Re: temperature test

[Matthew Shepherd <mashephe@indiana.edu>]

Elton and Beni,

Paul and I were talking about these bases -- see below.

-Matt

from Paul:

One thing Beni probably isn't doing is putting them into the "power  
down" mode which puts the processor and CAN transceiver to sleep  
(while maintaining the HV).  Although he already isn't seeing a  
temperature rise, and this will make them produce even less heat.  I  
saw an email from Elton suggesting Beni provide a pulsed light source  
to increase the current draw, but I've always found that with  
realistic light levels and rates this makes no detectable difference  
in the power consumption.  I believe the average anode current is only  
something like 1 microAmp.  This is into 50 ohms, so the base is only  
supplying 50 microWatts to the outside world.  The incremental  
efficiency is something like 50%, so the base consumes an extra 100  
microWatts; insignificant compared to 100 milliWatts.

In any case, this temperature rise seems like a very difficult  
measurement for such a small # of bases; he would have to thermally  
insulate the setup extremely well to see any temperature rise.  I'd  
just use the worst case power consumption of say 1/4 W per base,  
multiply by 2800 bases = 700 W that has to go somewhere.


On Jan 31, 2008, at 9:12 AM, Elton Smith wrote:

>
> HI Beni,
>
> You should have a source (anything will do) that runs the pmts at the
> rates expected for the experiment.
>
> Cheers, Elton.
>
>
>
>
> Elton Smith
> Jefferson Lab MS 12H5
> 12000 Jefferson Ave
> Suite # 16
> Newport News, VA 23606
> elton@jlab.org
> (757) 269-7625
> (757) 269-6331 fax
>
> On Thu, 31 Jan 2008, beni zihlmann wrote:
>
>> Hi Tim,
>> here some pictures of the temperature test setup. I hope that gives
>> a better idea what this test is worth (or not).
>> I checked on Elke's concern that the PMTs might not really draw
>> that much power because if there are no signals then the PMT does
>> not have to do any "work" hence less power consumption.
>> I do see signals because there is enough light leakage that the PMT
>> does some "work". However I found out that exactly the PMT/BASE where
>> I put the temperature probe in stopped working at some point. So
>> I put the temperature probe into the hole of a pmt that works for a
>> fast test and also there I see no  obvious temperature change.
>> Also the test with putting a  cover  (garbage bin) over the whole  
>> assembly
>> is not as good a check as I thouth because that shields also the  
>> light
>> and the PMTs have much less to do.
>> Any suggestions what I might "improve" to get a kine of "worst case
>> szenario"
>> are appriciated.
>>
>>
>> cheers,
>> Beni
>>
>