sPHENIX HCal discussion

[John Haggerty <haggerty AT bnl.gov>]

Hello,

Here are some comments from Elke in her role on the sPHENIX Project 
Management Group (PMG) on an early snapshot of pCDR to add to our list 
of corrections and additions we're working on.  If you've contributed to 
the pCDR, look through them for things you can correct or add if they 
haven't been addressed yet, and I'll do so as well as we try to finalize 
the document.

-------- Forwarded Message --------
Subject:        Comments to Draft sPHENIX pCDR
Date:   Mon, 12 Oct 2015 23:16:39 -0400
From:   Aschenauer Elke-Caroline <elke AT bnl.gov>
CC:     Aschenauer Elke-Caroline <elke AT bnl.gov>, Haggerty, John
<haggerty AT bnl.gov>, Kotcher, Jonathan <kotcher AT bnl.gov>, Lissauer, David
<lissauer AT bnl.gov>, Mueller, Berndt <bmueller AT bnl.gov>, O'Brien, Edward
<eobrien AT bnl.gov>, Makdisi, Yousef I <makdisi AT bnl.gov>, Ma, Hong
<hma AT bnl.gov>, Thomas Roser <roser AT bnl.gov>, Pile, Philip H
<pile AT bnl.gov>, Dunlop, James C <dunlop AT bnl.gov>, Christie Bill
<christie AT bnl.gov>, Mills, James A <mills AT bnl.gov>

Dear all,

so I went through the pCDR and it is not clear how to best comment on it
as still many chapters are not complete.

But here are a couple of high level comments I have going through the
document in not super detail.

One general remark, the document is most likely to long especially as
there are only 3 weeks left and the document has not yet been submitted
to the committee.
As there is no management, cost and schedule section, it is very
difficult to see how questions like the critical path for the project
and per detector component handled.

In general it would be good that for the detectors the design is
advanced the level of detail is consistent, currently it seems that this
is not the case.
Is there a unified approach on test beams, building of prototypes and so
on for the coming years per detector component.

I'm missing a section on safety.

Chapter 1:
========
As the document is for a more technical committee I think chapter 1 has
to many "theory" plots instead of plots showing truly the sPHENIX
performance.
This means I give a plot which shows the statistical precision  can
obtain on a observables which needs to be measured to address a certain
theoretical question.
It would be even better if a before and after sPHENIX data could be
shown, but I understand that this is difficult in HI physics as many
models don't even provide uncertainty bands which could be reduced by
new data.
But if there are 1 or 2 observables this would be possible it would be
good to have these plots.

The assumptions how to take the data sets are missing

Chapter 2:
========
page 25 is not one of the main requirement that you need such a high DAQ
rate, that you want to take minbias events to avoid any type of bias
through the trigger.

Chapter 2.2:
=========
is there any plot to show the impact on the jet reconstruction on the
calorimeter segmentation? If yes I would include it.

Chapter 3:
========
- what are the consequences if a magnet quench happens to the different
detector components, have any precautions for this been included in the
design?

Chapter 4:
========
- Does the measurement of the upsilon family not also put a limit on the
radiation length of the tracker material?

To switch between SI-Tracker, TPC and something else makes it very hard
to read.
I would make one section Si, next one TPC and last one alternative with
identical structures

Silicon:
- what are the requirements on number of Si-layers to keep the number of
ghost tracks low and the tracking efficiency high, what is the built in
redundancy
- how can any work on the Si-Pixel be done in FY2016, if we are running
till july and all needs to be unmounted.
- what is the radiation length, what are the alignment requirements. How
are the most outer layers kept stable and constant to keep alignment.

TPC:
- why are the requirements from sPHENIX different then the ones from
ALICE? Summarize this crisply in a table
- what is the manpower involved in the current TPC design and how does
it compare with the ALICE effort.
-which assumptions have been used for the 25 kHz A+A collisions rate

Alternative tracking:
- Has anybody in the collaboration experience with MAPS ?

Chapter 5:
========
are there studies which really show any influence of the detector
determining the underlying event. I read a lot of arguments but see no
proof of the importance of them.
How can it be that cracks are a problem because of missing energy, but
the double projective design which leads to loss in the electromagnetic
energy
the plots are to small
unfortunately all the info on the needed gain stabilization and how the
ECAl is used in the trigger is missing.
What are the calibration methods
What is the fraction of the shower loses due to the 2d geometry.
the caption of fig 5.23 does not fit the figure
there is still quite some text missing to describe the figures and the
performance
how can the ECAl SIPMs and readout electronics be serviced

Chapter 6:
========
has the large constant term in figure 6.31 been understood
has the difference between some MC and test beam results been understood
how can the HCAl SIPMs and readout electronics be serviced
here is still quite some text missing to describe the figures and the
performance

cheers elke

On Oct 6, 2015, at 8:56, Capasso, Frances <capasso AT bnl.gov
<mailto:capasso AT bnl.gov>> wrote:

> Hello:
> Please send comments to Ed O’Brien on both the pCDR and on the HCAL
> outline talk.
> Thank you, FranJ
> Fran Capasso
> Assistant to the Associate Laboratory Director
> Nuclear and Particle Physics
> Brookhaven National Laboratory
> 20 Pennsylvania Street
> P.O. Box 5000, Building 510F
> Upton, NY 11973
> Phone: 631.344.3830
> Fax:       631.344.5820
> Email: capasso AT bnl.gov <mailto:capasso AT bnl.gov>
> *From:*Lissauer, David
> *Sent:*Tuesday, October 06, 2015 8:10 AM
> *To:*Capasso, Frances
> *Subject:*FW: Draft sPHENIX pCDR
> Hi Fran,
>   Can you please dist to the PMG.
>    Please send comments to Ed O’Brien on both the pCDR and on the HCAL
> outline talk.
>   Thanks, David.
> ********************
> /David Lissauer/
> /Deputy Associate Lab Director for Nuclear and Particle Physics/
> /Brookhaven National Lab./
> /Lissauer AT bnl.gov <mailto:Lissauer AT bnl.gov>/
> /1-631-344-4864 (office)/
> 1-631-294-5089 (Cell)
> <pCDR_Comments_100515.doc><Hadronic_Calorimetry092415.pdf><sphenix_pcdr_20151005.pdf>

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--
John Haggerty
email: haggerty AT bnl.gov
cell: 631 741 3358