Photonic electron reconstruction efficiency is the background rejection efficiency. It's calculated to determine how effective the photonic electron reconstruction/identification method is in this analysis.

To put it simply,

efficiency = reconstructed photonic electron / input photonic electron

The process of identifying the reconstructed tracks is covered here.

The photonic reconstruction efficiency only covers the efficiency of the pairing method and the photonic pair cuts. It doesn't factor in the identifcation of the inclusive electron in the first place, which is covered by the electron id efficiency. Since there are different sources of photonic electrons, their efficiency is calculated separately:

• electron from pi0 Dalitz decay reconstruction efficiency
• electron from gamma conversion reconstruction efficiency

 For the overall photonic electron reconstruction efficiency, these two separate efficiencies will be combined in such a way as to correctly represent the contribution from the separate sources to the total background. This is not done yet.

Efficiencies will be calculated with p_T weighting using electron, pi0 and gamma spectra. This is not done yet.

2005 results (no p_T wighting yet) shown here, 2006 efficiencies are in progress:

Three different ways of calculating the efficiencies are shown here.

1. The first (black triangle) takes the ratio of identified photonic electrons (w/o emc) to all embedded photonic electrons. So this efficiency factors in the tpc track reconstruction efficiency.
2. The second (red open circle)  takes the ratio of identified photonic electrons (w/o emc) to tpc reconstructed photonic electrons. So this efficiency is only the efficiency of the method; however, in this one, the EMC is not used. The photonic electrons did not go through the inclusive electron id cuts, but only the pairing and photonic electron cuts.
3. The third (blue circle) takes the ratio of identified photonic electrons (w/ emc) to embedded photonic electrons that were identified as inclusive electrons. The efficiency here is also that of the method's only; however, this time, EMC is used. The photonic electrons, for both numerator and denominator, are requried to satisfy the inclusive electron cuts. The inefficiency in low pT is due to the EMC point-matching inefficiency. As this method is closest to what's done in the analysis, this method will be used to calculate the efficiency.

For gamma conversion:

vs p_T, vs V_Z, vs phi, vs eta

Similarly to the electron id efficiency, the efficiency calculcated here also takes into account the acceptance of the detector. Since the acceptance varies over time, the efficiency needs to be calculated with detector (BEMC in particular) status  that is most representative of the entire run by setting a time stamp (for the simulation data analysis) that corresponds to such a status.BEMC  status over time was studied, and a status table chosen for the simulation analysis.

2005 BEMC status study

 Selecting 2005 BEMC status table

Similar study will be done for 2006. Time regions with significantly different acceptance and BEMC status can (and probably will be) corrected at a later date.