CALCULATION OF FISSION FRAGMENT ANGULAR ANISOTROPY IN HEAVY-ION INDUCED FISSION

2008 ◽  
Vol 17 (02) ◽  
pp. 425-433 ◽  
Author(s):  
S. SOHEYLI ◽  
H. NOSHAD ◽  
I. ZIAIAN
Keyword(s):  
Experimental Data ◽  
Statistical Model ◽  
Saddle Point ◽  
Fission Fragment ◽  
Neutron Emission ◽  
Heavy Ion ◽  
Angular Anisotropy ◽  
Induced Fission

Fission fragment angular anisotropies from 16 O + 232 Th , 12 C + 236 U , 11 B + 237 Np , 14 N + 232 Th , 11 B + 235 U and 12 C + 232 Th systems were calculated by means of the standard saddle point statistical model (SSPSM). The results were obtained with and without neutron emission correction in the reactions, and comparisons were made with the corresponding experimental data. The normal and anomalous behaviors of fission fragment anisotropies are extensively discussed.

Effect of the energy spectrum and angular momentum of pre-scission neutrons on the prediction of fission fragment angular anisotropy by the models

2016 ◽  
Vol 25 (04) ◽  
pp. 1650031 ◽  
Author(s):  
Saeed Soheyli ◽  
Marzieh Varasteh Khanlari
Keyword(s):  
Angular Momentum ◽  
Fission Fragment ◽  
Neutron Emission ◽  
Theoretical Calculations ◽  
Heavy Ion ◽  
Energy Spectra ◽  
Angular Anisotropy ◽  
Excitation Energies ◽  
Emission Energy ◽  
Wide Range

Effects of the various neutron emission energy spectra, as well as the influence of the angular momentum of pre-scission neutrons on theoretical predictions of fission fragment angular anisotropies for several heavy-ion induced fission systems are considered. Although theoretical calculations of angular anisotropy are very sensitive to neutron emission correction, the effects of the different values of kinetic energy of emitted neutrons derived from the various neutron emission energy spectra before reaching to the saddle point on the prediction of fission fragment angular distribution by the model are not significant and can be neglected, since these effects on angular anisotropies of fission fragments for a wide range of fissility parameters and excitation energies of compound nuclei are not more than 10%. Furthermore, the theoretical prediction of fission fragment angular anisotropy is not sensitive to the angular momentum of emitted neutrons.

Study of photofission fragment mass distribution of 232Th, 238U, 237Np and 240Pu isotopes in various γ-ray energies

2018 ◽  
Vol 27 (03) ◽  
pp. 1850018 ◽  
Author(s):  
M. R. Pahlavani ◽  
P. Mehdipour
Keyword(s):  
Experimental Data ◽  
Satisfactory Agreement ◽  
Mass Distribution ◽  
Fission Fragment ◽  
Scission Point ◽  
Fragment Mass ◽  
Pu Isotopes ◽  
Induced Fission ◽  
Γ Ray ◽  
Peak To Valley Ratio

Photofission of [Formula: see text]Th, [Formula: see text]U, [Formula: see text]Np and [Formula: see text]Pu isotopes are investigated. Modified version of Gorodisskiy approach that is developed to study the neutron-induced fission are employed to simulate fission fragment mass distribution for these isotopes in different energies. The effect of emitted neutron prior to scission point is studied. Peak to valley ratio is also extracted. Obtained results using this approach are compared with original Gorodisskiy model as well as available experimental data. Satisfactory agreement is achieved between theoretical and experimental data especially in medium and low [Formula: see text]-ray energies than original formalism of Gorodisskiy.

