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EEmc Gammas via conversion method, systematics II
Updated on Tue, 2008-04-01 09:58. Originally created by jwebb on 2008-03-30 14:01.Abstract: The EEmc Gammas via conversion method for extracting single photons should, in principle, have easily quantified systematic uncertainties. One needs to know only two things -- the efficiency with which the signal and background pass the analyzing cut. In practice, since we have three sources of background, the systematic uncertainties become more complicated. We perform an extraction of the gamma yields vs pT, and determine the systematic uncertainties due to the measured efficiencies.
Contents:
0.0 Data Sample and Cuts
Event sample:
1. Data from ppLong2
2. All fills after L2gamma EEmc elevated to physics
4. Select trigger ID 137641
Cuts:
Before extraction:
1. Require candidate to be w/in the EEMC with pT > 5.0 GeV.
2. Isolation cut -- ET / ETR<0.3 > 0.9
3. Charged particle veto -- require sum of all preshower-1 tiles w/in R < 0.3 to be == 0
4. Analyzing cut -- sum preshower-2 tiles w/in R < 0.3 is greater than zero (i.e. at least one tile w/ ADC > 3 sigma + ped).
Post Extraction:
5. Extracted yields summed over -8 < D < -2.
Papers on proton interferometry
Updated on Sat, 2008-03-29 23:37. Originally created by chajecki on 2008-03-29 23:17.Papers on proton-proton interferometry (just for my record, list is not complete):
- "Proton evaporation time scales from longitudinal and transverse two-proton correlation fu
EEmc Gammas via conversion method, determine/cross check efficiencies
Updated on Sat, 2008-03-29 18:05. Originally created by jwebb on 2008-03-29 17:10.Abstract: In order to use the conversion method, we need to know the efficiencies with which single photons and the different sources of background candidates pass the analyzing cut. So far we have identified two sources of backgrounds: (1) photonic backgrounds arising from the decay of mesons, e.g. pi0 --> gamma gamma, and (2) neutral hadrons (or charged hadrons which pass the CPV) which hadronize w/in the calorimeter stack. We should be able to estimate the efficiencies for both of these directly from the data with good precision. The only parameter in his method which relies on the Monte Carlo is the probability for a single photon to convert in the 1st radiator of the EEmc.
EEmc Gammas via conversion method, improving yield extraction using postshower information
Abstract: We have EEmc Gammas via conversion method, relaxing the hadronic veto cut identified a background contribution which appears consistent with neutral hadrons (or charged hadrons which slip through our cuts) initiating a hadronic shower w/in the calorimeter stack. Such a neutral background is not accounted for in our estimate of the background efficiency. Thus, the extraction method breaks down. For this study, we use the postshower response to estimate the fraction of hadron-like vs photon-like backgrounds, and extract a more reliable single photon yield.
1.0 Description of the Method
Begin by applying the following cuts to the event sample
Cuts:
1. Require candidate to be w/in the EEMC with pT > 5.0 GeV.
2. Isolation cut -- ET / ETR<0.3 > 0.9
3. Charged particle veto -- require sum of all preshower-1 tiles w/in R < 0.3 to be == 0
4. Analyzing cut -- sum preshower-2 tiles w/in R < 0.3 is greater than zero (i.e. at least one tile w/ ADC > 3 sigma + ped
Plot the postshower-to-SMD energy ratio of these events. We see a broad gaussian on top of a much broader background. The gaussian "photonic" region occurs for relatively little energy in the postshower detector for relatively large SMD energy deposits. This is the type of signature we expect for electromagetic showers. It rides on top of a modest background of events, with a tail which extends to large energy deposits in the postshower with little energy showing up in the SMD. The events in this "hadronic" region are consistent with hadronic showers occuring w/in the endcap. We fit the distribution to the sum of two gaussians to estimate their relative contributions.
For the rest of this discussion, we define D = log(Epost/(Eu+Ev+delta)).
n.b. log is ln, i.e. natural logarithm. As in TMath::Log() ... which of course is undocumented in the root reference guide, and one has to look at the code to find out. Sheesh.
Figure 1 -- Fit to log(Epost/(Eu+Ev+delta)). The fit is to the sum of two gaussians. The fit chi2 (conviently left off of the plot) is somewhat poor... 79.47 per 29 dof. However, this gives us a starting point to estimate the relative fractions of (a) single photons, (b) photonic backgrounds, and (c) hadronic backgrounds.
SVT Ladder weighting exercise
Updated on Wed, 2008-04-02 09:53 by testadmin. Originally created by jeromel on 2008-03-28 11:16.The Silicon Vertex Tracking detector (SVT) in STAR was removed from the STAR setup and a weighting exercise was under-taken.
Measurements made on 2008/03/28
SMD Clustering Plots
Updated on Fri, 2008-03-28 10:59. Originally created by wleight on 2008-03-28 10:59.Below are SMD plots made from 5000 events each of gammas and piminus. First tower clustering is done by identifying all seed towers with energy > 1 GeV and then finding the 2x2 patch of to
tmpUpload
Updated on Mon, 2012-07-02 15:31. Originally created by balewski on 2008-03-28 07:13.temporary uploads from Jan
SSD simulation : signal (electron vs ADC)
Updated on Wed, 2009-02-18 11:34. Originally created by bouchet on 2008-03-27 10:32.In St_sls_Maker :
chargeSharingOverStrip : calls method ConvertToStrip (StSsdBarrel)-->ConvertToStrip(StSsdWafer) :
Pythia estimates, prompt photon yields
Updated on Wed, 2008-03-26 16:20. Originally created by jwebb on 2008-03-26 16:15.Abstract: We estimate prompt photon yields in the endcap for 4.3 pb-1 of data.
SsdEmbedding Maker
Updated on Wed, 2008-03-26 13:25. Originally created by bouchet on 2008-03-26 10:30.03/01 :
add protection in StSsdEmbeddingMaker for when no ssdhit table is found.
And in St_spa_Maker because then no sls_strip from StssdEmbeddingMaker is produced.