Henry W. Newson

Bio: Henry W. Newson is an academic researcher from Duke University. The author has contributed to research in topics: Neutron & Neutron spectroscopy. The author has an hindex of 20, co-authored 63 publications receiving 1010 citations. Previous affiliations of Henry W. Newson include Durham University & University of Chicago.

Li 7 ( p , n ) , ( p , p ′ γ ), and ( p , γ ) Reactions near Neutron Threshold

Abstract: The ${\mathrm{Li}}^{7}(p, n)$ total cross section has been measured in detail from threshold to 2.5-Mev proton energy. Between 1.88 and 1.92 Mev the cross section follows the equation for a very broad ${2}^{\ensuremath{-}}$ resonance and for $s$-wave particles: ${\ensuremath{\sigma}}_{\mathrm{pn}}=\frac{(\frac{5}{2})\ensuremath{\pi}{\ensuremath{\lambda}}^{2}x}{{(1+x)}^{2}}$, where $x=\frac{{\ensuremath{\Gamma}}_{n}}{{\ensuremath{\Gamma}}_{p}}=1$ at 50 kev above threshold. The remainder of the cross section up to 2.35 Mev is fitted by this level and the ${3}^{+}$ level at 2.25 Mev. The neutron reduced width exceeds that of the proton by a factor of about five for both the ${2}^{\ensuremath{-}}$ and ${3}^{+}$ levels; this is surprising for the self-mirror nucleus ${\mathrm{Be}}^{8}$. A small dip is observed just above neutron threshold in the yield of 478-kev gamma rays from ${\mathrm{Li}}^{7}(p, {p}^{\ensuremath{'}}\ensuremath{\gamma})$. The shape of these data support the assumption of the broad ${2}^{\ensuremath{-}}$ neutron producing resonance with ${\ensuremath{\Gamma}}_{p}g0.5$ Mev. No anomaly is observed in the yield of Li capture gamma rays at neutron threshold; the 2.10-Mev resonance in this reaction (which probably is due to a ${3}^{\ifmmode\pm\else\textpm\fi{}}$ level) yields mainly 16-Mev gamma rays leading to the 2.9-Mev ${2}^{\ifmmode\pm\else\textpm\fi{}}$ level in ${\mathrm{Be}}^{8}$. The ratio of 16 to 19 Mev gamma rays is $\frac{3}{2}$ at both 1.7- and 2.5-Mev proton energy. The behavior of the ${\mathrm{Li}}^{7}(p, n)$ extrapolated threshold was calculated as a function of target thickness and proton energy spread; shifts in the extrapolated thresholds and the distances between them and true threshold were less than one kev. The extrapolated threshold of a \textonehalf{}-kev target taken with a proton energy spread of 1 kev was observed to be \textonehalf{} kev lower in proton energy than a thick-target threshold.

Differential elastic and inelastic scattering of 9- to 15-MeV neutrons from carbon

Abstract: A fast-neutron time-of-flight spectrometer has been constructed for the purpose of measuring neutron differential cross sections of interest to the controlled thermonuclear reactor (CTR) program. T...

Table of isotopes

Abstract: A table is presented of a complete list of the radioactive and stable isotopes, with a number of their salient features, as recorded in the literature or by private communications up to February 1958. (W.D.M.)

A composite nuclear-level density formula with shell corrections

Abstract: At low excitation energies a "constant nuclear temperature" representation of nuclear-level densities is used, and at high excitation energies the regular Fermi gas formula is adopted. A method is ...

The statistical model and nuclear level densities

Abstract: A treatment from a theoretical point of view is given for the different aspects of the statistical model and nuclear level densities. General features of nuclear level densities, including angular momentum and parity distributions, are discussed. Several models for their description are given including the equidistant spacing model, the free gas model, the Newton-Cameron model, the Rosenzweig effect, the Newson model, the pairing model, and the nuclear phase transition. The shell model without pairing interactions seemed to provide an adequate description of the neutron binding energy with empirical values of the single-particle spacing. Qualitative considerations, formal solution of classical approximation, and special limits of the statistical model and angular momentum conservation are discussed. The evaporation approximation, inverse cross sections, multiple emission of particles, emission of complex particles, statistical fission, lifetime of the compound state, and fluctuation of cross sections and angular distributions are also discussed. (M.C.G.)