M. L. Evans

Differential cross-section for n p elastic scattering in the angular region 50-degrees < Theta* < 180-degrees at 459-MeV

The n-p elastic differential cross section in the angular range 51/sup 0/..d..pi../sup 0/). A monoenergetic neutron beam bombarded a liquid hydrogen target, and the protons and deuterons ejected from the target were detected by a multiwire proportional chamber spectrometer which measured their momentum, angle, and mass. The results resolve discrepancies between previous measurements of this observable, and are in reasonable agreement with Saclay data at large angles, and with a phase shift fit. Evidence for accuracy of the shape of the angular distribution is provided by the good value obtained for the pion-nucleon coupling constant (f/sup 2/ = 0.0759 +- 0.0030) when the pole-extrapolation method of Chew is used to extract f/sup 2/ from this shape.

Neutron spectra at 0° from proton-proton collisions between 647 and 805 MeV

Momentum spectra of neutrons at 0degree from the process pp ..-->.. np..pi../sup +/ have been measured at 647, 771, and 805 MeV. Absolute cross sections d/sup 2/sigma/d..cap omega..dp and dsigma/d..cap omega..* are given for all three energies. A phenomenological calculation using only S- and P-wave ..pi..N phase shifts and an NN final-state interaction appears to account for the shapes and magnitudes of the spectra quite well. Comparison with the process np ..-->.. pX indicates a non-negligible contribution from nonresonant amplitudes. (AIP)

Transport of Gamma rays through an infinite homogeneousore medium

Abstract A discrete-ordinates transport code has been used to transport gamma rays from the decay of the naturally occurring radioactive isotopes of potassium, uranium, and thorium through an infinite homogeneous medium. Parametric studies varying the medium type (i.e., shale and sandstone), porosity, and saturation were made to determine their effects on the calculated gamma-ray spectra. In addition, the effect on the gamma-ray spectra of trace quantities of heavy elements was studied by varying the uranium concentration in the formation from 0% to 6% by weight.

Differential Cross-Section for N-P Elastic-Scattering in the Angular Range 60-Degrees Less-than Theta-Star Less-than 180-Degrees at 801.9 Mev

The differential cross section for n-p elastic scattering at 801.9 MeV has been measured with high statistical precision and good relative accuracy over the angular range 60/sup 0/..d..pi../sup 0/ reaction and is good to 7%. A nearly monoenergetic neutron beam, produced by proton bombardment of a liquid-deuterium target, was directed through a liquid-hydrogen target. The angle, velocity, and momentum of charged particles ejected from the target were measured in a magnetic spectrometer equipped with multiwire proportional chambers and timing scintillators. The results are in good agreement with earlier Saclay and LAMPF data and include an angular region not covered before. The pole-extrapolation method of Chew was used to extract a value f/sup 2/ = 0.075 +- 0.005 for the pion-nucleon coupling constant which is in agreement with accepted values, thus providing evidence for the accuracy of the shape and normalization of the angular distribution.

Differential cross section for [ital n]-[ital p] elastic scattering in the angular region 50[degree][lt][theta][sup *][lt]180[degree] at 459 MeV

The differential cross section for [ital n]-[ital p] elastic scattering at 459 MeV in the c.m. angular region 50[degree][lt][theta][sup *][lt]180[degree] has been measured with high statistical precision and good relative accuracy. The uncertainty in the absolute normalization (based on the simultaneously measured yield of deuterons from the [ital np][r arrow][ital d][pi][sup 0] reaction) was initially estimated to be [similar to]7%. The results agree well with back-angle data obtained independently at LAMPF but less well with results from Saclay and the Princeton-Pennsylvania Accelerator and, except for a normalization difference of 10%, are fairly well represented by a phase-shift fit. The pole-extrapolation method of Chew was used to extract the pion-nucleon coupling constant [ital f][sup 2] from the back-angle portion of the data. The value obtained, [ital f][sup 2]=0.069, is somewhat smaller than the values 0.0735--0.0790 obtained from analyses of pion-nucleon scattering, tending to confirm the need for an upward renormalization of the angular distribution by [similar to]10%.

Differential cross section forn-pelastic scattering in the angular region 50°<θ*<180° at 459 MeV

The differential cross section for [ital n]-[ital p] elastic scattering at 459 MeV in the c.m. angular region 50[degree][lt][theta][sup *][lt]180[degree] has been measured with high statistical precision and good relative accuracy. The uncertainty in the absolute normalization (based on the simultaneously measured yield of deuterons from the [ital np][r arrow][ital d][pi][sup 0] reaction) was initially estimated to be [similar to]7%. The results agree well with back-angle data obtained independently at LAMPF but less well with results from Saclay and the Princeton-Pennsylvania Accelerator and, except for a normalization difference of 10%, are fairly well represented by a phase-shift fit. The pole-extrapolation method of Chew was used to extract the pion-nucleon coupling constant [ital f][sup 2] from the back-angle portion of the data. The value obtained, [ital f][sup 2]=0.069, is somewhat smaller than the values 0.0735--0.0790 obtained from analyses of pion-nucleon scattering, tending to confirm the need for an upward renormalization of the angular distribution by [similar to]10%.

Differential cross section for n-p elastic scattering in the angular range 51/sup 0/

The n-p elastic differential cross section in the angular range 51/sup 0/..d..pi../sup 0/). A monoenergetic neutron beam bombarded a liquid hydrogen target, and the protons and deuterons ejected from the target were detected by a multiwire proportional chamber spectrometer which measured their momentum, angle, and mass. The results resolve discrepancies between previous measurements of this observable, and are in reasonable agreement with Saclay data at large angles, and with a phase shift fit. Evidence for accuracy of the shape of the angular distribution is provided by the good value obtained for the pion-nucleon coupling constant (f/sup 2/ = 0.0759 +- 0.0030) when the pole-extrapolation method of Chew is used to extract f/sup 2/ from this shape.

Extreme back angle n/sup 2/H elastic scattering at 794 MeV

The cross section for elastic scattering of 794-MeV neutrons by deuterium has been measured for neutron center of mass angles from 139/sub D/ to 179/sub D/. The angular distribution is fitted very well both by an empirical function ..cap alpha..e/sup ..beta../(u-u180D)/sup / and by a calculation that uses the one parameter Craigie-Wilkin triangle diagram technique.

Extreme back anglenH2elastic scattering at 794 MeV

The cross section for elastic scattering of 794-MeV neutrons by deuterium has been measured for neutron center of mass angles from 139/sub D/ to 179/sub D/. The angular distribution is fitted very well both by an empirical function ..cap alpha..e/sup ..beta../(u-u180D)/sup / and by a calculation that uses the one parameter Craigie-Wilkin triangle diagram technique.

Neutron spectra at 0degree from proton-proton collisions between 647 and 805 MeV. [Absolute cross sections, sand P waves, phase shift, NN final-state interaction]

Momentum spectra of neutrons at 0degree from the process pp ..-->.. np..pi../sup +/ have been measured at 647, 771, and 805 MeV. Absolute cross sections d/sup 2/sigma/d..cap omega..dp and dsigma/d..cap omega..* are given for all three energies. A phenomenological calculation using only S- and P-wave ..pi..N phase shifts and an NN final-state interaction appears to account for the shapes and magnitudes of the spectra quite well. Comparison with the process np ..-->.. pX indicates a non-negligible contribution from nonresonant amplitudes. (AIP)