Stopping powers of Be,Al, Ti,V, Fe,Co, Ni,Cu, Zn,Mo, Rh,Ag, Sn,Ta, Pt and Au For 6.5 MeV protons

The stopping powers of Be, Al, Ti, V, Fe, Co, Ni, Cu, Zn, Mo, Rh, Ag, Sn, Ta, Pt and Au for 6.5 MeV have been measured using a surface barrier silicon detector. The accuracy of the results is ± 0.3%. The detail of the experimental procedures is described. The results have been compared with the Risø data and the Aarhus data of Andersen et al. The present results for Al, Cu and Ag agree very well with the Aarhus results at 6.5 MeV. The mean excitation energy has been extracted from the present results using the Bonderup shell correction, the Barkas correction and the Bloch correction. The parameters x and b which appear in the Bonderup shell correction and the Barkas correction have been newly determined as x = 1.358 and b = 1.3. The present mean excitation energy agrees very well with the I values obtained by other authors. It has been confirmed that the Bonderup shell correction is quantitatively correct for 6.5 MeV protons.     

Wavelengths,transition probabilities,and oscillator strengths for M-shell transitions in Co-, Ni-, Cu-, Zn-, Ga-, Ge-, and Se-like Au ions

Wavelengths, transition probabilities, and oscillator strengths have been calculated for M-shell electric dipole transitions in Co-, Ni-, Cu-, Zn-, Ga-, Ge-, and Se-like Au ions. The fully relativistic multiconfiguration Dirac–Fock method, taking quantum electrodynamical effects and the Breit correction into account, was used in the calculations. Calculated energy levels of M-shell excited states for Cu-, Zn-, Ga-, Ge-, and Se-like Au ions from the method were compared with available theoretical and experimental results, and good agreement with them was achieved.     

Measurements of the total effective cross sections for resonance neutrons in Pd,Os, Ir,Mo, In,I, Ta,Th, U238

The results of calculations of the level constants in the elements Pd, Os, Ir, Mo, I, In, Ta, Th, U²³⁸ are presented; the cross sections for these elements have been published earlier. New measurements for the cross sections in Ir, Th, U²³⁸ are cited. The measurements were made with a mechanical-chopper spectrometer with a resolution of 0.08 sec/m in the energy region from 4.5 to 10,000 ev. The integrated and differential curves for the distribution of neutron widths in these elements are plotted.Presented at the International Conference on Nuclear Reactions in Amsterdam (June 1956).The authors take this opportunity to express their gratitude to U. Chi-Kwa and Suan Chi-Ling for their assistance in the mathematical analysis of the experimental results, G. M. Kukavadze for the mass-spectro-graphic analyses of the samples, V. N. Bovinoi and M. P. Anikinoi for providing the chemical analyses and A. I. Ermakov, N. S. Rezvyakov, G. V. Rukolaine and K. A. Trostinoi for help in building the analyzer and in carrying out the measurements.     

Discovery of dysprosium,holmium, erbium,thulium, and ytterbium isotopes

Currently, thirty-one dysprosium, thirty-two holmium, thirty-two erbium, thirty-three thulium, and thirty-one ytterbium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.     

Discovery of yttrium, zirconium, niobium, technetium, and ruthenium isotopes

Currently, thirty-four yttrium, thirty-five zirconium, thirty-four niobium, thirty-five technetium, and thirty-eight ruthenium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.     

Environmental Radiation, Past, Present, and Future

At present, as in the past, the bulk of environmental radiation comes from natural sources, cosmic radiation, and natural radioactivity. The normal dose to man from natural sources ranges from about 60 to 250 mrads/year. Fallout from weapons testing has provided as much as 20 to 25 mrads/year during the early to mid-1960's. At present, medical uses provide 20 to 100 mrads/year to the average individual in the U.S. Radiation to the general population from nuclear power is insignificant at present. With the trend toward improved technology in the control and containment of radioactivity from nuclear facilities, future levels should not exceed those observed from fallout. Improvements in radiological procedures should materially reduce unnecessary exposure from this application.     

Energies, wavelengths, and transition probabilities for Ge-like Kr, Mo, Sn, and Xe ions

Energy levels, wavelengths, transition probabilities, and oscillator strengths have been calculated for Ge-like Kr, Mo, Sn, and Xe ions among the fine-structure levels of terms belonging to the ([Ar] 3d¹⁰)4s²4p², ([Ar] 3d¹⁰)4s 4p³, ([Ar] 3d¹⁰)4s²4p 4d, and ([Ar] 3d¹⁰)4p⁴ configurations. The fully relativistic multiconfiguration Dirac-Fock method, taking both correlations within the n=4 complex and the quantum electrodynamic effects into account, have been used in the calculations. The results are compared with the available experimental and other theoretical results.     

Gamma-Ray Production Cross Sections for Interactions of 14.8 MeV Neutrons with O,Na, Al,Cl, Cr,Fe, Ni,Cu and Pb

Production cross sections for 85 discrete γ-rays at 125° were measured with a Ge(Li) detector for interactions of 14.8 MeV neutrons with natural samples of O, Na, Al, Cl, Cr, Fe, Ni, Cu and Pb. The obtained cross sections were compared with the results of previous works. For O, Na, Al, Cr and Ni, the present results agree with the previous data measured with monoenergetic neutron sources; for Cl, Fe, Cu and Pb, the present results are larger than the previous data. In comparison between the present results shown by histograms of γ-ray energy and unfolded data, a considerable discrepancy is found from some of the previous data for Fe.