Isomer /sup 235/U(73 eV; 1/2/sup +/): its excitation in electron interactions
We consider a number of possible mechanisms for populating the isomeric level (73 +- 5 eV; 1/2/sup +/) of /sup 235/U by an E3 transition from the 7/2/sup -/ ground state induced by the Coulomb interaction of an electron with the nucleus. The effectiveness of populating the /sup 235/U isomeric level is estimated in the hypothetical resonance of the nuclear 7/2/sup -/..-->..1/2/sup +/ (h..omega..=73 eV) E/sub 3/ transition with a 5f..-->..6s electron transition in the shell of a uranium atom or ion. Radiation damping of the amplitudes of the electron shell states is taken into account. The inelastic cross section for ee' scattering of electrons by the /sup 235/U nucleus with excitation of the isomeric E3 transition is found by numerical computation. The calculations are made for the range of electron kinetic energies less than 10/sup 3/ eV characteristic of a plasma with temperature T<100 eV. Cross sections are obtained for anticonversion in a shell of the uranium atom or ion resulting in population of the isomeric level of the /sup 235/U nucleus. The calculations are made for systems (U)/sup Q/+1+e with total charge Q=0, 3, and 6. The yield is estimated for the /sup 235/U isomer immersed in a dense plasma with T<100 eV. It is shown that for T< or =20 eV the anticonversion process for populating the isomeric level dominates in ionic systems with charge Q=3--6. The contribution from the neutral component (Q=0) is negligibly small. In the range T>20 eV the contribution from ee' scattering is greater than that from anticonversion for systems with 0< or =6. An estimate is obtained for the relaxation time tau for isomer population in a plasma; for attainable electron densities (approx.10/sup 18/ cm/sup -3/) and Tapprox. =5--100 eV we find tauapprox.10/sup 9/--10/sup 10/ sec. Cross sections and probabilities are computed with wave functions obtained by numerical integration of the Dirac equation for the atom or ion field found in the Hartree-Fock-Slater method.
- Research Organization:
- I. V. Kurchatov Institute of Atomic Energy
- OSTI ID:
- 6023436
- Journal Information:
- Sov. J. Nucl. Phys. (Engl. Transl.); (United States), Vol. 28:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ELECTRON REACTIONS
INELASTIC SCATTERING
URANIUM 235
ISOMERIC NUCLEI
URANIUM 235 TARGET
ELECTRONIC STRUCTURE
EV RANGE 10-100
PLASMA
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
ENERGY RANGE
EV RANGE
EVEN-ODD NUCLEI
HEAVY NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LEPTON REACTIONS
MINUTES LIVING RADIOISOTOPES
NUCLEAR REACTIONS
NUCLEI
RADIOISOTOPES
SCATTERING
TARGETS
URANIUM ISOTOPES
YEARS LIVING RADIOISOTOPES
652013* - Nuclear Properties & Reactions
A=220 & above
Theoretical- Energy Levels & Transitions- (-1987)
652015 - Nuclear Properties & Reactions
A=220 & above
Theoretical- Nuclear Reactions & Scattering- (-1987)