[Halla12_software] BaBar magnet yoke question (two more questions then my last email)

[xqian]

Hi Zhiwen,
     Here are the my answers to 3. and 4.

     3.  In the first proposal, we used BABAR, but when we did the 
second proposal, there is a rumar saying that the BABAR magnet will not 
be available. So we decided to go for the CDF magnet, the exercise that 
we did is to look into this option to see whether it can satisfy our 
needs. Naively, for PVDIS, there is no major change, since one can move 
the target more down-ward, since the magnet is longer. For SIDIS, it is 
a big chance, since now the detector are in more forward angle. We would 
prefer to have BABAR magnet to position the detector in a slightly less 
forward angle. This option can also help with the SIDIS phase space.

     4. At that time, I did not have more time in updating the geometry 
in generating the field. So I took the easy approach of changing the 
Poisson geometry file directly from the BABAR option. In the proposal 
stage, we do not care very much about the exact field mapping. A general 
idea is good enough. For the new studies, we would like to have a more 
realistic field map. I think it is a very good idea to unify the design 
in both cases.

     Thanks a lot for looking carefully into both cases.

On 2/8/2011 8:05 PM, Zhiwen Zhao wrote:
> Hi, Paul,Eugene,Xin
>
> Four questions
>
> 1.
> I notice the there is a overllap between two parts of yoke just around 
> the coil, as you can see from the lines of the am file
>
> ==================================================
> &reg mat=    2 &                ;     6
> &po y=    -187.2    ,x=    180 &
> &po y=    187.2    ,x=    180 &
> &po y=    187.2    ,x=    186 &
> &po y=    -187.2    ,x=    186 &
> &po y=    -187.2    ,x=    180 &
>
> ;&reg mat=    2 &                ;     4
> ;&po y=    -187.2    ,x=    185.2 &
> ;&po y=    187.2    ,x=    185.2 &
> ;&po y=    187.2    ,x=    189.2 &
> ;&po y=    -187.2    ,x=    189.2 &
> ;&po y=    -187.2    ,x=    185.2 &
> ===================================================
> Then I notice it's the same in Eugene's geometry input file for comgeant
> So I just want to confirm with you guys before I correct it.
>
> 2.
> for the cryo of the coil, there's the outer part made of Iron. It's 
> not included in AM file. But I think it should because it will affect 
> the field. Or is there other reasons to exclude it?
>
> 3.
> Both PVDIS and SIDIS used Babar magnets in their first version of 
> proposal, then used CDF in the second version. Why is the change? 
> Maybe the reason was made clearer before I join in?
>
> 4.
> in SIDIS second version proposal, CDF yoke design was very similar to 
> Babar design, only longer. What's the reason you design CDF yoke very 
> differently now, Paul?
>
> Thanks
>
> Zhiwen


-- 

Best regards,

Xin

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Dr. Xin Qian
Postdoctoral Scholar @ Kellogg Radiation Lab of Caltech
Phone: 1-626-395-4267 (o)
MS 106-38 Caltech, 1200 East California Blvd,
Pasadena, California, 91125
skypename: lastgeorge
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