[PRad] Fw: PRad 2 Gem Spacing

[gasparan at jlab.org]

 Hi Eugene,

 I am out of my office and do not have a good access to my technical
 drawings. However, this is what we had when we developed the PRad-II
 and then the X17 experiment:
 1) for many reasons we have to start with the PRad-II experiment since
    the hydrogen gas flow target needs more time to install and make it
    working. Removing the inner part for the next experiments will be
    relatively easier..
 2) The only change of PRad-II geometry vs. PRad is the second GEM plane
    which should be 40 cm down (towards CLAS12) from the existing GEM-I
    (or the vacuum window). That we wanted to achieve by pushing the HyCal
    calorimeter down for that mach: 40 cm and install the GEM-II on the
    front of HyCal. This will do the PRad-II experiment.
 3) next should be the X17-Search experiment. For this one the HyCal and
    GEM two plans staying as for the Prad-II. Only the new solid film
    target will be installed with the harp upstream the hydrogen gas flow
    target (from PRad-II) location to provide the 7.5 m distance from the
    X17 target to the Calorimeter. The 7.5 m distance has tolerance of
    +/- 20 cm.
    Hgain, in all change of experiments the HyCal, GEMs and the vacuum
    chambers should not move. Only targets positions need to be adjusted
    pushing them upstream.
 The beam line drawing worked out by Dipangkar and Rafo reflecting this
 order. They may comment on my "comment" above, if needed.

 Let me know if any questions,
 Thanks,
 Ashot


> I have a couple of questions from Bob about the HyCal location: please
> respond ASAP.
>
> -Eugene
> ________________________________
> From: Bob Miller <rmiller at jlab.org>
> Sent: Monday, March 4, 2024 12:50
> To: Eugene Pasyuk <pasyuk at jlab.org>
> Subject: Re: PRad 2 Gem Spacing
>
> Thanks Eugene,
>
> As I develop the model, I will email you specific questions.
>
> Once I get a model complete, then we can review it together to go over
> more details.
>
> Next question:
>
> For PRad 2, with the addition of the second GEM, the distance from the
> harp center to the upstream window of the hycal is 7.09 m.
>
> For X17, the requested distance from the harp center to the upstream
> window of the hycal is 7.5 m.  To keep the 7.5 m, I will need to move
> hycal downstream another 0.41 m.  Is that the correct course of action?
>
> Thanks,
> Bob
> ________________________________
> From: Eugene Pasyuk <pasyuk at jlab.org>
> Sent: Monday, March 4, 2024 8:48 AM
> To: Bob Miller <rmiller at jlab.org>
> Subject: Re: PRad 2 Gem Spacing
>
> Hi Bob,
>
> 40 cm foil to foil
>
> -Eugene
> ________________________________
> From: Bob Miller <rmiller at jlab.org>
> Sent: Monday, March 4, 2024 08:31
> To: Eugene Pasyuk <pasyuk at jlab.org>
> Subject: PRad 2 Gem Spacing
>
> Hi Eugene,
>
> I am working on the GEM layout for PRad 2.
>
> If the 40 cm spacing for the GEMS from foil to foil, or is there to be a
> 40 cm gap between the GEM frames?
>
> Thanks,
> Bob
>
> [cid:c8373914-2a6b-484c-9380-00cf235bb945]
>
> [cid:4a2f5c4c-4928-4aa0-8019-87d02800e536]
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