Re: Temperature test FCAL plastic

[Tim Whitlatch <whitey@jlab.org>]

Hi Beni,

Another question. Was there a steel tube around the pmt's? Is there a 
picture of your setup available?

Tim

Matthew Shepherd wrote:
>
> Hi Elke,
>
> Were your HERMES bases conventional resistor bases?  The current 
> through the FEU bases when live might be a little less due to lower 
> gain.  Besides this, the CW bases generate a factor of 10 less heat 
> than the equivalent resistor base.  The bases were engineered by Paul 
> Smith precisely for this tight packing application.  Beni should be 
> able to answer these other questions -- I believe the setup he was 
> using had an active current meter.
>
> -Matt
>
>
> On Jan 29, 2008, at 6:41 PM, Elke-Caroline Aschenauer wrote:
>
>> On Tue, 29 Jan 2008, beni zihlmann wrote:
>>
>> Dear Beni,
>>
>> thanks for the results. But honestly is that what you would naively
>> expect. I can believe that you don't see a worrying increase but to 
>> see no
>> difference is from my expectation impossible. Beni remember the 2000 
>> tubes
>> of the rich caused the soft steel matrix to increase by 2-3 degree 
>> over some time
>> like a day or so. In your case the bases are in air, so there is some
>> convection cooling going on.
>>
>> What is the current this bases draw, I guess the measurement was done 
>> with
>> the cockroft walton ones, correct. Have you actually done this
>> measurements also under rate. so with a source in front of the PMTs or a
>> light source or ....
>>
>> Cheers elke
>>
>>
>>
>>
>>> Date: Tue, 29 Jan 2008 09:31:39 -0500
>>> From: beni zihlmann <bzihlman@indiana.edu>
>>> To: Tim Whitlatch <whitey@jlab.org>, Matthew Shepherd 
>>> <mashephe@indiana.edu>,
>>>     Elke-Caroline Aschenauer <elke@jlab.org>, Elton Smith 
>>> <elton@jlab.org>
>>> Subject: Temperature test FCAL plastic
>>>
>>> Hi Tim,
>>> The temperature test I did came out negative. Meaning I did not
>>> sea any measurable temperature increase while running 4 PMTs
>>> at 1800 Volts.
>>>
>>> 4 holes are drilled into the high density plastic. the plastic is about
>>> 16cm thick. The bases stick out in the back of the plastic by 5 cm
>>> the PMTs stick out in the front of the plastic by about 6 cm.
>>> The BASES are powered up to 1800 Volts and signals are seen on the
>>> PMTs. (The PMTs are covered with black plastic to shield light.)
>>> A temperature is inserted into the hole and located next to a PMT
>>> such that it is separated by the thin wall of plastic from the 
>>> neighbouring
>>> PMT. At some point a cover was put over the whole assembly to prevent
>>> air exchange (cooling). In all cases over a time period of 1 week I 
>>> did not
>>> see any temperature change withing the accuracy of the measurement.
>>>
>>> I think the conclusion is that high density plastic is a viable option.
>>>
>>> cheers,
>>> Beni
>>>
>>
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