Discussion surrounding IKIN flag of EXPT
Posted: Thu Feb 25, 2016 2:18 pmIn section 7.8 of the manual "EXPT (Mandatory suboption of OP,COUL and OP,GOSI)", the IKIN flag is explained for inverse kinematics experiments.
In my opinion it is very misleading to state that "When using OP,INTI, then the IKIN input is ignored and selection of the solution is chosen internally by GOSIA.". This is of course true as a standalone statement, but I fear that (and have evidence in support) people assume that IKIN has no bearing on anything other than the integration. However, the values given in EXPT are used to calculate the point yields, which are used to calculate correction factors and later used during the OP,MINI stage. If the IKIN flag is not set correctly here, there is potential for very strange things to happen in the minimisation because the point yields and correction factors will not match up to those calculated during the OP,INTI stage.
Therefore, I would suggest that this part is rephrased or a sentence added explaining that IKIN should be set correctly if one is to use OP,MINI later in the process.
As a side note in this section, it would be a good idea to define "backwards" and "forwards" CM angles in a less ambiguous way. Although I understand that this can be deduced, the ambiguity is unnecessary. One sentence stating that backwards CM angles correspond to larger centre-of-mass angles for the projectile and vice versa. Or the following:
Best regards,
Liam
In my opinion it is very misleading to state that "When using OP,INTI, then the IKIN input is ignored and selection of the solution is chosen internally by GOSIA.". This is of course true as a standalone statement, but I fear that (and have evidence in support) people assume that IKIN has no bearing on anything other than the integration. However, the values given in EXPT are used to calculate the point yields, which are used to calculate correction factors and later used during the OP,MINI stage. If the IKIN flag is not set correctly here, there is potential for very strange things to happen in the minimisation because the point yields and correction factors will not match up to those calculated during the OP,INTI stage.
Therefore, I would suggest that this part is rephrased or a sentence added explaining that IKIN should be set correctly if one is to use OP,MINI later in the process.
As a side note in this section, it would be a good idea to define "backwards" and "forwards" CM angles in a less ambiguous way. Although I understand that this can be deduced, the ambiguity is unnecessary. One sentence stating that backwards CM angles correspond to larger centre-of-mass angles for the projectile and vice versa. Or the following:
IKIN The centre-of-mass scattering angles chosen corresponding to laboratory angles
0 This selects the higher centre-of-mass angles of the projectile
1 This selects the lower centre-of-mass angles of the projectile
Best regards,
Liam