[phenixbb] Units in intensity?

[Murpholino Peligro]

I got from here http://webhome.phy.duke.edu/~kolena/hou/counts.html a
formula for the number of counts (c=faqt; where c is the number of counts,
f is the photon flux, a is the area, q is the quantum efficiency and t is
the exposure time) It is for telescopes but I guess is not a lot different
for the detector used in xrc.

Thank you very much.



El mié., 6 de mar. de 2019 a la(s) 19:20, Johan Hattne (hattne at ucla.edu)
escribió:

> I think that would depend on how the detector is measuring the photons
> that impinge on it.
>
> Unless you’re actually concerned with exactly how the detector does its
> thing, I think Tim’s dimensionless or something fuzzy like “detector unit”
> is fine.
>
> // Johan
>
> > On Mar 6, 2019, at 14:16, Murpholino Peligro <murpholinox at gmail.com>
> wrote:
> >
> > ...
> > The counts are the number of x-ray photons converted to electrons?
> >
> >
> > Thanks
> >
> > El mié., 6 de mar. de 2019 a la(s) 15:18, Tim Gruene (tim.gruene at psi.ch)
> escribió:
> > Dear Murpholino,
> >
> > the unit of intensity is '1' - it is the counts on the detector. The
> scale is
> > arbitrary, you can multiply your intensity with any positive number you
> want,
> > as long as you don't create an overflow or underflow in the computer
> program.
> >  As long as you do the same with the sigma-values, your refinement
> should not
> > change.
> >
> > Best regards,
> > Tim
> >
> > On Wednesday, March 6, 2019 10:00:55 PM CET Murpholino Peligro wrote:
> > > If I do `phenix.xtriage XDS_ASCII.HKL` I get a log file. In the
> "Statistics
> > > for data merging" of this log file I have:
> > >     Resolution: 26.02 - 1.40
> > >     Observations: 44675
> > >     Unique reflections: 16306
> > >     Redundancy: 2.7
> > >     Completeness: 70.37%
> > >     Mean intensity: 1656.8
> > >     Mean I/sigma(I): 19.8
> > >     SigI < 0 (rejected): 644 observations
> > >     R-merge: 0.027
> > >     R-meas:  0.032
> > >     R-pim:   0.017
> > >
> > > My question is... what units does Mean intensity has?
> > >
> > > Thanks
> > > Ps I am not sure if this has to do with the detector used which was a
> CCD
> > > (type) ADSC QUANTUM 210 (model).
> >
> > --
> > --
> > Tim Gruene
> > Head of the Centre for X-ray Structure Analysis
> > Faculty of Chemistry
> > University of Vienna
> >
> > Phone: +43-1-4277-70202
> >
> > GPG Key ID = A46BEE1A
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>
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