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Jorge P
12-27-2011, 09:22 AM
Well, I don't think taking the Americium-241 completely out of the chamber in a smoke detector is useful. I would be more interested in learning how I can use the intact ion-chamber to make a Random Number Generator or Radiation detector.

A few years ago, 2007, I wrote to Montana Lottery headquarters and asked them about how they generate their random numbers in their lottery machines. The following is their full reply.



I am not aware of any legal issues relating to persons who wish to sell number selection software or devices.

We do not allow use of our logo without compensation. We’ve spent millions of dollars to make the logo and brand able to attract people’s attention. That benefit is for us alone.


We write our own number picker software here, using radio-active material and a Geiger counter to produce true random numbers.




So if a smoke detector uses an ion-chamber to detect smoke, if you have two can you make a Geiger counter with one and use the other for a radio-active source in order to generate true random numbers?

OR, Is the device in smoke detectors the detector and source combined?

Also, how would you interface to it to generate true random numbers?

I have used a lotto picker when I worked as a Convenience store clerk every day, it's neat to understand completly how they work. All the ones I have used use Linux as their OS.

The Instructable - http://www.instructables.com/id/How-to-Obtain-and-Extract-Americium/step3/How-to-Obtain-and-Extract-Americium/
The Americium-241 Wiki article - http://en.wikipedia.org/wiki/Americium-241#Americium-241
The Ionization Chamber Wiki article - http://en.wikipedia.org/wiki/Ionization_chamber

Martin_H
12-27-2011, 02:12 PM
A Geiger counter has an audio output, so sampling and digitizing it should provide a stream of random bits versus time. I would think a PC sound card would work. Most cryptographic libraries have an api to generate random numbers from an entropy source (the bits from the counter).

ElectricAye
12-27-2011, 04:28 PM
Jorge,

There was a little discussion about "true" randomness on the forum sometime ago.
http://forums.parallax.com/showthread.php?93061-Real-Random-Number-Generator-Object&p=769543&viewfull=1#post769543

[EDIT: Hey Jorge, in fact you and I have had a similar conversation about this before.
http://forums.parallax.com/showthread.php?123135-Real-Random-number-generation....&p=913767&viewfull=1#post913767]

http://www.americanscientist.org/issues/pub/randomness-as-a-resource/1

Getting something truly random isn't easy. You might look at all the problems the Princeton PEAR research people had trying to convince the scientific community that their "random event generator" standards were good enough.


As for Americium in smoke detectors, I think it's mostly an alpha emitter, so the smoke detector's method of detection is set for alphas. Since alphas can be easily absorbed by many materials, including some few centimeters of air, you would have to have the detector very close to whatever you're trying to measure, and I doubt it would detect other forms of radiation such as betas and gammas. Personally, I would NOT mess around with trying to take apart these detectors for any reason. There are much safer ways to play with radiation detection, and radioactive sources for experiments are available that are safe and legal to use, even at home. I've seen geiger tubes on ebay, for example, that would make for a great DIY project, and you can buy small quantities of ores, etc that are radioactive enough to play around with. In fact, if you have granite around, you might find some of that is fun to play with. If you want to get more sophisticated, you can get some photomultiplier tubes, some scintillators of some sort, and make very sensitive gamma ray and cosmic ray detectors, etc.

http://quarknet.fnal.gov/toolkits/ati/crdetectors.html

As for taking apart old smoke detectors, you might Google "Radioactive Boy Scout" and read some of that horror story.

Peter KG6LSE
12-27-2011, 08:19 PM
its a @ emitter BUT also does low speed Gamma...



""" decays to 237Np emitting alpha particles of 5 different energies, mostly at 5.486 MeV (85.2%) and 5.443 MeV (12.8%). Because many of the resulting states are metastable, they also emit gamma-rays with the discrete energies between 26.3 and 158.5 keV""""



87995

in fact the button you see is holding the Am Foil disk ........
the Crimped in Foil is the nastys so as long as you dont Lick it . then its OK

its yellow-ish as they put a uber thin gold layer over it to keep it From ever shedding Am off the crimped in disk .

[URL="http://www.theodoregray.com/PeriodicTable/Elements/095/index.s7.html"]http://www.theodoregray.com/PeriodicTable/Elements/095/index.s7.html[/URL


I would not attempt to EVER remove the foil From the buttn ..

that said ... LND
http://www.lndinc.com/products/711/

has some good tubes and are Well known ...



Have Fun and Be smart and safe .. Wear Gloves Please ...

Tracy Allen
12-27-2011, 10:10 PM
Most cheap ionization detectors use a dedicated chip, the ubiquitous MC14467, which includes a sensitive charge amplifier as well as auxiliary functions such as the horn sound driver. The voltage output of the chip (avaliable from pin 14 -- the guard-lo pin) fluctuates quite a bit due to fluctuations in the emission of alpha particles. With a sensitive ADC, you could potentially use that voltage as a slow source of randomness, without having to tamper with the ionization chamber itself.

Other factoids:
A smoke detector contains about 1 microcurie of Am241, 0.28 microgram sandwiched in the gold foil. The source emits on the average 37000 alpha particles per second, and each particle comes off at a velocity of about 15000 km/s, about 5% the speed of light. The kinetic energy is about 5MeV. As those interact with air molecules, it takes about 34eV to generate an ion pair, so each alpha particle as it loses its 5MeV generates about 132000 ion pairs and in normal air that that takes 1 or 2 cm of travel. The electrical current associated with the 37000 alpha particles amounts to scarcely more than 10 femtoamps, but the potential elecrtical current due to the secondary ionization (37000*132000) amounts to around 1 nanoamp. The ions can attach to smoke particles which have a much lower mobility and also become more neutral when many ions attach.

Jorge P
12-28-2011, 04:20 AM
With a sensitive ADC, you could potentially use that voltage as a slow source of randomness, without having to tamper with the ionization chamber itself.


That's exactly what I was hoping to hear. I don't intend on tampering with the chamber, I'd rather make use of it! Thanks for the "factoids". I live 2 minutes to WVDP http://www.wv.doe.gov/ and I believe they store the various Isotopes of americium. If I, or anyone, can make an RNG with this, I think it will help with storage issues and ease cleanup costs by introducing its proper use to the electronics community.

Also, I would like to just say that if anyone decides to take apart their smoke detector, USE Nitril Gloves so you can prevent it getting in mucus membranes when you itch your eyes, nose, or mouth. Nitril gloves are required by Hospital staff when cleaning Cancer Treatment rooms and working with Radiation equipment. They are also in all certified Bio-Hazard cleanup kits and Certified Blood Spill kits.