[Hps-ecal] Radiation dose on HPS Ecal

[Andrea.Celentano at ge.infn.it]

Dear all,
next Wensday I will give a short update of the Ecal LED monitoring  
system at the HPS meeting. Next Monday I'll show to the weekly ECAL  
meeting the slides, to discuss them in advance.

I do have a preliminary question: do we have a reasonable estimate of

- The EM radiation dose in the crystals (an order of magnitude is  
enough), in rad/hour

- The incident neutron flux on the crystals OR the neutron dose.

I will show some results regarding LEDs radiation damage, that I  
anticipate here:

* LEDs are not sensitive to EM damage up to ~kGray doses. The light  
emitted, for a given current, in DC mode, does not change, and the  
pulse shape is the same

* LEDs are not sensitive to neutrons, at 20% level, for 3.6E11  
neutrons/cm2 @ 14 MeV integrated flux (neutrons provided by a d+t  
machine)

This work is NOT conclusive, in particular for neutrons, but before  
refining it I need to know what the order of magnitude of the flux is,  
to irradiate LEDs at least at the same flux, see if there is an  
effect, and then move on.

Bests

Andrea

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