Hycal Energy Resolution, Timing,

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Hycal Energy Resolution, Timing, Trigger
Efficiency,
Chris Mauney

• A cumulative study.

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Hycal Energy Resolution - Purpose

• In order to achieve proper estimation of
  systematic errors, as well as producing the most
  accurate simulation models, the energy resolution
  of the calorimeter were determined for each
  module.

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Hycal Energy Resolution Data Collection

• Data was acquired during snake scans, dry-runs
  for the purpose of calibrating and testing
  calorimeter.
• The calorimeter is constituted by two types of
  detectors, lead glass and lead tungstate (PbWO4).
• The snake scans were done with an incident photon
  beam of energies between 1 GeV and 5.5 GeV, which
  were categorized into energy bins between 1 and
  15.

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Hycal Energy Resolution Data Analysis

• Histograms were made for the ratio of energy
  defined by Hycal and by Tagger (which has 0.1
  energy resolution).
• After all histograms had been properly fit with a
  Gaussian, parameters of the fits were extracted,
  i.e. amplitude, mean, and sigma (along w/ errors).

• These parameters were separately gathered, and
  graphed for each channel, as a function of
  energy.

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Hycal Energy Resolution Data Analysis

• These graphed parameters were fit with the
  function
• A represents constant term of energy resolution,
  B represents energy fluctuations (stochastic
  term), and C represents electronic noise.
• E represents beam energy

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Hycal Energy Resolution Data Analysis

• Parameter C was fixed, parameters A and B were
  extracted and graphed.
• Channels with ID less than 1000 were lead glass,
  and channels with ID 1000 and up were tungstate.
  These channels were separated for a more precise
  result.

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Hycal Energy Resolution Data Analysis

• Parameter B was altered by roc-4 modules, which
  experienced higher than average distortion.
• Shown Below is a diagram of roc-4 in Hycal.

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Hycal Energy Resolution Final Analysis

• Hycal Resolution was extracted by looking at all
  sigma values for one energy bin.
• Shown right are the results from the two snake
  scans, both using energy bin 14 (5GeV).
• Resolution seems to hover around 1.65-1.8 (for
  crystal channels).

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Timing - Purpose

• To more properly understand Hycal timing in
  triggers.
• This data will be used in timing alignment and
  simulation processing.

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Timing Data Processing

• Along with resolution information, timing data
  was also extracted.
• Thankfully, there were many fewer histograms
  dealing with timing. This allowed for faster
  processing.

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Timing Data Analysis

• Much like resolution analysis, these histograms
  were fitted with a Gaussian, and had fit
  parameters stored for further analysis.
• Time Difference refers to the time between a beam
  trigger and a Hycal trigger

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Timing Data Analysis

• A problem was encountered with the first snake
  scan. The top graph shown right has duel peaks
  indicating two signals. This issue only arose
  for lead glass channels.
• The lower graph is from the same channel in the
  second snake scan. Clearly this issue was not
  present during that run
• The error was attributed to a broken or loose
  cable in the detector, causing a kind of internal
  reflection. These results were excluded in the
  final analysis.

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Timing Final Analysis

• Fit parameters were gathered into one histogram,
  both for collective mean and sigma.
• Shown right top are mean values for first snake,
  and right bottom are mean values from second snake

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Trigger Efficiency - Purpose

• Before this study, a detailed examination of
  trigger efficiency was lacking. This information
  will be used to see how close efficiency is to
  100. This will be used in p0 lifetime error
  budget.
• This is the first study done on trigger
  efficiency, more important data analysis needing
  to be done beforehand.

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Trigger Efficiency Data Processing

• Along with resolution and timing, efficiency data
  was extracted from snake scan data.
• However, for efficiency, analysis was only done
  one the first snake scan.
• First, data were selected with a proper beam
  trigger and energy deposition in Hycal. Then
  event count in sample were checked, followed by
  checking if sample had a Hycal trigger (trigger
  bit2).

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Trigger Efficiency Data Analysis

• To say it more accurately, what as analyzed was
  trigger miss efficiency, i.e. trigger miss rate.

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Trigger Efficiency Data Analysis

• Channels in the highlighted box shown (bottom
  right) were disconnected during the scan, and
  yielded nearly 0 efficiency.
• Since then, this hardware problem has been
  corrected.

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Trigger Efficiency Final Analysis

• It was discovered that nearly all channels, in
  energy bins greater than 10 (gt2.8 GeV) , had 100
  efficiency.
• Some channels were broken 12, 732, 900.
• Other channels had bad efficiency due to a dead
  dinode 79, 268, 877, and 1849.
• Shown right is a histogram, in logarithmic scale,
  of all channels (excluding the disconnected block
  and problem channels mentioned above).

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Special Thanks

• Dr. Liping Gan
• Ilia Larin
• Dr. Ashot Gasparian
• Aram Teymurazyan
• Dr. Pawel Ambrozewicz