Update: air samples revised, and two new samples added (6/17)
6/17 (8:55pm): Air results have been fully revised to compensate for the small amount of Cs-137 contamination detected in our lab. Removing the Cs-137 background has caused our measurements of Cs-137 to decrease by approximately 5–50% over the course of our sampling period. One effect of this revision is that the Cs-137 results now track even more closely with our Cs-134 measurements — in fact, a slight discrepancy between the measurements is what tipped us off to the possibility of contamination in the first place.
Two air samples were added, for 5/25-31 and 5/31-6/7. In the latter sample, no fission products from Fukushima have been detected.
Mark [BRAWM Team Member]
Elaboration
Hi all, I wanted to try to answer some of the questions that have been coming up:
We found a Cs-137 gamma-ray line in our spectrum when we were testing a "blank" filter over the course of a few days last week. The line is so weak that it doesn't appear in the spectrum until we have counted it for about 1—2 days. It is not due to contamination from Fukushima, since there are no other Fukushima contaminants present in our background. Most notably, there is no Cs-134 line in our background, which could only be from Fukushima and has been accompanying Cs-137 in roughly equal proportions in our measurements.
Since the line is so weak, it would take a long time (weeks) to figure out where exactly the Cs-137 background is coming from and it would not be worth the time. It could be inside the lead, since our bricks were cast since atmospheric weapons testing. It could be left over from an old experiment. We have never rearranged our lead bricks, so the background should be exactly the same for all our measurements. In any case, it is very small but must be accounted for in our calculations, which is what we have done here.
We went back and recalculated all of the Cs-137 count rates, subtracted off the background line count rate, and the results actually solve a mystery. The mystery was why we have been seeing Cs-137 in higher and higher amounts relative to Cs-134, as both activities have been decreasing toward MDA. Once the background is subtracted, the ratio between them is nearly constant over all measurements. So this is a sign that we made the right correction.
I hope this answers some questions, and assures you all that nothing "hinky" is going on.
Mark [BRAWM Team Member]
data refinement
Thanks for all the time and effort in refining these data and for explaining the results of the test.
Hooray for Brawm! Alot of
Hooray for Brawm! Alot of you profiteers and scaremongers could learn something about ethics from these folks. I'm considering naming my first born berkeley.
Future college admissions idea
Hmmm....naming your first born "Berkeley," may not be a bad idea. That, and an intriguing college application essay explaining the reason behind their name, might make little "Berkeley" stand out in the application process many years from now.
Also, it can be used for either a boy or a girl.
I wonder if our mutual mention of this will start a new baby "Berkeley" trend?
I hadn't even thought about
I hadn't even thought about that! I had already made up my mind that I was going to pester my kid to attend...BRAWM has renewed my faith in humanity and my interest in science AND has brought great comfort to my fiance and I. Thank you Mark, DChivers, JMiller...everyone involved in this effort...thank you!
Mark, do you know the contamination levels pre-Fukush?
Hi Mark, do you know the cesium contamination levels in your lab pre-Fukush? ie do you know what the baseline was? Otherwise I can't quite understand how such a subtraction can be valid (excuse me for doubting, and I love what you all have been doing for us, but I am not a scientist and have heard so many confusing things about this Fukush business that my head is spinning). Thanks.
Pre Fuk Cesium
In mid March I spoke to Jerry Hensley a health physicist at CDPH regarding pre fuk background and baseline for Cesium. He said it is or should be zero. It was a casual conversation so some lapse in exactitude may have occurred in communication.
Mark, Are you saying that
Mark, Are you saying that your lab is contaminated with Cesium-137 from Fukushima to such an extent that it is affecting your measurement method? If not, what is the source of the Cesium-137 contamination?
6/14 (12:25am): A milk
6/14 (12:25am): A milk sample with a Best By date of 6/20 was added to our Milk results. Cesium-134 was detected again at levels similar to previous measurements, but Cesium-137 levels decreased.
Also, a new raw milk sample collected on 6/8 was added to the raw milk page. We have our first non-detections of all isotopes in raw milk.
Lastly, we are in the process of revising our air results for Cesium-137. Since we have been counting samples for many days instead of only 24 hours, we decided to take a long background spectrum to check for possible contamination. A very weak gamma-ray line for Cs-137 was detected in the lab, probably due to contamination of our lead bricks from an old experiment or from radioactive cesium in the lead itself. The presence of this extra Cs-137 has been creating a systematic increase in the Cs-137 measurements we have been reporting. Now that we have measured its strength to good precision, we can subtract it off of our measurements. This is going to lead to a downward revision of our Cs-137 measurements in the coming days. We will make a note when the revision has been made and new air data have been posted.
