Sum Rule Photo-Disintegration Cross Sections for the Deuteron with Velocity-Dependent and Hard-Core Potentials

1971 ◽  
Vol 49 (17) ◽  
pp. 2211-2214 ◽  
Author(s):  
S. S. Raghavan ◽  
B. K. Srivastava
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Sum Rules ◽  
Hard Core ◽  
Dipole Approximation ◽  
Sum Rule ◽  
Core Potential ◽  
Cross Section Formula ◽  
Dependent Potential ◽  
Integrated Cross Section

We apply the sum rules of Levinger and Bethe to calculate the integrated cross section[Formula: see text]and the bremsstrahlung-weighted cross section[Formula: see text]for the deuteron in the dipole approximation. In our calculations we use (i) Nestor's velocity-dependent potential and (ii) Reid's hard-core potential. Our results for σint and σb obtained with the velocity-dependent potential of Nestor and the hard-core potential of Reid agree well with experiments.

Deuteron photoabsorption sum rule: Two-body effects

1982 ◽  
Vol 60 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Gisèle Goulard ◽  
Bernard Lorazo
Keyword(s):  
Cross Section ◽  
Electric Dipole ◽  
Soft Core ◽  
Body Density ◽  
Sum Rule ◽  
Core Potential ◽  
Dipole Operator ◽  
Paris Potential ◽  
Soft Core Potential ◽  
Integrated Cross Section

In deuteron photoabsorption, the effect of mesonic exchange currents is considered in detail. Related to the electric dipole operator D1 (Siegert form) and to the nuclear interactions, a factor k appears in the integrated cross-section σ0, previously obtained by the Thomas–Reiche–Kuhn dipole sum rule. The introduction of the two-body density [Formula: see text] modifies the form of D1 and increases κ which becomes κ + Δκ. The influence of several NN potentials is clearly shown on the factor Δκ, some 25% difference occurring between a super soft core potential and the Paris potential. In this last case the value of Δκ is about 50% of the initial κ value.

Sum Rule Photodisintegration Cross Sections of 6Li

1974 ◽  
Vol 52 (3) ◽  
pp. 202-206
Author(s):  
H. L. Yadav ◽  
B. K. Srivastava
Keyword(s):  
Charge Distribution ◽  
Cross Sections ◽  
Sum Rules ◽  
Wave Functions ◽  
Radial Wave ◽  
Sum Rule ◽  
Dependent Potential ◽  
Good Agreement

We apply the sum rules of Levinger and Bethe to calculate the integrated [Formula: see text] cross sections for 6Li using the Gaussian and Irving forms of radial wave functions whose parameters are determined by fitting the r.m.s. radius of charge distribution in 6Li. For the potential in the σint calculation we use the central velocity-dependent potential of Herndon et al. Our results for σint and σb for 6Li show reasonably good agreement with experiments.

Photodisintegration of the alpha particle with tensor forces and a velocity-dependent potential

1969 ◽  
Vol 47 (13) ◽  
pp. 1343-1347
Author(s):  
S. C. Jain
Keyword(s):  
Wave Function ◽  
Cross Section ◽  
Alpha Particle ◽  
Ground State ◽  
Reasonable Agreement ◽  
Sum Rules ◽  
Variational Calculation ◽  
Dependent Potential ◽  
Integrated Cross Section ◽  
Tensor Part

We calculate the integrated cross section (σint) and the bremsstrahlung-weighted cross section (σb) for the photodisintegration of the alpha particle by applying the sum rules of Levinger and Bethe. The two-body interaction is assumed to be a mixture of a central part, having a velocity-dependent term, and a tensor part. The ground-state wave function of the alpha particle is taken to be a mixture of the principal 1S0 and 5D0(1) states, whose parameters are obtained from a variational calculation of the binding energy of the alpha particle with the above potential. We find our results for σint and σb to be in reasonable agreement with the experiments.

