View unanswered posts | View active topics It is currently Fri Dec 13, 2019 8:45 pm



Reply to topic  [ 6 posts ] 
 FWIW three spikes above 4000 CPM in San Diego 
Author Message

Joined: Thu Oct 24, 2013 8:10 pm
Posts: 7
Location: San Diego, CA
The first spike was Friday 9:30 pm and lasted maybe two minutes duration or so. Over 5000 CPM. An attention getter.

Saturday in early afternoon there were two more very similar events (they are recorded - all file types -- since I have been recording 24/7 for over a week). Since these events, background looks 'familiar' to me and quite normal. Since the background level looks completely normal in the absence of the spike events, the GMC 300E calibration and function looks OK. Ordered a calibration source nevertheless.

These Saturday 4000 CPM ++ spikes lasted for 2 - 3 min for each event, These rates are over 100 uSv/H and are multiples of the normal avg US background radiation.


Sat Nov 23, 2013 8:01 pm
Profile

Joined: Fri Nov 22, 2013 5:31 pm
Posts: 17
Hmmm, a somewhat disconcerting report there. :shock:

How long have you been monitoring a GC? Have you ever seen similar things there since you started monitoring, or is this a first? What part of San Diego do you live in (e.g., beaches, North County, East County, Chula Vista, etc.)?

It would be interesting if you could trap any of it in an air filter, and then check the air filter with a pancake tube (short of conducting a more expensive spectrum analysis).

Peace.


Sat Nov 23, 2013 9:34 pm
Profile
Moderator
User avatar

Joined: Mon Jan 28, 2013 7:40 pm
Posts: 2879
Location: Illinois
A climb that high and for such a short time frame, I find it hard to believe this is not a false reading.

Is your unit inside or outside?

If your unit is inside, a real spike like this is even more unlikely unless someone who recently had radioactive medical testing done passed by your unit. If your using the Windows PC NETC program, there is a known bug that allows a large spike due to moving the geiger counter around while testing. This bug will be fixed in the future and does not happen when using the Raspberry Pi version.

Can you please post a link to your station so I can look at the graph?

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Sat Nov 23, 2013 11:51 pm
Profile

Joined: Thu Oct 24, 2013 8:10 pm
Posts: 7
Location: San Diego, CA
I have been working overtime to find out how to ignore this info. That's why the calibrated source is on order. I am posting this to encourage others to look through their data for this kind of high intensity low duration kind of thing.

The Friday 9:30 pm event data file was lost in the shock of seeing the high levels. Turned off the unit. Duh. I do have files showing two events for Saturday and one event so far Sunday, however. Same high intensity. This makes four events in all.

Re the other questions. I live next to Fashion Valley near San Diego river. Have a few weeks of 24/7 recordings. Detector is inside.

Here is the reason I posted. If I didn't have an alarm just above the background I probably would have never noticed these events. They didn't change the average level enough to be noticed. They could be happening at other locs and not seen for the same reasons. While the gross averages are not affected much, sparse density hot particles may be blowing overhead.

Of course would be happy to upload my bin files if that were to ever be relevant. Not sure how to do that BTW.


Sun Nov 24, 2013 8:42 pm
Profile

Joined: Fri Nov 22, 2013 5:31 pm
Posts: 17
KingCobra wrote:
A climb that high and for such a short time frame, I find it hard to believe this is not a false reading.

Is your unit inside or outside?

If your unit is inside, a real spike like this is even more unlikely unless someone who recently had radioactive medical testing done passed by your unit. If your using the Windows PC NETC program, there is a known bug that allows a large spike due to moving the geiger counter around while testing. This bug will be fixed in the future and does not happen when using the Raspberry Pi version.

Can you please post a link to your station so I can look at the graph?


I don't think GO answered your question in other posts, but I'm guessing he does not have it on the NETC network, and thus probably not running the PC NETC program. I too do not yet have a GC on the NETC network, but am curious whether the bug has been fixed.


Tue Dec 03, 2013 9:29 am
Profile
Moderator
User avatar

Joined: Mon Jan 28, 2013 7:40 pm
Posts: 2879
Location: Illinois
JohnD wrote:
I don't think GO answered your question in other posts, but I'm guessing he does not have it on the NETC network, and thus probably not running the PC NETC program. I too do not yet have a GC on the NETC network, but am curious whether the bug has been fixed.


I should not have called it a bug, because most assume a bug would be an error in the program. There is not an error in the free program app but rather an operator error condition that was not programed to be ignored. This condition I understand are high spikes caused from the user moving the unit/geiger around while testing which with any audio out device, the sound is likely to change as the connection varies. It is this poor connection that causes the software program to receive bad data.

This correction has already been made to the Raspberry Pi software, after all the Rspberry Pi software is NOT free so the priority for the fix obviously needed to start with that version. There are plans to revise the FREE Windows PC version to avoid/ignore this condition but I do not have a scheduled release data as of yet.

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Tue Dec 03, 2013 10:28 am
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 6 posts ] 

Who is online

Users browsing this forum: No registered users and 19 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group
Designed by STSoftware.