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Journal ArticleDOI

Neutron-Proton Scattering at Small Angles

TL;DR: In this paper, the authors measured neutrons of effective energy from 6 to 61$\cdot $5 degrees c.m. for neutrons with effective energy between 105 and 137 MeV using a liquid hydrogen scatterer and a large counter.
Abstract: Neutron-proton scattering has been measured from 6 to 61$\cdot $5 degrees c.m. for neutrons of effective energy 105 $\pm $ 3 and 137 $\pm $ 5 MeV using a liquid hydrogen scatterer and a large neutron counter. The results confirm previous measurements and show a near symmetry around 90 degrees at 105 MeV, and a fairly definite asymmetry at 137 MeV. The 'Serber force' does not, therefore, give a good approximation to the experimental data at 137 MeV.
Citations
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Journal ArticleDOI
TL;DR: Using the covariant spectator theory (CST), the authors presented two one-boson-exchange kernels that have been successfully adjusted to fit the 2007 world$ data (containing 3788 data) below 350 MeV.
Abstract: Using the covariant spectator theory (CST), we present two one-boson-exchange kernels that have been successfully adjusted to fit the 2007 world $\mathit{np}$ data (containing 3788 data) below 350 MeV. One model (which we designate WJC-1) has 27 parameters and fits with a ${\ensuremath{\chi}}^{2}/{N}_{\mathrm{data}}=1.06$. The other model (designated WJC-2) has only 15 parameters and fits with a ${\ensuremath{\chi}}^{2}/{N}_{\mathrm{data}}=1.12$. Both of these models also reproduce the experimental triton binding energy without introducing additional irreducible three-nucleon forces. One result of this work is a new phase-shift analysis, updated for all data until 2006, which is useful even if one does not work within the CST. In carrying out these fits we have reviewed the entire database, adding new data not previously used in other high precision fits and restoring some data omitted in previous fits. A full discussion and evaluation of the 2007 database is presented.

133 citations

Journal ArticleDOI
TL;DR: In this article, the authors presented a successful fit to neutron-proton and protonproton scattering data below pion production threshold using the delta-shell representation, which includes data within the years 1950 to 2013.
Abstract: Using the delta-shell representation we present a successful fit to neutron-proton and proton-proton scattering data below pion production threshold. A detailed overview of the theory necessary to calculate observables with this potential is presented. A new data selection process is used to obtain the largest mutually consistent data base. The analysis includes data within the years 1950 to 2013. Using 46 parameters we obtain chi^2/Ndata = 1.04 with Ndata = 6713 including normalization data. Phase shifts with error bars are provided.

110 citations

Journal ArticleDOI
TL;DR: Research on the two-nucleon problem during the period 1959-1971 is reviewed and the status of this field is assessed in this paper, where an attempt is also made to give a complete bibliography covering this period.
Abstract: Research on the two-nucleon problem during the period 1959-1971 is reviewed and the status of this field is assessed. An attempt is also made to give a complete bibliography covering this period. This review was completed in August 1972.

41 citations

Journal ArticleDOI
TL;DR: In this paper, a large liquid scintillator was used to obtain elastic scattering cross sections for lead, cadmium, copper, aluminium, oxygen, nitrogen, carbon, beryllium and lithium.
Abstract: The neutron elastic scattering cross sections for lead, cadmium, copper, aluminium, oxygen, nitrogen, carbon, beryllium and lithium have been measured for an effective neutron energy of 136 Mev. A large liquid scintillator was used, and the cross sections were obtained on an absolute scale. The integrated total elastic cross sections are consistent with previous measurements of total and inelastic cross sections.

30 citations

Journal ArticleDOI
TL;DR: In this paper, the free neutron-proton polarization has been measured at center-of-mass angles from 20° to 160° and the asymmetries were obtained using fixed detectors and by rotating the plane of polarization of the neutron beam with respect to the scattering plane by means of a long solenoid.
Abstract: The free neutron-proton polarization has been measured at centre-of-mass angles from 20° to 160°. The asymmetries were obtained using fixed detectors and by rotating the plane of polarization of the neutron beam with respect to the scattering plane by means of a long solenoid. The polarization cross-section was found to be strongly non-antisymmetrical about 90° centre-of-mass and evidence forD-wave interaction was obtained.

17 citations

References
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170 citations

Journal ArticleDOI
TL;DR: In this article, the total cross sections of twelve different elements were measured using the neutron beam from the 184-inch cyclotron operating with deuterons, and the mean energy of detection of the neutrons in this experiment is estimated to be 95 Mev.
Abstract: The total cross sections of twelve different elements were measured using the neutron beam from the 184-inch cyclotron operating with deuterons. Bismuth fission ionization chambers were employed as both monitor and detector in conventional "good geometry" attenuation measurements in the neutron flux emerging from the three-inch diameter collimating port in the 10-foot thick concrete shielding. The mean energy of detection of the neutrons in this experiment is estimated to be 95 Mev.Measurements were also made with a monitor and detector placed inside the concrete shielding where we could obtain an intense neutron flux over a large area. Attenuators of four different elements were placed in front of the detector in a "poor geometry" arrangement so that attenuation was due essentially to inelastic collisions which degrade the neutron energy below the fission threshold. A second detector was placed outside the concrete shielding in the collimated neutron beam in line with the neutron source, absorber, and first detector. Attenuation in it is caused by both inelastic and elastic scattering. By this arrangement the ratio of inelastic to total cross section can be determined directly in one experiment.The nuclear radii as calculated from the observed cross sections using the theory of the transparent nucleus vary as 1.38\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}13}$ A\textonehalf{} cm. In this energy range the ratios of the inelastic to total cross sections are all less than one-half.

49 citations

Journal ArticleDOI
TL;DR: The neutron total cross sections of carbon, aluminium, copper, cadmium and lead have been determined as a function of energy in the range 30 to 139 mev.
Abstract: The neutron total cross sections of carbon, aluminium, copper, cadmium and lead have been determined as a function of energy in the range 30 to 139 mev. The lead total cross section shows a dip at about 60 mev and corresponding dips in the cadmium and copper cross sections appear to occur between 30 and 40 mev. The neutron total cross section of hydrogen has been measured as 56·9±1·8×10-27 cm2 at a neutron energy of 126±2 mev.

39 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the differential scattering cross section as a function of the scattering angle of the neutrons produced by 350 Mev protons impinging on beryllium.
Abstract: Neutrons produced by 350 Mev protons impinging on beryllium are scattered by hydrogen. We measure the differential scattering cross section as a function of the scattering angle. Results are summarized in Fig. 3 of the paper.

32 citations