Wednesday 27 January 2010

Not Working in Ottawa today --Homemade Geiger Counter

Okay, I really took it on the chin from many of you for the lack of any story or factoid in Tuesday's email.  Some of the responses included
  That's it ? Weak!
  OMG what the hell!
  No anecdote or health tips?
  You may have already won the lottery, send us your bank account info now!
Ahem.. I am sorry, it was very selfish, but it was Yanick and Sophie's fault.  They provided me with several seasons of 'The IT Crowd' on a USB key.  So instead of writing some brilliant editorial I sat on the plane and passed the time being amused watching a few episodes.
So in penance, I will provide you with some helpful tips on how to determine if you are being bombarded with Alpha, Beta, or Gamma rays.
I was reading this last evening on the use of potassium chloride as an alternative to sodium chloride in foods.  While at first it seemed like a good idea, it may not be a good idea for the general population.  First off, it doesn't taste very good, you are much better off using garlic, lemon juice, cumin, ground pepper, etc.  Secondly, the added potassium is not a good idea for anyone with kidney troubles or those taking heart, kidney or liver medications.
As I continued to surf I came across a website that listed radioactive consumer products including Potassium chloride salt.  I have to stop you right there, I know what you are thinking --where can you find dice made of depleted uranium?
I read on about the potassium.. There are 3 potassium isotopes, K39 which is stable and more than 93% of the total potassium on the planet, K41 also stable and at 6.73% of the total and then K40 --not stable but a half life of around 1 and a quarter billion years.  Its decay results in the emission of beta rays for the most part and some gamma rays just for fun.
Perhaps a very quick and totally incomplete primer on radiation occurring in radioactive decay.
Alpha rays are the nuclei of helium atoms -2 protons bonded to 2 neutrons, they have a positive charge.  Beta rays are electrons, they have a negative charge.  Gamma rays are high energy photons -they have very high matter penetrating power but no at-rest mass.
Hey, I warned you that it would be incomplete.  I then wondered if I had the necessary components in my kitchen or basement to construct a rudimentary Geiger counter.  That is, a radiation detector.  Geiger counters are named after the relatively unknown interpretive dancer and momma's boy turned well known physicist Hans Geiger.
First you need a tube of metal or a glass tube coated with graphite, this will be your cathode.  Mount a single wire through the center of the tube, end to end suspended by suitable insulators, this is your anode.  At one end affix a lens of mica or very thin glass and seal the other end with a suitable insulator.  Fill the tube with a noble gas such as helium, argon, or neon.
Now you need a source of several hundred volts --low amps though so you could step up the voltage of a 9 volt battery-- connected to your cathode and anode. You also need an amplifier, but you could probably use just use some duct tape and firmly affix that old pocket AM band radio to this tube of fun and turn her way up.  Voila! A Geiger counter that Red Green would be proud of.  BTW, I did not have the necessary components, but have a look in your kitchen drawers, you may have better luck.
As a Alpha, Beta or Gamma ray enters through the mica lens a few molecules of the noble gas are ionized resulting in positively charged ions and electrons.  The high voltage field between your tubes cathode and anode pull the ions toward the cathode and the electrons toward the anode.  The ions cause additional ionization of the gas creating a brief storm of charged particles.  The result is a pulse of current between the cathode and anode that the AM radio should be able to detect and amplify through its speaker.
Now then, you should be able to hear background radiation of around one click every 3 seconds or so, but if your speaker is clicking like mad then you may be standing near a nuclear reactor.
Let's try to classify your detected rays.  You will need a few sheets of paper, a MacBook Pro laptop or a sheet of aluminum perhaps 1/8 inch thick and finally a Buick that is not painted cadmium yellow.
If the clicking slows to background levels after placing the paper in front of your lens, then you have detected alpha rays;  If the clicking slows to background levels after placing the MacBook in front of your lens, then you have detected beta rays;  And if the clicking slows down when filtering with a Buick, you have detected gamma rays.
Now for you Star Trek fans, reversing the field polarity WILL NOT enable you to detect tachyon particles --which is probably a good thing since a detector would also be an emitter and if we had a tachyon emitter/detector we could send information to ourselves faster than light and that would suggest that you could be reading this email before I sent it and I would hate to be a party to anything that violated causality :p
Have a good Wednesday and keep the clicks low.
-----Original Message-----
From: Daniel Puckett
Sent: January 26, 2010 9:40 AM
Subject: Working in Ottawa today
Good morning folks,
I will be working in Ottawa today.
That's all I have; enjoy your day.
Sent from my BlackBerry wireless handheld -- Envoyé sans fil par mon terminal mobile BlackBerry


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