Re: X-ray crystalography

[tdc@ehssun.lbl.gov (Ted M. de Castro)]

ABSOLUTELY!!!

>>If you're forced to work with old, unenclosed, no interlocks machines, as 

Yes out machines are old too - the oldest 1948!!!  BUT - we enclosed them 
all anyhow!

>>I  was, 2 inexpensive, but effective upgrades are: 
>>(1) a fail safe "x-ray on" light - if the bulb is burnt out or removed, 
>>the machine won't work. 

 We have designed just such a light here at LBL.  That is both effective and 
cheap (just like us!!).  It will turn off the machine when the bulb burns 
out and uses a 12 car tail light bulb, a 12.6v filament xfmr and a 6.3 volt 
ac relay.

We put it in a simple enclosure and we surround the bulb with a frosted and 
masked lucite cylinder.  The mask says "X-RAY ON" and can be positive or 
negative masked.  We also baffle the end to vent bulb heat and prevent light 
from coming out the end.  We put these inverted over the machines.

The result is a totally unambigious display:  When OFF the legend cannot be 
read or even seen.  When ON it is a clear display even right up again bright 
room lighting!

BUT more importantly the end baffle means it does not cast light on the 
experimental area and with the negative mask little out the sides.  THUS 
there is _NEVER_ a need to cover the light to see a phosphor glow when 
trying to find the beam.  In reviewing analytical x-ray machine accident 
history I found that the covering of the light was usually an event leading 
directly to the accident!  Also - just telling the experimenter not to cover 
the light does no good if it interferes with the experiment - SO the best 
plan - I felt - was to remove the need to cover it.

The printe can be gotten from our print room and if I can get to a color 
scanner - I can put a picture of it up on anonymous FTP.  If anyone is 
interested.

>>(2) a  "backscatter monitor" - which is a area radiation monitor designed 
>>to  detect low energy x-rays, and designed to alarm on either a radiation 
>>level  above background or a rate of rise.  This should detect any x-ray 
>>leakage,  hopefully before someone gets hurt. 
 
Argonne delevoped and EXCELLENT instrument just for this purpose back in the 
early 80's.  We adapted and improved there design and have over 30 in use!  
Recently I coerced HPI to offer an improved version of this device 
commercially.  NOW we can get them more cheaply than building out own!