KEK beam test analysis

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KEK beam test analysis

• Aron Fish
• On behalf of
• (Hideyuki Sakamoto
• MICE tracker review)
• 2nd May,2006
• MICE UK

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Contents

• Setup of KEK beam test
• Stability
• Common mode, Pedestal, Gain and Noise rate
• Light yield
• Efficiency
• Summary

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KEK Beam Test
Schematic view of detectors located in the beam
line

• KEK beam test was performed on September 30th to
  October 7th in 2006 at KEK-PS p2 beam line with
  the collaboration of UK, US, Europe and Japan.
  Main purpose is to confirm the performance of
  SciFi tracker in 1-Tesla solenoid field.
• Prototype SciFi tracker
• SciFi tracker is consists of 4 stations, and
  there are 3 views for station B,D and 2 views for
  station A,C.
• VLPCs
• Photon signals from Scintillating fiber were
  readout by VLPCs.
• We used two VLPC cassettes. One of them has high
  gain and the other has low gain.
• VLPCs were cooled down to 9K by a cryocooler.

Prototype SciFi Tracker with 4 Stations
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Setup
Readout System
P2 Beam Line
Before installing waveguides
AFE Board
JACEE MAGNET (B1T)
TOF hodoscope
Cryocooler
BEAM
Low Gain Cassette
High Gain Cassette
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Stability Study

• Stability of pedestal mean, pedestal width, gain
  and noise rate is checked during beam data
  taking.
• For low gain cassette (AFE Board104,107), only
  pedestal peak and its width are checked.
• Firstly, subtracting a common mode from each
  channels. Then fitting the ADC distributions by
  triple-gaussian. The first 8 channels of each AFE
  board are merged into a histogram.
• Right figure shows an example to determine each
  components.
• Pedestal peak P4 -0.780.04
• Pedestal width P6 4.260.04
• Gain P5 P4 12.30.2
• Noise rate P2 / P1 0.1230.005

P1
P2
P6
P4
P5
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Common Mode

• Common mode is determined at each ADC chip (an
  unit of 16 channels), so 128 (2048/16) are
  calculated in total.
• Common mode is calculated as an average of a
  summation of ADC count for 12 channels for each
  ADC chip. Here, 2 channels of maximum and 2
  channels of minimum are rejected.

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Results of Stability
AFE Board 105 Each components are shown as a
function of run number
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Analysis Scheme

• This analysis aims to estimate light yield and
  efficiency. First, fiber hits are defined on each
  view. Then, tracks are reconstructed in the 3
  stations other than the test station, and are
  extrapolated to the test station. Finally, the
  residual between extrapolated track and the hits
  on the test station is calculated. Residual
  distribution is also calculated by Monte Carlo to
  be compared with data.
• Hit definition
• A fiber channel of which measured pulse height is
  above 2.5 photo-electron is defined as a hit.
  Most of VLPC noise are rejected by this cut.
• Tracking
• Track is reconstructed by 2D tracking using 3
  stations other than the test station. Hits on the
  test station are not included in the tracking. To
  select good tracks, chi-squared of the
  reconstructed track is required to be less than 1.

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Event Selection

• To ensure that a pion surely passes through SciFi
  tracker, PID by TOF of D1 and D2 counter are
  required.
• Integration window in Trip chip is measured. Time
  difference from the beam trigger is restricted to
  reject events in which beam particles are not
  synchronized to Trip gate.

STATION B
STATION A
STATION D
STATION C
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Light Yield

• Light yield is estimated by fitting the peak with
  gaussian.
• Measured light yield is similar to the result of
  cosmic-ray test.

This peak is caused by ADC saturation.
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Residual Distribution
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Efficiency

• Efficiency is determined by N1/ N2
• N1 Number of events which contains fiber hits
  within the road width determined at each station
• N2Number of events with L1A cut TOF(D1D2) ,
  and required fiber hits above 2.5 photo-electron
  in every views.

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Summary

• KEK beam test was performed in the fall of 2006.
• Stability of VLPC are checked.
• Pedestal peak is within 1 count,
• Pedestal width is within 1-2,
• Gain is stable within 2, and
• Noise rate is within 5-8.
• Light yield and efficiency are studied with
  3GeV/c pion beam without B-Field.