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Rolex

Thanks Iceheller

 

Thanks for your comments. Very helpful. I have a couple of things to add to what you stated.....

There are way to convert GM counter uSv/hr reading to Bq if you know the calibration source radiation material and the efficiency of your GM counter for the particular radiaoactive material. 

Yes, this is true, but in the case of detecting radiation from Rolex watches, one never knows the radiation source beforehand. People just use Geigers without knowing the radiation source. 

Although science textbook tells us that aplha particcles can be block by thin piece of paper and beta can be block by few cm of polycarbon, that is only small amount they are talking about. If you have more than MBq, it will be pickup the GM counter. 

Can't argue with that. But when it comes to the radiation on watch dials, I suspect that the amount of radiation is generally quite low.

you do not need to get more than 25 samples sizes just to statsitically prove that the vintage dial is still radioactive (as watch dial are not suppose to have any radioactive reading to being with, ie from 0uSv/hr to even 2.5uSv/hr, how many time or multiple is that, infinity?).

On this, I do not agree with you. I believe that you do need more than 25. Statistically, the lower the sample size, the greater will be the distribution variance. Put another way, if sample size is too low, the probability of making false assumptions from the sample evidence rises probabilistically. The variation in micro-Sievert readings from just the very small sample size that I used would suggest that a sample size of just 20 or so would lead to potentiality misleading results. Sample size is something that cannot be definitive, of course. The smaller the sample, the bigger the risk of making errors. In this instance, given the fact that Rolex were using so many different types of radiation and that dials were subject to differing demands from clients, it would be a particular problem if sample sizes of 20 or so were used. Of course, such samples would need to be drawn from properly tested watches from a laboratory...not just from Geiger readings that can vary for so many reasons ... as you indeed point out. 

 If you really want to test radiation level, you should do a swipe test and measure using scintillating counter or dump the watch in an ion chamber and measure the radium radiation. I suggest that you should properly dispose or seal away those rolexes if its of valuable to you. Your health is your wealth. Be safe or be safe. Just my two cents here. Cheers.

100% agree. if you want to test the radiation....do it properly.That is the overwhelming conclusion provided by every expert I have asked. Just sticking a Geiger on a dial and drawing a conclusion based on that is...well....un-scientific.  

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