The scattering of fast nucleons from nuclei

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.

http://inspirehep.net/record/779208/files/arXiv:0802.1552.pdf

Covariant spectator theory of np scattering: Phase shifts obtained from precision fits to data below 350-MeV

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.

Coarse-grained potential analysis of neutron-proton and proton-proton scattering below the pion production threshold

Neutron total cross-sections in the energy range 15 to 120 MeV

Neutrino-induced coherent charged pion production on nuclei ν(–)μA → μ±π∓A is a rare, inelastic interaction in which a small squared four-momentum |t| is transferred to the recoil nucleus, leaving it intact in the reaction. In the scintillator tracker of MINERvA, we remove events with evidence of particles from nuclear breakup and reconstruct |t| from the final-state pion and muon. In addition, we select low |t| events to isolate a sample rich in coherent candidates. By selecting low |t| events, we produce a model-independent measurement of the differential cross section for coherent scattering of neutrinos and antineutrinos on carbon. We find poor agreement with the predicted kinematics in neutrino generators used by current oscillation experiments.

/pdf/measurement-of-coherent-production-of-p-in-neutrino-and-1u7em5ma4e.pdf

Measurement of coherent production of π(±) in neutrino and antineutrino beams on carbon from Eν of 1.5 to 20 GeV.

The neutron, inelastic cross-sections for lead, cadmium, copper, aluminium and carbon have been measured at 140, 105, 81 and 55 MeV, by using a large liquid scintillation counter in a bad-geometry experiment. A t the lower energies the cross-sections decrease monotonically with increase in energy, but thereafter remain practically constant as the energy is increased.

Neutron Inelastic Cross-Sections between 55 and 140 MeV

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.

Neutron-Proton Scattering at Small Angles

The neutron inelastic cross-sections reported in the previous paper are interpreted in terms of the square-well and harmonic oscillator optical models, and also the tapered density-distribution. Neutron and proton inelastic cross-sections are compared, and are shown to suggest that the neutrons in a nucleus have a larger spatial distribution than the protons. Finally, neutron total cross-sections are used to put an upper limit to the permissible surface thickness of a nucleus.

R. G. P. Voss

Papers

Neutron Inelastic Cross-Sections between 55 and 140 MeV

Neutron-Proton Scattering at Small Angles

The Analysis of High-Energy Neutron Cross-Sections