Appendix A: BaBar and WIRED 4

BaBar geometry is included in a separate plugin under the name WIRED 3 Graphics Format. If this plugin is loaded, any BaBar event will automatically also show the BaBar geometry.

BaBar events are made accessible via a CORBA server. To see these events you need the WIRED CORBA HepRep Client Plugin installed, see the installation inctructions.

To select a CORBA server of BaBar, choose Open Data Source... from the File menu and select the HepRep CORBA Servers wizard and click on Next.

You are now connected to a tree of servers, which will initially only show you the folder HepRep CORBA Servers at SLAC. Open this folder and the next one which says BaBar WIRED JProcMan. A list of servers will now show. As you select one of them, the description field will change, explaining what this server contains. Servers which show up in italics may have a problem. The description field will tell you their status. You can now select the server you want and click on Finish. Your data source is now open for browsing.

If you wish to connect to a server which is not in the list, for instance your own server, you can paste the IOR into the IOR or URL field and click Add to List. You may give it a different name than New Node of course. New servers are added to the top-level, and only visible to you. You can then select the new server, see its status/description and click Finish to open the dataset for browsing.

Instead of clicking on Finish, you may select Next, which allows you to use a prepared event list. You will see a default event in the Event box at the bottom. This default event is suggested by the server. If you click on Finish now, it will be no different than if you clicked on Finish in the previous window. However, you can also use your own event list, by pasting the full list into the EventList box at the top, or by giving the filename of the Event List File box in the center. When you click Finish, make sure the correct box is selected.

The BaBar event ID consist of three parts, though the first two are enough to identify the event:

CollectionName OrdinalNumber HexID
  • The CollectionName refers to the name of a collection.
  • The HexID (referred to within BaBar as the real EventID) is the most persistent form of event id. It encodes the time that the event was detected by the BaBar online. A given event may then appear in one or more event collections (a raw form of the event, a later reconstruction collection, a re-reconstruction collection, and so forth). Thus to uniquely identify a particular reconstruction version of an event, one needs both the CollectionName and the HexID.
  • The OrdinalNumber is just the ordinal position at which this event appears in the given collection. Thus the event from some particular collision may appear as ordinal number 505 in one collection, ordinal number 101 in some more refined collection, etc.

You can use the following in an event list:

  • CollectionName OrdinalNumber: The fastest way, since the database allows random access by this method.
  • CollectionName HexID: Slower in practice, since the WIRED server has to actually start at the head of the collection and read through the tag part of every event until it finds a match for this HexID.