In fluorescence imaging (FI) x-ray fluorescence lines excited by the intense incident beam are simultaneously recorded on an energy-dispersive detector, as the sample is scanned through the beam. This way, maps of the concentration of specific chemical elements in the sample are obtained. Applications range from materials science, environmental science, soil science, and biology to archeology and fine arts.
The detector is connected by custom cables to the XFlash controller through the labyrinth. The serial port of the XFlash controller is connected to the second serial port of the control computer (ttyS1).
The following lines have to be added in the spec config
MCA- and CCD-Acquisition Type Device
MCA-like DEVICE ADDR <>MODE <>TYPE
0 YES /dev/ttyS1 <> 115200 Roentec XFlash MAX MCA
The following lines were added to the image setup
# macros for
# create sufficiently large scanfile for fluorescence spectroscopy mesh scans
max size of default data group
# p data_grp(-1,0,0)
# typical output:
# The current data group configuration is:
# Group Width Last_Added Max_Pts
# 0 2 0 32768
NOTE: By uncommenting the respective lines macros can be invoked.
The presently used macro compares the XFlash counting time and the spec counting time. The latter gets gated with the "HEP in Progress" signal from the cross connect. If spec and XFlash counting time differ by more than 5sec (default used in the "mcasmode" macro - see below), the data point is remeasured, until it is measured outside a refill.
A home-built CHESS logic box allows various conditions to be checked. We typically only make use of the "HEP in Progress" signal which goes to the "CESR TTL IN" input. The "TTL LOW ON INHIBIT" output gets connected to the gating logic array in the CAMAC crate.
Note: Always check whether the "HEP in
cable is correctly connected at the cross connect. As only 4 of the 10
of the crossconnect patch panel at the station are working (to be
sometimes channels get reassigned (e.g. for CESR timing signal).
Most FI users like to use the CHESS macros, as the generated output files are compatible with Rong Huang's analysis software. Here are a couple of the most useful commands:
NOTE: some macros seem to be obsolete (use "prdef" or "lsdef" to see
whether the macro is known to spec
There is presently an incompatibility between Rong's program and the
new MatLab version 7.0 for LINUX, with the effect that Rong's program
can't run on the station
computer. Please use the Windows computer in the trailer.