SAFECAST ANALYSIS

http://blog.safecast.org/2011/08/drive-report-august-7/

They measured both CPM (beta count) and microsieverts an hour in Japan. They found the following at different locations:

(highest readings were at ground level)

Location 1

192 CPM air level

.503 micosieverts an hour

–

Location 2

322 CPM air level

2746 CPM ground level
7.266 microsieverts an hour ground level

–

Location 3

1000 CPM air level inside car

pulled over and put the devices on the ground and found

1600 CPM ground level

15.96 microsieverts an hour ground level

--

Location 4

(excerpted) “20,000 CPM and 9 µSv/hr. We pulled out our SAM 940 to try and identify the isotopes and found things we weren’t expecting at all. So we grabbed some samples to send to a lab for professional analysis and got out of there quick.”

MAJIA HERE: Is there a way to establish a ration between CPM and microsieverts?

This is a very important question for me when trying to figure out exposure levels.


In locations 1 and 2 there is a relatively constant relationship between CPM and microsievert readings.


However, this relationship does not hold at all for Locations 3 and 4.

I am looking for help here and any would be much appreciated.

Thanks!