Mattione Update 11302011

DC dE/dx Study Overview

Introduction

• DC dE/dx information used for PID is bad, is disabled until fixed.
  • DC dE/dx Confidence Level (for protons, similar for K+'s, π⁺'s, and π^-).

protons

Procedure

• Look at reconstructed dE/dx in CDC & FDC (treated separately: different gas mixtures).
  • CDC: 52.6% CO₂, 47.4% Argon
  • FDC: 62.0% CO₂, 38.0% Argon
  • Half of the track hits in each of the FDC/CDC (those with the largest dE/dx) are ignored: truncates Landau distribution to resemble Gaussian distribution.
• Fit mean and σ of these distributions and use them in calculation of χ²

FDC

• FDC π⁺ dE/dx μ & σ
  • σ is dependent on amount of information: # hits USED (= 1/2 of total # hits: reject largest dE/dx hits to remove Landau tail)

FDC, π+, μ

FDC, π+, σ

• FDC protons dE/dx μ & σ
  • σ is dependent on amount of information: # hits USED (= 1/2 of total # hits: reject largest dE/dx hits to remove Landau tail)

FDC, protons, μ

FDC, protons, σ

CDC

• CDC π⁺ dE/dx μ & σ
  • σ is dependent on amount of information: # hits USED (= 1/2 of total # hits: reject largest dE/dx hits to remove Landau tail)

CDC, π+, μ

CDC, π+, σ

• CDC protons dE/dx μ & σ
  • σ is dependent on amount of information: # hits USED (= 1/2 of total # hits: reject largest dE/dx hits to remove Landau tail)

CDC, protons, μ

CDC, protons, σ

CDC Proton Confidence Levels

• Confidence Level of all protons with # CDC hits >= 6 (# used hits > 3)

CDC, protons, # CDC hits >= 6

• Confidence Level of protons with varying # of CDC hits used

CDC, protons, # Hits Used = 4	CDC, protons, # Hits Used = 6
CDC, protons, # Hits Used = 8	CDC, protons, # Hits Used = 10
CDC, protons, # Hits Used = 12	CDC, protons, # Hits Used = 14

• Confidence Level of protons in CDC with different βγ

CDC, protons, 0.3 <= βγ < 0.6	CDC, protons, 0.6 <= βγ < 0.9
CDC, protons, 0.9 <= βγ < 1.2	CDC, protons, 1.2 <= βγ < 1.5
CDC, protons, 1.5 <= βγ < 1.8	CDC, protons, 1.8 <= βγ < 2.1