A. W. Stetz

Cross section and analyzing powers for the reaction pd→3He + γ at intermediate energies

Abstract We report the results of measurements of the differential cross section and analyzing power for the reaction pd → γ 3 He at six energies in the range 200 E p E p = 500 MeV are not yet explained by microscopic models.

Radiative capture of polarized neutrons by hydrogen below the pion production threshold

Abstract We report the results of measurements of the differential cross section and analyzing power for the radiative capture of polarized neutrons by hydrogen at E n = 180 and 270 MeV. The experimental results are compared to predictions of various theoretical models of this process to examine the sensitivity to details of the short range part of the NN interaction and to those contributions which arise due to non-nucleonic degrees of freedom in the interaction of the photon with the nucleus.

The reaction 2H(p,π+)3H at 470 and 500 MeV

Abstract Angular distributions of the cross section at 470 and 500 MeV and the analyzing power at 500 MeV incident proton energy are presented for the reaction 2 H ( p ,π + ) 3 H . The cross section and analyzing power measurements cover the respective angular ranges 10°

Pion double charge exchange on 3He and 4He

Abstract We have measured the differential cross section d 2 σ/ d Ω d T for the double charge exchange reactions 4He(π+, π−)4p and 3He(π−, π+)3n at 140, 200 and 295 MeV. By fitting this data with a simple phase-space model we have estimated the integrated cross section d σ/ d Ω and the total cross section. The 4He data agree qualitatively with the predictions of a meson exchange calculation and with one version of the successive single charge exchange model. The 3He cross sections are considerably larger than those of 4He and in some cases the missing mass plot shows a strong enhancement, which resembles a broad three-nucleon resonance.

Large angle 2H(p, 2p)n at 507 MeV

Abstract Fivefold differential cross sections for the reaction 2 H(p, 2p)n have been measured at 507 MeV, for symmetric kinematics at 50°, 52°, and 66°. The results are in excess of the PWIA prediction, but in good agreemment with a recent calculation of pion exchange diagrams including virtual excitation of the Δ(1232).

A study of the reaction pd → 3Heγ

Abstract We have measured the cross sections for the radiative capture reacrtion pd → 3 He γ at a range of proton energies from 200 to 500 MeV. The results are presented in the form of excitation functions at center-of-mass angles 60° and 90°. These results are compared with other radiative capture cross sections and with equivalent photodisintegration experiments using detailed balance.

Analyzing powers in the np → dγ reaction at 180 and 270 MeV

Abstract Using a polarized neutron beam and liquid hydrogen target, we have measured the analyzing power for the reaction np → d γ at neutron beam energies of 180 and 270 MeV. Our results are compared with recent calculations.

Elastic π± + 3He scattering

Abstract Differential cross sections have been measured at θ ≈20–120° at 50, 100 and 200 MeV. Salient features of the angular distributions are Coulomb interference effects at 50 MeV and clear spin-flip contributions to π − compared to π + scattering in the angular region of θ ≈80° dominated by the πN p-wave minimum. Comparison with optical model calculations account for the data up to 200 MeV while this first-order scattering theory misses conspicuous features of data at 295 MeV.

Cross section and analyzing powers for the reaction p3H → γ4He at Ep = 227, 300 and 375 MeV

Abstract Cross sections and analyzing powers for the radiative capture of polarized protons by tritium have been measured at energies of 227, 300, and 375 MeV. The cross-section results are in good accord with data taken for the inverse photodisintegration reaction assuming detailed balance which indicates there is no violation of time-reversal invariance. The experimental results are compared with distorted wave impulse approximation calculation and it is found that the inclusion of meson exchange current effects is important in this energy range.

The efficiency of counter telescopes for intermediate energy protons

Abstract The efficiency of counter telescopes containing a 15.2 cm thick NaI(Tl) crystal for detecting protons with energies in the range 50–350 MeV has been measured. An investigation was made of the dependence of the efficiency on the position of the proton in the counter. The results of the measurements are in close agreement with the calculations of efficiencies using available reaction cross section data.