# 2008.03.20 Sided residual and chi2 distribution for gamma-jet candidates

Ilya Selyuzhenkov *March 20, 2008*

### Side residual (no pt cut on gamma jet-candidates)

The procedure to discriminate gamma candidate from pions (and other background)

based on the SMD response is described at Pibero's web page.

**Figure 1:** Fit integral vs maximum residual for gamma-jet candidates requesting

**no energy deposited in the EEMC pre-shower 1 and 2**

(within a 3x3 clusters around tower with a maximum energy).

**Black line** is defined from MC simulations (see Jason's simulation web page, or Pibero's page above).

**Figure 2: **Fit integral vs maximum residual for gamma-jet candidates requesting requesting

**no energy** deposited in **pre-shower 1** cluster and

**no energy** deposited in **post-shower** cluster (this cut is not really essential in demonstrating the main idea)

**Figure 3: **Fit integral vs maximum residual for gamma-jet candidates requesting requesting

**non-zero energy** deposited in both clusters of pre-shower 1 and 2

### Side residual: first and second jet pt are greater than 7GeV

Event by event EEMC response for gamma-jet candidates for the case of

no energy deposited in the EEMC pre-shower 1 and 2 can be found in this pdf file

**Figure 4: **Fit integral vs maximum residual for gamma-jet candidates requesting

**no energy deposited in the EEMC pre-shower 1 and 2**

**Figure 5: **Fit integral vs maximum residual for gamma-jet candidates requesting requesting

**no energy** deposited in **pre-shower 1** cluster and

**no energy** deposited in **post-shower** cluster

**Figure 6:** Fit integral vs maximum residual for gamma-jet candidates requesting requesting

**non-zero energy** deposited in both clusters of pre-shower 1 and 2

### Chi2 distribution for gamma-jet candidates

### Monte Carlo shape

Event Monte Carlo shape allows to distinguish gammas from background by cutting at chi2/ndf < 0.5

(although the distribution looks wider than for the case of Will's shape).

**Figure 7:** Chi2/ndf for gamma-jet candidates using Monte Carlo shape requesting

**no energy** deposited in both clusters of pre-shower 1 and 2

**Figure 8:** Chi2/ndf for gamma-jet candidates using Monte Carlo shape requesting

**non-zero energy** deposited in both clusters of pre-shower 1 and 2

### Will''s shape

Less clear where to cut on chi2?

**Figure 9:** Chi2/ndf for gamma-jet candidates using Monte Carlo shape requesting

**no energy** deposited in both clusters of pre-shower 1 and 2

**Figure 10:** Chi2/ndf for gamma-jet candidates using Monte Carlo shape requesting

**non-zero energy** deposited in both clusters of pre-shower 1 and 2

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