Notes about
changes
to qfs_new12_sub.f
- Modified the form factors Ge and Gm for proton and neutron
in function sigqfs . This function calculates elastic and
quasi-elastic cross sections.
- Add the subroutines get_gegm_prot and get_gegm_neut at the end of
qfs_new12_sub.f . These codes return Ge and Gm/u . For
get_ge_gm_prot there are two options: "dipole" and "bosted" . "bosted'
is a fit by Peter Bosted. Previously the code was using "dipole". For
get_gegm_neut the two options are: "dipole" and "walcher". "walcher" is
a fit to data by J. Friedrich and Th. Walcher in Eur.Phys.J. A17 (2003)
607-623. "dipole" is the usual dipole shape for proton Ge, Gm and
neutron Gm with the neutron Ge treated specially as shown below in
example of the old code. To change from one model to another, one has
to change the variable model in
the subroutines.
- Modified section of
code in function sigqfs so that one can have Ge and Gm have different
values. The following code:
formp=1.+qms*up**2/4./pm**2
formp=formp/(1.+qms/4./pm**2)
formp=formp+qms*up**2*tan(thr/2.)**2/2./pm**2
formp=formp*fd(qms,ap)**2
sigep=signs*formp
falloff=(1.+5.6*qms/4./pm**2)**2
formn=(qms*un/4./pm**2)**2/falloff+qms*un**2/4./pm**2
formn=formn/(1.+qms/4./pm**2)
formn=formn+qms*un**2*tan(thr/2.)**2/2./pm**2
formn=formn*fd(qms,ap)**2
call get_gegm_prot(qms,ap,gepsq,gmpsq)
gmpsq=gmpsq*up**2
formp=gepsq+qms*gmpsq/4./pm**2
formp=formp/(1.+qms/4./pm**2)
formp=formp+gmpsq*qms*tan(thr/2.)**2/2./pm**2
sigep=signs*formp
call get_gegm_neut(qms,ap,gensq,gmnsq)
gmnsq=gmnsq*un**2
formn=gensq+qms*gmnsq/4./pm**2
formn=formn/(1.+qms/4./pm**2)
formn=formn+gmnsq*qms*tan(thr/2.)**2/2./pm**2
- Comparison of the
above parametrization to world data is shown in plots of proton Ge and Gm and
neutron Gm. Also, in
the proton Ge and Gm plots are comparisons to a fit by John Arrington
and the parametrization that is in MASCARAD. At the kinematics of
RSS elastic, Ge is not important. For proton Gm, the MASCARAD
parametrization is a little high.