Nonaxial hexadecapole deformation effects on the fission barrier

2016 ◽  
Vol 25 (08) ◽  
pp. 1650047 ◽  
Author(s):  
A. Kardan ◽  
S. Nejati
Keyword(s):  
Heavy Nucleus ◽  
Degree Of Freedom ◽  
Fission Barrier ◽  
Deformation Space ◽  
Microscopic Approach ◽  
Barrier Heights ◽  
Deformation Parameters

Fission barrier of the heavy nucleus [Formula: see text]Cf is analyzed in a multi-dimensional deformation space. This space includes two quadrupole ([Formula: see text]) and three hexadecapole deformation ([Formula: see text]) parameters. The analysis is performed within an unpaired macroscopic–microscopic approach. Special attention is given to the effects of the axial and non-axial hexadecapole deformation shapes. It is found that the inclusion of the nonaxial hexadecapole shapes does not change the fission barrier heights, so it should be sufficient to minimize the energy in only one degree of freedom in the hexadecapole space [Formula: see text]. The role of hexadecapole deformation parameters is also discussed on the Lublin–Strasbourg drop (LSD) macroscopic and the Strutinsky shell energies.

ROLE OF HIGHER MULTIPOLARITY DEFORMATIONS IN THE HEIGHT OF FISSION BARRIER OF A DEFORMED HEAVY NUCLEUS

2005 ◽  
Vol 14 (03) ◽  
pp. 409-415 ◽  
Author(s):  
A. SOBICZEWSKI ◽  
I. MUNTIAN
Keyword(s):  
Barrier Height ◽  
Heavy Nucleus ◽  
Fission Barrier ◽  
Axially Symmetric ◽  
Microscopic Approach ◽  
Deformed Nucleus

Role of higher-multipolarity deformations of a nucleus in its (static) fission-barrier height [Formula: see text] is studied. The study is done within a macroscopic-microscopic approach. A heavy deformed nucleus 250 Cf is taken for the analysis. It is found that, in the case of axially symmetric shapes, the inclusion of higher-multipolarity deformations increases [Formula: see text].

ROLE OF HIGHER-MULTIPOLARITY DEFORMATIONS IN THE POTENTIAL ENERGY OF HEAVIEST NUCLEI

2007 ◽  
Vol 16 (02) ◽  
pp. 425-430 ◽  
Author(s):  
M. KOWAL ◽  
A. SOBICZEWSKI
Keyword(s):  
Potential Energy ◽  
General Feature ◽  
Degrees Of Freedom ◽  
Deformation Parameter ◽  
Superheavy Nucleus ◽  
Deformation Space ◽  
Microscopic Approach ◽  
Deformation Parameters ◽  
6 Degrees Of Freedom

Potential energy of the superheavy nucleus 284114 is analyzed in a 6-dimensional deformation space. This space includes two quadrupole, three hexadecapole and one multipolarity-6 deformation parameter. The energy is minimized simultaneously in all 6 degrees of freedom. The analysis is done within a macroscopic-microscopic approach. As in the studies of other superheavy nuclei, the result is found to be very individual for a given nucleus. A more general feature is a small effect of one (γ4) of the hexadecapole deformation parameters on the energy of the nucleus.

ESTIMATION OF THE INACCURACY OF CALCULATED MASSES AND FISSION-BARRIER HEIGHTS OF HEAVY NUCLEI

2011 ◽  
Vol 20 (02) ◽  
pp. 325-332 ◽  
Author(s):  
A. SOBICZEWSKI ◽  
P. ROZMEJ
Keyword(s):  
Heavy Nucleus ◽  
Ground State ◽  
Interaction Strength ◽  
Fission Barrier ◽  
Heavy Nuclei ◽  
Pairing Interaction ◽  
Microscopic Approach ◽  
Barrier Heights ◽  
Pairing Strength ◽  
Microscopic Models

The inaccuracy of calculated masses M and (static) fission-barrier height [Formula: see text] of heaviest nuclei is estimated. The estimation is performed within a macroscopic-microscopic approach for two nuclei: a heavy nucleus 250 Cf and a superheavy one 294118. The source of the inaccuracy is the inaccuracy of calculated deformation of a nucleus and of calculated pairing-interaction strength. It is shown that the inaccuracy of the ground-state mass M, due to the inaccuracy of the calculated deformation is small, up to about 20 keV. The inaccuracy of M, due to the inaccuracy of the pairing strength is much larger, up to 310 keV. The inaccuracy of [Formula: see text], due to the inaccuracy of the deformation is up to about 70 keV, while this due to the inaccuracy of the pairing strength is up to 520 keV. For both studied nuclei, the calculated inaccuracy of [Formula: see text] is smaller than the discrepancy between the values of [Formula: see text] obtained recently within different macroscopic-microscopic models.