Integrated Cross Section for a Velocity-Dependent Potential

1961 ◽  
Vol 123 (6) ◽  
pp. 2177-2179 ◽  
Author(s):  
O. Rojo ◽  
J. S. Levinger
Keyword(s):  
Cross Section ◽  
Dependent Potential ◽  
Integrated Cross Section

The Scattering of Positrons by Helium: Total Cross Sections up to 270 eV

1975 ◽  
Vol 53 (10) ◽  
pp. 962-967 ◽  
Author(s):  
B. Jaduszliwer ◽  
A. Nakashima ◽  
D. A. L. Paul
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Born Approximation ◽  
Reasonable Agreement ◽  
Experimental Results ◽  
Formation Cross Section ◽  
Sum Rule ◽  
Total Cross Sections ◽  
High Energies

The total cross sections for the scattering of positrons by helium have been measured by the method of transmission in the 16 to 270 eV energy range. The experimental results are higher than those of Canter et al. but are in reasonable agreement with recent results of Griffith et al., and at high energies tend towards Born approximation calculations. The integral of the cross section over positron momentum is smaller than the sum rule estimate made by Bransden et al. A tentative value of (0.034 ± 0.017)πa02 is assigned to the positronium formation cross section at threshold.

Photoneutron Cross Sections in 14N

1972 ◽  
Vol 50 (15) ◽  
pp. 1689-1696 ◽  
Author(s):  
R. W. Gellie ◽  
K. H. Lokan ◽  
N. K. Sherman ◽  
R. G. Johnson ◽  
J. I. Lodge
Keyword(s):  
Excited States ◽  
Cross Section ◽  
Cross Sections ◽  
Neutron Emission ◽  
Giant Resonance ◽  
Sequential Decay ◽  
Dipole Resonance ◽  
Intermediate States ◽  
Integrated Cross Section ◽  
High Degree

Photoneutron distributions from 14N have been obtained by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 15.5 to 29.5 MeV. A large part of the neutron yield is associated with the sequential decay of 14N to 12C, through well-defined intermediate states of 13C, at 7.55, 8.86, and 11.80 MeV, which are unstable against neutron emission. The (γ,n0) cross section for neutron emission to the ground state of 13N is found to agree very closely with the corresponding (γ,p0) cross section, implying a high degree of isospin purity for the giant dipole resonance of 14N. It is observed that the decay of the giant resonance proceeds freely through those odd-parity excited states of the A = 13 nuclei which are single hole states formed by the removal of a p-shell nucleon from the parent 14N.The integrated cross section for all neutron-producing interactions is found to be 88 ± 5 MeV mb.

Systematic decay analysis of 202Po∗ compound nucleus using Dynamical Cluster-decay Model

2019 ◽  
Vol 28 (12) ◽  
pp. 1950105 ◽  
Author(s):  
Pooja Kaushal ◽  
Manoj K. Sharma
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Degrees Of Freedom ◽  
Cluster Decay ◽  
Channel Cross Section ◽  
Decay Model ◽  
Cross Section Formula ◽  
Collective Clusterization ◽  
Mechanical Fragmentation

The decay analysis of [Formula: see text]Po[Formula: see text] compound nucleus (CN), formed via [Formula: see text]Ca+[Formula: see text]Gd reaction, with inclusion of additional degrees-of-freedom, i.e., the higher multipole deformations, the octupole ([Formula: see text]) and hexadecupole ([Formula: see text]), the corresponding “compact” orientations ([Formula: see text]), and noncoplanarity degree-of-freedom ([Formula: see text]0), is investigated within the collective clusterization approach. The Quantum Mechanical Fragmentation Theory (QMFT)-based Dynamical Cluster-decay Model (DCM), wherein the point of penetration [Formula: see text], fixed via the in-built neck-length parameter [Formula: see text] in [Formula: see text] (equivalently, the “barrier lowering” [Formula: see text]), is used to best fit the channel cross-section ([Formula: see text]) and predict the quasi-fission (qf)-like nCN cross-section [Formula: see text], if any, and the fusion–fission ([Formula: see text]) cross-sections. We also look for other target-projectile (t-p) combinations for the synthesis of CN [Formula: see text]Po[Formula: see text].

