Excitation energy dependence of charge odd-even effects in the fission of 238U close to the fission barrier

Pommé, S.; Jacobs, E.; Persyn, K.; Frenne, D. De; Govaert, K.; Yoneama, M.L.

doi:10.1016/0375-9474(93)90041-u

Cited by 50 publications

(48 citation statements)

References 21 publications

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“…As there exists a clear decrease of the even-odd effect with increasing excitation energy at saddle [23,24] and a prediction for an increasing energy release between saddle and scission with the Coulomb parameter [5,10], it is conventionally assumed that the decrease in even-odd effect with the fissility or with the Coulomb parameter is due to the increase in dissipated energy from saddle to scission. However, figures 1 and 3 show that the global even-odd effect is correlated also with other parameters which are not directly connected to the energy dissipated between saddle and scission; the fissility x and the average asymmetry < a > of the fragment distribution.…”

Section: Global Even-odd Staggering and Dissipated Energymentioning

confidence: 99%

Evidence for the predominant influence of the asymmetry degree of freedom on the even–odd structure in fission-fragment yields

Caamaño

Rejmund

Schmidt

2011

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

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Abstract. Based on a comprehensive set of fission-fragment distributions measured in low-energy fission, the even-odd staggering in the fission-fragment element yields is investigated. The well-established evolution of the global even-odd effect with the fissioning system is found to be only a partial aspect of the even-odd structure. Indeed, it is shown that the global even-odd effect varies systematically with the mean asymmetry of the fission-fragment distribution, and that the general increase of the even-odd staggering with asymmetry depends on the fissioning system. Thus, the dependency of the even-odd effect with the fissioning system is accredited in part to the asymmetry evolution of the charge distribution, and not solely to the dissipated energy as it has been done earlier. This interpretation is strongly supported by data measured in inverse kinematics, which cover the complete fission-fragment charge distribution and include precise yields at symmetry. The relevance of the ordering parameter for the description the even-odd effect in fission-fragment yields as a general property is explored.PACS numbers: 24.75.+i, 25.85.Ec, 25.85.Jg

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Section: Global Even-odd Staggering and Dissipated Energymentioning

confidence: 99%

Evidence for the predominant influence of the asymmetry degree of freedom on the even–odd structure in fission-fragment yields

Caamaño

Rejmund

Schmidt

2011

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

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“…(16). Such an approach assumes that the series expansions of the overlap and Hamiltonian kernels converge rapidly.…”

Section: B Reduction Of the Symmetric Moment Expansion To A Schrödinmentioning

confidence: 99%

“…However, there are some experimental indications that pairs are broken during the fission process. For instance, manifestations of proton pair breaking are observed in 238 U and 239 U nuclei for an excitation energy of 2.3 MeV above the barrier: first the proton odd-even effect observed in the fragment mass distributions decreases exponentially for an excitation energy slightly higher than 2.3 MeV [16] and then the total kinetic energy drops suddenly [17,18]. Some theoretical calculations have studied the dissipation during the fission process, most of them are based on a semi-classical formalism such as Focker-Plank equations [19][20][21], or Hamiltonian equations with one body dissipation and two-body viscosity [22,23], or Langevin equations [24,25].…”

Section: Introductionmentioning

confidence: 99%

Microscopic and nonadiabatic Schrödinger equation derived from the generator coordinate method based on zero- and two-quasiparticle states

et al. 2011

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A new approach called the Schrödinger Collective Intrinsic Model (SCIM) has been developed to achieve a microscopic description of the coupling between collective and intrinsic excitations. The derivation of the SCIM proceeds in two steps. The first step is based on a generalization of the symmetric moment expansion of the equations derived in the framework of the Generator Coordinate Method (GCM), when both Hartree-Fock + BCS (HF+BCS) states and two-quasiparticle excitations are taken into account as basis states. The second step consists in reducing the generalized Hill and Wheeler equation to a simpler form to extract a Schrödinger-like equation. The validity of the approach is discussed by means of results obtained for the overlap kernel between HF+BCS states and two-quasi-particle excitations at different deformations.

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“…The bremsstrahlung photons for inducing photofission have been attributed to a minimum threshold, such as approximately 5 -6 MeV [15] [16]. Ultra-intense lasers on the order of approximately 10 20 W/cm 2 have produced bremsstrahlung photons through the generation of laser initiated plasma.…”

Section: Background Of Photofissionmentioning

confidence: 99%

Fundamental Architecture and Performance Analysis of Photofission Pulsed Space Propulsion System Using Ultra-Intense Laser

LeMoyne¹,

Mastroianni²

2015

JAMP

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Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bremsstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission; however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.

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Excitation energy dependence of charge odd-even effects in the fission of 238U close to the fission barrier

Cited by 50 publications

References 21 publications

Evidence for the predominant influence of the asymmetry degree of freedom on the even–odd structure in fission-fragment yields

Evidence for the predominant influence of the asymmetry degree of freedom on the even–odd structure in fission-fragment yields

Microscopic and nonadiabatic Schrödinger equation derived from the generator coordinate method based on zero- and two-quasiparticle states

Fundamental Architecture and Performance Analysis of Photofission Pulsed Space Propulsion System Using Ultra-Intense Laser

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