Fusion-fission in the reactions of the 58Ni + 251Cf and 64Zn + 248Cm combinations

Introduction: In the present study, we evaluate the nucleon evaporation, alpha decay, and fission widths in the fusion-fission of the 58Ni+251Cf and 64Zn + 248Cm reactions for the synthesis of the super-heavy 309, 312126 nuclei. Methods: The feasibility of the synthesis of the 309, 312126 isotopes via the mentioned systems is investigated based on the widths. The widths in the excitation energy range of E* = 10 – 100 MeV are calculated in the scope of the statistical model, in which the level density is calculated by using the Fermi-gas model. By employing the LISE++ code, the level densities the compound nuclei, 309, 312126 nuclei, are calculated to be about 105 – 1050 (MeV-1) in the energy range of interest. Results: The lifetime of the compound nuclei, 309, 312126 nuclei, which are estimated based on the total width, is about 10-22-10-20 s. The fission has the largest width compared to those of the alpha decay and nucleon evaporations. Hence, the 58Ni+251Cf and 64Zn + 248Cm combinations are appropriate to the study of the mass distribution. In addition, the large alpha decay widths suggest the 309, 312126 isotopes be the alpha-decay nuclei. Conclusion: The results are expected to be useful for considering measurements at facilities in the near future.

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Level studies of 73As via 73Ge(p, nγ)73As reaction and density of discrete levels in 73As

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp0902082b ◽

2009 ◽

Vol 24 (2) ◽

pp. 82-85 ◽

Cited By ~ 2

Author(s):

Aziz Behkami ◽

Rohallah Razavi ◽

Tayeb Kakavand

Keyword(s):

Proton Beam ◽

Excited States ◽

Level Scheme ◽

Level Density ◽

Fermi Gas ◽

Temperature Model ◽

Nuclear Level Density ◽

Nuclear Level ◽

Level Densities ◽

Experimental Level

The excited states of 73As have been investigated via the 73Ge(p, n?)73As reaction with the proton beam energies from 2.5-4.3 MeV. The parameters of the nuclear level density formula have been determined from the extensive and complete level scheme for 73As. The Bethe formula for the back-shifted Fermi gas model and the constant temperature model are compared with the experimental level densities.

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Energy sharing based on microscopic level densities

EPJ Web of Conferences ◽

10.1051/epjconf/202125600013 ◽

2021 ◽

Vol 256 ◽

pp. 00013

Author(s):

Jørgen Randrup ◽

Martin Albertsson ◽

Gillis Carlsson ◽

Thomas Døssing ◽

Peter Möller ◽

...

Keyword(s):

Excitation Energy ◽

Level Density ◽

Coulomb Repulsion ◽

Microscopic Level ◽

Level Densities ◽

Initial Excitation ◽

Specific Fragment ◽

Quadratic Surfaces ◽

Neutron Evaporation ◽

Energy Sharing

The transformation of a moderately excited heavy nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape. The resulting Brownian motion in the multi-dimensional deformation space is guided by the shape-dependent level density which has been calculated microscopically for each of nearly ten million shapes (given in the three-quadratic-surfaces parametrization) by using a previously developed combinatorial method that employs the same single-particle levels as those used for the calculation of the pairing and shell contributions to the five-dimensional macroscopic-microscopic potential-energy surface. The stochastic shape evolution is followed until a small critical neck radius is reached, at which point the mass, charge, and shape of the two proto-fragments are extracted. The available excitation energy is divided statistically on the basis of the microscopic level densities associated with the two distorted fragments. Specific fragment structure features may cause the distribution of the energy disvision to deviate significantly from expectations based on a Fermi-gas level density. After their formation at scission, the initially distorted fragments are being accelerated by their mutual Coulomb repulsion as their shapes relax to their equilibrium forms. The associated distortion energy is converted to additional excitation energy in the fully accelerated fragments. These subsequently undergo sequential neutron evaporation which is calculated using again the appropriate microscopic level densities. The resulting dependence of the mean neutron multiplicity on the fragment mass, as well as the dependence of on the initial excitation energy of the fissioning compound nucleus, exhibit features that are similar to the experimentally observed behavior, suggesting that the microscopic energy sharing mechanism plays an important role in low-energy fission.