ROLE OF HIGHER MULTIPOLARITY DEFORMATIONS IN THE FISSION-BARRIER HEIGHT OF A SPHERICAL SUPERHEAVY NUCLEUS

2005 ◽  
Vol 14 (03) ◽  
pp. 417-420 ◽  
Author(s):  
I. MUNTIAN ◽  
A. SOBICZEWSKI
Keyword(s):  
Barrier Height ◽  
Superheavy Nucleus ◽  
Spherical Nucleus ◽  
Fission Barrier ◽  
Deformation Space ◽  
Microscopic Approach

Role of the dimension of deformation space used in calculations of the (static) fission-barrier height [Formula: see text] is analyzed for a spherical nucleus. The superheavy nucleus 294116 is taken for the analysis. The study is done within a macroscopic-microscopic approach. It is found that the barrier height [Formula: see text] importantly decreases with increasing dimension of the space.

DEFORMATIONS OF MULTIPOLARITY SIX AT THE SADDLE POINT OF HEAVIEST NUCLEI

2008 ◽  
Vol 17 (01) ◽  
pp. 265-271 ◽  
Author(s):  
L. SHVEDOV ◽  
S. G. ROHOZIŃSKI ◽  
M. KOWAL ◽  
S. BELCHIKOV ◽  
A. SOBICZEWSKI
Keyword(s):  
Potential Energy ◽  
Saddle Point ◽  
General Type ◽  
Superheavy Nucleus ◽  
Deformation Space ◽  
Microscopic Approach ◽  
Main Attention ◽  
Point Configuration ◽  
Independent Parameters

Saddle-point configuration of heaviest nuclei is studied in a multidimensional deformation space. Main attention is given to the role of the deformation of multipolarity six of a general type, described by four independent parameters. The dependence of the potential energy of a superheavy nucleus on these parameters at the saddle-point configuration is illustrated. The analysis is performed within a macroscopic-microscopic approach.

EFFECT OF NON-AXIAL DEFORMATIONS ON THE FISSION BARRIER OF HEAVY AND SUPERHEAVY NUCLEI

2009 ◽  
Vol 18 (04) ◽  
pp. 914-918 ◽  
Author(s):  
M. KOWAL ◽  
A. SOBICZEWSKI
Keyword(s):  
Large Deformation ◽  
Neutron Number ◽  
Quadrupole Deformation ◽  
Fission Barrier ◽  
Superheavy Nuclei ◽  
Deformation Space ◽  
Microscopic Approach ◽  
Proton Number ◽  
Heavy And Superheavy Nuclei

The effect of the non-axial quadrupole deformation γ2 on the height of the static fission barrier B f of heaviest nuclei is studied. Even-even nuclei with the proton number 92 ≤ Z ≤ 122 and the neutron number 136 ≤ N ≤ 188 are considered. The analysis is done within a macroscopic-microscopic approach with the use of a large deformation space. It is found that the effect reduces B f by up to about 2 MeV.

EFFECT OF NON-AXIAL DEFORMATIONS OF HIGHER MULTIPOLARITY ON THE FISSION-BARRIER HEIGHT OF HEAVIEST NUCLEI

2010 ◽  
Vol 19 (04) ◽  
pp. 493-499 ◽  
Author(s):  
A. SOBICZEWSKI ◽  
P. JACHIMOWICZ ◽  
M. KOWAL
Keyword(s):  
Barrier Height ◽  
Neutron Number ◽  
Fission Barrier ◽  
Superheavy Nuclei ◽  
Deformation Space ◽  
Microscopic Approach ◽  
Main Attention ◽  
Proton Number ◽  
Heavy And Superheavy Nuclei

The static fission-barrier height [Formula: see text] of heaviest nuclei is studied in a multidimensional deformation space. The main attention is given to the effect of the hexadecapole non-axial shapes on [Formula: see text]. The analysis is performed within a macroscopic-microscopic approach. A 10-dimensional deformation space is used. A large number of about 300 even-even heavy and superheavy nuclei with proton number 98 ≤ Z ≤ 126 and neutron number 134 ≤ N ≤ 192 are considered. It is found that the inclusion of the non-axial hexadecapole shapes lowers the barrier by up to about 1.5 MeV.

