[Frost] The hydrogen contamination pf the carbon target in g9a data

[Park, Sungkyun]

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Hi Keith,

Thank about your comment. I will update your comment in my presentation. However, If the shoulder of the CH2 target  in g9a data is from the super-insulation on the 20K shield, why we can not see any shoulder in CH2 vertex distribution of g9b data or additional peak near the CH2 peak?

Sung
________________________________
From: frost-bounces at jlab.org [frost-bounces at jlab.org] on behalf of Christopher Keith [ckeith at jlab.org]
Sent: Thursday, March 14, 2013 10:20 AM
To: frost at jlab.org
Subject: Re: [Frost] The hydrogen contamination pf the carbon target in g9a data

Hi Sungkyun,
The 12.5 cm peak that you see in the g9b spectrum is probably due to superinsulation (SI) on the downstream end of the 1K shield. In g9a, a similar quantity of SI was used, but it was pressed against the carbon target and is probably visible as the slight shoulder at 7cm on the carbon peak.

In g9a there is a similar shoulder on the CH2 at 17cm, and this may also be due to SI on the 20K shield.  I don't see the corresponding shoulder in the g9b spectra, though.  I'll look at our notes.

Chris Keith

On 3/13/13 5:38 PM, Park, Sungkyun wrote:
Hi Eugene,

I made the presentation using the Keith pictures to have better understanding about the hydrogen contamination. I think this can be the good reference to discuss our current issue "hydrogen contamination in the carbon target"

  hadron.physics.fsu.edu/~skpark/document/FROSTM_Mar1313.pdf<http://hadron.physics.fsu.edu/%7Eskpark/document/FROSTM_Mar1313.pdf>

 In slide 1, the carbon and CH2 target in g9a vertex have shoulders downstream and there are new peak between carbon and CH2 target in g9b vertex. Our current conclusion may be the peak between the carbon and CH2 target is from the super-insulation and this super-insulation make the shoulder part in the carbon data. However, there is no description about the should of the CH2 target.

I think that (E)outer vacuum can, (D)20K heat shield, and (B)1K heat shield in Figure 3.6 in slide 1 are used in g9a and g9b together. I think the vertex difference between theg9a and g9b is from the holding magnet with the different size.
If so, we can not find any reason for the CH2 shoulder part  because the CH2 target is installed out the 20K heat shield.

Can I update this presentation on our FROST meeting web-page?

Sung
Florida State University



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Christopher D. Keith
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