Re: Kapton aluminized

["Fernando J. Barbosa" <barbosa@jlab.org>]

Hi Eugene,

Indeed, we experienced that with our prototype straw detectors at BNL 
(EVA850) in the late 1980's. After a period  of operation with strontium 
sources and on the test beam, our prototype 1um Aluminum on Mylar 
developed visible loss of the aluminum, which is deposited at this 
thickness. We tried copperized Kapton straws and they worked well, with 
much lower noise due to the Malter effect but were much more expensive. 
We settled on 8 um Aluminized Mylar clad straws (not deposited) and they 
were very robust. The straws were fabricated by Euclid Spiral.

A few years ago, Hall A used the same techniques for their planar straw 
detectors. You may want to contact Ron Gilman for additional information.

Best regards,
Fernando


Eugene Chudakov wrote:
> Hi Curtis,
>
> I heard (long ago) from CERN chamber experts that aluminum coating on 
> films
> tends to develop cracks which effectively insulate some
> areas from the rest. Naively, one may expect that a 5um thick layer 
> should
> be stronger than a thin one.
>
> Which thickness are you using for the prototypes?
>
> Thanks,
> Eugene
>
>
> On Fri, 6 Mar 2009, Curtis A. Meyer wrote:
>
>> Hi Tim -
>>
>>    what we observed with the 1mu is that there are scratches on it. I 
>> was
>> hoping that by going to a thicker layer, we could reduce the the chance
>> of that occuring. As long as the finish is "clean", I am ok with 1 
>> mu, I was
>> just hoping to reduce the chance of problems.
>>
>>   Curtis
>> On Fri March 6 2009, you wrote:
>>> Hi Curtis,
>>>
>>> I believe you currently have 1 micron thick aluminum which was vapor
>>> deposited on 3 mil Kapton. You had mentioned that you wanted to go to 2
>>> micron aluminum. I spoke with Sheldahl and they said the thickest they
>>> could do was 1 micron (and that is pushing it). Is the 2 micron really
>>> required? I will check availability with other vendors.
>>>
>>> Cheers,
>>>
>>>        Tim
>>>
>>>
>>
>>
>>
>> -- 
>> Professor Curtis A. Meyer        Department of Physics
>> Phone:  (412) 268-2745          Carnegie Mellon University
>> Fax:    (412) 681-0648            Pittsburgh PA 15213-3890
>> cmeyer@ernest.phys.cmu.edu  http://www.curtismeyer.com/
>>
>
begin:vcard
fn:Fernando J. Barbosa
n:Barbosa;Fernando J.
org:Jefferson Lab
adr:Suite #10, 12B3;;12000 Jefferson Ave.;Newport News;VA;23606;USA
tel;work:757-269-7433
version:2.1
end:vcard