Archived posting to the Leica Users Group, 1998/03/13

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: Re: [Leica] Off-Topic: Airport X-ray Machines, Physics 101
From: Simon Ogilvie <simon_ogilvie@ionica.co.uk>
Date: Fri, 13 Mar 1998 15:52:59 -0000

ATanabe wrote:
> As a rule the thicker the object (lead bags) the more energy (Xray) needed
to
> penetrate the object.  For example, xray penetration or energy is measured
in
> KiloVolts (KV) the higher the energy the greater the interactions with
objects
> in its way (bouncing of electrons) = fogging of film.  With the emulsions
> today, there is less silver than old emulsions, silver being metalic,
reflects
> the xray energy and causes the halides to be fogged.  One can duplicate this
> scatter by piling on cassette after cassette on one another (metal casings
> will cause the scatter).  The best way to survive airport xrays (if you have
> to) is to have a single layer of cassettes on the belt, making the energy
> lower (less mass) and reducing the scatter.  If you put the film in a lead
> bag, the machine will automatically crank up the energy (auto exposure) on
the
> xray and fog your film.

Does this mean that if I use bulk-loaded film in plastic cassettes I'm
much
less likely to have a problem?  In fact, if I don't use metal cassettes
at all
I suppose it would be possible to hide the films "about one's person"
and
carry it through the metal detectors so it wouldn't go through the X-ray
machines?

Simon.