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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 ([email protected]) 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
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 ([email protected]) 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
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