sPHENIX HCal discussion

[John Lajoie <lajoie AT iastate.edu>]

Dear HCAL'ers:

    In the morning session today we had a walkthrough of the major items discussed during the workfest and a summary of the action items.  I've attempted to summarize these discussions and explicitly list out action items below. 

    Once again, I'd like to thank our GSU hosts for their hospitality - they make coming to Atlanta for these workfests a real pleasure!

Light Collection/Tile Testing
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• Achim – ray trace simulations coupled to SiPM holder design (iterate)
• JH - Send additional parts to Colorado (4 SiPMs with latest production preamp boards), should be able to see single-pixel hits (establish gain)

• Need to understand L/R response of small reference tile. Trigger?

JH/EK – Need to get Bicron glue to Uniplast before we can get 10-20 1m tiles (unpatterned, dual glue tiles). Largest extrusion from Uniplast currently 21cm (!) so need to test dual, glued tiles.

• First general awareness of this issue at this meeting
• When will we ask Uniplast to toolup for full tile width?
• EK will talk with them early next week. Will this be an NRE on the next order?  How does this affect prototype lead time?
• 3 month lead time required when ordering for prototype assumed

Need to visit FNAL in near future, revisit Elgin quote? Due diligence!

• JH will contact FNAL management about future of scintillator facility and open discussions.

Calibrations/Monitoring:
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• Agreed on  LED scheme

• 5 groups of 12 LED’s fired at a time, controlled by interface board
• Steve/Eric charged with further development, LED selection

We now have a strawman calibration strategy (from John H’s notes):

• Absolute tile calibration (tile + SiPM/holder) with cosmics

• Implications for assembly procedure, must all be kept together!

Module calibration with cosmics Cosmics in full detector (rates? small signals?) Need cosmics trigger algorithm (EK/JL) Requires simulations for geometry AND solid test beam data for h/m, etc.

• Will need a beam test of a final design.   Will this be the modules as tested at FNAL test beam next year? Might not be, need a contingency plan!

Cosmics calibration between runs. Within a run:

• LED for short-term variations
• Match with tracked particles to check calibration

Don’t expect this is final, but it is a plan we can start from and evolve as we investigate each piece in detail MC and HCAL response
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• HCAL response studies are time-critical for prototype design! (see calibrations – the prototype MUST be the final design)

• Liang/Xiaochun – Check tile grading response in prototype MC!
• Can be done quickly, begin to understand main effects
• Lots of discussion, will not be perfect but will allow us to get a first look at the effect on fluctuations (resolution and tails!)

Partial framework already in place, need to extend (JL + Liang +??)

• Birk’s law in place for EMCal, copy over?
• Need tile response in G4step
• Need to extend tower container to keep track of multiple pieces of information

Achim  - more realistic field map in outer HCAL

• First order – field in plates, none in scintillator

Simulation goals:

• Tile tilt angle (underway as part of Simulations meeting)
• Verify/optimize tile patterning to even out HCAL response vs. shower depth.
• Verify calibrations scheme:

• Perform a blind calibration with cosmics, study systematics, estimate statistics and time required.

Work with EMCal to optimize inner HCAL

• Cu or Stainless?

• Not a choice for practical reasons?
  

What if we have no inner HCAL (room for EIC PID?) Regards,
John Lajoie

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John Lajoie

PHENIX Deputy Spokesperson

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

Contact me: john.lajoie