scholarly journals Large Basis Calculation of Positron?Hydrogen Scattering at Low Energies

1995 ◽  
Vol 48 (4) ◽  
pp. 645 ◽  
Author(s):  
Jim Mitroy
Keyword(s):  
Cross Sections ◽  
Reaction Cross ◽  
Positronium Formation ◽  
Total Reaction Cross Section ◽  
Close Coupling ◽  
Variational Calculations ◽  
Low Energies ◽  
Coupling Approach ◽  
Channel Space ◽  
Basis Calculation

Calculations of low energy positron-hydrogen scattering using the close coupling approach are reported at low energies. The channel space includes nine physical hydrogen and positronium states and in addition twelve hydrogen and positronium pseudo-states. For energies below the positronium formation threshold, phase shifts are reported for J = 0 to 6 and are believed to have an absolute accuracy of 0�0015 radian or better. Elastic scattering and positronium formation cross sections in the Ore gap for the J = 0 and J = 1 partial waves are essentially identical with previous variational calculations. Total elastic and positronium formation cross sections are reported at incident energies below the ionisation threshold. Cross sections for the excitation of the H(n=2), H(n=3) and Ps( n=2) levels are also reported over a restricted energy range, and the total reaction cross section has been computed and compared with experiment.

scholarly journals Positronium-Proton Scattering at Low Energies

1995 ◽  
Vol 48 (6) ◽  
pp. 893 ◽  
Author(s):  
Jim Mitroy
Keyword(s):  
Electron Transfer ◽  
Cross Sections ◽  
Low Energy ◽  
Proton Scattering ◽  
Close Coupling ◽  
Low Energies ◽  
Coupling Approach ◽  
Channel Space ◽  
Three Body

Calculations of low energy positronium-proton scattering using the close coupling approach are reported at energies below the three-body breakup energy of 0�5 Rydberg. The channel space includes nine physical hydrogen and positronium states and in addition twelve hydrogen and positronium pseudo-states. Total elastic and electron-transfer cross sections are reported at incident energies below the ionisation threshold. Cross sections for electron transfer to the H(n=2) and H(n=3) levels are also reported.

scholarly journals Positron - Hydrogen Scattering at Intermediate Energies

1996 ◽  
Vol 49 (5) ◽  
pp. 919 ◽  
Author(s):  
Jim Mitroy
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Maximum Energy ◽  
Reaction Cross ◽  
Impact Excitation ◽  
Total Reaction Cross Section ◽  
Positron Impact ◽  
Close Coupling ◽  
Formation Cross Section ◽  
Intermediate Energies

Calculations of positron–hydrogen scattering at intermediate energies up to a maximum energy of 10 Ryd are performed using the close coupling (CC) approach. A large L2 basis of positron–hydrogen channels (28 states) is supplemented by the Ps(1s), Ps(2s) and Ps(2p) channels. The inclusion of the positronium states in the CC expansion leads to a model which can describe most of the physics of the positron–hydrogen system with a reasonable degree of accuracy. In particular, the positronium formation cross section, the total reaction cross section and the ionisation cross section are all in agreement with experiment. The elastic scattering cross section and the cross sections for positron impact excitation of the H(2s) and H(2p) levels are also reported.

scholarly journals 7Be and 8B reaction dynamics at Coulomb barrier energies

2018 ◽  
Vol 184 ◽  
pp. 02015
Author(s):  
E. Strano ◽  
M. Mazzocco ◽  
A. Boiano ◽  
C. Boiano ◽  
M. La Commara ◽  
...  
Keyword(s):  
Cross Sections ◽  
Coulomb Barrier ◽  
Reaction Cross Section ◽  
Optical Model ◽  
Reaction Dynamics ◽  
Reaction Cross ◽  
Total Reaction Cross Section ◽  
Weakly Bound ◽  
Total Reaction ◽  
Reaction Cross Sections

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.

scholarly journals The feasibility of measuring the nuclear reaction cross sections at energies of several KeV in a target under laser compression

