Re: Kapton aluminized

["Curtis A. Meyer" <cmeyer@ernest.phys.cmu.edu>]

As a note here, we started with the mylar straws from Euclid, but found
them far too "fragile" for use in our chamber. Aside from the fact that we
had to reject about 90+ percent of them because of damage (probably at
euclid), as we have shown an number of times, they do not "spring back":
from even the slightest indentation or squeezing, thus we felt that it would
be extremely difficult to build the chamber with these. On the other hand
 the kapton is quite resiliant.On a more positive note, the mylar was a lot 
less suscpetable to sag than the kapton.

Our problem six years ago was that no one seemed to make aluminum clad
kapton. There was not enough of a market for it. Thus, we were forced to 
go to Sheldahl and have the kapton made. 


  - curtis

On Fri March 6 2009, Fernando J. Barbosa wrote:
> 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/
> >>
> >
> 



-- 
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/