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Re: Temperature test FCAL plastic
Hi Tim,
no there was no steel because I thought that steel will help in cooling
and I wanted
to have a kind of worst case szenario. I have no picture yet but I will
take one.
cheers,
Beni
Tim Whitlatch wrote:
> 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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>>
>