Reaction Cross Section Measurements for p,d,3He and 4He at Intermediate Energies

Abstract: Reaction cross sections were measured for protons at 65.5 MeV, for deuterons at 37.8, 65.5, 97.4 MeV, for 3He at 96.4, 137.8, 167.3 MeV, and for 4He at 69.6, 117.2, 163.9 and 192.4 MeV. Targets were 9Be, 12C, 16O, 28Si, 40,48Ca, 58,60Ni, 112,116,118,120,124Sn and 208Pb. 48Ca and 118Sn targets were used only for some of the measurements. Rest of the targets have been measured for all energies and projectiles but 4He at 69.6 MeV where reaction cross sections were measured for 9Be, 12C, 16O, 28Si, 40Ca targets. A modification of a standard attenuation technique was used. Details of the experimental design are presented.Experimental uncertainties were 2-3% for p, 3% for d and 3-10% for 3,4He. A strong forward peaking of the reaction products was observed for 3,4He. Therefore the standard reaction cross section measurement technique was not applicable for these projectiles. The forward peaking is also responsible for the increase of experimental uncertainties for these projectiles. The forward peaking of the reaction products is not known for other projectiles and has also not been observed with 3,4He at different - both higher and lower - energies. Possible explanations for this phenomenon are discussed.Optical model calculations of the reaction cross sections are in good agreement with the measured values.The measurements were performed with beams from the Gustav Werner cyclotron at the The Svedberg Laboratory, Uppsala.