| T O P I C R E V I E W |
| Exeter |
Posted - 10/11/2015 : 13:06:43
Hello, I'm new here, so bear with me as I learn. Thank's everyone.
VeteransToday.com published their week # 25 radiation counts for the ' hottest cities in America .'
It looks like Billings, Montana took the top spot, at around 2,700 CPM average for the week.
I live reasonably close, and my GQM 320 Plus, is showing around 18-25 CPM.
I looked and saw they listed about 15-20 cities, with many over the 1000 CPM readings.
The writer is, Bob Nichols.
My question is, how are they deriving and coming up with such high CPM averages ?
I don't understand, though I would like to learn. I am in no way affiliated with Veterans Today.
If anyone can help, it would be really appreciated.
Thank-you, Exeter |
| 5 L A T E S T R E P L I E S (Newest First) |
| GBG12 |
Posted - 10/18/2015 : 20:19:49
I found the reports on VeteransToday. For example, www.veteranstoday.com/2015/10/17/your-radiation-this-week-no-26
The reporter seems to be mixing up GM tube expected counts with actual scintillation ones, and saying that readings are '392 times normal'. Oddly, the posted readings are all at least 200 times 'normal' across the entire country and have been for years. Go figure. |
| Exeter |
Posted - 10/18/2015 : 19:24:02
Thank-you, GBG12 !
Unfortunately, I agree, we live in an era of sensationalism.
Thank-you for your help and guidance.
Sincerely,
Exeter |
| GBG12 |
Posted - 10/18/2015 : 18:32:34
Most laboratories have sensitive counters that are specific to certain radiation energies. The main type is a scintillation counter that is very different from the GM (Geiger-Muller) tubes used in most portable detectors (such as the GQ units). As ZLM says, there are different GM tubes as well. I think the data used by VeteransToday.com may come from the EPA sites; there is one in Billings Montana. Their direct website is www.epa.gov/radnet/near-real-time-and-laboratory-data-state
The 2,700 CPM average looks to be in the range of the EPA's gamma counts using one of the sensitive scintillation counters. The map at that web address shows a total gamma for Billings around 10,000, and a link from there shows 10 different counter readings for that location, some of which seem near 2,700. However there does not seem to be a significant recent rise in this data, and other nearby sites are similar over the past 4 months. VeteransToday may be using other data, or using this data in an alarmist fashion (based on my limited knowledge).
Other sites with real-time data to check out: www.Netc.com www.Radmon.org www.radioactiveathome.org/map
(edit: I just found the edit feature) |
| Exeter |
Posted - 10/18/2015 : 12:52:19
Thank-you, ZLM.
VeteransToday.com posted week 26 today.
Over 20 US cities counting over 1000 CPM. Billings, Montana at 1962 CPM.
Maybe they are adding in Alpha decays. I don't know.
It's got me stumped.
Sure appreciate your reply. Thank-you, again.
Exeter |
| ZLM |
Posted - 10/16/2015 : 21:34:04
The CPM is Geiger Tube type dependent. On same radiation level, different type tubes read different CPM. However, the CPM can be converted to independent unit, such as uSv/h, mR/h etc.
So, one tube CPM is not meaningful to another type of tube.
To compare the reading between different type tubes, we have to convert the CPM to uSv/h or mR/h unit. |
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