Re: strength of vacuum

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

The phrase you'll see a lot is ALARA (as low as reasonably attainable)..
Lots of dispute about whether small doses of radiation are cumulative. Large
doses certainly are.  A lot has to do with how fast your body repairs the
damage.

Rads are an obsolete (but still commonly used) measurement based on how much
energy is in the particles, in terms of ionizing air to a certain degree.
Few high energy particles or lots of low energy particles could calculate
out to the same rads.  REM -> roentgen equivalent man (mammal) attempts to
compensate for the different effects of different energies by multiplying
the particle flux by a RBE (relative biological effect).. Thermal neutrons,
for instance, have a RBE of 20.   Rad(Si) has to do with ionizing silicon.

The Gray and Sievert are the new units.

Curies have only to do with how many particles are produced in a unit of
time (or more properly how many disintegrations in a substance). 1 Ci is the
amount of disintegrations in 1 gram of Radium.  The typical smoke detector
has 1 microCi of Americium 241, and will have 27,000 disintegrations per
second. The particles given off are alpha, with an energy of about 5 MeV
(which, by the way, is really zipping for an alpha).  So, to calculate dose,
you could figure out how many of those particles you will intercept (they go
out in all directions, right?), multiply by the RBE for alpha particles at 5
MeV, and so forth.

In any case several millirem per year isn't anything to worry about, since
that's the kind of dose you get from cosmic rays, the potassium 40 in your
bones, the U and Th decaying in the rocks underneath you and in the
concrete, etc.  Move to where Terry lives, and your cosmic ray dose
increases somewhat because there's less air.  Ride the Concorde a lot or fly
the U-2, and it's a potential problem.


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, November 02, 2003 3:14 PM
Subject: Re: strength of vacuum


 > Original poster: "RIAA/MPAA's Worst Nightmare" <mike.marcum-at-zoomtown-dot-com>
 >
 > So what would be considered unsafe/dangerous? Is there a chart somewhere
 > that gives a time exposure limit for so many rads (btw, what's a curie?
I've
 > seen that unit used on smoke detectors)?
 >
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Sunday, November 02, 2003 3:54 PM
 > Subject: Re: strength of vacuum
 >
 >
 >  > Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net>
 >  >
 >  > Antonio and all,
 >  >
 >  > I've found that some elongated lamps that are intended for scroll lamps
do
 >  > indeed have a high vacuum instead of inert gas. The glass fluoresces a
 >  > brilliant yellow-green color, especially if the filament becomes
 >  > incandescent from field emission (with lots of electrons being
emitted).
 > An
 >  > old antique light bulb I have does a similar thing, only the glass
 >  > fluoresces a brilliant blue color. In either case, I could easily
detect
 >  > the presence of X-rays via a Geiger counter 8 feet away. Remember that
 >  > distance is your friend (inverse square law), keep run times down, or,
 >  > preferably, don't irradiate yourself at all... :^)
 >  >
 >  > Best regards,
 >  >
 >  > -- Bert --
 >  > --
 >  > --------------------------------------------------------------------
 >  > We specialize in UNIQUE items! Coins shrunk by Ultrastrong Fields,
 >  > Lichtenberg Figures (electrical discharges in acrylic), & Scarce OOP
 >  > Technical Books. Stoneridge Engineering -- http://www.teslamania-dot-com
 >  > --------------------------------------------------------------------
 >  >
 >  > Tesla list wrote:
 >  >
 >  > >Original poster: "Antonio Carlos M. de Queiroz"
<acmq-at-compuland-dot-com.br>
 >  > >Tesla list wrote:
 >  > >  > Original poster: John <fireba8104-at-yahoo-dot-com>
 >  > >  >
 >  > >  >   How many people do you think got more
 >  > >  >   than the recommended dose of rads in the last year while
 >  > >  > experimenting with standard vacuum light bulbs?
 >  > >"Normal" lamps don't have high vacuum inside, but are actually filled
 >  > >with an inert gas at low pressure. If in the experiments some corona
 >  > >or similar light appears inside the bulb, there is no problem. But
 >  > >if nothing appears, and worse, the glass fluoresces with a green
 >  > >light, this is sign of X-ray generation. Some small lamps are said
 >  > >to have high vacuum inside. I am not sure. Vacuum tubes certainly
 >  > >have (Humm... VTTCs may be dangerous...).
 >  > >Antonio Carlos M. de Queiroz
 >  > >
 >  > >.
 >  >
 >  >
 >  >
 >  >
 >  >
 >
 >