Beam charge
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Intro
The HERA lepton storage ring can operate with electrons (charge -1) or positrons (charge +1). At HERMES there should be no difference in the running conditions between electrons and positrons.
Essentials
The lepton beam charge can be retrieved from the field iBeamCharge in the table g1Beam of the uDST files.
The following table summarizes the beam charge used during specific years:
| Period | Run range | Lepton type |
|---|---|---|
| 1996-1997 | full | +1 (positrons) |
| 1998 | full | -1 (electrons) |
| 1999-2000 | full | +1 (positrons) |
| 2002-2004 | full | +1 (positrons) |
| 2005 | full | -1 (electrons) |
| 2006 | 1-14244 | -1 (electrons) |
| 2006 | 14245-48195 | +1 (positrons) |
| 2007 | full | +1 (positrons) |
More info
On the HERMES uDST page a summary can be found for every year of data taking. This includes the information about the beam charge.
Other beam related pages