Ilya Selyuzhenkov February 13, 2008
Gamma-jet selection cuts are discussed here. There are 278 candidates found for runId=7136022.
Transverse momentum distribution for the gamma-jet candidates can be found here.
Figure 1: Vertex z distribution.
Red line presents gamma-jet candidates (scaled by x50). Black is for all di-jet events.
Same data on a log scale is here.
EEMC response event by event for all 278 gamma-jet candidate can be found in this pdf file.
Each page shows SMD/Tower energy distribution for a given event:
First row on each page shows SMD response
for the sector which has a maximum energy deposited in the EEMC Tower
(u-plane is on the left, v-plane is on the right).
In the left plot (u-plane energy distribution) numerical values for
pt of the first jet (with maximum EM fraction) and the second jet are given.
In addition, fit results assuming gamma (single Gaussian, red line) or
neutral pion (double Gaussian, blue line ~ red+green) hypotheses are given.
If m_{gamma gamma} value is negative, then the reconstruction procedure has failed
(for example, no uv-strips intersection found, or tower energy and uv-strips intersection point mismatch, etc).
EEMC response for these "bad" events can be found in this pdf file.
If reconstruction procedure succeded, then
m_{gamma gamma} gives reconstructed invariant mass assuming that two gammas hit the calorimeter.
Figure 3: invariant mass distribution (assuming pi0 hypothesis).
Note, that I'm still working on my fitting algorithm (which is not explained here),
and fit results and the invariant mass distribution will be updated.
It is also shown the ratio for each u/v plane
of the integrated single Gaussian fit (red line) to the total energy in the plane
(look for "gamma U/V " values on the right v-plane plot).
Second and third rows on each page show the energy deposition in the
tower, pre-shower1, pre-shower2, and post-shower as a function of eta:phi (etaBin:phiBin).
Trying to isolate the real gammas which hits the calorimeter,
I have sorted events into different subsets based on the following set of cuts:
if (invMass < 0) reject
if (jet2_pt > jet1_pt) reject
if (jet1_pt < 7) reject
if (minFraction < 0.75) reject
(minFraction = gamma U/V - is a fraction of the integrated single Gaussian peak to the total energy in the uv-plane)
Figure 4: Sample gamma-jet candidate EEMC response
(all gamma-jet candidates selected according to these conditions can be found in this pdf file):
if (invMass < 0) reject
if (jet2_pt < jet1_pt) reject
if (jet2_pt < 7) reject
if (minFraction < 0.75) reject
Event by event EEMC response for pi0 (di-jet) candidates
selected according to these conditions can be found in this pdf file.
Ilya Selyuzhenkov February 20, 2008
After processing all available jet-trees for pp2006 (ppProductionLong),
and applying all "gamma-jet" cuts (which are described below):
there are 47K di-jet events selected
for pt1>7GeV there are 5,4K gamma-jet candidates (3,7K with an additional cut of pt1>pt2)
Figure 1: 2,4K events with both pt1, pt2 > 7GeV
721 candidates within a range of pt1>pt2 and both pt1, pt2 > 7 GeV
jet trees by Murad Sarsour for pp2006 run, number of runs processed: 323
4.7M di-jet events found (no triggerId cuts yet)
R_EM1 >0.9 and R_EM2 < 0.9
cos(phi1 - phi2) < -0.9
nChargeTracks1 < 2
0 < nEEMCtowers1 < 3
Ilya Selyuzhenkov February 27, 2008
Gamma-jet isolation cuts:
R_EM1 >0.9 and R_EM2 < 0.9
cos(phi1 - phi2) < -0.8
nCharge1 = 0
for each gamma-jet candidate finding a tower with a maximum energy
associated with a jet1 (jet with a maximum EM fraction).
Calculating energy of the cluster by finding all adjacent towers and adding their energy together.
R_cluster is defined as a ratio of the cluster energy
to the total energy in the calorimeter associated with a jet1.
Note, that with a cut Ncharge1 =0, energy in the calorimeter is equal to the jet energy.
Figure 4: R_cluster vs number of towers fired in EEMC (left) and BEMC (right). No pt cuts.
Figure 5: R_cluster vs number of towers fired in EEMC (left) and BEMC (right). Additional cut: pt1>7GeV
Figure 6: jet1 pseudorapidity vs number of towers fired in EEMC (left) and BEMC (right).
EEMC candidates: nTowerFiredBEMC=0
BEMC candidates: nTowerFiredEEMC=0
Figure 7: Pseudorapidity (left EEMC, right BEMC candidates)
Figure 8: Azimuthal angle (left EEMC, right BEMC candidates)
Figure 9: Transverse momentum (left EEMC, right BEMC candidates)
Figure 10: Transverse momentum (left EEMC, right BEMC candidates): pt1>7GeV
Figure 11: Transverse momentum (left EEMC, right BEMC candidates): pt1>7 and pt2>7