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Psana stores both the experiment and expNum in the environment object - Env that Modules are passed, or that one obtains from the DataSource in interactive Psana. See Interactive Analysis document and the C++ reference for Psana::Env

Why isn't there anything in the Psana Event?

This may be due to a problem in the DAQ software that was used during the experiment. For some experiments collected around Oct 2013 to Jan 2014, the DAQ software may have incorrectly been setting the L3 trim flag. This flag is supposed to be set for events that should not processed (perhaps they did not meet a scientific criteria involving beam energy or a DAQ criteria). When the flag is set, there should be very little in the xtc datagram - save perhaps epics updates. Psana (as of release ana-0.10.2) will by default not deliver these events to the user. The bug is that the flag was set when there was valid data. To force psana to look inside datagram's where L3T was set, use the option l3t-accept-only, from the command line do:

psana -o psana.l3t-accept-only=0 ...

Or you can add the option to your psana configuration file (if you are using one):

[psana]
l3t-accept-only=0

Hdf5

Topics specific to hdf5

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