scholarly journals Estimating Reaction Cross Sections from Measured (Gamma)-Ray Yields: The 238U(n,2n) and 239Pu(n,2n) Cross Sections

2002 ◽  
Author(s):  
W Younes
1996 ◽  
Vol 74 (9-10) ◽  
pp. 618-625 ◽  
Author(s):  
H. B. Patel ◽  
M. S. Gadkari ◽  
Bhruna Dave ◽  
N. L. Singh ◽  
S. Mukherjee

Excitation functions of the reactions 107Ag[(α, n); (α, 2n); (α, αn); (α, α2n)] and,109Ag[(α, 2n); (α, 3n); (α, 4n); (α, α3n); (α, α4n)] were investigated up to 70 MeV by the stacked foil activation technique and Ge(Li) gamma-ray spectroscopy method. Since the natural silver used as the target has two odd mass stable isotopes of abundance 51.83% (107Ag) and 48.17% (109Ag), their activation in some cases gives the same residual nucleus through different reaction channels, but with very different Q values. In such cases, the individual reaction cross sections are separated with the help of the ratio of theoretical cross sections. The experimental cross sections were compared with the predictions of a pre-equilibrium hybrid model. The (α, xn) reactions are fairly well reproduced with initial exciton number n0 = 4(4p0h), whereas (α, αxn) reactions are underestimated in magnitude by a factor of five to six.


2003 ◽  
Vol 18 (1) ◽  
pp. 22-30 ◽  
Author(s):  
Mila Pandurovic ◽  
Strahinja Lukic ◽  
Paule Baumann ◽  
Stpehane Hilaire ◽  
Jasmina Jeknic ◽  
...  

New concepts in nuclear reactor technology require precise neutron reaction data in the intermediate and high energy range. At present, experimental and evaluated nuclear data, particularly for (n, xn) reactions, are very scarce. Moreover, real discrepancies exist between different databases. The lack of experimental data is essentially due to the difficulty of measuring (n, xn) reactions. No universal method applicable to all isotopes exists. One of the possible methods is the in-beam y-ray spectroscopy and neutron time of flight technique on white neutron beams. In this way one actually directly measures (n, xny) reaction cross-sections. These serve as a starting point in the subsequent derivation of (n, xn) reaction cross-sections using nuclear models. This method was applied with a natural lead sample at me GELLNA white neutron beam facility in Geel, Belgium.


Science ◽  
2021 ◽  
Vol 371 (6526) ◽  
pp. 260-264 ◽  
Author(s):  
Junki Tanaka ◽  
Zaihong Yang ◽  
Stefan Typel ◽  
Satoshi Adachi ◽  
Shiwei Bai ◽  
...  

The surface of neutron-rich heavy nuclei, with a neutron skin created by excess neutrons, provides an important terrestrial model system to study dilute neutron-rich matter. By using quasi-free α cluster–knockout reactions, we obtained direct experimental evidence for the formation of α clusters at the surface of neutron-rich tin isotopes. The observed monotonous decrease of the reaction cross sections with increasing mass number, in excellent agreement with the theoretical prediction, implies a tight interplay between α-cluster formation and the neutron skin. This result, in turn, calls for a revision of the correlation between the neutron-skin thickness and the density dependence of the symmetry energy, which is essential for understanding neutron stars. Our result also provides a natural explanation for the origin of α particles in α decay.


2018 ◽  
Vol 184 ◽  
pp. 02015
Author(s):  
E. Strano ◽  
M. Mazzocco ◽  
A. Boiano ◽  
C. Boiano ◽  
M. La Commara ◽  
...  

We investigated the reaction dynamics induced by the 7Be,8B+208Pb collisions at energies around the Coulomb barrier. Charged particles originated by both the col- lisions were detected by means of 6 ΔE-Eres telescopes of a newly developed detector array. Experimental data were analysed within the framework of the Optical Model and the total reaction cross-sections were compared together and with the 6,7Li+208Pb colli-sion data. According to the preliminary results, 7Be nucleus reactivity is rather similar to the 7Li one whereas the 8B+208Pb total reaction cross section appears to be much larger than those measured for reactions induced by the other weakly-bound projectiles on the same target.


2011 ◽  
Vol 84 (3) ◽  
Author(s):  
J. C. Zamora ◽  
V. Guimarães ◽  
A. Barioni ◽  
A. Lépine-Szily ◽  
R. Lichtenthäler ◽  
...  

2010 ◽  
Vol 73 (10) ◽  
pp. 1700-1706 ◽  
Author(s):  
H. Büyükuslu ◽  
A. Kaplan ◽  
A. Aydin ◽  
E. Tel ◽  
G. Yıldırım

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