V. Abaev | Searcharxiv

arXiv2009

Differential cross sections of the charge-exchange reaction pi- p --> pi0 n in the momentum range from 103 to 178 MeV/c

Measured values of the differential cross sections for pion-nucleon charge exchange, pi- p --> pi0 n, are presented for pi- momenta of 103, 112, 120, 130, 139, 152, and 178 MeV/c. Complete angular distributions were obtained by using the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Statistical uncertainties of the differential cross sections vary from 3% to 6% in the backward angle region, and from 6% to about 20% in the forward region with the exception of the two most forward angles. The systematic uncertainties are estimated to be about 3% for all momenta.

hep-ex↗

arXiv2001

Spin-triplet final-state dominance in the pp -> pn pi+ reaction at 492 MeV

The near-forward cross section for the pp -> pn pi^+ reaction has been measured at 492 MeV by using the large acceptance ANKE magnetic spectrometer placed at an internal target position of the storage ring COSY-Juelich. Protons and pions emitted near zero degrees were detected in coincidence, and those with theta_pi <= 2 degrees and theta_p <= 2.5degrees were subjected to detailed analysis. Under these conditions, the excitation energy in the np system was below 3 MeV over the measured momentum range. This is the region of the np final-state-interaction peak, which was measured with a resolution of a fraction of an MeV. The shape of the peak allows one to conclude that the fraction of final spin-singlet np pairs is below about 10%. By using the results of scattering theory, this limit is confirmed through a comparison with the cross section for pp -> d pi^+. The smallness of the singlet contribution is consistent with trends seen in lower energy data.

nucl-ex↗