Evidence For Enhancement Of The Total Reaction Cross Sections For P-27,P-28 With A Si-28 Target And Examination Of Possibly Relevant Mechanisms

The reaction cross sections of P-27,P-28 and the corresponding isotones on Si target were measured at intermediate energies. The measured reaction cross sections of the N=12 and 13 isotones show an abrupt increase at Z=15. The experimental results for the isotones with Zless than or equal to14 as well as P-28 can be well described by the modified Glauber theory of the optical limit approach. The enhancement of the reaction cross section for P-28 could be explained in the modified Glauber theory with an enlarged core. Theoretical analysis with the modified Glauber theory of the optical limit and few-body approaches underpredicted the experimental data of P-27. Our theoretical analysis shows that an enlarged core together with proton halo are probably the mechanism responsible for the enhancement of the cross sections for the reaction of P-27+Si-28.