Compound nucleus fluctuation cross section in the intermediate coupling regimeΓ¯/D¯≊1

1986 ◽  
Vol 33 (1) ◽  
pp. 14-16
Author(s):  
M. S. Hussein
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Intermediate Coupling

scholarly journals Testing Compound Nucleus Hypothesis Across the 17O Nucleus Excitation

2019 ◽  
Vol 211 ◽  
pp. 02001 ◽  
Author(s):  
Aloys Nizigama ◽  
Pierre Tamagno ◽  
Olivier Bouland
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Center Of Mass ◽  
Ground States ◽  
Mass System ◽  
Resonance Parameters ◽  
Second Stage ◽  
Reference Framework ◽  
Kinetic Transformation

The excited compound nucleus 17O* has been studied over (n,α) and (α,n) cross sections modelling, respectively for 16O and 13C targets in their ground states. The modelling is fulfilled within the Reich-Moore formalism. We were able to calculate the (α,n) cross section by two separate ways: the direct kinematic standard route and by inversion of the (n,α) cross section using the compound nucleus hypothesis. Resonance parameters of the resolved resonance range (0 to 6 MeV) were borrowed from the CIELO project. In a first stage, the modelling is carried out in the referential of the incident particle (either way neutron or α) requesting conversion of the CIELO neutron-type resonance parameters to the α-type. In a second stage, the implementation is uniquely designed in the center of mass system of the excited compound nucleus. The resonance parameters are thus converted in that unique reference framework. The present investigation shows the consistency of the kinetic transformation that relies on the compound nucleus hypothesis.

MEASURING CAPTURE CROSS SECTIONS FOR HEAVY-ELEMENT PRODUCTION

2004 ◽  
Vol 13 (01) ◽  
pp. 293-300
Author(s):  
NEIL ROWLEY ◽  
NABILA GRAR
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Reaction Path ◽  
Superheavy Element ◽  
Evaporation Residue ◽  
Capture Cross ◽  
Total Capture ◽  
Capture Cross Sections

The creation of the nucleus of a superheavy element follows an extremely complex reaction path starting with the crossing of an external potential barrier (or distribution of barriers). This is followed by the evolution towards an equilibrated compound nucleus, which takes place in competition with pre-compound-nucleus fission (quasi-fission). Once formed the equilibrated compound nucleus must still survive against true fusion to yield a relatively long-lived evaporation residue. Much of this path is poorly understood, though recently, progress has been made on the role of the entrance-channel in quasi-fission. This will be briefly reported and a method proposed to measure the total capture cross section for such systems directly.

COMPOUND NUCLEUS FORMATION IN NITROGEN–OXYGEN AND OXYGEN–OXYGEN REACTIONS

1962 ◽  
Vol 40 (1) ◽  
pp. 139-149
Author(s):  
W. A. Cartledge
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Center Of Mass ◽  
Branching Ratio ◽  
Nuclear Interaction ◽  
Experimental Cross Section ◽  
Interaction Radius ◽  
Nucleus Formation ◽  
Experimental Cross ◽  
Compound Nucleus Formation

The experimental cross section for the reaction O16(N14,2p)Al28 is compared with the predictions of the square-well model of compound nucleus formation over the range 6.3 to 12 Mev (center of mass energy). The branching ratio is estimated from the experimental cross section for the comparison reaction Si29(p,2p)Al28 over the same range of excitation in the compound nucleus P30*. It is found that the branching ratio probably increases from about 10% to 20%, which requires the nuclear interaction radius for N14 + O16 to decrease from about 8.5 to 7.5 fermis as the energy is increased over this range.Because of the similarity in mass and observed charge distributions in N14 and O16, the interaction radius for compound nucleus formation in a collision between two oxygen nuclei is probably also similar and in the range 8.0 to 9.1 fermis at energies far below the Coulomb barrier. A consequence of this result is that oxygen ions, which may be present in the cores of sufficiently developed red giant stars, will be destroyed by O16 + O16 collisions in about 105 years and 1 year respectively, at temperatures in the vicinity of 13.0 and 18.5 × 108 °K.

COLD FUSION REACTIONS USING NEUTRON-RICH PROJECTILES

2013 ◽  
Vol 22 (08) ◽  
pp. 1350061 ◽  
Author(s):  
A. SULAKSONO
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Estimation Method ◽  
Cold Fusion ◽  
Evaporation Residue ◽  
Fusion Reactions ◽  
Fusion Barrier ◽  
The Cross ◽  
Evaporation Residues

This paper studies the formation cross-sections of super heavy (SH) nuclei in some cold fusion reactions of radioactive neutron-rich projectiles with double-magic 208 Pb target. In this study, the cross-sections of capture, fusion and evaporation residues in one- and two-neutron (1n and 2n) channels are calculated by using neutron-rich Fe , Ni and Zn projectiles are compared to the cross-sections calculated using stable Fe , Ni and Zn projectiles. The heights of fusion barrier and their positions in all reactions considered in this study are also compared to the heights and positions calculated using the estimation method proposed by Dutt and Puri. For cold fusion reactions with stable Fe , Ni and Zn projectiles, the heights of fusion barrier and the cross-sections of evaporation residues in 1n and 2n channels are compared to their corresponding experimental data. In general, for reactions using projectiles with the same proton number, the neutron-rich projectile is found to yield relatively-heavier mass of SH nucleus and larger evaporation residue cross-section, compared to those of the corresponding stable projectiles. However, in certain reactions, the cross-sections of neutron-rich projectile can be slightly larger or slightly smaller than that of the corresponding stable projectile. This behavior is highly affected by the charge of projectile and the fission barrier of the formed compound nucleus (CN). In addition, the 292114 is found to be the heaviest compound nucleus formed in cold fusion reaction by using neutron-rich nuclei as the projectile, but the cross-section of evaporation residue in one-neutron channel is still around few pico barns (pb).

