Pion-nucleus total cross sections in the (3,3) resonance region

Abstract

The results of total cross section measurements are presented for~' on targets of natural Li, C, Al, Fe, Sn, and Pb in the region of 65 -320 MeV laboratory kinetic energy.The data are fitted with a simple phenomenological model, which allows one to extract the A dependence of the peak energy and width which characterize the pion-nucleus interactiorr.There have been several recent experiments to measure pion-nucleus total cross sections on light nuclei in the energy region corresponding to the (3, 3) resonance in the elementary vN interaction. 'Ĩ n the present note, we present results for total cross sections o", of v' on a range of nuclei from Li to Pb. One of the principal motivations of the experiment was to study the dependence of the position and width of the peak in 0", on target mass number A. The shift and broadening of the peak has been discussed theoretically in terms of multiple scattering effects, ' the Pauli principle, ' and "collisions damping" processes. ' The latter two effects lead to modifications of the pion-nucleon amplitude in the nucleus. Calculations with simple first order optical potentials8 [proportional to the nuclear density p(r) times the Fermi-averaged free space vN amplitude] do not correctly predict the position or the width of the peak in cr",. Since the present experiment provides the first measurements involving heavy targets, the results may be useful in untangling the various competing mechanisms which shift and broaden the mN isobar in the nucleus.We have performed measurements of the total cross sections for 7t' at 14 lab kinetic energies between 65 and 320 MeV, and for m at 8 energies between 80 and 320 MeV, on natural targets of Li, C, Al, Fe, Sn, and Pb. We used the same low energy separated beam from the AGS and the same detector system as in two previous experiments. '" Incident pions were selected by a differential Cerenkov counter and proportional wire chamber system. The nuclear targets were 15 cm && 15 cm && 5 g/cm' thick, and were positioned just downstream of the liquid-hydrogen-deuterium target system used in the previous experiments. The simultaneous measurements on hydrogen and deuterium will be "eported elsewhere. At each inci-dent energy, the transmission of the beam was measured, for no target and for each of the six nuclear targets, with nine circular scintillation counters of different size. Compensation for particle absorption was made electronically. " The counters were always positioned corresponding to a fixed region of four-momentum transfer~tf rom 0.002 to 0.004 (GeV/c)'. The total cross sections were obtained in the usual way by using a linear extrapolation to t; =0 of the partial cross sections o'", measured with each counter.Before extrapolating, it was important to make corrections to the observed 0'" to remove the effects of (1) beam decay losses a, "' which were different for target and no-target measurements, and (2) Coulomb a~c" and Coulomb-nuclear interference chic'"' corrections. The values o~"' were computed by a Monte Carlo method, which i...

Transport-theoretical description of nuclear reactions

“…[143,144,145,146]). However, there exist only a few data points for pions scattering off complex nuclei [147,148,149,150,151,152,153]. Our results on reaction and charge-exchange cross sections are presented in [140,55].…”

Measurement of muon neutrino and antineutrino induced single neutral pion production cross sections

“…In the case of the total cross section, the Breit-Wigner function is replaced by a parameterization laid out by Carrol et al [166]. e available data, models, and parameterizations just described appear in In each reaction interaction, the multiplicity of a given secondary is drawn from a Poisson distribution whose mean is the ratio of the total cross section for that channel to the total reaction cross section, i.e.…”

A search for muon neutrino and antineutrino disappearance in the Booster Neutrino Beam

“…The detector is assumed to be a sphere with small "top hat" at the top, filled with mineral oil of the appropriate density based on measurement (Section 3.4). The detector sits inside a concrete, cylindrical vault filled with air, which is surrounded by "dirt" (ρ = 2.15 g/cm 3 ) on all sides and [101], open [103], solid [100], open [50]). The total cross section (black), inelastic (blue), absorption (red) and charge exchange (green) are shown.…”