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I think you need to be more careful here. We all do for that matter.Remember,
we're the pros and we need to KNOW, not just think. I don't know, so I'mlooking
forward to more decisive answers here. I don't think that "I don'tthink" is good
enough when you're dealing with ionizing radiation. Make sense? It's ourhealth as
well as the faculty, students, etc. Whoever handles this rig should bewell
informed.accelerating
What evidence do you have for that statement? Have you measured the
voltage, emission current, etc? How about doing as Cliff suggested andmonitored the
x-rays? Guess what I'll be doing tomorrow?as
Thanks,
Sam
"Jason St. John" wrote:
> I don't think that these old tubes accelerate (decelerate) enough
> electrons to generate appreciable X-ray radiation. Not enough current.
>
> -jmsj
> ____________________________________________________
> Jason St. John 617.353.2634 stjohn@bu.edu
> Boston University Physics Lecture Demonstrations
>
> On 2002-10-10.14:49 owner-tap-l@listproc.appstate.edu sent:
>
> Would that include the old demo at this website?
>
> http://www.physics.brown.edu/Studies/Demo/modern/demo/7b3510.htm
>
> ----- Original Message -----
> From: Cliff Bettis
> Sent: Thursday, October 10, 2002 1:42 PM
> To: tap-l@listproc.appstate.edu
> Subject: Re: Cathode ray tubes for demos
>
> The voltage you apply determines the energy, the current determines the
> intensity. You can limit the emission by keeping the voltage and current
> low as possible. The problem is that, traditionally, these tubes wererun
> off of induction coils and the only regulation was a spark gap inparallel
> with the circuit.do. A
>
> As far as detecting the radiation, a Geiger counter or film badge will
> friend of mine turned this issue into a class project using the tube tomake
> some x-ray photographs!not
>
> Usually the audience is far enough away from the device that there is
> much risk for them, however, the lecturer or set-up person has to be upviolate
> close. There is also the matter of the law and in our state we would
> the law if we operated an unlicensed x-ray source. So we generally useI
> cathode ray tubes designed to run at low voltages (a few kV) with heated
> cathodes.
>
> I don't mean to alarm anyone, just to point out something you should be
> aware of if you operate these tubes. I, personally, wear a film badge if
> set up one.they
>
> Incidentally, gas filled tubes (plasma globes and the like) don't emit
> x-rays because the electrons in them never get going fast enough before
> collide with a gas atom and have to start accelerating over again.length
>
> Cliff
>
> ----- Original Message -----
> From: "Jim Kernohan" <Jim_Kernohan@Milton.Edu>
> To: <tap-l@listproc.appstate.edu>
> Sent: Thursday, October 10, 2002 11:24 AM
> Subject: Re: Cathode ray tubes for demos
>
> > tap-l@listproc.appstate.edu writes:
> > >
> > >Be careful when you use these old tubes as they can emit x-rays.
> >
> >
> >
> > UNder waht conditions will they emit x-rays? Should I shorten the
> > of time? lessen the voltage?http://explorer.msn.com
> >
> > How do I easily detect if I'm emiting x-rays?
> >
> > thanks!
> >
> > JimGet more from the Web. FREE MSN Explorer download :
Dr. Karl I. Trappe, outreach consultant Home (512) 264-1616Austin, Texas 78712-1081
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