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Full-Text Articles in Physics
Cross Sections For Ionizaton Of Gases By 5-4000-Kev Protons And For Electron Capture By 5-150-Kev Protons, M. Eugene Rudd, R. D. Dubois, L. H. Toburen, C. A. Ratcliffe, T. V. Goffe
Cross Sections For Ionizaton Of Gases By 5-4000-Kev Protons And For Electron Capture By 5-150-Kev Protons, M. Eugene Rudd, R. D. Dubois, L. H. Toburen, C. A. Ratcliffe, T. V. Goffe
M. Eugene Rudd Publications
Using the parallel-plate-capacitor method and a capacitance manometer to determine pressures, total cross sections for the production of positive and negative charges were measured for 5-4000- keV-proton impact on He, Ne, Ar, Kr, Hz, N2, CO, 02, CH4, and C02. From these, ionization and electron-capture cross sections were obtained and fitted to semi-empirical equations describing the energy dependence in terms of a few parameters. At high energies very good agreement is obtained in the comparison of the ionization cross sections to earlier proton- and electron-impact measurements and with theoretical treatments where they …
Ionic-Configuration-Interaction Effects On Xe 5S-Subshell Photoionization Processes, Göran Wendin, Anthony F. Starace
Ionic-Configuration-Interaction Effects On Xe 5S-Subshell Photoionization Processes, Göran Wendin, Anthony F. Starace
Anthony F. Starace Publications
Recent measurements of the 5s-subshell photoelectron angular distribution of xenon have found larger values for the asymmetry parameter β in the region of the 5s-subshell cross-section minimum than predicted by relativistic random-phase-approximation calculations. Final-state ionic configuration interaction is adduced as a possible explanation for this and other discrepancies.
Atomic Photoionization, Anthony F. Starace
Atomic Photoionization, Anthony F. Starace
Anthony F. Starace Publications
We present here a brief overview of the theory of atomic photoionization. The main aim is to describe current theoretical understanding of the dynamics of the photon-atom collision process. In particular the discussion focuses on those kinds of electron correlation that have been found to be most important for photoionization processes. The general theoretical formulation of the interaction between an incident photon and an N-electron atom is presented first. This is followed by a description of those quantitative and qualitative features of the photoionization cross section that can be understood within a central potential model. The particle-hole type of electron …
Using Nuclear Resonance Excitation To Observe United Atoms In Symmetric Ion-Atom Collisions, James M. Feagin, Ladislov Kocbach
Using Nuclear Resonance Excitation To Observe United Atoms In Symmetric Ion-Atom Collisions, James M. Feagin, Ladislov Kocbach
Department of Physics and Astronomy: Faculty Publications
We consider nuclear resonance excitation as a means to observe the distribution of united-atom orbitals in symmetric ion-atom collisions. We develop this possibility with the application of a two-state adiabatic model to an analysis of a 8Be nuclear resonance experiment. To test our model, and to provide a more direct determination of the nuclear resonance width, we propose that the 8Be experiment be repeated with metastable helium targets.
Interpretation Of Anomalies In The Raman Spectrum Of K2Seo4 In Terms Of Oxygen Sublattice Disorder, Nestor Massa, Frank Ullman, John R. Hardy
Interpretation Of Anomalies In The Raman Spectrum Of K2Seo4 In Terms Of Oxygen Sublattice Disorder, Nestor Massa, Frank Ullman, John R. Hardy
John R. Hardy Papers
Raman scattering from K2SeO4 crystals has been studied in the (20-800)-K temperature range. Three portions of the spectrum are discussed: defect-induced scattering, primarily below 100 cm-1, the external mode spectrum below 200 cm-1, and the internal mode spectra in two regions, 300-500 and 800-950 cm-1. The temperature dependence of the low-frequency, defect-induced scattering has been correlated (in previous studies) with the temperature dependence of certain nonzero-wave-vector phonons that have been observed by others using inelastic neutron scattering. Close to the incommensurate transition temperature, Ti= 129 K, a large enhancement …
Quality Factor For Low Doses Of High-Let Radiations, Werner Hofmann, Robert Katz
Quality Factor For Low Doses Of High-Let Radiations, Werner Hofmann, Robert Katz
Robert Katz Publications
The International Commission on Radiological Protection (ICRP77) and the International Commision on Radiation Units and Measurements (ICRU70) have recommended that the evaluation of radiation hazards be based on the “dose equivalent” defined as the product of the absorbed dose and some modifying factors, the most important of which is the quality factor (Q). The quality factor is intended to allow for the effect on the resulting detriment of the microscopic distribution of the absorbed energy. It is therefore defined as a function of the collision stopping power (L∞) in water at the point of interest. Thus Q rises …
Track Formation In Plastics, Robert Katz
Track Formation In Plastics, Robert Katz
Robert Katz Publications
It is proposed that the “threshold for etchable track formation” in plastics is associated with the linear density of activated polymeric clusters along the path of an ion, in the “grain-count regime.” Existing data for CR-39 reveal a change in etching rate in the neighborhood of z/β having the value of about 15-20. We infer that this defines the transition from the grain count regime to the track width regime, as the activation cross-section exceeds the cross-sectional area of the cluster. This interpretation is consistent with available data for the G value for polymer scission and the dose of gamma-rays …
Thermal Propagation And Stability In Superconducting Films, Kenneth E. Gray, Robert T. Kampwirth, John F. Zasadzinski, Stephen P. Ducharme
Thermal Propagation And Stability In Superconducting Films, Kenneth E. Gray, Robert T. Kampwirth, John F. Zasadzinski, Stephen P. Ducharme
Stephen Ducharme Publications
Thermal propagation and stable hot spots (normal domains) are studied in various high Tc superconducting films (Nb3Sn, Nb, NbN and Nb3Ge). The prediction of the thermal propagation velocity of the long-standing model of Broom and Rhoderick (1960) is verified quantitatively in the regime of its validity. A new energy balance model is shown to give reasonable quantitative agreement of the dependence of the propagation velocity on the length of short normal domains. The steady state (zero velocity) measurements indicate the existence of two distinct situations for films on high thermal conductivity (sapphire) substrates. For low power per unit area the …
Intermediate-Band Photometry Of Stars In Three Clusters Containing Classical Cepheids, Edward G. Schmidt
Intermediate-Band Photometry Of Stars In Three Clusters Containing Classical Cepheids, Edward G. Schmidt
Edward Schmidt Publications
Four-color and Hβ photometry has been carried out of stars in three sparse and distant clusters which are thought to contain Cepheids. From these data the distance moduli and color excesses of the clusters have been derived. In general the new values agree with those in the literature but are somewhat more precise.
Comment On Coefficients Of Fractional Parentage Of The Form (L2L+1|}L2L+2), Anthony F. Starace
Comment On Coefficients Of Fractional Parentage Of The Form (L2L+1|}L2L+2), Anthony F. Starace
Anthony F. Starace Publications
For the special case of half-filled subshells, Racah showed in 1943 that his formula relating the coefficients of fractional parentage for a given particle configuration to those for the corresponding hole configuration requires an additional phase factor (-1) (v-1)/2, where v is the seniority of the half-filled configuration. This phase factor is incorrectly printed in Racah's 1943 paper as (-1) v-1/2. Furthermore, this phase factor is omitted in the 1952 paper by Rosenzweig, resulting in sign errors in the table of (d5|}d6) coefficients. These rather old errors have often …