[Halld-pid] [GlueX] Start Counter NIM Article Draft (fwd)

[Alexander Somov]

Hello Werner, All,

I quickly went through the ST paper, please
find below a few comments/questions.


Cheers,
        Alex





" .. is utilized in the level 1 trigger".

I would say " ... can be utilized", it's not
used in the main production trigger at the moment.


---------

25:  "  ... primary component of the  level  1 trigger of
the GlueX experiment  during  high  luminosity running[1]."

Ref. [1] contains no information about the trigger and
performance at high rate. Corresponding references have
to be added if you want to mention this (like GlueX-doc-3193;
there are also a couple of docs in the GlueX-doc related to this)

"Primary"  is not the right word. I would say
"we consider to use ST..."


--------

70:  " ... nose is at a radial distance of 2 cm from the
beam line."

The GlueX-doc-1241 (Start Counter Simulation) note has
to be cited here. Studies described in this note were used
to optimize the hole size, which was 1 cm in diameter in the
original design.

Also, I don't see any detector rates (per paddle) in the
performance section; this is an important characteristic
of the detector performance.


--------

SiPM Readout Detectors section

Studies of several photo-detectors were performed in the
initial phase of the ST construction. Based on these studies
S10931-050P was chosen for the ST instrumentation. I believe
that this has to be mentioned in the paper. The reference is
(GlueX-doc-2877 and "Time characteristics of silicon
photomultipliers used in the GlueX experiment",Proceedings
of Nuclear Science Symposium Conference Record (NSS/MIC),
2015 IEEE )


--------

Fig. 21: pulse amplitude should not be in mV,
the same in Fig. 26 (correct units).

--------

How did you simulate the time resolution in Fig. 12, and
Fig. 13 (scint emission time, electronics response, ...) ?


---------

590:  " Since the amplitude better characterizes  the  rise
time of  the  ADC  pulse  profile  as compared to the pulse
integral ..."

I think that I kind of understand what you are saying here,
but some explanations would be helpful.


---------

What is the detection efficiency of tracks in the ST ?

What is the light yield in units of SiPM pixels fired
("photo electrons") for MIPS ?


---------


Using both "sigma" and "FWHM" (in the table) for the time
resolution is confusing. It is not clear how to relate
sigma ~ 280 ps listed in the abstract with numbers presented
in the summary table (which are in units of FWHM). Assuming
a normal distribution, the resolution in the nose section
is 450 / 2.36 ~ 200 ps (better than 280 ps). In the abstract,
it is better to provide the range for the time resolution.

In the  "Conclusion" section correct 555 ps to 550 ps to be
consistent with the table. Also replace 0.5 uA to the "flux of
5x10^7 photons/sec in the energy range of interest".


Fig. 29:  I can barely distinguish the difference among these
four plots. It would be better just to show one distribution;
all numbers are listed in the table.


---------

In general, some parts of the paper resemble a technical note
and contain a lot of details, which are difficult to follow,
like the text on pages 12 and 13 (between marks 700:  - 735:).
Readers may also not be familiar with the GlueX TOF, RF is
also not described.

Some equations are  overwhelmed with unidentified indexes.
What are S, N, c, b (South, North,  ...) in Eq. 9 ?


Fig. 23 and Fig. 27 present uncorrected and corrected dE/dx
distributions; it's easy to compare them if they are on
the same plot (like Fig. 22).





---------- Forwarded message ----------
Date: Fri, 22 Dec 2017 12:28:15 -0500
From: Eric Pooser <pooser at jlab.org>
To: collaboration at gluex.org
Cc: Carlos Yero <cyero at jlab.org>, Anthony Llodra <allodra01 at gmail.com>
Subject: [GlueX] Start Counter NIM Article Draft

Dear Collaborators,

We have composed a draft of the start counter detector NIM article.  The draft is available on DocDB at the following location: https://halldweb.jlab.org/DocDB/0034/003497/001/st_nim_article.pdf <https://halldweb.jlab.org/DocDB/0034/003497/001/st_nim_article.pdf>.  The source code is located at the following Git Hub repository: https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_pooser_st-2Dnim-2Darticle&d=DwIFAg&c=lz9TcOasaINaaC3U7FbMev2lsutwpI4--09aP8Lu18s&r=4_DlAe3hBfyOZtYc-RaW1h6_pJskTvAsAH4Css9mM74&m=sGjzk8WTMQ4QLLT3pFDGOtbC3_fqPhtSkN6HZ62O690&s=2E9J5mr7aOY8RdgIe7oGzQAyYHi1lOU-eMJsKa4GDKA&e=  <https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_pooser_st-2Dnim-2Darticle&d=DwIFAg&c=lz9TcOasaINaaC3U7FbMev2lsutwpI4--09aP8Lu18s&r=4_DlAe3hBfyOZtYc-RaW1h6_pJskTvAsAH4Css9mM74&m=sGjzk8WTMQ4QLLT3pFDGOtbC3_fqPhtSkN6HZ62O690&s=2E9J5mr7aOY8RdgIe7oGzQAyYHi1lOU-eMJsKa4GDKA&e= >.

In compliance with the collaboration publications policies for instrumentation articles we would like to provide all collaborators with the opportunity to add their name to the article if they have contributed to the efforts discussed in the article.

We welcome any comment or suggestions to improve the current draft of the article.  Please provide me with your feedback by Friday, January 5.

Kind regards,
-Eric (on behalf of the start counter working group)

Eric Pooser
Hall C Postdoctoral Fellow
Building 12-1 Room C115
Thomas Jefferson National Accelerator Facility
12000 Jefferson Avenue
Newport News, VA 23606
Office: (757) 269 7216