Holy cow, you guys don't
Holy cow, you guys don't even know what contaminates your own controlled laboratory? That's scary.
Holy cow, you guys
Holy cow, you guys don't
Submitted by Anonymous (not verified) on Sat, 2011-06-18 07:16.
Holy cow, you guys don't even know what contaminates your own controlled laboratory? That's scary.
Not sure if troll...or just stupid...
In Internet slang, a troll
In Internet slang, a troll is someone who posts inflammatory[citation needed], extraneous, or off-topic messages in an online community, such as an online discussion forum, chat room, or blog, with the primary intent of provoking readers into an emotional response[2] or of otherwise disrupting normal on-topic discussion.
A concern troll is a false flag pseudonym created by a user whose actual point of view is opposed to the one that the user claims to hold. The concern troll posts in Web forums devoted to its declared point of view and attempts to sway the group's actions or opinions while claiming to share their goals, but with professed "concerns". The goal is to sow fear, uncertainty and doubt within the group.[17]
http://en.wikipedia.org/wiki/Troll_%28Internet%29
What are you contributing to the discussion with this attack? Contamination of the lab is a legitimate concern, a lot of people are counting on this data.
you = troll
Nope, just actually recall
Nope, just actually recall the scientific method and how this doesn't mean a damn thing unless it can be peer reviewed/verifiable.
Go away shill.
Go away shill.
Go away shill. Submitted by
Go away shill.
Submitted by Anonymous (not verified) on Sat, 2011-06-18 16:50.
Go away shill.
This /\
This revision makes me very
This revision makes me very uncomfortable. Did you actually find the contamination and remove it, or just lower all your numbers for Cs-137?
I am trying to give you the benefit of the doubt but something seems hinky here.
SOMETHING DOES SEEM HINKY
SOMETHING DOES SEEM HINKY HERE...and it's your posts.
You obviously aint no
You obviously aint no scientist. The whole point is to be able to back up your claims to the scientific community. Considering they tested this stuff for 2 months unaware their lab was 5-50% contaminated, I would hazard a guess this raises more questions than answers. Who is to say they didn't get the word China Syndrome is a go and we need an excuse to cut the levels by 50% from here to the end of time? Because that is certainly a plausible scenario looking in from the outside. One thing I do appreciate about BRAWM, at least they can take the heat and let us have a discussion.
This seems plausible. I do
This seems plausible. I do remember at some point on these forums some of the BRAWM team was really tough on Chris Busby on the subject of peer review.
Here's the post
Christopher Busby seems to
Submitted by dchivers on Tue, 2011-04-26 18:12.
Christopher Busby seems to have undermined his scientific legitimacy due to he association with anti-nuclear political organizations. He has come to conclusions about low-level radiation exposure before observations can clearly support his claims. Scientists do this to either be first to the market on theory or because they have political bias. Both motivations are not rooted in science. His conclusions are subjected to peer review just as anyone else, but it seems there is a dearth of real peer-reviewed publications to support his claim, either by him or anyone else. For anyone who reads his reports and informal publications, please ensure you are knowledgable of the source and the bias behind it. Bias is everywhere and scientists must fight it at all costs,...,even within your own writings.
http://en.wikipedia.org/wiki/Christopher_Busby
"Christopher Busby seems to
"Christopher Busby seems to have undermined his scientific legitimacy due to he association with anti-nuclear political organizations"
Correct me if I'm wrong, but isn't this the pot calling the kettle black?! Then trying to discret the Mangano philadephia iodine story by saying it's "not statistically significant", when in fact NOTHING the brawm team has done is statistically significant. Tragic comedy
Honest Question
Do test results require peer review? I can understand a research report requiring peer review. But, test results?
Where did you get peer
Where did you get peer review from? That isn't the correct terminology but it does need to be verified. They could send soil, air, water samples to other labs, you know?
From the other post
I was responding to the post above that used the term.
http://www.nuc.berkeley.edu/node/4669#comment-11559
And yes, I do know. That's why I posted the other thread about collaboration.
So would another lab have to
So would another lab have to add Cesium to their controlled lab conditions to duplicate these results?
Shouldn't the tests of the clean air filter have been done first? Wouldn't that make more sense?
Why the 3 month lag to check this?
The short answer is that we
The short answer is that we did test a clean air filter early on, at the end of March. We only took data for about 12 hours, since that was how long we originally intended to run the air filters. Twelve hours was too short to detect the line then.
However, now that we're counting the filters for about one week at a time, the background line has begun to matter more and more. Even if we hadn't suspected there was such a problem, it would have still been a good idea to do this test.
Mark [BRAWM Team Member]
Thanks, Mark
Regarding the posters other question:
"So would another lab have to add Cesium to their controlled lab conditions to duplicate these results?"