1987 ◽  
Vol 5 (2) ◽  
pp. 399-404 ◽  
Author(s):  
V. I. Kukulin ◽  
V. M. Krasnopol'sky ◽  
V. T. Voronchev
Keyword(s):  
Nuclear Reaction ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Velocity Distribution Function ◽  
Reaction Cross ◽  
Straightforward Method ◽  
Energy Behaviour ◽  
Low Energies ◽  
Ion Velocity Distribution Function ◽  
Reaction Cross Sections

The work proposes a straightforward method for determining the nuclear reaction cross sections at extremely low energies (E ≃ 1–100 keV) on the basis of the measurements of the relative yield of fast particles which are products of the nuclear reactions in a target under laser compression. On the other hand, the proposed method makes it possible to find the averaged form of the ion velocity distribution function if the low-energy behaviour of the respective cross sections is known.

A SCHEMATIC MODEL FOR (p, xn) CROSS SECTIONS IN HEAVY ELEMENTS

1956 ◽  
Vol 34 (8) ◽  
pp. 767-779 ◽  
Author(s):  
J. D. Jackson
Keyword(s):  
Cross Sections ◽  
Reaction Cross ◽  
Heavy Elements ◽  
Total Reaction Cross Section ◽  
Schematic Model ◽  
Nuclear Temperature ◽  
A Minor ◽  
Neutron Evaporation ◽  
Average Neutron ◽  
Evaporation Stage

A schematic model for the description of (p, xn) reactions in heavy elements is presented. Reactions are divided into two steps, a prompt multiple collision process, followed by an evaporation stage. The various prompt processes are given by the results of Monte Carlo calculations, while the evaporation processes are described by a simplified model assuming constant nuclear temperatures and only neutron evaporation. The resulting (p, xn), and to a minor degree (p, pxn), cross sections are compared with the experimental data of Bell and Skarsgard (1956) in the energy range up to 100 Mev. With an average neutron binding energy of around 7.3 Mev., a nuclear temperature of about 1.8 Mev., and a nuclear radius of 8.0 × 10−13 cm., a reasonable over-all fit can be made to the data for Pb206, Pb207, Pb208, and Bi209. Characteristic fluctuations in the experimental results for the (p, 2n), (p, 3n), and (p, 4n) reactions for all targets seem to be attributable to variations in the total reaction cross section, and are not reproduced by the present model.

scholarly journals Deuteron–Deuteron Reaction Cross Sections at Very Low Energies

2020 ◽  
Vol 51 (3) ◽  
pp. 649
Author(s):  
K. Czerski ◽  
N. Targosz-Ślęczka ◽  
M. Kaczmarski
Keyword(s):  
Cross Sections ◽  
Reaction Cross ◽  
Low Energies ◽  
Reaction Cross Sections

scholarly journals On the Experimental Investigation of the Angular Distributions in the Reaction 112Cd(p,γ)113In

2019 ◽  
Vol 26 ◽  
pp. 188
Author(s):  
A. Zyriliou ◽  
A. Khaliel ◽  
T. J. Mertzimekis
Keyword(s):  
Cross Sections ◽  
Nuclear Physics ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Angular Distributions ◽  
Special Focus ◽  
Tandem Accelerator ◽  
Section Data ◽  
Hpge Detectors ◽  
Low Energies

Some of the mid–weight nuclei lie in the region of the isotopic chart where the astrophysical p-process has a prominent role in the nucleosynthetic scenarios. Experimentally deduced reaction cross section data can provide stringent tests for the astrophysical models, especially at low energies. In this framework, the reaction 112Cd(p,γ)113In has been studied experimentally at four proton beam energies 2.8 ≤ Ep≤ 3.4 MeV, partly inside the astrophysically interesting Gamow window. Proton beams were provided by the 5.5 MV T11 Van de Graaff Tandem Accelerator of the Institute of Nuclear Physics of the National Center for Scientific Research (NCSR) “Demokritos”. In–beam spectroscopy was carried out with an array of four HPGe detectors sitting on a rotating table. In total, eight (8) different angles were used to record gamma–ray spectra. Special focus was given on constructing the angular distribution of each gamma–ray feeding the ground state of 113In directly, so as to determine the reaction cross sections from the in–beam data, exclusively. The resulting cross sections were compared to Hauser–Feshbach calculations using the code TALYS v1.9.

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