sPHENIX EMCal discussion

["Bailey, Virginia Ruth" <vbailey2 AT illinois.edu>]

Hi Huan,

The nominal hodoscope cuts are 2x1 (UIUC) and 2x2 (THP) as shown on slide 3 of the presentation.  These were determined by finding the mean energy after cutting on individual hodoscope fingers, and then choosing the vertical/horizontal cut pairs that produced the highest mean energy.  The plot of the mean energy for each pair of hodoscope cuts for the UIUC calibration set 2 data can be found here: https://wiki.bnl.gov/sPHENIX/index.php/EMCalAnalysis#Mean_Energy_by_Hodoscope_Cuts  Here https://wiki.bnl.gov/sPHENIX/index.php/EMCalAnalysis#Energy_by_Horizontal_Hodoscope_Cut are plots of the energy response across the tower in both the horizontal and vertical directions.  The response across the tower seems consistent with the shape of the light guides, peaked at the center of the light guide and decreasing as light hits the edges. 

I've copied this to the list so that we can open up the discussion to others who might have some input.

Best,

Virginia

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From: Huan Zhong Huang [huang AT physics.ucla.edu]
Sent: Thursday, August 18, 2016 2:36 PM
To: Bailey, Virginia Ruth
Subject: RE: [Sphenix-emcal-l] EMCal Analysis Update

Hi Virginia,

  Thanks for the explanation. What is the size for the nominal selection, 1x1?

  For the data you showed did you make sure that 3x3 is actually centered on the center of a tower?

  To understand the physical quality of the tower construction it will be useful to be able to convert from the resolution study into knowledge of the magnitude and size of the local density fluctuations in the tower construction. Is there any way or plan to achieve this?

  Thanks. Regards,

  Huan

 

From: Bailey, Virginia Ruth [mailto:vbailey2 AT illinois.edu]
Sent: Thursday, August 18, 2016 9:10 AM
To: huang AT physics.ucla.edu
Subject: RE: [Sphenix-emcal-l] EMCal Analysis Update

 

Hello Huan,

 

During the testbeam two 8 finger hodoscopes were placed in front of the EMCal, one positioned vertically and one horizontally.  The data from these are being used to cut on the section of the EMCal we look at.  Specifically we are trying to understand the resolution of the blocks themselves, without effects caused by hitting the edge of the light guides or gaps between blocks.  Therefore we looked at which hodoscope cuts corresponded to the greatest energy response in order to use data coming from the center of the tower.  Of course, these edge effects are important to understand for a real experiment and are being looked into, but this analysis is focused on the best possible resolution of the blocks.

 

The 3x3, 5x5, and 8x8 cuts mean that the hodoscope cuts have been widened from the nominal cuts that we have been using (for example 3x3 means we are cutting on 3 horizontal and 3 vertical fingers of the hodoscope).  This essentially is looking at a wider area of the test EMCal, and thus the resolution gets worse as we start to include the edges of the towers (note that one tower is approximately 5 by 5 hodoscope fingers in area).  

 

So to answer your question, I believe that this information would not be available during an actual experiment as the purpose is to help us understand the prototype itself and the varied response across the towers.

I hope this helps and let me know if you have any further questions.

 

Best,

Virginia

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From: Huan Zhong Huang [huang AT physics.ucla.edu]
Sent: Thursday, August 18, 2016 10:25 AM
To: Bailey, Virginia Ruth
Subject: RE: [Sphenix-emcal-l] EMCal Analysis Update

Hi Virginia,

  Sorry that I have not followed the analysis closely. I wonder if you could tell me briefly what exactly Hodoscope cut 3x3, 5x5 and 8x8 means. Is this a kind of position locality cut? If so, how that kind of information will be available in a real experiment?

  Thanks. Regards,

  Huan

 

From: sphenix-emcal-l-bounces AT lists.bnl.gov [mailto:sphenix-emcal-l-bounces AT lists.bnl.gov] On Behalf Of Bailey, Virginia Ruth
Sent: Thursday, August 18, 2016 7:27 AM
To: sphenix-emcal-l AT lists.bnl.gov
Subject: [Sphenix-emcal-l] EMCal Analysis Update

 

Hello all,

 

I was unable to attend Tuesday's EMCal meeting so I wanted to send around the slides I put together this week.  I looked at the effects of widening the hodoscope cuts on the resolution for both the UIUC and THP blocks with calibration set 2 (the one we have been using) as well as the UIUC block with calibration set 4.  Let me know if you have any questions or comments.

 

Best,

Virginia