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Hi TIm,

Yes, I suspected that it might be a visualization issue.
The reason I was not sure is that I can see the same as you described
about colors and arrows but simply as 1/2 field with Z=0 not at the
center of the magnet.

Thanks, Stepan
On 3/10/14 10:36 AM, Nelson, Timothy Knight wrote:
> Hi Stepan,
>
> I think the problems at this point are all due to the visual representation. Colors and arrow lengths are field strength, red being large and green to blue being relatively smaller. I am not sure why the field is cut off on the downstream side, but still well past z=0, in this image but I'm pretty sure that's a problem with the visualization based on the map data I saw that goes into this.
>
> Tim
>
> Sent from my iPad
>
>> On Mar 7, 2014, at 8:48 AM, "Stepan Stepanyan" <[log in to unmask]> wrote:
>>
>> Hello Jeremy,
>>
>> Thanks for implementing the field. I am not sure how much I should trust
>> the visual picture, but the field you have is generated from the middle of
>> the magnet (in Z), so if I am reading the picture correctly, field is
>> shifted
>> relative to the magnet. For completeness the same (X,+Z) distribution must
>> be repeated for (X,-Z) half plane.
>> One of things we have discussed with Norman some time ago is the need
>> for a full 3-D field map (B_x, B_y, B_z) for (X, Y, Z) points. Will be
>> good to
>> know this early on.
>>
>> Regards, Stepan
>>
>>> On 3/6/14 7:28 PM, McCormick, Jeremy I. wrote:
>>> Hi,
>>>
>>> I made a few fixes to SLIC/LCDD for the support of 3D magnetic field maps.  The map’s offsets were not being set correctly, and I believe this is now fixed in the HEAD configuration of SLIC in ilcinstall.
>>>
>>> I also added the missing field data to the SVN at hps/java/trunk/fieldmap which is referenced by the detector that includes the field map.
>>>
>>> I was able to get simple visualization working with the 10.00.p01 release of Geant, and the best picture I have so far is this:
>>>
>>> http://www.slac.stanford.edu/~jeremym/hps/field/hps_field7.png
>>>
>>> This visualization tool is at an “alpha” stage of development in that project, unfortunately, but it at least gives some idea that the field has been loaded in successfully.
>>>
>>> That’s the good news.
>>>
>>> The bad news is that the performance is approximately 150x worse when using the 3D field in a Proposal2014 geometry compared to a setup with the simplistic fixed dipole.  This compares the HPS-Proposal2014-v5-2pt2 detector with HPS-Proposal2014-v4-fieldmap using the event file egs_tri_2.2gev_0.00125x0_200na_5e5b_30mr_001.stdhep.
>>>
>>> So it appears to me this is not really going to be useable in large scale simulation production until the algorithm for retrieving and interpolating the field values has been significantly optimized.
>>>
>>> —Jeremy
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