sPHENIX HCal discussion

[Edward Kistenev <kistenev AT bnl.gov>]

Hi, everyone. 

I may already confirm that tiles are consistent within 20% even before they 
are out of the boxes. Tiles are all labeled, label is scannable using your 
smart phone, it is also linked to the data base entry on a server at UNIPLAST 
(VLADIMIR). One may immediately see all data on geometrical dimensions of 
tile, measure of luminosity and measure of light attenuation in scintillator 
on his/her screen.

In the last few days I made an efoort to quickly calibrate tiles from one of 
the boxes (using tiles from Small-30 subset, meaning HInner, tile #30 in 
Richie’s parlance). I used two different setups and two different sets of 
SiPM’s coupled to DT5702 CAEN DAQ board. Both SiPM sets (from GSM and 
recently from Sean) were supposed to be matched within  the set. As it 
happened both sets are either not matched and/or the individual channels  in 
DT5702 are mismatched too (even when all controls are set to the same 
numbers). Likely the biggest part of the problem is mismatch in the CAEN 
channel’s calibration (preamps and/or bias generators). When tiles are moved 
one-by-one through the same input channel of the board the measured light 
emission in response to cosmic exitation is nearly the same for every tested 
tile (10 tiles). 

What is not yet tested  is uniformity of LED light delivery to tiles but that 
can be done even with tiles loaded into detector. 

Conclusion 1:  with good probability tiles in the boxes could be installed 
into detector even without further testing (unknown 20% ( 6% rms) in tile 
average luminosity) - wisual inspection and dust removal from fiber area 
should be sufficiens.

Conclusion 2:  unfortunately "as is" both setups which I used - one around 
GSM built SiPM interface board and second with individual SiPM’s installed on 
individual tiles  in a way similar to how it will be done in the future HCal 
are not ready - need quite a bit of work.

                        Edward

                        

On Dec 18, 2017, at 11:16 AM, Michael Lenz <mlenz AT rcf.rhic.bnl.gov> wrote:

I will be happy to install all tiles in the new inner as soon as they are 
available and I have a map of where they go. I am working on covers now and 
should be done by Friday.