Analysis of the excitation function of alpha-particle-induced reactions on natural silver

1996 ◽  
Vol 74 (9-10) ◽  
pp. 618-625 ◽  
Author(s):  
H. B. Patel ◽  
M. S. Gadkari ◽  
Bhruna Dave ◽  
N. L. Singh ◽  
S. Mukherjee
Keyword(s):  
Cross Sections ◽  
Gamma Ray ◽  
Residual Nucleus ◽  
Reaction Cross ◽  
Activation Technique ◽  
Individual Reaction ◽  
Reaction Channels ◽  
Stacked Foil Activation Technique ◽  
The Individual ◽  
Reaction Cross Sections

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.

Nonequilibrium effects in α-particle induced reactions on gallium isotopes

1989 ◽  
Vol 67 (9) ◽  
pp. 870-875 ◽  
Author(s):  
I. A. Rizvi ◽  
M. K. Bhardwaj ◽  
M. Afzal Ansari ◽  
A. K. Chaubey
Keyword(s):  
Cross Sections ◽  
Residual Nucleus ◽  
Reaction Cross ◽  
Activation Technique ◽  
Individual Reaction ◽  
Reaction Channels ◽  
Stacked Foil Activation Technique ◽  
The Individual ◽  
Reaction Cross Sections

The stacked foil activation technique and Ge(Li) γ-ray spectroscopy have been employed for the determination of the excitation functions, up to 60 MeV, of six reactions, 69Ga(α,n), (α,2n), (α,3n), (α,p3n); 71Ga(α,n) and (α,4n). Since natural gallium used as the target has two odd-mass stable isotopes of abundance, 69Ga(60.1%) and 71Ga(39.9%), 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 their theoretical cross sections. A preliminary theoretical comparison with the preequilibrium geometry-dependent hybrid (GDH) model has been done using an initial exciton number no = 4 (2n + 2p + 0h), and general agreement was found for all reactions at high energies.

Measurement and analysis of excitation functions for alpha-particle-induced reactions in rhenium

2004 ◽  
Vol 82 (3) ◽  
pp. 227-237
Author(s):  
N L Singh ◽  
M S Gadkari
Keyword(s):  
Cross Sections ◽  
Residual Nucleus ◽  
Reaction Cross ◽  
Activation Technique ◽  
Excitation Functions ◽  
Theoretical Predictions ◽  
Reaction Channels ◽  
Stacked Foil Activation Technique ◽  
The Individual ◽  
First Time

Excitation functions of the reactions 185Re[(α,n); (α,2n); (α,3n)] and 187Re[(α,n); (α,2n); (α,3n); (α,4n)] were investigated up to 50 MeV using the stacked-foil activation technique and high-purity germanium γ-ray spectroscopy method. Since the natural rhenium used as a target has two odd-mass stable isotopes of abundance 37.4% (185Re) and 62.6% (187Re), 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 theoretical predictions considering equilibrium as well as pre-equilibrium contributions using code ALICE/90. It was found that the initial exciton configuration n0 = 4 (4p0h) appears to give a good fit to the experimental data. To the best of our knowledge, the excitation functions for 185Re[(α,n); (α,2n); (α,3n)] and 187Re[(α,3n); (α,4n)] reactions were measured for the first time. PACS No.: 25.55.–e

scholarly journals Measurement of the 241Am(n,2n)240Am cross section at 17.5 MeV

2019 ◽  
Vol 21 ◽  
pp. 160
Author(s):  
A. Kalamara ◽  
R. Vlastou ◽  
M. Diakaki ◽  
M. Kokkoris ◽  
M. Anastasiou ◽  
...  
Keyword(s):  
Cross Section ◽  
Neutron Beam ◽  
Cross Sections ◽  
Reaction Cross ◽  
Activation Technique ◽  
Tandem Accelerator ◽  
Hpge Detectors ◽  
Reaction Cross Sections ◽  
Reference Reaction ◽  
High Radioactivity

The 241Am(n,2n)240Am reaction cross section has been measured at neutron beam energy 17.5 MeV, relative to the 27Al(n,α)24Na, 197Au(n,2n)196Au and 93Nb(n,2n)92mNb reference reaction cross sections, using the activation technique. The irradiation was carried out at the Van der Graaff 5.5 MV Tandem accelerator laboratory of NCSR “Demokritos” with monoenergetic neutron beam provided by means of the 3H(d,n)4He reaction, implementing a new Ti-tritiated target. The high purity Am target has been constructed at IRMM, Geel, Belgium and consisted of 40 mg 241Am in the form of AmO2 pressed into pellet with Al2O3 and encapsulated into Al container. Due to this high radioactivity (5 GBq), the Am target was enclosed in a Pb container for safety reasons. After the end of the irradiation, the activity induced by the neutron beam at the target and reference foils, was measured off-line by two 100%, a 50% and a 16% relative efficiency, HPGe detectors.

scholarly journals Critical review of CIELO evaluations of n+ 235U, 238U using differential experiments

