Tables for
Volume G
Definition and exchange of crystallographic data
Edited by S. R. Hall and B. McMahon

International Tables for Crystallography (2006). Vol. G, ch. 3.3, p. 126

Section Detectors that do not count pulses

B. H. Tobya*

aNIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8562, USA
Correspondence e-mail: Detectors that do not count pulses

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When the method used to detect intensities does not count individual quanta as they hit the detector, for example, the digitization of intensities recorded on film or on an imaging plate, or even with data recorded using a detector having a built-in deadtime correction, the standard-uncertainty values are not the square root of the intensities. [Note that when the actual deadtime correction is known, it is best to incorporate this scaling into the monitor value (see _pd_meas_counts_monitor in Section[link]) or else save the uncorrected measurements and create a second set of corrected intensity values as _pd_proc_intensity_net (see Section[link]).] The _pd_meas entries for an experiment using non-pulse-counting detection will look like the examples given in Section[link], except that the data loop will be in the form [Scheme scheme29] or [Scheme scheme30] If standard uncertainties for the intensity values are known, they can be given using the conventional notation [Scheme scheme31] Note that when _pd_meas_intensity_* is used, it is best to specify _pd_meas_units_of_intensity as well.

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