Electrodisintegration of lithium

1970 ◽  
Vol 48 (16) ◽  
pp. 1917-1923 ◽  
Author(s):  
C. F. Wong ◽  
R. M. Hutcheon ◽  
Y. M. Shin ◽  
H. S. Caplan
Keyword(s):  
Solid State ◽  
Cross Sections ◽  
Ground State ◽  
Virtual Photon ◽  
Residual Nucleus ◽  
Charged Particles ◽  
Magnetic Spectrometer ◽  
Energy Spectra ◽  
Solid State Detectors ◽  
Photon Spectra

Energy spectra of charged particles produced by electron and bremsstrahlung bombardment of 6Li and 7Li were measured by means of a magnetic spectrometer and solid-state detectors. Assuming that all transitions leave the residual nucleus in the ground state, the photonuclear cross sections were obtained using both bremsstrahlung and E1 virtual photon spectra. Comparison of the present real and virtual photon results is made with those of previous experiments.

Photoneutron cross sections in 7Li

1977 ◽  
Vol 55 (5) ◽  
pp. 428-433 ◽  
Author(s):  
H. Ferdinande ◽  
N. K. Sherman ◽  
K. H. Lokan ◽  
C. K. Ross
Keyword(s):  
Fine Structure ◽  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Reasonable Agreement ◽  
Branching Ratio ◽  
Energy Spectra ◽  
Average Value ◽  
First Excited State

Photoneutron energy spectra from 7Li have been measured by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 13 to 25 MeV. The ground-state and approximate first-excited-state differential cross sections at 90° have been obtained from 8.5 to 23 MeV. No pronounced fine structure has been observed. The measured branching ratio to the first excited state falls from an average value of 0.70 between 10.3 and 14.5 MeV to an average of 0.29 between 14.5 and 18 MeV, and rises again to an average of 0.38 between 18 and 23 MeV. This behaviour can be explained by a crude theoretical model in which 1p → 2s and 1p → 1d single particle transitions dominate below 18 MeV. The calculation predicts a branching ratio of 0.50 near threshold, falling to 0.23 at higher energies, in reasonable agreement with the experiment. The integrated value of the ground-state cross section up to 23 MeV is about (38.7 ± 3.9) MeV mb, while that for the first excited state is about (17.2 ± 3.4) MeV mb. Together they account for 39% of the exchange-augmented dipole sum of 7Li.

COMMENT ON A FREQUENT ERROR IN CALCULATIONS OF THE Γn/Γf RATIO

2009 ◽  
Vol 18 (04) ◽  
pp. 823-829 ◽  
Author(s):  
K. SIWEK-WILCZYŃSKA ◽  
J. WILCZYŃSKI
Keyword(s):  
Binding Energy ◽  
Cross Sections ◽  
Ground State ◽  
Residual Nucleus ◽  
Heavy Elements ◽  
Shell Effect ◽  
Excitation Energies ◽  
Neutron Binding Energy ◽  
Energy Dependent ◽  
Leading Journals

In the last decade some 20–30 publications in leading journals appeared in which cross sections for production of super-heavy elements are calculated with an erroneous formula for the Γn/Γf ratio. The erroneous treatment of shell structure corrections leads to an energy-dependent fission barrier that is inserted to the expression for the fission width Γf. In this approach the shell effect in the residual nucleus that emitted the neutron is ignored. We give examples of calculations that illustrate the deviations of the erroneous formula from the correct one. The errors reach several orders of magnitude, especially for low excitation energies and those compound nuclei for which large ground-state shell effect exceeds the neutron binding energy.

Photoneutron Reactions in 18O

1975 ◽  
Vol 53 (8) ◽  
pp. 786-794 ◽  
Author(s):  
J. D. Allan ◽  
J. W. Jury ◽  
R. G. Johnson ◽  
K. G. McNeill ◽  
J. G. Woodworth ◽  
...  
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Ground State ◽  
Energy Spectra ◽  
Continuum State ◽  
Average Value ◽  
First Excited State ◽  
Time Of Flight Spectroscopy

Photoneutron energy spectra from 18O have been measured by time-of-flight spectroscopy at bremsstrahlung endpoint energies from 11 to 18 MeV in 1 MeV steps to obtain the (γ, n0) and (γ, n1) differential cross sections. The ground state photoneutron cross section contains at least 8 major resonances in the region from 10 to 17 MeV and has an average value of 100 μb/sr. The cross section to the first excited state of 17O contains only two major resonances, at 11.4 and 14.4 MeV, and the average cross section in the region from 11 to 16 MeV is about 40 μb/sr. Of particular interest is a resonance at 14.4 MeV which appears to reflect a simple excitation of one of the valence neutrons to the 2p3/2 state. Analysis of the (γ, n0) and (γ, n1) cross sections for this continuum state leads to estimates of the configuration amplitudes of the 2s1/2 and 1d5/2 components of this state to be 0.62 ± 0.06 and 0.78 ± 0.08 respectively and the ratio of the (2s1/2)2 to (1d5/2)2 amplitudes in the ground state of 18O to be 0.39 ± 0.02.

