Incident Neutron Momenta Research Articles

Measurement of neutron and proton analyzing powers on C, CH, $$CH_2$$ and Cu targets in the momentum region 3–4.2 GeV/c

The analyzing powers for proton elastic scattering ($\vec p A\to pX$) and neutron charge exchange ($\vec n A\to p X$) reactions on nuclei have been measured on $ C$, $CH$, $CH_2$ and $Cu$ targets at incident neutron momenta 3.0 - 4.2 GeV/c by detecting one charged particle in forward direction. The polarized neutron measurements are the first of their kind. The experiment was performed using the Nuclotron accelerator in JINR Dubna, where polarized neutrons and protons were obtained from breakup of a polarized deuteron beam which has a maximum momentum of 13 GeV/c. The polarimeter ALPOM2 was used to obtain the analyzing power dependence on the transverse momentum of the final-state nucleon. These data have been used to estimate the figure of merit of a proposed experiment at Jefferson Laboratory to measure the recoiling neutron polarization in the quasi-elastic $^2H(\vec e,e'\vec n)$ reaction, which yields information on the charge and magnetic elastic form factors of the neutron.

Results of Measurements of the Analyzing Powers for Polarized Neutrons on C, CH2 and Cu Targets for Momenta Between 3 and 4.2 GeV/c

The analyzing powers for neutron charge exchange nA → pX reactions on nuclei have been measured on C, CH2 and Cu targets at incident neutron momenta 3.0 - 4.2 GeV/c by detecting one charged particle in forward direction. The polarized neutron measurements are the first of their kind. The experiment was performed using the Nuclotron accelerator in JINR Dubna, where polarized neutrons and protons were obtained from breakup of a polarized deuteron beam which has a maximum momentum of 13 GeV/c. The polarimeter ALPOM2 was used to obtain the analyzing power dependence on the transverse momentum of the final-state nucleon. These data have been used to estimate the figure of merit of a proposed experiment at Jefferson Laboratory to measure the recoiling neutron polarization in the quasi-elastic 2H(e, e′n) reaction, which yields information on the charge and magnetic elastic form factors of the neutron.

Effects of ground-state correlations on high energy scattering off nuclei: The case of the total neutron-nucleus cross section

With the aim at quantitatively investigating the longstanding problem concerning the effect of short-range nucleon-nucleon correlations on scattering processes at high energies, the total neutron-nucleus cross section is calculated within a parameter-free approach which, for the first time, takes into account, simultaneously, central, spin, isospin, spin-isospin, and tensor nucleon-nucleon correlations, and Glauber elastic and Gribov inelastic shadowing corrections. Nuclei ranging from $^{4}\mathrm{He}$ to $^{208}\mathrm{Pb}$ and incident neutron momenta in the range 3 GeV/$c$--300 GeV/$c$ are considered; the commonly used approach which approximates the square of the nuclear wave function by a product of one-body densities is carefully analyzed, showing that $\mathit{NN}$ correlations can play a non-negligible role in high energy scattering off nuclei

Diffractive dissociation reaction np → Λ0K0p for incident neutron momenta between 30 and 70 GeV/c

Diffractive dissociation reaction np → Λ0K0p for incident neutron momenta between 30 and 70 GeV/c

Study of the dissociation reactionn+p→pπ−+pfor incident neutron momenta between 50 and 300 GeV/c

We present results of our study of the neutron dissociation reaction n + p ..-->.. (p..pi../sup -/) + p for incident neutron momenta between 50 and 300 GeV/c. The integrated dissociation cross section for small values of (p..pi../sup -/) mass is essentially constant over this momentum interval. A strong correlation exists between the square of the four-momentum transfer (t) and the (p..pi../sup -/) rest mass, as well as between t and the decay angles of the (p..pi../sup -/) system. The observed (p..pi../sup -/) mass distribution is comprised of contributions from both narrow resonance like peaks and a broad low-mass continuum. Moments of the (p..pi../sup -/) decay angular distributions reveal rich structure, suggesting the presence of many partial waves.

Neutron-deuteron elastic scattering from 6 to 12.5 GeV/c

The differential cross section for neutron-deuteron elastic scattering was measured for four-momentum transfers 0.3 < − t < 2.0 (GeV/c) 2 with incident neutron momenta between 6 and 12.5 GeV/c. The measurement was made with spark chambers at the Argonne ZGS. Results are compared with proton-deuteron elastic scattering at comparable energies as a test of isospin invariance in strong interactions and with the predictions of the Glauber multiple scattering theory. Very good agreement is found.

Neutron-proton charge-exchange scattering between 600 and 2000 MeV/c

$n\ensuremath{-}p$ elastic differential cross sections in the charge-exchange region have been measured for incident neutron momenta between 600 and 2000 MeV/c. The momentum of neutrons incident on a liquid-${\mathrm{H}}_{2}$ target was determined by a measurement of flight time over a 32.9-m flight path. The momentum and scattering angles of the recoil proton were measured by a wire-spark-chamber magnetic spectrometer. Approximately 450 000 elastic events were detected for proton laboratory angles between 0\ifmmode^\circ\else\textdegree\fi{} and 62\ifmmode^\circ\else\textdegree\fi{}. Differential cross sections are presented at 16 energies. An absolute normalization of the cross sections was achieved by measuring the incident neutron flux with a detector whose efficiency was determined experimentally.

Neutron-nucleus total cross sections from 900 to 2600 MeV/c

Neutron-nucleus total cross sections have been measured for 12 elements with an overall accuracy of ≈ 5%. Incident neutron momenta, determined by time of flight, were between 900 and 2600 MeV/ c. The momentum and atomic weight dependence of the data have been parametrized in the form σ T = σ o ( P) A β where β = 0.75 ± 0.02.

Neutron-proton elastic scattering from 5 to 30 GeV/c

The differential cross section for neutron-proton elastic scattering was measured in the diffraction region with incident neutron momenta between 5 and 30 GeV/ c. The experiment was an optical-spark-chamber-counter experiment conducted at the Brookhaven National Laboratory alternating gradient synchrotron. A well collimated neutron beam with a broad energy spectrum was incident on a liquid hydrogen target. The scattered neutrons were detected in a thick-plate spark-chamber array while the recoil protons were detected and momentum analyzed in a magnetic spectrometer with thin-foil spark chambers. The results indicate that the neutron-proton cross sections are very similar to but not identical with the proton-proton cross sections. The diffraction peak in the neutron-proton system does show shrinkage with increasing incident momentum but exhibits no auxiliary structure.

Neutron-Proton Elastic Scattering from 8 to 30 GeV/c

The differential cross section for neutron-proton elastic scattering was measured in the diffraction region with incident-neutron momenta between 8 and 30 GeV/c. The experiment was a spark-chamber-counter experiment, conducted at the alternating-gradient synchrotron. Results are presented and compared with currently available lower energy $\mathrm{np}$ data and comparable energy $\mathrm{pp}$ data.

Structure in Neutron-Proton Charge Exchange

Neutron-proton charge-exchange differential cross sections for incident-neutron momenta between 600 and 2000 MeV/c show a sharp change in the slope of $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ vs -$u$ in the vicinity of $\ensuremath{-}u=0.01$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. Near the one-pion threshold the slope at $u=0$ shows a maximum which reaches a value of order 100 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{\ensuremath{-}2}$. Also presented, as a function of $s$, is the intercept at $u=0$ which shows a pronounced deviation from smoothness in the region above the inelastic threshold.