I assume the answer is "no", since you have already adjusted your results to remove the background measurement. And therefore, if another lab analyzed your filters, they should match your current results because they won't have (at least shouldn't) that background measurement of Cs-137.
VB, you are correct, the
VB, you are correct, the answer is no. Another lab would just have to measure our filter; Cs-137 and Cs-134 would be in the filter alone.
Come to think of it, another group in our department did measure one of our air filters several weeks back and confirmed the presence of Cs-134 and Cs-137 in it. We have not done a thorough cross-calibration with them, but it would be possible with that data.
Mark [BRAWM Team Member]
"Shouldn't the tests of the
"Shouldn't the tests of the clean air filter have been done first?"
They have recalculated these measurements so many times now I don't believe a word of it. In fact, if BRAWM tells me to jump, imma duck.
Think harder
You "doubters" are not listening to the explanation. I'll try to clarify.
Clean filter tested for 12 hours. No fission products show up, no surprise. The C137 data from the lead bricks does not show, because it is too weak.
Exposed filters now run for days, in order to find extremely low levels of isotopes. What do they find? Extremely low levels of isotopes, including some in the bricks that were left behind from nuclear testing decades ago.
If the team knew in the beginning that they would have needed to run the tests for days instead of hours, their initial multi-day tests would have shown the C137 at that time, and they would have adjusted their measurements to compensate from the beginning.
Sorry, this just doesn't
Sorry, this just doesn't make sense to me. I'm assuming that we have seen higher levels than were expected at the start of this mess. Kirk Smith told us we wouldn't see any iodine(France even got some). Why would they expect such a short time period for testing when the estimates were for "miniscule" amounts of fallout?
It worked at first
The short counting time period was appropriate at first. It was long enough for them to measure the Cs-137 relatively accurately. But, as the Fukushima Cs-137 levels got lower and lower, and their counting time increased to still be able to detect it, the background Cs-137 became significant all the way to the point where *all* they were measuring was the background Cs-137 in the last result. Where as it was dwarfed by the Fukushima Cs-137 in the beginning and not noticable. So, fine at first for "miniscule" levels, but the background Cs-137 got in the way as they chased it down to "super miniscule" levels :-)
new basline same as the old baseline ?
Golly, this looks like a great teaching moment as the Engineers can now colab w the Physicists to create a synthetic baseline / testing scenario. Will this attenuation test phase be as good an analysis as it might have been? Novel real world data analysis is not without some work it seems.
So all of the tests ever
So all of the tests ever done with this equipment need to be adjusted with Cs-137 subtracted?
Basically
Each of the air filter tests had to have a precise amount of Cs-137 subtracted from the total amount of Cs-137 measured. The leftover Cs-137 is from Fukushima.
Mark [BRAWM Team Member]
It is a bummer, I had a lot
It is a bummer, I had a lot of faith in these guys at the start of this crisis before the plane flights, banana doses, and now this. Now.. not so much :(
Theoretically, the samples
Theoretically, the samples themselves can be rigged.
That could definitely be
That could definitely be true. Invite Stanford to collect and test the samples? lol
Keep trolling dude.
Keep trolling dude.
They just subtracted what
They just subtracted what they calculated the contamination to be. Since no other universities are monitoring or corroborating/repeating these measurements this whole operation flies in the face of the science. Unverified this is a waste of time.
I'll take it. It is a hell
I'll take it. It is a hell of a lot better than nothing.
isotope identification and quantification
I think I get it.
The contaminant could be a pollutant in or from so many different sources. In hindsight things might have been don differently.
It is a huge gaping whole that could almost swallow the test results whole. The reality is that detection at these EXTREMELY LOW LEVELS is now understood to be subject to margins of error that likely often exceed MOE of the test parameters / methodology. This is perhaps the first set of 'in the wild' AND 'real world' / 'real world disaster' tests this lab group has dug into. Fukushima's are not the usual.
Since OUR NSA wants OUR schools to produce Security Personnel FOR THEM the NSA should be putting the labs of the CTBTO into collaboration with BRAWN at a minimus.
Ah but then again our rulers have seen fit to keep the workings of CTBTO secret. The people of The World are putting up with Horseshit.
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you really just said that?
I did. Are you implying I
I did.
Are you implying I want to believe this?
Then, yes, I do.
Does that imply that you want to believe what I think you do?
Sure. I reckon.
OK. Draw on the count of 3.
You are not alone in your
You are not alone in your thinking!
Excellent news, Mark!!!
"Less than MDA" is what we are looking for :-)
Thanks for the update. And thanks for constantly working to make your measurements as accurate as possible. It is much appreciated.