2018 ◽  
Vol 4 ◽  
pp. 27 ◽  
Author(s):  
Roberto Capote ◽  
Andrej Trkov
Keyword(s):  
Cross Sections ◽  
Critical Review ◽  
Nuclear Data ◽  
Reaction Cross ◽  
Reaction Models ◽  
Reaction Channels ◽  
Data Files ◽  
Integral Data ◽  
Evaluated Nuclear Data ◽  
Reaction Cross Sections

Key reactions have been selected to compare JEFF-3.3 (CIELO 2) and IAEA CIELO (CIELO 1) evaluated nuclear data files for neutron induced reactions on 235U and 238U targets. IAEA CIELO evaluation uses reaction models to construct the evaluation prior, but strongly relied on differential data including all reaction cross sections fitted within the IAEA Neutron Standards project. The JEFF-3.3 evaluation relied on a mix of differential and integral data with strong contribution from nuclear reaction modelling. Differences in evaluations are discussed; a better reproduction of differential data for the IAEA CIELO evaluation is shown for key reaction channels.

Nonequilibrium effects in α-particle-induced reactions in Cs and I

2000 ◽  
Vol 78 (2) ◽  
pp. 133-139 ◽  
Author(s):  
M K Bhardwaj ◽  
I A Rizvi ◽  
A K Chaubey
Keyword(s):  
Cross Sections ◽  
Gamma Ray ◽  
Theoretical Calculations ◽  
High Energy ◽  
Particle Energy ◽  
Substantial Contribution ◽  
Equilibrium Geometry ◽  
Activation Technique ◽  
Excitation Functions ◽  
Stacked Foil Activation Technique

The excitation functions for the reactions 127I(α,n)130Cs, 127I(α,2n)129Cs, 127I(α,4n)127Cs, 133Cs(α,2n)135La, and 133Cs(α,4n)133La have been measured up to 50 MeV alpha-particle energy using the stacked-foil activation technique and Ge(Li) gamma-ray spectroscopy. The measured cross sections were compared with theoretical calculations considering equilibrium as well as the pre-equilibrium geometry-dependent hybrid models of Blann. The high-energy tails of the excitation functions show a substantial contribution from pre-equilibrium emission. A general agreement is observed between the experimental results and theoretical predictions with an initial exciton configuration n0 = 4(2n + 2p + 0h).PACS No. 25.40-h

scholarly journals Statistical-model calculations for α-capture reactions relevant to the p process

2019 ◽  
Vol 26 ◽  
pp. 228
Author(s):  
C. Fakiola ◽  
I. Karakasis ◽  
I. Sideris ◽  
A. Khaliel ◽  
T. J. Mertzimekis
Keyword(s):  
Experimental Data ◽  
Statistical Model ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Reaction Network ◽  
Reaction Cross ◽  
Model Parameters ◽  
Model Calculations ◽  
Reaction Channels ◽  
Reaction Cross Sections

About 35 nuclides which lie on the neutron deficient side of the isotopic chart cannot be created by the two basic nucleosynthetic processes, the sand the rprocess. Due to scarce experimental data and the vast complexity of the reaction network involved, cross sections and reactions are estimated theoretically, using the Hauser–Feshbach statistical model. In the present work, theoretical calculations of cross sections of radiative α-capture reactions on the neutron–deficient Erbium and Xenon isotopes are presented in an attempt to make predictions inside the astrophysically relevant energy window (Gamow). The particular reactions are predicted to be sensitive branchings in the γprocess path.The most recent versions of TALYS (v1.9) and Fresco codes were employed for all calculations, initially focusing on investigating the influence of the default eight (8) α–nucleus optical potential models of TALYS on reaction cross sections. The theoretical results of both codes are compared and for the reactions where experimental data exist in literature, the optical model parameters were adjusted appropriately to best describe the data and were subsequently used for estimating (α,γ) reaction cross sections. Predictions for the (α,n) reaction channels have also been calculated and studied.

MEASUREMENT OF 79Br(n, 2n)78Br, 63Cu(n,2n)62Cu, 58Ni(n,2n)57Ni, 54Fe(n,2n)53Fe, 50Cr(n, 2n)49Cr AND 46Ti(n, 2n)45Ti REACTION CROSS-SECTIONS AT 14.7 MeV NEUTRON ENERGY

1993 ◽  
Vol 02 (01) ◽  
pp. 259-264 ◽  
Author(s):  
G.R. PANSARE ◽  
V.N. BHORASKAR
Keyword(s):  
Compound Nucleus ◽  
Neutron Energy ◽  
Cross Sections ◽  
Reaction Cross ◽  
Activation Technique ◽  
Semiempirical Relation ◽  
Reaction Cross Sections

Cross-sections of the reactions 79 Br (n, 2n)78 Br , 63 Cu (n,2n)62 Cu , 58 Ni (n, 2n)57 Ni , 54 Fe (n, 2n)53 Fe , 50Cr(n, 2n)49Cr and 46 Ti (n, 2n)45 Ti induced by 14.7 MeV neutrons are measured with reference to 27Al(n, ∝)24 Na and 56 Fe (n, p)56 Mn reactions using activation technique and also derived theoretically using compound nucleus model, semiempirical relation and ALICE code. Accuracy around 5% was achieved in measurement of these reaction cross-sections which is better compared to existing literature values.

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