CROSS SECTIONS OF (p, xn) REACTIONS IN THE ISOTOPE OF LEAD AND BISMUTH

1956 ◽  
Vol 34 (8) ◽  
pp. 745-766 ◽  
Author(s):  
R. E. Bell ◽  
H. M. Skarsgard
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Proton Energy ◽  
Neutron Cross Section ◽  
Smooth Curve ◽  
Nucleon Nucleon ◽  
Reaction Cross ◽  
Total Reaction Cross Section

Measurements have been made by the activation method of cross sections of (p, xn) reactions in Bi209, Pb206, Pb207, and Pb208. The present results cover x = 3 to 7 in Bi209, 2 to 6 in Pb206, 2 to 4 in Pb207, and 3 and 4 in Pb208, over a total proton energy range from 12 to 85 Mev. The absolute accuracy is about 15%. Each cross section plotted as a function of proton energy rises above its threshold to a peak whose height is of the order of one barn, and then falls again to a low and fairly constant value. The results from x = 3 to 7 are consistent with a compound nucleus plus prompt nucleon–nucleon cascade model using reasonable nuclear parameters, but the experimental (p, 2n) cross section appears to be almost double the value so predicted. Since (p, xn) reactions are dominant in the energy range 10 to 40 Mev., their sum approximates the total reaction cross section; the experimental sum fluctuates around the smooth curve computed for the compound nucleus model with r0 = 1.3 × 10−13 cm. The fluctuations are similar to, but more marked than, those in the total neutron cross section of heavy elements in the same energy range. A more detailed theoretical discussion of these results is given by Jackson in the paper immediately following.

PROTON TOTAL REACTION CROSS SECTION MEASUREMENTS FOR DEUTERIUM IN THE ENERGY RANGE 20–50 MeV

1972 ◽  
pp. 475-478
Author(s):  
R.F. Carlson ◽  
I. Slaus ◽  
S.Y. Tin ◽  
W.T.H. van Oers ◽  
P. Doherty ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Reaction Cross Section ◽  
Reaction Cross ◽  
Total Reaction Cross Section ◽  
Total Reaction

scholarly journals Chemical Reaction Kinematics

1968 ◽  
Vol 23 (12) ◽  
pp. 2080-2083 ◽  
Author(s):  
D. Hyatt ◽  
K. Lacmann
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Mass Spectrometer ◽  
Cross Sections ◽  
Impulse Approximation ◽  
Reaction Cross ◽  
Molecule Reaction ◽  
Polarization Theory ◽  
Reaction Cross Sections

A Bendix time of flight mass spectrometer has been modified to enable the determination of some ion-molecule reaction cross sections in the energy range 1 — 100 eV.In the reactions studiedX+ + D2 → XD++Dwhere X may be Ar, N2 or CO, the results obtained agree with the predictions of the polarization theory in the range below 10 eV despite the fact that no intermediate complex is formed at these energies. Between about 10—50 eV where spectator stripping occurs the cross section follows an approximate E-l dependence. Above these energies the results are consistent with a transition to a region in which knock-on processes predominate and where an impulse approximation treatment would be valid.

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.

ALPHA-NUCLEUS TOTAL REACTION CROSS SECTION IN THE RIGID PROJECTILE MODEL USING MICROSCOPIC N-α AMPLITUDE

2001 ◽  
Vol 10 (01) ◽  
pp. 43-53 ◽  
Author(s):  
I. AHMAD ◽  
M. A. ABDULMOMEN ◽  
L. A. AL-KHATTABI
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross Section ◽  
Scattering Amplitude ◽  
Reaction Cross ◽  
Glauber Model ◽  
Total Reaction Cross Section ◽  
Total Reaction ◽  
Rigid Projectile ◽  
Optical Limit Approximation

Coulomb modified Glauber model has been applied to calculate α total reaction cross-section for 12 C , 16 O and 40 Ca nuclei in the rigid projectile model using microscopic N-α amplitude which is evaluated in terms of NN scattering amplitude parameters. Using realistic densities for target nuclei and the same input information, we find that the predictions of the rigid projectile approximation for α reaction cross sections are, in general, in better agreement with the experimental data than those of the optical limit approximation.

ACTIVATION CROSS SECTIONS FOR C12(p, pn)C11, O16(p, α)N13, and F19(p, pn)F18

1958 ◽  
Vol 36 (10) ◽  
pp. 1276-1285 ◽  
Author(s):  
A. B. Whitehead ◽  
J. S. Foster
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Smooth Function ◽  
Lower Energy ◽  
Proton Energy ◽  
Proton Irradiation ◽  
Nuclear Reactions ◽  
Smooth Curve ◽  
Laboratory System ◽  
Activation Cross Sections

The activation cross sections for proton-induced nuclear reactions were studied in the region from threshold over a range of about 10 Mev proton energy. The scattering and 180°-focussing technique for proton irradiation was employed to realize improved energy resolution.The reaction O16(p, α)N13 exhibited three large peaks at proton energies of 8.6 Mev, 11.3 Mev, and 14.6 Mev in the laboratory system. The maximum cross sections were 46 mb, 55 mb, and 45 mb respectively.Though not so pronounced as in the oxygen case, minor peaks in the cross section for C12(p, pn)C11 + C12(p, d)C11 modulated the previously smooth curve. These occurred at energies of 19.8 Mev, 20.9 Mev, and 22.2 Mev. The known excitation function for this reaction was extended from 32 Mev to 42 Mev and proved to be flat, thereby clarifying the normalization between the higher- and lower-energy regions.The irradiation of F19 with protons to produce F18 yielded a cross section which was a smooth function of energy, and thus differed in shape from the corresponding carbon curve.

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 Cross Section Measurements in the 54Cr(p, ?)55Mn Reaction

1979 ◽  
Vol 32 (4) ◽  
pp. 335 ◽  
Author(s):  
R. J. Wilkinson ◽  
A S. R. Kennett ◽  
A Z. E. Switkowski ◽  
D. G. SargoodA and F. M. MannC
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross Section ◽  
Proton Energy ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Model Calculations ◽  
Global Parameter ◽  
Dramatic Effect ◽  
Bombarding Energy

Cross sections for production of individual y rays in the 54Cr(p, y)55Mn reaction have been measured over the proton energy range 1�0-3�8 MeV. Gamma-ray yields are observed to fall by factors of between 5 and 10 at the crossing of the neutron threshold for a proton bombarding energy of 2�2 MeV. Statistical model calculations with global parameter sets successfully account for the dramatic effect of neutron competition on the (p, y) cross section, and at the same time correctly predict the 54Cr(p,n)54Mn reaction cross section.

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