Re: [Phys-L] Half-Life measurement

[Paul Nord <Paul.Nord@valpo.edu>]

Brian,

Yes, on that one I got 860.6092 +/- 66.024595 minutes.

That's actually in reasonable agreement with the first data set:
765.6829 +/- 74.729073 minutes
The difference, which should be zero, has a Z value of 0.95.

Paul


On Fri, Oct 15, 2021 at 6:40 PM Brian Whatcott <betwys1@sbcglobal.net>
wrote:

>  Paul, you mentioned this:
> one of the model fit numbers came within 0.5% of the world
> value.  While that is nice to see, I should remind you that the standard
> deviation on that fit was still ~10%.
> Which reminds me; you mentioned a half life value on a second data set was
> 1.5 SDsoff the published value. What percentage difference was that?
>     On Friday, October 15, 2021, 05:50:37 PM CDT, Paul Nord <
> paul.nord@valpo.edu> wrote:
>
>  Brian,
>
> You note that one of the model fit numbers came within 0.5% of the world
> value.  While that is nice to see, I should remind you that the standard
> deviation on that fit was still ~10%.  There are infinitely many incorrect
> solutions that will still give you the answer in the back of the book.  The
> number really isn't as good as it seems to be.
>
> Paul
>
>
> On Fri, Oct 15, 2021 at 2:59 PM Brian Whatcott <betwys1@sbcglobal.net>
> wrote:
>
> > John Denker via Phys-l <phys-l@mail.phys-l.org
> > > UnsubscribeTo:phys-l@phys-l.orgCc:John Denker
> > Thu, Oct 14 at 7:56 PM
> > Addendum to previous message:Here is what the fits look like:
> > https://www.av8n.com/copper-decay/img48/rate-v-short-time-1.png
> > https://www.av8n.com/copper-decay/img48/rate-v-long-time-1.pngor
> > equivalently
> > https://www.av8n.com/copper-decay/pdf/rate-v-short-time-1.pdf
> > https://www.av8n.com/copper-decay/pdf/rate-v-long-time-1.pdf
> > This is pretty much what you expect to see when fitting tonoisy data.
> ###############################################################################
> > The two plots John gave above were plotted from data in his previous
> > message. This mentioned two datasets: "my_data" and "sean_data". I am not
> > sure which data developed the plots. The iterative quadratic
> approximation
> > method he used in lopt provided the following estimates.5.587 min for the
> > shorter half life + 9% high  )13.68 hrs for the longer half life  + 7.7%
> > high) Background rate was 12.7 counts/min          )  using  my_data (not
> > sure if he incorporated Pauls corrected values around 3 minutes)
> > 5.264 min for the shorter half life was +2.8% high )13.67 hrs for the
> > longer half life was 12.1% high  ) Background rate was  14.35 counts/min
> >            ) using Sean_data
> > This nlopt routine does not appear to use Bayesian probability
> > estimates, but I think John mentioned using published values of half
> > lives for his initial iteration.( what I called brute force Bayesian in
> my
> > estimates)
> > These compare well with Paul Nord's Bayesian estimates below:
> > 4.67 min for the shorter half life was 8.8% low        )12.76 hrs for the
> > longer half life was 0.5% high (!)  )Background rate was 13.995
> > counts/min                ) using my_data
> >
> > So far so good! Finally,  I admit to some puzzlement about the plots
> which
> > John provided.
> > When I digitized his plots I found the Short tau was 8.74 min, 6.06 min
> > half life which is 18% highand the long tau was 8.05 hrs, half life 5.58
> > hrs was extremely low at -56%The background rate also seemed very high.
> >  Not sure how I could stray so far from his good data.
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