[PRad] [EXTERNAL] Fwd: PR12-23-011 questions

Dipangkar Dutta d.dutta at msstate.edu
Mon Jul 10 09:32:39 EDT 2023

Hi All,
We have received the following questions from one of our readers. It
mentions a TAC report which we have not received yet. I think most of
the questions can be readily
addressed. I will start an overleaf document for the response and
start populating our answers. We may need a mid-week meeting to
discuss our response.
Based on who is cc-ed on this email, It seems we may have 3 readers
and the two other readers are Marco Contalbrigo and Feng Yuan.


---------- Forwarded message ---------
From: Concettina Sfienti <sfienti at uni-mainz.de>
Date: Mon, Jul 10, 2023 at 6:23 AM
Subject: PR12-23-011 questions
To: <d.dutta at msstate.edu>
Cc: Markus Diehl <markus.diehl at desy.de>, <mcontalb at fe.infn.it>, <fyuan at lbl.gov>

Dear Dipangkar,

I have gone through your proposal and have a few questions that we
might clarify ahead of the PAC week.

(i) By reading the TAC report it seems there are a couple of technical
open questions concerning the experiment.
 On the other side on pag. 18 of the proposal it is stated that the
experiment is as PRad plus Si-Strip and a second pair of GEM Chambers.
What about all the other different changes mentioned by the TAC

In principle (compare Figure 23 with 22) GEM will indeed be replaced
by mRWELL, one plane will be added and in between there will be a
Helium bag (before the HyCal). In addition it is stated that the
HYcall will be "upgraded" (new readout incl.):
so I do understand some of the worries expressed in the TAC. Probably
the easier would be if you’d forward me your answer to the TAC report.

(ii) Option faster GEM Readout: Is the decision still postponed?

(iii) It would be really helpful to have a table of what is already in
there and does not need to be change (original PRad piece of equipment
so to say) and what is not there or should be
changed substantially. In all cases I would like to have noted down
the group responsible for it.

(iv) Will there be any major differences in using the gas-jet target
now with deuterium instead of hydrogen?

(v) I do agree that moller und e-d looks separated in Fig 50 and 51.
It wold have been better to have the whole distribution though. With
the data below 0.7 not shown it seems a pretty arbitrary cut.

(vi) Fig. 63:  it would be useful if the corrections were given in
linear form (e.g. in %), so that one can compare better. Would it be
possible to have such a plot?

(vii) Fig. 69 why do you need so much overlap in Q^2 between 1.1 and 2.2 GeV

(viii) I’d like to have a rough idea on the overall timeline: When are
Prad-ii suppose to take data? How many modifications will be needed to
the setup for the X17 searches (C12-21-003) and how many modifications
will then be needed for Drad.
In addition how much of the different collaborations overlap and how
will be the work distributed amongst the different groups? (if it is
easier you could expand the table in (iii) to show the involvement in
the other two experiments)

(ix) On a similar line: there is another proposal to use the PRad
setup in a slightly different configuration with positron beam. How do
you envisage the arrangements between the two experiments?

Kindest regards

Prof. Dr. Concettina Sfienti
Institut für Kernphysik
Johannes Gutenberg-Universität Mainz
Johann-Joachim-Becher Weg 45
D-55099 Mainz
Tel.: + 49 (0)6131 39-25841
Fax:  + 49 (0)6131 39-20850
EMail: sfienti at uni-mainz.de

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