sPHENIX HCal discussion

[Edouard Kistenev <kistenev AT bnl.gov>]

Hi, Megan, 
I believe I have shown few pictures to prove that luminous properties of 
tiles are rather close and we may upload them into prototype without too much 
of an extra measurements and testing. It would be great to have similar 
degree of  uniformity in splitting the light from monitoring system - will 
help at a time of installation. 
Unfortunately I was really unable to get calibration style pictures (with 
single pixel signals separated) and I do not understand why. Want to try a 
bit more next week. 
Haggerty installed all SiPM’s, there are few cases when holder’s locking in 
place still leave thin gap between holder and base black block - need to 
understand it better, this gap should not be there.
50% of tiles were placed into gaps yesterday. Look reasonable. 
There is an open question about cookies - also next week. Definitely no 
cookies in the gaps for the prototype but I am planning for comparative 
study. 

Byproduct - we now understand that CAEN generated biases are not really what 
we expected them to be, they are not only unmeasurable, I would say they do 
not exist separately from SiPM’s connected to those biases (channels). The 
two must be calibrated together. How stable is that calibration, will 
temperature affect the SiPM’s only or CITIROC is equally susceptible - this 
is the question to answer. 

You probably have more questions - write them, I’ll think of answers and then 
let's talk.

                Edward


> On Jan 10, 2018, at 8:33 AM, Megan Connors <meganeconnors AT gmail.com> wrote:
> 
> Hi Edward,
> 
> Happy New Year! I was wondering if you are planning to present an update on 
> your studies of the tiles and tester at BNL at today’s HCal meeting. We 
> started back at GSU this week. It would be good if we could chat outside 
> from the HCal meeting too about a few things. In particular you said some 
> changes needed to be made. I want to make sure we understand and address 
> them. Do you have time Thursday afternoon for a Skype chat?
> 
> Best,
> Megan