ROLE OF THE NON-AXIAL OCTUPOLE DEFORMATION IN THE POTENTIAL ENERGY OF HEAVY NUCLEI

2010 ◽  
Vol 19 (04) ◽  
pp. 768-773 ◽  
Author(s):  
P. JACHIMOWICZ ◽  
M. KOWAL ◽  
P. ROZMEJ ◽  
J. SKALSKI ◽  
A. SOBICZEWSKI
Keyword(s):  
Potential Energy ◽  
Large Deformation ◽  
Neutron Number ◽  
Deformation Space ◽  
Heavy Nuclei ◽  
Microscopic Approach ◽  
Large Space ◽  
Global Energy ◽  
Octupole Deformation

Role of the non-axial octupole deformation a32(Y32 + Y3-2) on the potential energy of heavy nuclei is studied in a large deformation space. The study is performed within a macroscopic-microscopic approach. A large region of nuclei with proton number 88 ≤ Z ≤ 112 and neutron number 128 ≤ N ≤ 156 is considered. It is found that while the a32 deformation alone lowers the energy of the nuclei by up to about 3 MeV (for nuclei around 238 Fm ), it has practically no effect on the global energy minima of considered nuclei, when the analysis is done in a large space.

STRUCTURE OF BARRIER DISTRIBUTIONS: PROBING THE ROLE OF NEUTRON-TRANSFER CHANNELS

2007 ◽  
Vol 16 (02) ◽  
pp. 502-510 ◽  
Author(s):  
E. PIASECKI ◽  
Ł. ŚWIDERSKI ◽  
K. RUSEK ◽  
M. KISIELIŃSKI ◽  
J. JASTRZEBSKI ◽  
...  
Keyword(s):  
Large Deformation ◽  
Excited States ◽  
Previous Experiment ◽  
Neutron Transfer ◽  
Barrier Heights ◽  
Deformation Parameters ◽  
Transfer Channels ◽  
Q Values ◽  
Strong Barrier

In view of its large deformation, which should give rise to strong barrier structures, the 20 Ne projectile has been used to study the influence of neutron-transfer channels on the distribution of barrier heights. A previous experiment with a combination of projectiles 20,22 Ne suggested that the role of α-particle transfer channels is small. By an appropriate choice of targets (90 Zr and 92 Zr ), having very similar intrinsic structures (excited states and deformation parameters) but giving rise to different Q-values for neutron transfers, we highlight the role of these channels.

scholarly journals Theoretical Study on the Photo-Oxidation and Photoreduction of an Azetidine Derivative as a Model of DNA Repair

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2911
Author(s):  
Miriam Navarrete-Miguel ◽  
Antonio Francés-Monerris ◽  
Miguel A. Miranda ◽  
Virginie Lhiaubet-Vallet ◽  
Daniel Roca-Sanjuán
Keyword(s):  
Electron Transfer ◽  
Energy Barrier ◽  
Ring Opening ◽  
Dna Lesions ◽  
Barrier Heights ◽  
Dna Lesion ◽  
Electron Reduction ◽  
The Stability ◽  
Electron Transfer Processes

Photocycloreversion plays a central role in the study of the repair of DNA lesions, reverting them into the original pyrimidine nucleobases. Particularly, among the proposed mechanisms for the repair of DNA (6-4) photoproducts by photolyases, it has been suggested that it takes place through an intermediate characterized by a four-membered heterocyclic oxetane or azetidine ring, whose opening requires the reduction of the fused nucleobases. The specific role of this electron transfer step and its impact on the ring opening energetics remain to be understood. These processes are studied herein by means of quantum-chemical calculations on the two azetidine stereoisomers obtained from photocycloaddition between 6-azauracil and cyclohexene. First, we analyze the efficiency of the electron-transfer processes by computing the redox properties of the azetidine isomers as well as those of a series of aromatic photosensitizers acting as photoreductants and photo-oxidants. We find certain stereodifferentiation favoring oxidation of the cis-isomer, in agreement with previous experimental data. Second, we determine the reaction profiles of the ring-opening mechanism of the cationic, neutral, and anionic systems and assess their feasibility based on their energy barrier heights and the stability of the reactants and products. Results show that oxidation largely decreases the ring-opening energy barrier for both stereoisomers, even though the process is forecast as too slow to be competitive. Conversely, one-electron reduction dramatically facilitates the ring opening of the azetidine heterocycle. Considering the overall quantum-chemistry findings, N,N-dimethylaniline is proposed as an efficient photosensitizer to trigger the photoinduced cycloreversion of the DNA lesion model.

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