sPHENIX EMCal discussion

["Huang, Jin" <jhuang AT bnl.gov>]

Hi, Ed,

 

Thank you for catching this point.

 

In the reference channel counts (96 x 256), we need 96 polar segments to cover -1.1 < eta< 1.1 with average eta segments of 0.023 per tower. In the next level of reality, Chris Cullen showed that we can maintain this channel count in his 2-D projective SPACAL design, as in your attachment.

 

The caveats sit in 1-D projective layout: with towers of same cross section (e.g. ~1 inch *1 inch towers), the 1D projective tower takes smaller eta bite per tower at the forward rapidity than that of the 2-D towers (due to non-objectivity). Therefore, if we use towers of the same cross section size (or same fiber counts or same light collection area), 1-D projective version leads to more towers and higher channel count.

 

Quantitatively, to cover EMCal absorber Z-length of 2x1494.7 mm (Chris’ slide 3) with 1D projective tower with a cross section of (25.2 mm x 25.2 mm @ shower max of R = 102.5 cm), we would need (118 eta x 256 phi) towers/channels, ~24% more towers than the reference channel counts. Of course, these numbers are still up to variation until we fully flush out a 1-D projective layout. In the pre-CDR simulation exercise, 1-D projective SPACAL used a variation of (124 x 256) towers, while 2-D projective SPACAL used Chris’ design of (96 x 256) towers.

 

An alternative choice to reduce channel count for 1-D projective SPACAL would be building towers of non-square cross section that is 20-30% wider in the polar direction than the 2-D projective version at shower max. Its performance has not been studied.

 

Best regards,

 

Jin

 

 

______________________________

 

Jin HUANG

 

Brookhaven National Laboratory

Physics Department, Bldg 510 C

Upton, NY 11973-5000

 

Office: 631-344-5898

Cell:   757-604-9946

______________________________

 

From: EdwardOBrien [mailto:eobrien AT bnl.gov]
Sent: Wednesday, April 27, 2016 9:36 AM
To: Sickles, Anne M <sickles AT illinois.edu>; Huang, Jin <jhuang AT bnl.gov>
Cc: O'Brien, Edward <eobrien AT bnl.gov>; sphenix-emcal-l AT lists.bnl.gov
Subject: Re: [Sphenix-emcal-l] (minutes) Re: sPHENIX EMCal meeting April 26

 

    Hi Anne,
     Jin's statement at yesterday's meeting that 2-D projective required 30%
    fewer towers surprised me. That is not how the engineers have done the
    early design. In the working design, the tower count remains the same but
    they are tilted toward z=0 and are cut with the proper angle so that
    there are no cracks or gaps. Chris Cullen showed the picture of this concept at the
    November Cost and Schedule review. Does the proposed mechanics for the
    2D design need to be revised? Can you or Jin explain the difference?
    See slide 5-6 in the attached file. Thanks.

    Ed

On 4/26/2016 10:16 PM, Sickles, Anne M wrote:

Here are the minutes from today’s meeting.  Please let me know of comments/questions/omissions.

 

Anne

 

 

EMCal cost reduction strategies:

 

regrouping EMCal towers: saves about $90 / EMCal channel eliminated assuming that the light collection and SiPMs count are not altered

—Jin notes that the 2D projective EMCal already has a reduced channel count compared to the 1D projective

—Jin will use pCDR simulations to evaluate the impact on hadron rejection with reduced granularity 

—old simulations will be used to make apples to apples comparisons

—strong concern for jet measurements in the scenario where the EMCal towers are built out to |eta| < 0.5 only

 

task list:

great list from Jin, names filled in in real time and list posted to the wiki:

 

https://wiki.bnl.gov/sPHENIX/index.php/T-1044

 

Mike Skoby: calibration

—working on understanding of variation of MIP peak locations with calibration sets shown on slide 3

—ideas are to clean up the event selection (to reject non-MIP events) and to use timing information

—there are additional runs (from today) in the 180 rotated configuration (like set 2), Mike will analyze those and update the slides

—the peak location vs channel count on slide 5 is not understood 

—there is discussion about the possibility of temperature gradients causing this

—Mike will add set 2 (the 180 degree rotated runs) to this plot to see if the dependence is the same

—will also add the channel by channel temperature information to a similar plot to see if the trend is the same

 

Vera: analysis

 

current analysis shows a different resolution than earlier analyses by Vera and Jin (independently)

Jin’s plot in the wiki: https://wiki.bnl.gov/sPHENIX/index.php/File:T-1044_fouth_DrawPrototype2EMCalTower_Resolution_Run2042_col1_row2_5x5_Valid_HODO_center_col1_row2.png

(uses the same calibration, but a different (earlier) set of runs

—trying to understand the differences

—Vera and Jin will work together to optimize the Cherenkov cuts and implement the cut on the hodoscope

—other changes/differences in the analysis will be investigated and sent to the list

—both analyses were done using the calibrations from Mike (set 2)

 

Best,

Anne

 

 

 

On Apr 25, 2016, at 9:00 AM, Sickles, Anne M <sickles AT illinois.edu> wrote:

 

Hi,

 

We’ll meet tomorrow for the bi-weekly EMCal meeting at 3 ET.  The indico page with the bluejeans link is here:

 

https://indico.bnl.gov/conferenceDisplay.py?confId=2036

 

I would obviously like to discuss various aspects of the test beam.  I would like to hear about the calibration (Mike, Jin), analysis (Jin, Vera), and the status of the data taking and specifically is there any additional data we need to take (Craig, Sean, John H).

 

Have I forgotten anything?  Can the people named confirm that they can present?

 

Best,

Anne

 

--------------------------------------------------------------

Anne Sickles

Assistant Professor, Department of Physics

University of Illinois at Urbana-Champaign

--------------------------------------------------------------

 

 

 

 

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--------------------------------------------------------------

Anne Sickles

Assistant Professor, Department of Physics

University of Illinois at Urbana-Champaign

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