P. Radvanyi

The p(3He,t)Δ++ reaction

Abstract Data are presented for the p(3He,t)Δ++ reaction at 2.0, 2.3 and 1.5 GeV. The reaction specifically excites the Δ++ with very little yield outside the resonance. The data are analysed as one pion exchange and the hadronic form factor for the 3He−1 system is extracted and compared with the magnetic form factor from electron scattering.

Coherent pions in charge-exchange reactions☆

Abstract Data are presented on the 12 C ( 3 He , t π + ) reaction at 2 GeV bombarding energy. In coincidence with forward scattered tritons, pions are momentum-analysed in a large acceptance detector. For events where the target is left in its g.s. or low-lying states, the angular correlation between the momentum transfer vector and the momentum of the pion is sharply peaked at small relative angles.

Exchange effect in the 166 MeV α-particle elastic scattering on 6Li

Abstract The angular distribution of the elastic scattering of 166 MeV α-particles on 6Li nuclei has been measured from 3° to 175° (c.m.). The backward rise of the cross section is explained in terms of two-nucleon pick-up. The symmetry of the entrance and exit channels makes the measurement a good test of the applicability of finite-range DWBA calculations for this exchange effect. This effect is shown to become negligible for heavier nuclei like 40Ca.

Pion photoproduction on 3He at and above the 3-3 resonance

Abstract The differential cross section for the 3 He (γ, π + ) 3 H reaction has been measured at fixed values of q2 in the region of the first resonance, and at fixed θπ versus q2 up to 13 fm−2. The observed shift of the resonance towards lower energies, and the absence of a minimum near 11.6 fm−2 might be explained by recent theoretical calculations.

Excitation of the Δ resonance in relativistic heavy ion charge exchange reactions

Abstract Excitation of the Δ resonance has been observed for the first time in a heavy ion reaction. The strength of the Δ signal depends on the projectile nuclear structure. In the same incident energy range, about 900 MeV per nucleon, we observe — a strong Δ excitation in 27 Al( 20 Ne, 20 F) and 27 Al( 20 Ne, 20 Na), — a weak Δ in 12 C( 14 N, 14 C) and — nearly no Δ excitation in ( 12 C, 12 B) and ( 12 C, 12 N) whatever the target is among a sample of nuclei from 12 C to 89 Y.

Study of elastic ?-scattering from2H and12C at E?=4.2 GeV

Elastic scattering ofα-particles from deuterium and12C has been investigated usingα-particles from Saturne. The differential cross sections have been analysed within an optical model description using a folding potential. Matter radii extracted at this energy are consistent with radii deduced from electron scattering.

Search for a nucleon-participant multiplicity effect on a possible anomalous fragment production

Momentum spectra of projectile fragments from 1.1 A GeV20Ne interactions with a Fe target have been measured with associated charged-particle multiplicity of participant nucleons. We also measured fragment absorption by introducing a Fe absorber. We searched for enhanced anomalous fragment production for fragments of charge 6≦Z≦ 10 as a function of multiplicity. To the possible exception of18Ne, a negative result is reported.