Optical Model Analysis Of The Elastic Scattering Of Alpha Particles By Helium Between 53 And 120MEV

For discussing reciprocal common rule of particle and nucleus or calculating some no easy determining differential cross sections ,we must look for what is called at large optical model potential ,namely,in a limited energy range and target range ,it is result in concordance with experimential data. In terms of the view point of the least square fitting, at the same time ,the three sort in common use optical model's form was known. Throught elastic scattering differential cross section of α? α,Utilizing obtain the optical potential parameters of the optical potential for the α? αsystem by fitting to each energy experimental data, at the first ,the form ,we made use of, three sorts potential ,namely: (1) V(r)=-V₀/[exp((r-r₀A¹/3)/a₀)]-i*W/[exp((r-r_wA¹/3)/a_w)]+V_c(2) V(r)=-V₀exp[-a₀*r²]-i*W/[exp((r-r_wA¹/3)/a_w)]+V_c(3) V(r)=-V₁exp[-a₁*r²]-V₂exp[-a₂*r²]-i*W/[exp((r-r_wA¹/3)/a_w)]+V_cAt the first ,we took the first potential as real part of the optical potential we found that the parameters of r0 ,a0 change are not very big wide ,thus we limited r1 , A1,only alter V W r0 A0 to optimize the fit to the experimental data. We looked out the real parameter V1 numerical value has relation to the energy of incidence particle .using this potential as the real part of we need ,we adopt the partial wave method to deduce the formula of scattering amplitude ,use fortran compiling to calculate phase shifts ,and then calculate elastic differential cross sections of α? αat the energies of Tα=53.40,　58 .49,　63 .91,69. 91,　77 .55,1　00 , 1　20 ,158, 　20 0,　280MEV.compared with the experimental data ,all the calculations prove that the variation tendency of the cross sections is all shown .the calculations are in agreement with the experimental data ,the value of the cross sections and the positions of the minimum and maximum are well predicted. Secondly we used the second form to fit experimental data .we found that the relation of α0 and energy is not osculation .According to the same method, We looked out the real parameter V 0 numerical value has relation to the energy of incidence particle .Using the relation ,we have been calculated the elastic differential cross sections of all energy .but it is not good compare with form(1) Lastly ,using the last form ,we found that the result of fitting experiment data very good ,but non-parameter has not relation to the energy of incidence particle. But this attempt of find the parameter of at large apply optical model potential failed.