GUANGXI NORMAL UNIV,DEPT PHYS,GUILIN 541001,PEOPLES R CHINA
; CHINA CTR ADV SCI & TECHNOL,WORLD LAB,BEIJING 100080,PEOPLES R CHINA
; ACAD SINICA,INST HIGH ENERGY PHYS,BEIJING 100039,PEOPLES R CHINA
; SCH ZHEJIANG LIGHT IND,DEPT PHYS,HANGZHOU 310015,PEOPLES R CHINA
; ZHEJIANG UNIV,DEPT PHYS,HANGZHOU 310027,PEOPLES R CHINA
Elastic and inelastic scattering data of 1.37 GeV alpha particles on C-12 and Ca-40,Ca-42,Ca-44,Ca-48 are analyzed within the framework of the Glauber theory. Collective excitations to one-phonon levels are treated using the Tassie model. The effect of the coupling between the elastic and inelastic channels is considered. It is shown that a phase variation of the nucleon-nucleon elastic scattering amplitude leads to a large increase in the calculated differential cross section. The presence of a phase variation leads to a substantial improvement.