The NSLS ring parameters file

The ring parameters file is provided by the NSLS and tells about guess what? It is provided for NFS mounting by the machine bnlls3.nsls.bnl.gov as /mnts/userdata/beaminfo/xrbeam.dat. (We generally have the whole beaminfo folder mounted on our Linux machines as /mmt/nsls_beam.)

The file contains many entries of which only some are interesting to us. We automatically read the ones given in Tab. 13.2.

Table 13.2: Interesting ring parameters

Time	The time when all entries where last updated
BEAM ON/OFF	Flag telling the beam status 1: beam on, 0: beam off
xrcurr	Ring current in mA
xrenergy	Energy of ring electrons in MeV
xsxugap	Gap of the X1 undulator in mm

Besides their informational character (go into sm_par) we use some of them to determine if the beam is usable for microscopy. Stacks (see 2.11) for example are stalled by default, if beam is not "usable".