Dynamical absorbers system

The dynamic range of any of the detectors is much more limited than the intensity of the beam. In order to increase the linear dynamic range of the scintillator counter and other detectors, a system of dynamical absorbers has been installed. The linearity of the detector is specially important when making comparisons of the absolute intensity, as it is often the case when using the anomalous scattering effect. Furthermore, when measuring both Bragg diffraction and diffuse scattering in the same scan, the dynamical range of the interesting signal can be many orders of magnitude. 

A special card calculates the detector dead time, and depending of the experimental value and a range of acceptable values set by the user, the system change the absorber to increase or decrease the intensity arriving to the detector. The whole operation is automatic, and the controlling program calculates the corrected intensity in real time. There are absorbers of different materials and thickness, in order to cover the whole range of energies used (2.1 – 35 keV). 

The following table helps to choose the appropriate absorber material and thickness:

 use rather Mo than Cu whenever possible

 technical description of the absorber system  

Some commands

filteron
filteroff
filterwhich
f0   … f15             fn = filter with n units of absorber material
fa         filter automatic
fm        filter manual and maximum (f15)
fw            filterwhich 
detcor_cal            card software reset