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

[Eugene Chudakov]

Yes, it was a mistake in the geometry.
I should be something like:

GPARVOL41  'SY01'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  180.0 182.0  187.2

What happens with overlapped  volume like that, is that one of them might be skipped
at the tracking stage. Fortunately, it is a part of the yoke barrel and not on the way 
of useful particles. Sitting behind the coil it also would hardly affect the background.

The GEANT geometry contained fine steel plates, close to the drawings of
the BaBar yoke. However, it is cylindrical - a simplification with respect to the
hexogonal BaBar structure.
The Poisson geometry contained thicker cylinders - in order to speed up the calculations 
(a coarser mesh is sufficient).

Eugene

On Wed, 9 Feb 2011, Zhiwen Zhao wrote:

> On 02/09/2011 11:30 AM, Eugene Chudakov wrote:
>>>>> for the cryo of the coil, there's the outer part made of Iron. It's
>> 
>> The cryo tanks are made from stainless steel, non-magnetic.
> I didn't know that. I only notice in geometry file, they are same material 
> coded as 210
>
> GPARVOL30  'SOLE'    0  'HALL'    0.    0.    0.    0  'TUBE'  3  1. 1. 1.
> GPARVOL31  'CRYO'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  142. 177. 
> 192.5
> GPARVOL32  'CRYV'  221  'CRYO'    0.    0.    0.    0  'TUBE'  3  147. 172. 
> 187.5
> GPARVOL33  'SCL1'  209  'CRYV'    0.    0.    0.    0  'TUBE'  3  152. 154. 
> 175.0
>> 
>>> Eugene answered this. one of them is commented out in am file, I will
>>> correct it in geometry file.
>> 
>> What was there in the geometry file?
> SY02 was not comment out
>
> C --     BaBar barrel yoke simplified
> C
> GPARVOL41  'SY01'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  180.0 186.0 
> 187.2
> GPARVOL42  'SY02'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  185.2 189.0 
> 187.2
> GPARVOL43  'SY03'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  195.6 199.6 
> 187.2
> GPARVOL44  'SY04'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  206.0 210.0 
> 187.2
> GPARVOL45  'SY05'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  216.4 220.4 
> 187.2
> GPARVOL46  'SY06'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  226.8 230.8 
> 187.2
> GPARVOL47  'SY07'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  237.0 246.0 
> 187.2
> GPARVOL48  'SY08'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  255.6 264.6 
> 187.2
> GPARVOL49  'SY09'  210  'SOLE'    0.    0.    0.    0  'TUBE'  3  275.0 290.0 
> 187.2
>
>> 
>> Eugene
>> 
>> 
>> On Wed, 9 Feb 2011, Zhiwen Zhao wrote:
>> 
>>> On 02/09/2011 10:30 AM, Paul E. Reimer wrote:
>>>> Hello Zhiwen,
>>>> 
>>>>> 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
>>>> I'll have to look at this in more detail
>>> Eugene answered this. one of them is commented out in am file, I will
>>> correct it in geometry file.
>>>>> 
>>>>> 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?
>>>> I don't know what the material is.
>>> shape materiel inner outer half length
>>> Tube Iron 142. 177. 192.5
>>> Tube Air 147. 172. 187.5
>>> Tube Al 152. 154. 175.0
>>>>> 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?
>>>> In fact, I was under the impression that Babar was used for the
>>>> acceptance of both detectors, while CDF was used for the engineering
>>>> report. This was because we had engineering reports and access to the
>>>> CDF magnet at Argonne and our engineer's worked on this. At the
>>>> proposal stage, since we were just dealing with a concept, that seemed
>>>> to work.
>>> refer to Xin's reply
>>>>> 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?
>>>> I spent more time looking at the field shape this time. In particular,
>>>> I tried to obtain the same footprint for the detector area with minimal
>>>> magnetic field in that area. In reality, the question goes back to the
>>>> detector designers--how much space to you need? The other thing that I
>>>> did on the recent CDF design is to assume that the target is moved
>>>> forward in the magnet.
>>> Besides the two end cups, the middle part of the yoke are different.
>>> Are those middle part come with magnet so we can't really modify them?
>>> BaBar design has many more details in the middle part which I think
>>> Eugene did it not only for field but also engineering concern. Do want
>>> CDF to take advantage of that?
>>>> 
>>>> Paul
>>>> 
>>> Zhiwen
>>> 
>