Investigation of Fine Structure in the Photoneutron Cross Sections of 16O and 208Pb

1975 ◽  
Vol 53 (15) ◽  
pp. 1434-1442 ◽  
Author(s):  
R. G. Johnson ◽  
J. D. Irish ◽  
K. G. McNeill
Keyword(s):  
Fine Structure ◽  
High Resolution ◽  
Differential Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Center Of Mass ◽  
Energy Spectra ◽  
Neutron Time ◽  
Good Agreement

The structure in the photoneutron cross sections of 16O and 208Pb has been studied by the measurement of high resolution photoneutron energy spectra using the neutron time-of-flight technique and bremsstrahlung irradiations. For 16O, the ground state differential cross section at 98° has been deduced between 17.3 and 28.5 MeV and is in good agreement with most previous studies. Fine structure is seen throughout the cross section. Eight neutron energy spectra for 208Pb from bremsstrahlung endpoint energies in the range 11.0 to 15.5 MeV were obtained. Strong peaks are seen at center of mass neutron energies of 1.67, 1.85, 2.06, 2.19, 2.68, 3.15, 3.27, 3.50, 3.77, and 4.03 MeV with weaker peaks elsewhere. The energies of these peaks are in good agreement with previous measurements in this laboratory. The energies of peaks in the spectra are compared with recent cross section measurements.

Absolute cross sections for electron- and positron-induced fission of 238U and tests of DWGA virtual-photon spectra

1982 ◽  
Vol 378 (2) ◽  
pp. 237-250 ◽  
Author(s):  
H. Ströher ◽  
R.D. Fischer ◽  
J. Drexler ◽  
K. Huber ◽  
U. Kneissl ◽  
...  
Keyword(s):  
Cross Sections ◽  
Virtual Photon ◽  
Induced Fission ◽  
Photon Spectra

scholarly journals Saturation effects in SIDIS at very forward rapidities

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
E. Iancu ◽  
A. H. Mueller ◽  
D. N. Triantafyllopoulos ◽  
S. Y. Wei
Keyword(s):  
Inelastic Scattering ◽  
Cross Section ◽  
Cross Sections ◽  
Virtual Photon ◽  
Large Fraction ◽  
Quark Distribution ◽  
High Energy ◽  
Longitudinal Momentum ◽  
Black Disk ◽  
Gluon Saturation

Abstract Using the dipole picture for electron-nucleus deep inelastic scattering at small Bjorken x, we study the effects of gluon saturation in the nuclear target on the cross-section for SIDIS (single inclusive hadron, or jet, production). We argue that the sensitivity of this process to gluon saturation can be enhanced by tagging on a hadron (or jet) which carries a large fraction z ≃ 1 of the longitudinal momentum of the virtual photon. This opens the possibility to study gluon saturation in relatively hard processes, where the virtuality Q2 is (much) larger than the target saturation momentum $$ {Q}_s^2 $$ Q s 2 , but such that z(1 − z)Q2 ≲ $$ {Q}_s^2 $$ Q s 2 . Working in the limit z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we predict new phenomena which would signal saturation in the SIDIS cross-section. For sufficiently low transverse momenta k⊥ ≪ Qs of the produced particle, the dominant contribution comes from elastic scattering in the black disk limit, which exposes the unintegrated quark distribution in the virtual photon. For larger momenta k⊥ ≳ Qs, inelastic collisions take the leading role. They explore gluon saturation via multiple scattering, leading to a Gaussian distribution in k⊥ centred around Qs. When z(1 − z)Q2 ≪ Q2, this results in a Cronin peak in the nuclear modification factor (the RpA ratio) at moderate values of x. With decreasing x, this peak is washed out by the high-energy evolution and replaced by nuclear suppression (RpA< 1) up to large momenta k⊥ ≫ Qs. Still for z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we also compute SIDIS cross-sections integrated over k⊥. We find that both elastic and inelastic scattering are controlled by the black disk limit, so they yield similar contributions, of zeroth order in the QCD coupling.

scholarly journals The Non-Relativistic Many-Body Quantum-Mechanical Hamiltonian with Diamagnetic Current-Current Interaction

2021 ◽  
Author(s):  
Ladislaus Alexander Bányai
Keyword(s):  
Solid State ◽  
Analogous Result ◽  
Charged Particles ◽  
Coulomb Gauge ◽  
Quantum Mechanical ◽  
Photon Propagator ◽  
Coulomb Interactions ◽  
Many Body ◽  
Transverse Current ◽  
Current Interaction

AbstractWe extend the standard solid-state quantum mechanical Hamiltonian containing only Coulomb interactions between the charged particles by inclusion of the (transverse) current-current diamagnetic interaction starting from the non-relativistic QED restricted to the states without photons and neglecting the retardation in the photon propagator. This derivation is supplemented with a derivation of an analogous result along the non-rigorous old classical Darwin-Landau-Lifshitz argumentation within the physical Coulomb gauge.

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