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Report on the Beam Test Analysis

Report on the Beam Test Analysis. Satoru Uozumi Apr-25 2007 GLDCAL meeting. Topics of this talk are: Comparison of various MIP calibration methods Some problems …. DESY II Electron Synchrotron. The DESY Beam-line. Veto2. Veto1. e -. T1. T3. T2. ECAL module. e + 1~6 GeV.

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Report on the Beam Test Analysis

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  1. Report on theBeam Test Analysis Satoru Uozumi Apr-25 2007 GLDCAL meeting • Topics of this talk are: • Comparison of various MIP calibration methods • Some problems …

  2. DESY II Electron Synchrotron The DESY Beam-line Veto2 Veto1 e- T1 T3 T2 ECAL module e+ 1~6 GeV Movable stage Drift chambers Drift chambers ECAL e+ beam Trigger-1 Trigger-2 & Veto-1 Veto-2

  3. MIP Event Selection (Trigger & Veto) Reject Reject Reject Reject Not used Reject Reject Reject Cuts on analog signal of the Trigger and Veto counters are introduced to select certain 1 MIP events.

  4. MIP Event Selection (cont’d) Black … trigger/veto cuts Red … Yellow strips have non-pedestal signal Blue … Green strips have no signal

  5. Extracting MIP calibration constants Four methods examined : • Fit around the MIP peak with asymmetric Gaussian (m is used as the calibration constant). 2. Fit around the MIP peak with Landau function convoluted with Gaussian (Most Probable Value (a) is used as the calib. const.). 3. Just take a mean value of the selected MIP events. 4. No calibration, just use uniform calibration constants, (but do perform inter-module correction).

  6. Method 1 : Fit with Asymmetric Gaussianfit region : m-2.5s1 ~ m+2.5s2 Fiber modules Direct modules KNU modules Typical fit Typical fit Typical fit Worst fit Worst fit Worst fit

  7. Method 1 : Fit with Asymmetric Gaussian(cont’d) Calibration constants With 1st configuration

  8. Method 1 : Fit with Asymmetric Gaussian (Inter-module correction) • In the longitudinal shower curve, there is a gap at the border of • different module types. • To correct this effect, “Inter-module correction factor” finter-module is applied • to calculate the total measured energy: • finter-module is calculated to have the best s/E in each beam energy. 1st config 1 GeV 1 . . . 6 GeV Gap Inter-module correction

  9. Method 2 : Fit with Landau x Gaussianfit region : (0.5 ~ 2.5)xMPV (fiber module), (0~3)xMPV (other two) Fiber modules Direct modules KNU modules Typical fit Typical fit Typical fit Worst fit Worst fit Worst fit

  10. Method 2 : Fit with Landau x Gaussian (cont’d) Calibration constants With 1st configuration

  11. Method 3 : Just Take a Mean Value An apparent problem : Remaining pedestal events will affect to the mean value. Calibration Constants with 1st configuration

  12. Method 4 : No calibration(but perform inter-module correction)

  13. