MAR345S Fast Mode Operation

MAR345S, a new version of mar345 image plate detector equipped with fast-mode controller, is used at 16-BM-D as a default detector since December 2015. The image of CeO2 standard powder diffraction measured using the fast mode with 150 µm 2300 mode (345 mm scan diameter) at 40 keV and 290 mm detector distance shows remarkable reproducibility of its image quality compared to its normal mode product. The geometric calibrations for both fast and normal mode images are effectively identical. The costs of using the fast mode relative to the normal mode are 1) the total counts less than ~30% compared to those of the normal mode image; 2) increase in the peak width ~12% (at their FWHMs estimated by Pseudo-Voigt profiles; see the direct comparison in the figure). The S/N ratio through most of the radial distances except for those within ±150 pixels from the image center turns out to be identical. While the costs of using the fast mode are minimal, the benefit is huge by reducing the total read out time by ~40%. The table at the bottom summarizes the measured read out time at various modes. Note that the manufacturer removed the original 100 µm 3450 image mode from the new MAR345S detector, after confirming there was no real difference between 3450 mode and 2300 mode for the most of images obtained for both powder and single crystal diffraction. Users are recommended to use the fast 150 µm 2300 image mode as default. The ~12% peak broadening can be easily compensated by pushing the detector distance farther.

 

Scan mode

Scan Diameter (mm)

Pixel size (mm)

Image mode

Image readout (sec)

Machine ready (sec)

normal

345

0.15

2300

67

83

normal

300

0.15

2000

53

69

normal

240

0.15

1600

37

53

fast

345

0.15

2300

38

54

fast

300

0.15

2000

29

45