Ionizing radiation detector troubleshooting

For a Science Fair project I have, I am building an ionizing radiation detector. I am using this guide and building on it by connecting it to an Arduino. Unfortunately, I have built the Experimenter’s’ Ionization Chamber from that guide. Here is a diagram of what I have built. When trying to test a granite sample for radioactivity, the voltage doesn’t change. I have tried having the lid on and off and putting another tin (Not 100% sealed) over the circuitry. I have tried putting the sample in the chamber. I have tried switching the Collector and Emitter, which simply makes the voltage on the multimeter negative and changes the baseline slightly. Switching the positive wire for the multimeter to the other slot gives me no reading. I have tried all of the settings on the multimeter, and am currently using 2, 20, and 200 V. Nothing gives me an increase in voltage when testing a granite sample. Is the granite not radioactive, or is something interfering with the circuit? Is the circuit set up properly? If the circuit is fine, where and how can I easily obtain a somewhat safe & legal radioactive sample in Canada? Thanks to anyone who can help.

Please do not double post.

You cannot detect the weak radiation from granite with that very insensitive detector. You need the source from a smoke alarm, or a genuine old style radioactive Coleman lantern mantle.

BotJohn:
... When trying to test a granite sample for radioactivity, the voltage doesn't change. ...

Buy a geiger counter. If you can't read anything with that, don't even try with your device. My previous suggestions of an electroscope and a cloud chamber were based on 30 years experience in an undergrad environment, doing just what you are trying to accomplish.

You need to decide if you want to have a trendy project or do you need results?

jremington:
Please do not double post.

You cannot detect the weak radiation from granite with that very insensitive detector. You need the source from a smoke alarm, or a genuine old style radioactive Coleman lantern mantle.

Sorry for double posting. I did not realize there was a rule against that.

I have tried taking apart a smoke detector, and managed to get a small plastic and metal piece from inside the metal casing on the board inside the smoke detector. From a guide I was using to take apart the smoke detector, it seems to contain Americium. I'm not sure if it's the right piece though, and I'm currently not seeing any different when putting the piece inside the chamber. I have attached two pictures of both sides of the piece. Are these results different from what I should be getting?

ChrisTenone:
Buy a geiger counter. If you can't read anything with that, don't even try with your device. My previous suggestions of an electroscope and a cloud chamber were based on 30 years experience in an undergrad environment, doing just what you are trying to accomplish.

You need to decide if you want to have a trendy project or do you need results?

A geiger counter is very expensive which is why I didn't use one for this project.

A geiger counter is very expensive which is why I didn't use one for this project.

If there is a university with a chemistry or physics department, or a high school physics instructor near you, it is very likely they will have access to a Geiger counter and might be willing to help. They may also have radioactive sources.

Be very, very careful with Americium from a smoke detector. If you inhale or swallow any particles, the radiation could lead to serious tissue damage or cancer.

jremington:
SBe very, very careful with Americium from a smoke detector. If you inhale or swallow any particles, the radiation could lead to serious tissue damage or cancer.

I don't think it's worth it to try to test Americium and further take apart the smoke detector.

Using this guide , I created a Voltimeter using an Arduino Uno. I substituted a 100k resistor for the 90.9k resistor and changed it in the code. The circuit worked fine when testing it virtually on Autodesk Circuits with a 9V, but when hooking it up in real life, the voltage shows 55 V instead of 9. Is this normal?