half-Life ofU235m

Cited by 21 publications

References 4 publications

Quantum Zeno Effect, Nuclear Conversion and Photoionization in Solids

Quantum Zeno Effect, Nuclear Conversion and Photoionization in Solids

Toward an energy measurement of the internal conversion electron in the deexcitation of the Th229 isomer

Internal conversion of nuclear transition in the 235mU–C60−nXn molecules and related compounds

Contact Info

Product

Resources

About