Certain LoadEventNexus settings do not split workspaces into periods

[rbauststfc]

When using LoadEventNexus with LoadMonitors=True and MonitorsLoadOnly=Events to load a run with periods then the monitor data loads as a single workspace, rather than split into the separate periods. This code shows the behaviour:

ws = LoadEventNexus(Filename="POLREF43491", LoadMonitors=True, MonitorsLoadOnly="Events")

If we don't load only event monitors then the monitors are loaded as histogram workspaces and split into periods, e.g.

ws = LoadEventNexus(Filename="POLREF43491", LoadMonitors=True)

I've had a very brief look at the code, and the results of running the above, and it looks like we may actually still be getting everything in the single monitor workspace, just that for whatever reason we don't split it out like we do for histogram monitor data. Andrew, who reported this behaviour, has confirmed that he is able to filter the single monitor workspace on periods and then put the data into a group to split it out as needed.

Another example that is similar but affects the detector workspace rather than the monitor workspace is if LoadAllLogs=True and LoadLogs=True, e.g.

ws = LoadEventNexus(Filename="POLREF43491", LoadAllLogs=True, LoadLogs=True)

This loads a single workspace containing the data from the detector. I haven't looked into this to see what's going on, but Andrew has explained that he wasn't able to filter this single workspace to split it into separate periods in the way he could with the single monitor workspace.

If the following is run instead:

ws = LoadEventNexus(Filename="POLREF43491", LoadLogs=True)

Then the detector data is loaded as a workspace group, with the separate periods split out.

It would be good to investigate both cases to confirm why we're not splitting the data by period in these scenarios, and consider whether we should be, or at least offering the option to do this. If we think that it's valid that we don't, then we could consider whether it would be good to provide an explanation in the documentation to help avoid confusion in future. This query was raised as a support issue by Andrew Caruana at ISIS, on behalf of POLREF, as they were trying to run an experiment using event mode monitors and found the loading behaviour confusing.