[Clas_gsim] Help needed on GSIM FFREAD cards

[Francois-Xavier Girod]

Dear Krishna,

1) only the 4 first letters are used, so this is the same card

2) in the current version of GSIM under
/u/home/claseg4/software/packages/gsim
I have found trace of PTGSCALE only in the readfile

I have not found trace of PTMGSCALE
I think the correct key is TMGSCALE

Those statements are also true from the package version under the common CLAS environment.

3) still from the package under claseg4
PTGFIELDM is in ffky_sol.F (Saclay solenoid)
TMGFIELDM is in ffky_ptg.F (polarized target)
Both of them set the same variable ptg_fieldm which is the _design_ maximum of the field

my understanding is that both TMGSCALE and TMGFIELDM are used
the default "maximum field" (design maximum) for ptg is 51 kG
the default scale is 0.979
so the actual maximum field by default is 49.92 kG

If you specify TMGFIELDM = 49.92 and TMGSCALE = 0.979
then the resulting maximum field would be 49.92*0.979 !
(disclaimer : that is my understanding from a grep of the variables in the source code directory)

4) I did not find a key PTGIFIELD but I did a key find TMGIFIELD
this key sets the internal variable ptg_ifield
ptg_ifield = 1 -> polarized target
ptg_ifield = 2 -> Saclay solenoid

5) see 4)

I hope that helps. I suppose someone more familiar with eg4 simulation should look into this.

Best regards,
Francois

----- Original Message -----
From: adhikari at jlab.org
To: "clas gsim" <clas_gsim at jlab.org>
Sent: Friday, February 22, 2013 8:08:39 PM
Subject: [Clas_gsim] Help needed on GSIM FFREAD cards

Can anyone explain to me the difference between the following cards?

1) BAFF & BAFFES - Which one is the correct card name for the Baffels -
BAFF or BAFFES? I have seen BAFF used & the following reference page only
lists BAFFES? Should either one work or are they different?

2) PTGSCALE & PTMGSCALE : Equivalent?

3) Is it redundant to use both PTGFIELDM, & PTGSCALE. If not what's the
difference?

4) How about PTGIFIELD? And, what should be the value to simulate for the
EG4 experiment which used polarized NH3 & ND3 targets (with 5T=50kG
field)? There doesn't seem to be enough information in the only reference 
(http://nuclear.unh.edu/~maurik/Gsim/gsim_doc_ffread.shtml) that I could
find.

5) Now, I have seen other people also using TMGIFIELDM. May I know what is
the difference between TMGIFIELDM & PTGFIELDM?

Any bit of information will be greatly appreciated.

With best regards,
Krishna
















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