Detection Limit

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Detection Limit

Post by Stanford » 04 Mar 2017, 04:32

Interesting page on the limits of detection from Woodshole.

In the attached image, it looks like their whole shield is lined with copper. Am I wrong in having assumed that the copper shield is only needed around the detector? Or is this a different case because, as described in the woodshole article, it is a well detector?
Detection limit:
Our current detection limit using this method is about 0.1 Bq/m3 for 137Cs and 0.2 Bq/m3 for 134Cs. Values below this are reported as “below detection,” but this detection limit will vary with the sample size, the methods and detector used, and the total time each sample spends on the gamma detector. In general, larger sample sizes (we process a relatively large 20 liter sample), longer counting times (we typically leave a sample on for 48 hours or more), and more efficient detectors (we use some of the world’s most sensitive gamma detectors) lead to the lowest possible detection limits. ... l#analysis


great summary here: ... &cid=94989

tests results here:
large shield.jpg
large shield.jpg (551.19 KiB) Viewed 2428 times
Stanford Siver

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Re: Detection Limit

Post by sgt_bear » 12 Mar 2017, 04:47

About the lining of copper. Personally, if i would line a professional shield on the inside with copper, the price might be not that high to line it completely. The shield is probably made of lead -which is toxic. So a completely copper-lines lead block makes the lead untouchable and gives a harder protection than just paint. Also the surface on the closing hat will be smoother - making it more thight.

Just my thoughts
- Jonathan from Switzerland

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