# 2008.11.21 Energy fraction from 2x1 vs. 2x2 vs. 3x3 or 0.7 radius: rapidity dependence

Ilya Selyuzhenkov *November 21, 2008*

### Data sets:

### 2x1, 2x2, and 3x3 clusters definition:

**3x3 cluster**: tower energy sum for 3x3 patch around highest tower
**2x2 cluster**: tower energy sum for 2x2 patch

which are closest to 3x3 tower patch centroid.

**3x3 tower patch centroid** is defined based

on tower energies weighted wrt tower centers:

**centroid = sum{E_tow * r_tow} / sum{E_tow}**.

Here r_tow=(x_tow, y_tow) denotes tower center.
**2x1 cluster**: tower energy sum for high tower plus second highest tower in 3x3 patch
**r=0.7 energy** is calculated based on towers

within a radius of 0.7 (in delta phi and eta) from high tower

**Cuts applied**

all gamma-jet candidate selection cuts except 3x3/r=0.7 energy isolation cut

### Results

There are two sets of figures in links below:

Gamma candidate **detector eta < 1.5**

(eta region where we do have most of the TPC tracking):

- Cluster energy fraction in 0.7 radius
- 2x1 and 2x2 cluster energy fraction in 3x3 patch

Gamma candidate **detector eta > 1.5**:

(smaller tower size)

- Cluster energy fraction in 0.7 radius
- 2x1 and 2x2 cluster energy fraction in 3x3 patch

### Some observation

- For pre1>0 condition (contains most of events)

yield in Monte-Carlo for eta > 1.5 case

is about factor of two different than that from pp2006 data,

while for eta < 1.5 Monte-Carlo yield agrees with data within 10-15%.

This could be due to trigger effect?
- For pre1=0 case yiled for both eta > 1.5 and eta < 1.5 are different in data and MC

This could be due to migration of counts from pre1=0 to pre1>0

in pp2006 data due to more material budget than it is Monte-Carlo
- For pre1=0 condition pp2006 data shapes are not reproduced by gamma-jet Monte-Carlo.

With a larger cluster size (2x1 -> 3x3) the pp2006 and MC gamma-jet shapes

are getting closer to each other.
- For pre1>0 condition (with statistics available),

pp2006 data shapes are consistent with QCD Monte-Carlo.

# Cluster energy fraction in 3x3 patch: detector eta > 1.5

## Energy fraction from NxN cluster in 3x3 patch: detector eta > 1.5

**Figure 1a:** 2x1/3x3 energy fraction [number of counts per given fraction]

**Figure 2a:** 2x2/3x3 energy fraction [number of counts per given fraction]

## Yield vs. NxN cluster energy fraction in 3x3 patch: detector eta > 1.5

**Figure 4a:** 2x1/3x3 energy fraction [yield]

**Figure 5a:** 2x2/3x3 energy fraction [yield]