5.6.6.2   Dataspy and Dhist

Dataspy and Dhist are online diagnostic programs based on the ``DD'' shared-memory system for obtaining a fraction of data from the event builder; the fraction is determined by the requirement that the programs add no deadtime. If the event rate is sufficiently low the program will be able to check every event, otherwise only a random subset are processed. Dataspy prints event information from various detectors to the screen. Dhist plots detector data using the HPLOT package from CERNLIB. The intention of these programs is to provide rapid online diagnostics of the raw data with absolutely no cuts, biases, or processing.

1.

The first step to running these programs is to go to the $EXPERIMENT/onlana directory by typing ``goonlana''.

2.

To use dataspy type the following:

dataspy [-f filename -r -s -v -p -l -g]

where [...] are arguments:

-f is for CODA file `filename' (if no file is specified the default is to obtain data from the online DD system which is how you normally run dataspy).

-r to display raw data dump in CODA format

-s to display scintillator results

-v to display VDC results

-p to display preshower results

-l to display shower (leadglass) results

-g to display gas cerenkov results

If you type a wrong argument dataspy will remind you of the usage.

3.

To use dhist type ``dhist'' and a series of plots will be displayed on a HIGZ screen after a short delay. The plots come in a sequence of typically 12 pages, each of which are displayed for about 10 seconds in sequence. The pages may be turned on and off using 1's and 0's in the text file hist_opt, where the page contents are also explained with comments. If you change hist_opt, the change will take effect on the next cycle through the pages. I repeat that you must be running in the onlana directory. The histograms are updated continuously and cleared periodically, typically once every half hour. Postscript files with obvious names corresponding to the histogram pages are created for convenient printing. Standard plots of normal results are kept in a folder binder in the counting room and should be compared to the online plots. If the online plots don't look normal the expert on the detector system should be notified immediately.