[Halld-pid] TOF PMT selection and scintillator selection

[eugenio at fsu.edu]

Hi,

Recall at yesterday's meeting we discussed how we planned to match PMT pairs for gluing onto modules.  The plan was to match those with similar gain but different noise characteristics(i.e. noisy with quiet).   We also mentioned that we planned to have high gain tubes used on modules near the center beam hole.  That way, as gain deteriorates  due to dynode ablation, we can increase the gain on these tubes.

Sasha and I continued this discussion after the meeting yesterday, and we think that the scintillator attenuation lengths should also be considered in matching PMT pairs to modules.   The measured attenuation lengths vary from 250 cm to 400cm.  We would like to select those with the highest values for modules near the center.   The modules near the outer edge can have lower values as hits in the outer modules are confined to the paddle center and therefore light would only travel half a paddle length.

For us to proceed in this manner, we would have to measure all scintillators before attaching PMTs.  


--
Prof. Paul Eugenio
Florida State University
Department of Physics
Tallahassee, Florida,  USA 32306

(850) 325-0314
eugenio at fsu.edu