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Mean free path for electrons is much greater than that for air molecules, at the same pressure.
Yep, about a factor of 5 for 100eV electrons. Got this from the "internet" and not from my own education as well as the statement, that todays light bulbs are gas filled
Registered Member #60240
Joined: Mon May 16 2016, 07:01PM
Location:
Posts: 304
Hi Klugesmith
"Physicsfan, are you equipped to extend Po's x-ray experiment using a high-vacuum pump and pressure gauge?"
Now I got a vacuum pump and a pressure gauge to do an experiment with a very old selfmade cold cathode discharge tube at different low pressures and at different voltages (different electron energies).
But still I have a problem. Last time many years ago when I did this experiment the high voltage at the discharge tube destroyed my low pressure sensor.
I could switch on the pump and also the pressure gauge to get a certain pressure inside the discharge tube. But before switching on the high voltage I should remove the pressure sensor from the equipment to be able to use this device a second time. Or anybody has some hints for me to keep the pressure sensor alive when connected to the discharge tube?
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I'd like to point out that the radiographs mentioned above that I've made using very soft rays have been of subjects like flies' wings and microscopic plant sections.
Also: remember that the energy-response curve of uncompensated GM tubes is wildly distorted in the way of massive non-linear overcounting below about 75 keV. It wouldn't be unusual for a GM tube to over-count by a factor of twenty times and more when exposed to X-rays of 25 keV or so. This is because the counting efficiency increases in a non-linear way as more of the low energy photons are stopped in the counting gas.
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X-Rays in small microwave bulb?
