Production of long-lived hafnium isomers in reactor irradiations

Karamian, S. A.; Carroll, J. J.; Adam, J.; Kulagin, E.; Shabalin, E. P.

doi:10.1016/j.hedp.2006.03.001

Cited by 14 publications

(6 citation statements)

References 20 publications

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“…A surprisingly large thermal cross section of σ b = 235 ± 30 b was deduced for burnup of this high-spin isomer, with a significant part of that value being attributed in the analysis of Ref. [12] to the (n,γ ) reaction branch populating the 179 Hf ground state. In the present work, an estimate is made of the portion of this burnup cross section that is due to inelastic neutron acceleration by the K-hindered, long-lived, four-quasiparticle isomer of 178 Hf.…”

Section: Introductionmentioning

confidence: 92%

“…Equation (1) can then be used to determine the portion of the burnup due to inelastic neutron acceleration, σ INNA , based on the experimental result for σ b [12] and once a value of σ g is known. The latter value can be determined using the measured σ m and an estimated isomer-to-ground-state ratio, σ m /σ g .…”

Section: Isomer-to-ground-state Ratio Via Model Estimatesmentioning

confidence: 99%

“…[12], and the coauthors of that work are gratefully acknowledged for their efforts during those experiments, performed in 2003-2005. The authors acknowledge support by DTRA under contract HDTRA1-08-1-0014.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…A relatively high cross section of σ INNA = 258 ± 58 b was deduced for INNA by the isomer, a value much larger than the theoretical estimate described in that work. Independently and at nearly the same time, a similar method was used at the Joint Institute for Nuclear Research, Dubna, Russia, to study the production, σ p , and burnup, σ b , cross sections for 178 Hf m2 (16 + ) due to reactor neutrons [12]. Metal Hf samples of natural composition were exposed to the neutron flux from the IBR-2 reactor and the induced activities of various daughters were studied.…”

Section: Introductionmentioning

confidence: 99%

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Cross section for inelastic neutron ``acceleration'' by178Hfm2

Karamian

Carroll

2011

Phys. Rev. C

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The scattering of thermal neutrons from isomeric nuclei may include events in which the outgoing neutrons have increased kinetic energy. This process has been called inelastic neutron acceleration, or INNA, and occurs when the final nucleus, after emission of the neutron, is left in a state with lower energy than that of the isomer. The result, therefore, is an induced depletion of the isomer to the ground state. A cascade of several γ 's must accompany the neutron emission to release the high angular momentum of the initial isomeric state. INNA was previously observed in a few cases, and the measured cross sections were only in modest agreement with theoretical estimates. The most recent measurement of an INNA cross section was σ INNA = 258 ± 58 b for neutron scattering by 177 Lu m . In the present work, an INNA cross section of σ INNA = 168 ± 33 b was deduced from measurements of the total burnup of the high-spin, four-quasiparticle isomer 178 Hf m2 during irradiation by thermal neutrons. Statistical estimates for the probability of different reaction channels past neutron absorption were used in the analysis, and the deduced σ INNA was compared to the theoretically predicted cross section.

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Section: Introductionmentioning

confidence: 92%

Section: Isomer-to-ground-state Ratio Via Model Estimatesmentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cross section for inelastic neutron ``acceleration'' by178Hfm2

Karamian

Carroll

2011

Phys. Rev. C

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“…However all three reactions represent the destruction of the isomer. In a 2006 publication, Karamian et al 7 reported, with natural Hf metal samples irradiated in a reactor, 178m2 Hf , could be produced with the following reaction cross sections;…”

Section: Introductionmentioning

confidence: 99%