Performance of Aerogel Detectors

Yi Qiangfor Pentaquark Experiment

Collaboration Meeting

March 14, 2005

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Outline

Geometry and parameters of A1/A2 detectors

Amplitude alignment

PID performance

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Geometry and Parameters

Aerogel index: A1 1.015 A2 1.055

Radiator area: A1 32X170 cm2

A2 30X192 cm2

Radiator thickness: A1 9 cm A2 5 cm

PMT types: A1 RCA8854 24 PMT

s A2 XP4572B 26 PMT

s

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Detector Configuration

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Amplitude Alignment

Typical single photon spectrum

The Alignment makes: A1 single photon peak = 100 A2 single photon peak = 60

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Sliced A1 sum spectrum after alignment

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Particle ID For index n, the threshold for Cerenkov

Radiation is β > 1/n

n(A1) = 0.015 n(A2) = 0.055

1/ n 1/ n dddd

dlkjdslfkjasdf

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Fit for A1/A2 sum spectra

Function: Poisson distribution convoluted with Gaussian

Fitted Parameters: Average N.P.E: μ Single Photon amplitude deviation: σ

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Puzzle in A1 sum spectra

Unexpected shape in A1 sum

Reason is still under investigation

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Electron A1 sum spectra Comparison of electron and pion A1 su

m spectra at 2.06 GeV/c

From electron spectrum, we have

Max N.P.E(A1) = 3.8

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Momentum Dependence of N.P.E for A1/A2 The average N.P.E is proportional to:

N ~ (1 – 1/β 2n2) Max N.P.E at β = 1

Max N.P.E(A1) = 3.8 Max N.P.E(A2) = 14.5

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

A1 efficiency

Fraction of kaon not firing A1

Using 550 MeV/c pion to simulate kaon condition

Fraction of pion not firing A1

e-μ = e- 3.8 = 2.2 %

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

A2 efficiency

Fraction of kaon not firing A2

e-μ = e- 9 << 1 Contamination from pion and c

ut selection

Pentaquark Experiment Collabration Meeting, JLab

Y.Qiang 2005-03-14

Overall PID performance

Selection of kaonEfficiency: 82%Pion Rejection: 90

Selection of pionEfficiency: 98%Kaon Rejection: 10

Compare to Original Performance (From Lingyan’s homepage)

N.P.E(A1): 8 → 3.8N.P.E(A2): 30 → 14.5