Where are my GEM data?

How GEM Data Files are Stored after the Experiment

Location of Data Files

Whilst data are being accumulated, the data files (.RAW, .TXT and .SAV files) are stored on disk on the instrument control PC (called NDXGEM) in c:\data . Shortly after ending the run, the datafiles are moved to a safe archive location. At present, this has the result that there is a short period of time when the datafiles are unavailable. If you want to find the location of a GEM .RAW file, say GEM20000.RAW, then type gempath 20000 in an OpenGenie window - this will redefine the x:\ drive to stand for the location of the file. Summary information for a .RAW file may be obtained by typing head 12345 or gemtitle 12345 (for run number 12345) in an OpenGenie window.

Older data files, for run 16504 and before, are stored on the VMS system - see here.

Restoring Data Files

Currently all data files taken using the PC control system are online, and it is not necessary to restore them.

Downloading Data Files

Data files taken using the PC control system can be downloaded to a user's home site from http://data.isis.rl.ac.uk/

Journal Files

When a run is ENDed, information about the run is stored in a journal file named GEM_DATA:JOURNAL.TXT . This file contains the run number, the user’s name, the run title, the run start time, and the amount of beam used in units of micro-Amp-Hours. At the end of each ISIS operating cycle, the GEM instrument scientists produce a unique journal file for that cycle, named GEM_DATA:JOUR002.TXT , for example. (Cycles are numbered according to a convention where, for example, cycle 002 is the second cycle in the operating/financial year 2000.) Several commands have been set up to give GEM users easy access to the information in the journal files, as follows:

TJ	Type the journal file to the screen. (The default is for the current cycle, for any other cycle you must give the cycle number on the command line, for example TJ 992 .)
EJ	Edit the journal file. (The default is for the current cycle, for any other cycle you must give the cycle number on the command line, for example EJ 001 . To edit the journal for other than the default instrument type EJ 944 SLS for example.)
SJ aaa	Search the journal file for the characters aaa . (The default is for the current cycle, for any other cycle you must give the cycle number on the command line, for example SJ aaa 994 .)
EC	Edit the optical disc archive catalogue. (The default is for the current cycle, for any other cycle you must give the cycle number on the command line, for example EC 002 . To edit the catalogue for other than the default instrument type EC 974 SLS for example.)

Last updated on 15 Dec 2005 by Alex Hannon (a.c.hannon@rl.ac.uk)