Many-Electron Correlations in the Photoionization of a Nitrogen Atom

1974 ◽  
Vol 52 (4) ◽  
pp. 349-354 ◽  
Author(s):  
N. A. Cherepkov ◽  
L. V. Chernysheva ◽  
V. Radojević ◽  
I. Pavlin
Keyword(s):  
Nitrogen Atom ◽  
Cross Section ◽  
Cross Sections ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Electron Correlations ◽  
Sum Rule ◽  
Hartree Fock ◽  
The Cross ◽  
Good Agreement

Photoionization cross sections for the outer shell of the nitrogen atom ground state are calculated in the single-particle Hartree–Fock approximation and, in order to take into account many-electron correlations, also in the Random Phase Approximation with Exchange (RPAE). To be able to apply the RPAE, its modification for the half-filled shell atom, such as nitrogen atom, is presented. Calculation of length and velocity forms of the cross section in both approximations are compared with the available experimental data, and a good agreement is obtained. It has been found that in the RPAE the influence of many-electron correlations in a nitrogen atom is not great, but it is very important since, in contrast to the Hartree–Fock approximation, it results in the validity of the sum rule and the coincidence of the length and velocity forms of the cross sections, in agreement with the requirement of the general theory. The angular distribution of photoelectrons is also calculated in the RPAE, which has not been measured so far.

PHOTONEUTRON CROSS SECTIONS IN SILICON AND CALCIUM

1953 ◽  
Vol 31 (1) ◽  
pp. 70-77 ◽  
Author(s):  
R. G. Summers-Gill ◽  
R. N. H. Haslam ◽  
L. Katz
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Neutron Yield ◽  
Threshold Energy ◽  
Threshold Effect ◽  
Monitoring Method ◽  
Dose Monitoring ◽  
Γ Rays ◽  
Integrated Cross Section ◽  
Peak Value

Using the dropping apparatus and dose monitoring method previously reported, the cross sections for the reactions Si28(γ, n)Si27 and Ca40(γ, n)Ca39 have been measured by detecting positron activities in the residual nuclei. The Si28(γ, n)Si27 cross section has a peak value of 21 mbarns at 20.9 Mev. and an integrated cross section to 24 Mev. of 0.070 Mev-barns. The threshold energy is 16.9 ± 0.1 Mev. The Ca40(γ, n)Ca39 cross section has a peak value of 15 mbarns at 19.3 Mev. and an integrated cross section to 24 Mev. of 0.065 Mev-barns. The threshold is 15.8 ± 0.1 Mev.A comparison of our results with the neutron yield measurement of Price and Kerst at 18 and 22 Mev. gives good agreement. A further comparison with the neutron yield work of Baldwin and Elder is made.The sharp discontinuity in (γ, n) yields using lithium γ rays observed by Wäffler and Hirzel is explained as a threshold effect. Integrated cross sections increase more or less smoothly with Z.In addition, improved values for the half-lives of the residual nuclei Si27 and Ca39 have been measured. These are 4.45 ± 0.05 and 1.00 ± 0.03 sec. respectively.

THE MEASUREMENT OF PHOTONUCLEAR CROSS SECTIONS IN ISOTOPES LEADING TO SHORT-LIVED DECAY PRODUCTS

1952 ◽  
Vol 30 (3) ◽  
pp. 257-269 ◽  
Author(s):  
R. N. H. Haslam ◽  
R. G. Summers-Gill ◽  
E. H. Crosby
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Half Life ◽  
Half Width ◽  
Reaction Threshold ◽  
Parent Materials ◽  
Dosage Rate ◽  
Decay Products ◽  
Integrated Cross Section ◽  
Peak Value

A dropping apparatus, including a new means of dosage rate monitoring, has been designed to allow the observation of short-lived activities produced by betatron irradiation of various parent materials. The photonuclear cross section for the reaction S32(γ, n)S31 has been measured by this means. The cross section has a peak value of 24.6 millibarns at 20.1 ± 0.5 Mev., a half width of 4.5 Mev., and an integrated cross section of 0.12 Mev-barns. The reaction threshold was found to be 15.0 ± 0.1 Mev. The experiment has also yielded a new half life for S31 − 2.66 ± 0.03 sec.

Sign in / Sign up

Export Citation Format

Share Document