Pre-saddle and pre-scission neutron emission rates in heavy-ion induced fission of 16O +208Pb and 16O +209Bi systems

2019 ◽  
Vol 28 (03) ◽  
pp. 1950013
Author(s):  
Saeed Soheyli ◽  
Morteza Khalil Khalili ◽  
Ghazaaleh Ashrafi
Keyword(s):  
Emission Rate ◽  
Neutron Emission ◽  
Nonlinear Behavior ◽  
Heavy Ion ◽  
Neutron Multiplicity ◽  
Emission Rates ◽  
Reaction Systems ◽  
Initial Excitation ◽  
Induced Fission ◽  
First Time

Whereas there is a slight information on the pre-saddle neutron emission rate and neutron multiplicity, as well as it is impossible to separate the pre-saddle and saddle to scission neutron contributions experimentally, the theoretical studies of pre-saddle neutron emission rate and neutron multiplicity are of great importance. In the present work, the calculations of pre-saddle neutron multiplicity are performed using the analysis of fission fragment angular anisotropy data for [Formula: see text] and [Formula: see text] reaction systems. The obtained results show that the pre-saddle neutron multiplicity decreases by increasing the initial excitation energy and it has found to be characterized by a nonlinear behavior. Through the analysis of pre-saddle neutron multiplicity and pre-saddle transition time by means of the neutron clock method, the pre-saddle neutron emission rate is calculated for the first time. The findings of this study show that the pre-scission neutron emission rate is lower than the pre-saddle neutron emission rate.

MEASUREMENT OF FISSION FRAGMENT ANISOTROPIES FOR PROTON-INDUCED FISSION OF TWO PRE-ACTINIDE NUCLEI AT SEVERAL ENERGIES

2007 ◽  
Vol 22 (05) ◽  
pp. 1027-1037 ◽  
Author(s):  
S. SOHEYLI ◽  
H. NOSHAD ◽  
M. LAMEHI-RACHTI
Keyword(s):  
Angular Distribution ◽  
Statistical Model ◽  
Cross Sections ◽  
Fission Fragment ◽  
Anomalous Behavior ◽  
Surface Barrier ◽  
Mass Asymmetry ◽  
Fission Fragments ◽  
Induced Fission ◽  
Barrier Detectors

The angular distribution of fission fragments has been measured for proton-induced fission of 197 Au and 209 Bi nuclei at several energies between 25 and 30 MeV using surface-barrier detectors. The measured anisotropies are found to be in agreement with the predictions of the standard saddle-point statistical model. The measured anisotropies for neither of the nuclei show any anomalous behavior as a function of both energy and entrance channel mass asymmetry. The fission cross sections of 197 Au and 209 Bi nuclei were also measured and compared with that of the previous works.

Role of entrance channel properties in heavy ion induced fission fragment angular distribution studies

2004 ◽  
Vol 734 ◽  
pp. 249-252 ◽  
Author(s):  
Bivash R. Behera ◽  
S. Kailas ◽  
K. Mahata ◽  
A. Chatterjee ◽  
P. Basu ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Fission Fragment ◽  
Heavy Ion ◽  
Entrance Channel ◽  
Fragment Angular Distribution ◽  
Induced Fission ◽  
Distribution Studies ◽  
Channel Properties

Progress in the investigation of fission fragment angular anisotropy in the resonance neutron induced fission of aligned [sup 235]U target

1998 ◽  
Author(s):  
W. I. Furman ◽  
Yu. N. Kopach ◽  
A. B. Popov ◽  
N. N. Gonin ◽  
L. K. Kozlovsky ◽  
...  
Keyword(s):  
Fission Fragment ◽  
Angular Anisotropy ◽  
Resonance Neutron ◽  
Induced Fission

scholarly journals Study of selected fission reactions with the application of Nilsson orbitals

2011 ◽  
Vol 26 (3) ◽  
pp. 245-248 ◽  
Author(s):  
Aziz Behkami ◽  
Soleiman Rasouli
Keyword(s):  
Statistical Model ◽  
Fission Fragment ◽  
Transition States ◽  
Fission Reactions ◽  
Nilsson Model ◽  
Frame Work ◽  
Induced Fission

Fission fragment angular anisotropies from neutron induced fission of 232Th and 235U were analyzed within the frame work of the statistical model. The analysis were made at neutron energies from threshold up to 50 MeV to deduce the variance K 2 of the K-distribution of levels in the transition nucleus. Our analysis shows, that the strength for the K-transition states comes mainly from the higher angular momentas and is in accordance with Nilsson model orbitals.

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