A Geiger counter measures various types of ionising radiation such as Gamma rays. Shown here with antique Uranium marbles that were bright due to some fluorescence.
“Continue reading” for a hotter Uranium sample, specifications and links…
This is a reasonably sensitive pancake style Geiger counter which measures various types of radiation. It has a 4.45 cm (1.75 inch) mica window. It is a GM-45 from Blackcat systems. Specifications. Alpha radiation can be detected from 3 MeV (e.g. from a smoke detector). Beta radiation can be detected from 50 keV (e.g. from potassium). Gamma radiation can be detected down to 7 keV (e.g. Uranium or x-rays).
I have an updating graph of background radiation in my home town in Western Australia (updated 6 hourly). It runs whenever I have my Geiger counter on.
Radioactivity had been topical with the Japanese nuclear accident. A lot of Geiger counters were sold then for household use. Here is a readout from my Geiger counter.
Above is the Geiger counter registering 108,000 CPM from a Uranium ore sample.
So, where does the background radiation come from? Just for a test, I covered the Geiger counter in lead sheet.
The lead sheet when folded over makes a reasonable shield. Result? There was no difference in the background radiation at all. The counts per minute were 50 vs 52 with a standard deviation of around 4. So this is unlikely to be due to low level beta or gamma radiation in my shed or from cosmic rays. Intrinsic noise from the counter itself is perhaps most likely.
Related pages
Background radiation in Bunbury Australia
Try something else
External links
Photo Date: 2006