CALCULATIONS OF CROSS SECTIONS FOR THE SYNTHESIS OF SUPER-HEAVY NUCLEI IN COLD FUSION REACTIONS

2004 ◽  
Vol 13 (01) ◽  
pp. 261-267 ◽  
Author(s):  
W. J. ŚWIATECKI ◽  
K. SIWEK-WILCZYŃSKA ◽  
J. WILCZYŃSKI
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Free Parameter ◽  
Cold Fusion ◽  
One Dimension ◽  
Brownian Diffusion ◽  
Heavy Nuclei ◽  
Fusion Reactions ◽  
Super Heavy Nuclei

The fusion cross sections are considered to be given by the product of three factors: the cross section to overcome the Coulomb barrier, the probability for the resulting system to reach the compound nucleus configuration by diffusion, and the probability for the compound nucleus to survive fission. The first and third factors are treated by more or less conventional equations, and the second by Brownian diffusion in one dimension. Adjusting one free parameter in the theory one can reproduce the twelve measured cross sections to within a factor of two.

scholarly journals Statistical model calculations of the 7Li +11 Β reaction

2019 ◽  
Vol 10 ◽  
pp. 165
Author(s):  
C. Tsabaris ◽  
C. T. Papadopoulos ◽  
R. Vlastou ◽  
A. A. Pakou ◽  
P. A. Assimakopoulos ◽  
...  
Keyword(s):  
Experimental Data ◽  
Statistical Model ◽  
Energy Range ◽  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Coulomb Barrier ◽  
Reaction Channel ◽  
Model Calculations ◽  
The Individual

The 7Li + 11 Β reaction has been studied in the energy range from a little below to about three times the Coulomb barrier by measuring the cross section of the 7- ray transitions in the residual nuclei produced. Statistical compound nucleus calculations have been performed in order to interpret the experimental data as well as to extract cross sections of the individual exit channels. The statistical compound nucleus theory can reproduce rather well the absolute j - ray and the various reaction channel excitation functions.

scholarly journals FISSION CROSS SECTION IN THE SYNTHESIS OF THE 264Rf NUCLEUS VIA 26Mg+238U COMBINATION

2018 ◽  
Vol 127 (1A) ◽  
pp. 95
Author(s):  
Trần Viết Nhân Hào
Keyword(s):  
Mass Distribution ◽  
Cross Section ◽  
Compound Nucleus ◽  
Transfer Reaction ◽  
Fission Cross Section ◽  
Transfer Reactions ◽  
Heavy Nuclei ◽  
Fission Process ◽  
Rich Side

Our understanding of the fission mechanism has been still limited up to date, especially, for mass distribution of heavy nuclei or actinide ones. Since the heavy isotopes on the neutron-rich side of the nuclear chart cannot be accessed via capture reactions, it is thought that the mechanism can be studied via compound nuclei produced by multi-nucleon transfer reactions. In which, the fission process should be understood. In this report we mention the role of the transfer reaction <sup>26</sup>Mg + <sup>238</sup>U and an estimation of the cross section of the fission leds by the compound nucleus, <sup>264</sup>Rf.

scholarly journals Incorporating a two-step mechanism into calculations of (p,t) reactions used to populate compound nucleus spin-parity distributions in support of surrogate measurements

2020 ◽  
Vol 239 ◽  
pp. 03009
Author(s):  
James Benstead
Keyword(s):  
Reaction Mechanism ◽  
Cross Section ◽  
Compound Nucleus ◽  
Reaction Model ◽  
Neutron Transfer ◽  
Reaction Method ◽  
Spin Parity ◽  
Direct Reactions ◽  
Pass Through ◽  
Step Mechanism

The surrogate reaction method may be used to determine the cross section for neutron-induced reactions not accessible through standard experimental techniques by creating the same compound nucleus which the desired reaction would pass through, but via a different entrance channel. A variety of direct reactions have been employed in order to generate the required compound nuclei for surrogate studies. In this work, a previously developed (p,t) reaction model has been extended to incorporate a two-step reaction mechanism, which takes the form of sequential neutron transfer. This updated model is applied to the 92Zr(p,t)90Zr reaction and is found to modify the strengths of the previously predicted populated levels. It is planned that this improved (p,t) model will be used to attempt to constrain cross section predictions for a number of (n,γ) reactions in future, as well as provide a possible comparison against other surrogate studies utilising different direct reactions such as (p,d).

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