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Level studies of 93Mo via 93Nb(p, nγ)93Mo reaction and density of discrete levels in 93Mo

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp1101069r ◽

2011 ◽

Vol 26 (1) ◽

pp. 69-73 ◽

Cited By ~ 2

Author(s):

Rohallah Razavi ◽

Tayeb Kakavand

Keyword(s):

Proton Beam ◽

Excited States ◽

Level Scheme ◽

Level Density ◽

Fermi Gas ◽

Temperature Model ◽

Nuclear Level Density ◽

Nuclear Level ◽

Level Densities ◽

Experimental Level

The excited states of 93Mo have been investigated via the 93Nb(P,n?)93Mo reaction with proton beam energies of 2.5-4.3 MeV. The parameters of the nuclear level density formula were determined from the extensive and complete level scheme of 93Mo. The Bethe formula for the back-shifted Fermi gas model and the constant temperature model are compared with experimental level densities.

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A COMPOSITE NUCLEAR-LEVEL DENSITY FORMULA WITH SHELL CORRECTIONS

Canadian Journal of Physics ◽

10.1139/p65-139 ◽

1965 ◽

Vol 43 (8) ◽

pp. 1446-1496 ◽

Cited By ~ 1869

Author(s):

A. Gilbert ◽

A. G. W. Cameron

Keyword(s):

Lower Energy ◽

Level Density ◽

Energy Levels ◽

Fermi Gas ◽

Experimental Information ◽

Shell Correction ◽

Nuclear Level Density ◽

Excitation Energies ◽

Nuclear Level ◽

Level Densities

At low excitation energies a "constant nuclear temperature" representation of nuclear-level densities is used, and at high excitation energies the regular Fermi gas formula is adopted. A method is developed for determining the parameters of the Fermi gas formula by using both the pairing and the shell-correction energies found by Cameron and Elkin for their semiempirical atomic mass formula in its exponential form. This procedure determines level densities at neutron-binding-energy excitations subject to an average factor error of 1.8. Methods are also developed for determining the parameters for the lower-energy formula in such a way that it best fits the lower-energy levels and joins smoothly to the Fermi gas formula. Correlations of the resulting parameters with shell and pairing effects are found. A composite prescription is given for calculating level densities in nuclei for which no experimental information is known. Tables give level density parameters for a wide variety of nuclei for which some experimental information is known. Some of the derivations of the Fermi gas formula in the literature were found to be slightly incorrect, so new derivations are presented in Appendixes.

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Theoretical Prediction of the Preferred Production Routes of 225Ac from Proton Induced Reactions on 232Th

Journal of Scientific Research and Reports ◽

10.9734/jsrr/2020/v26i530262 ◽

2020 ◽

pp. 84-89

Author(s):

Emmanuel C. Hemba ◽

Olumide O. Ige ◽

Haruna Ali ◽

Sunday A. Jonah

Keyword(s):

Experimental Data ◽

Energy Range ◽

Level Density ◽

Nuclear Level Density ◽

Nuclear Level ◽

Level Densities ◽

Production Route ◽

Alpha Emitter ◽

Proton Induced Reactions ◽

High Linear Energy Transfer

Alpha emitting radionuclides have potential for the therapy of cancers because of their high linear energy transfer, and short range biologic effectiveness. Alpha emitter 225Ac(T1/2 = 10.0 days) is a potent nuclide for targeted radionuclide therapy. 225Ac excitation functions via 232Th (p,7np)225Th→225Ac, 232Th (p,6n2p)225Ac, 232Th (p,4nα)225Ac, 232Th (p,5n3p)225Th→ 225Ac, and 232Th (p,3nαp)225Ra→225Ac reactions were calculated by Empire 3.2 code up to 200MeV and compared with existing data. No single nuclear level density with a pre-equilibrium model produce results which agree with the existing experimental data all through the energy range. However, a hybrid of the different nuclear level densities with the Hybrid Monte Carlo Simulation (HMS) and the exciton PCROSS pre-equilibrium models at different energy range provide results which are in good agreement with the existing experimental data. Hence the preferred production route for the direct and indirect production of 225Ac has also been suggested.

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Charmed and bottomed hadronic cross sections from a statistical model

The European Physical Journal A ◽

10.1140/epja/s10050-020-00251-4 ◽

2020 ◽

Vol 56 (9) ◽

Author(s):

Gábor Balassa ◽

György Wolf

Keyword(s):

Statistical Model ◽

Energy Range ◽

Cross Sections ◽

Heavy Quarks ◽

Open Charm ◽

Low Energy ◽

Final State ◽

Proton Antiproton ◽

Proton Proton

Abstract In this work, we extended our statistical model with charmed and bottomed hadrons, and fit the quark creational probabilities for the heavy quarks, using low energy inclusive charmonium and bottomonium data. With the finalized fit for all the relevant types of quarks (up, down, strange, charm, bottom) at the energy range from a few GeV up to a few tens of GeV’s, the model is now considered complete. Some examples are also given for proton–proton, pion–proton, and proton–antiproton collisions with charmonium, bottomonium, and open charm hadrons in the final state.

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