sPHENIX HCal discussion

["Lajoie, John G [PHYSA]" <lajoie AT iastate.edu>]

Hi Anthony,

 

Thanks a bunch for sending out these slides, this is very helpful. It looks like you have a reasonable trigger setup (Edward, do you want to comment?) and offline cleanup.

 

I disagree that you can’t use this data with the old test stand to draw reasonable conclusions.  Your main objection seems to be that the pilot tiles have the old light block and therefore connect properly to the backplane, w/o the 2mm gap the tiles with the new light blocker have. Therefore, the pilot (reference) tile will have a higher response than the tiles you are testing, and when you plot the distribution of “test tile/reference” the distribution won’t be peaked around 1 but at some number below one, and the sigma of this distribution will be suppressed by the ratio of the mean of the test tile response to the reference “<test>/ref”.

 

We encounter something similar when looking at jets when the JES is not one; you just correct up the sigma by “ref/<test>” and that value is an accurate representation of the variation you expect between tiles (relative to a reference tile that gives a similar response). 

 

So, I would argue that you *can* use this data to make the kind of plots we have been looking to get for several weeks now.  Yes, it is certainly “better” to have the new backplane, but I really think it would be useful to analyze at least some of the data (as described above) so you have something to compare to the new test stand. The new test stand has a number of other features in addition to the new connectors – in particular new electronics that should be more noise-immune.  It would be very nice to at least have some tiles tested both ways for comparison.

 

So – while you are waiting for the new test stand, could you analyze some subset of tiles as described above, and make a plot of the corrected tiles response/reference?

 

John

   
John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

 

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From: Anthony Michael Hodges <ahodges21 AT student.gsu.edu>
Sent: Wednesday, January 30, 2019 11:23:20 AM
To: Lajoie, John G [PHYSA]; sphenix-hcal-l AT lists.bnl.gov
Subject: Re: Interim HCal Meeting 1/30

 

Hi John, 

Sure, let me attach some slides as to what's gone on here at GSU. Additionally, it should be noted that the pilot tiles have the old light blocker, and all the new tiles have the newer one; I'm not sure if that was clear at the meeting last week. The first several slides detail how I've chosen the testing configuration; slides 10 and 11 address the use of the pilot tiles. Essentially, we're looking at a sample deviation of about 50% in the slides that I show, which translates to a >100% deviation from the pilot tile at points. So that's obviously worrisome, but before we panic, of course, we should see where properly seating the SiPM's gets us. These tests were from one stack (as Edward pointed out, the first stack usually stays in the tester the longest to make sure there are no strange systematics at work), so now the plan is to see if this variance occurs over the rest of the tiles we have. 

Hope this helps, 

-Anthony 

Anthony Hodges

PhD. Student, Georgia State University

Nuclear and High Energy Physics

ahodges21 AT student.gsu.edu

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From: Lajoie, John G [PHYSA] <lajoie AT iastate.edu>
Sent: Wednesday, January 30, 2019 9:54:50 AM
To: Anthony Michael Hodges; sphenix-hcal-l AT lists.bnl.gov
Subject: RE: Interim HCal Meeting 1/30

 

Hi Anthony,

 

Thanks for the update. I do have a few questions, however.

 

At last week’s HCAL meeting we talked about testing tiles relative to reference tiles (the pilot tiles), which is the information that we really want. We decided that was possible even with the existing test stand.  In particular, we decided that results like this would be very useful to have before we switch over to the new test stand.  You email makes it sound like you’re not getting results you feel comfortable with; could you give some more detail as to why? What part of our assumptions from last week’s HCAL meeting was incorrect?

 

If you really need the new test stand, what is the schedule for shipping the new test stand to GSU? It sounds like Mike had this nearly ready to go last week.

 

Regards,

John

 

   
John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

 

From: Anthony Michael Hodges
Sent: Wednesday, January 30, 2019 8:33 AM
To: Lajoie, John G [PHYSA]; sphenix-hcal-l AT lists.bnl.gov
Subject: Interim HCal Meeting 1/30

 

Hi everyone, 

 

Last week we discussed having an interim HCal meeting today to discuss the progress of the tile testing at GSU. Testing has been going on, but without the new test stand, particularly the new SiPM holders, it's hard to draw any useful, definitive conclusions on the tiles' performance. So, I propose we just keep with our regularly scheduled HCal meeting next week, by which point, presumably, we'll have the new test stand and something more concrete to show. 

 

Cheers, 

-Anthony

 

Anthony Hodges

PhD. Student, Georgia State University

Nuclear and High Energy Physics

ahodges21 AT student.gsu.edu

 

From: sPHENIX-HCal-l <sphenix-hcal-l-bounces AT lists.bnl.gov> on behalf of Lajoie, John G [PHYSA] <lajoie AT iastate.edu>
Sent: Tuesday, January 22, 2019 11:04 AM
To: sphenix-hcal-l AT lists.bnl.gov
Subject: [Sphenix-hcal-l] HCAL meeting 1/23

 

Dear HCAL'ers:

    We will have an HCAL meeting this Wednesday, Jan. 23rd at 3PM BNL time (NOTE NEW TIME):

https://indico.bnl.gov/event/5637/

I am hoping to hear something from GSU on tests of the new tiles as well on the development of the new tile tester. Other reports and updates are certainly welcome!

Regards,
John

--

John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu