[Halld-cal] Notes of SiPM status review posted

[George Lolos]

Hi Elton:

It was a pity that the connection became so problematic that both IU  
and UofR had to terminate the connection and we missed such an  
important discussion.

Zisis and I had expressed many times our opinions about the FM option  
with the horrendous light guides so we are relieved that Hamamatsu  
rose to the challenge and delivered SiPM arrays that seem to meet our  
specifications.  The SiPM's from Hamamatsu have some characteristics  
that make it imperative to control their temperature to a tighter  
degree than for SensL, for gain (breakdown voltage stability) but even  
more so to avoid drifting out of the narrow operating voltage into the  
after pulsing domain.  I believe that this is a challenge that can be  
met.  I would also urge to cooling them to a comfortably above  
condensation point in addition to stabilizing their temperature.

As we had expressed our desire to work with JLab and SMU on testing a  
fraction of the arrays, we are prepared to commit Stamatis on a Ph.D.  
program on testing the SiPM arrays using the infrastructure we have  
built up on this in Regina and use the time while Kathryn is still at  
the UofR to teach Stamatis the methodology.  Andrei will also  
contribute.  The testing and characterization of the SiPM arrays will  
be one facet of the project.  We propose to  instrument a production  
module and study in an exhaustive way the actual photo-electron yield  
of the module, fibers and arrays with cosmic rays and extract the  
final parameters of performance of the modules/read-out and refine the  
simulations of the BCAL performance based on such actual data.

What we propose here is a long term project that will take us to  
installation and first cosmic ray data runs after BCAL assembly.  As  
such, we will need to work on a more detailed plan and commitments  
form all sides.  In the meantime we will be very happy to receive some  
of the arrays and familiarize ourselves with them.

All in all, a milestone in photo-sensor technology, the first large  
detector utilizing solid state read out exclusively...

George


On 17-Dec-09, at 2:17 PM, Elton Smith wrote:

>
> Dear collaborators,
>
> We apologize for network connections difficulties during the meeting.
> Fernando and Carl reviewed the presentations that were posted and
> available from the portal. There was substantial discussion during the
> presentations.
>
> Radiation tests of the Hamamatsu sensors is still planned in the  
> next few
> days. One sensor will be irradiated while it is powered and its dark
> current will be monitored during the irradiation and afterwards.
>
> Barring any unexpected results from the SiPM radiation tests, the
> consensus was to move foward with the decision to instrument the  
> Bcal with
> SiPMs. This will entail completing all the details that are needed to
> implement this solution both mechanically and electrically. We will  
> need
> to develop a plan for addressing all the relevant issues for this
> technology including accurate estimates of calorimeter light yields,
> temperature and bias stabilization, mechanical assembly and cabling,  
> etc.
>
> Measurements of the calorimeter light yields is important with the
> Hamamatsu SiPMs. Carl will coordinate with George and Zisis  
> regarding how
> to transfer some to Regina.
>
> Thanks for all the work to bring this study to this point.
>
> Cheers, Elton.
>
> Elton Smith
> Jefferson Lab MS 12H5
> 12000 Jefferson Ave
> Suite # 16
> Newport News, VA 23606
> elton at jlab.org
> (757) 269-7625
> (757) 269-6331 fax
>
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