[Halld-cal] gluing BCAL light guides

[Zisis Papandreou]

Hi folks:

I spent Wednesday at LNF, Frascati.  I spoke extensively with Stefano  
Miscetti about many things.  In this email I want to relay the KLOE  
experience in gluing their light guides (much bigger in area per unit  
than ours).

The method they followed, in broad strokes, is to rotate each module  
so that it was vertical (long axis pointing up-down) and then they  
glued all light guides as a single unit on each module's end.  They  
had a jig made to hold them together as a unit.  They applied a  
carefully measured amount of epoxy (probably BC600, but definitely  
nothing with fast UV curing properties) and let it set overnight.   
There was some capillary action/seepage of epoxy between light guides,  
but it was confined to a few mm length along the main axis of the  
light guides.  They measured the optical cross talk that resulted from  
this and it was only a few percent, so it did not hurt reconstruction  
and it may have even helped by "smoothing" out the cluster distribution.

The technician who was a  master at doing this is still at the lab,  
although close to retirement.  Tim, if you wish to have more details  
than this, please let me know and I can relay your questions to Stefano.

As many of you know, their collaboration is working towards KLOE-2, an  
upgraded detector, with plans to employ SiPMs.  They are currently  
testing several Hamamatsu 1x1mm2 and 3x3mm2 SiPMs and they are also  
interested in arrays.  Stefano plans to email Carl Zorn and Fernando  
to get their wisdom on the SiPMs and electronics.  They are also  
thinking of using these devices in other experiments.  Stefano is also  
thinking to send one of his group members to Fermilab on their work  
there, and then have to person stop over at JLab for one day of  
discussions.  When he fixes his plans, I guess he will contact Elton  
to make arrangements.

Cheers, Zisis...

---
Dr. Zisis Papandreou		|  email: zisis at uregina.ca
Department of Physics	|  tel. : (306) 585-5379
University of Regina		|  tel. : (306) 585-4149
Regina, SK  S4S 0A2		|  fax. : (306) 585-5659
World Wide Web:   http://web.me.com/zisis/professional/