Date: Wed, 31 Jan 1996 21:51:40 -0600
Subject: "Windows 96" (of the polypropylene persuasion)
From: "Dr. Nicholas E. Pingitore"
X-Listprocessor-Version: 6.0b -- ListProcessor by Anastasios Kotsikonas
Status: OR

Dear users,
I purchased a set of two ProLINE 20 polypropylene windows for my
low-pressure spectrometer. These came from EMS 1-800-523-5874;
215-646-1566; -8931 FAX; 321 Morris Road, Box 251, Fort Washington, PA
19034, USA. I asked them to aluminize the surface, and to have them fit
an SX-50. They said they knew the size. What arrived did not fit at all,
but it was good stuff. The super-delicate poly is backed by a hexagonal
open-lattice network of stiff material (Carbon??). I cut a piece of this
with scissors (yes, it is STIFF) to fit exactly the size of the Cameca
brass window support - the thing with the wire arches to support the
polypropylene. I replaced the brass part with the cutout and closed up.
That is, the brass is no longer in the spectrometer. The window is stiff
enough to hold with its own supports, and the appropriate screws still
worked. You have to orient the window so the hexagonal support system is
on the same side as the wire supports on the Cameca brass piece.
The window leaked, so I took it back out and put it on a
petrographic scope with transmitted light. Beautiful green with the
hexagonal lattice work. The pinholes are easy to spot this way. I
repaired two of those under the microscope with nail polish (check your nail
polish with your EDS - I found some with lots of sulfur. I use nail
polish for quickie grain and soil mounts). I recommend checking all
windows under the scope before installation - it can save a lot of time.
I don't know if the windows got the holes during manufacture,
transport, or my handling. They are a minor problem. The good news is
that the two sheets of the material can be cut to produce 4 windows. The
set of two cost about $ 500, so this is $ 125 for each window.
It has now held for three months. I think my counts are 3 or 4
times higher than before. EMS advertises these windows as extra thin,
and it looks that way to me. I may try to find some old analyses to get
a better quantification, but it seems that these are superior windows
that are very easy to handle and install. The label on the package was
Moxtek (801-225-0930) - you may be familiar with their recent series of
articles on x-ray detectors in Microscopy Today. I do not know if they
sell direct, but it would be worth it to buy a sheet of material directly
from them, and then cut out the size you need.
I don't know if EMS and Moxtek also supply mylar for people
needing that type of window.
If anyone else has used the ProLINE 20's, you might add your
comments. It would be good to verify my idea that they yield superior
count rates as well as hear if they mess up any type of analysis which we
have not yet done here. Some folks might want to switch even if their
present windows are OK (DON'T DO THIS UNTIL SOMEONE ELSE CONFIRMS MY
IMPRESSION ABOUT COUNTS).
Meantime, the crack in the rear window of my Mercedes roadster is
still there. Have not figured a cheap way out of that one yet.

The weather in El Paso is grand.

Take care,
Nick Pingitore