Mattione Update 10312011

Procedure

• Reconstruct π(1600) -> b1π events with t-slope = 2.0 (was 5.0 for X(2000)) using both the 334 and 1234 segmentations
• Plot Δβ vs p for π⁺ candidates to see proton, π⁺ separation.

1234 Segmentation BCAL Time-Smear Details

• The 1234 segmentation is not available in the HDGEANT simulation, so its BCAL shower time was smeared manually during reconstruction
• The BCAL hit-time smear was disabled in mc_smear
• The shower time was smeared by: σ_smear = sqrt(σ²_{t_334} - σ²_{t_334_NoSmear}) * σ_{t_1234} / σ_{t_334}
  • These time uncertainties were studied as a function of dE and θ
  • The σ_{t_1234} / σ_{t_334} ratio was obtained from fitting the results of David Lawrence's studies of photons
  • The σ²_{t_334} and σ²_{t_334_NoSmear} variances were determined separately for protons and pions

Improvements from last week's study

• Looking at π(1600) -> b1π events with t-slope = 2.0 instead of π(2000) -> b1π events with t-slope = 5.0: Higher proton momentum in BCAL for studying separation
• The σ_{t_334_NoSmear} resolution is no longer assumed to be zero: it is non-negligible in the region of the FDC support structure at for large energy deposits (determined separately for protons and pions)
• The σ_{t_334} resolution is determined separately for protons and pions (was using the pion resolution for both previously)

David's BCAL Photon Time Resolution Studies

• γ BCAL σ_t vs. dE (GeV):

Time Resolution Segmentation Ratio

• γ BCAL σ_{t_1234} / σ_{t_334} vs. dE (GeV):

• Fits to γ BCAL σ_{t_1234} / σ_{t_334} vs. θ in dE bins:
• Don't trust fits at low-θ, so linearly-interpolate between 12 and 16 degrees.

BCAL π^- 334 Segmentation σ_t Fits

• BCAL π^- 334 Segmentation σ_t Fits vs. θ in dE bins:

π(1600) -> b1pi Events, π⁺ BCAL Δβ vs p

Δβ = β_p - β_t = p/sqrt(p*p + m*m) - path/(c*TOF)

• π(1600) -> b1pi Events, π⁺ BCAL Δβ vs p, 334 Segmentation:

• π(1600) -> b1pi Events, π⁺ BCAL Δβ vs p, 1234 Segmentation: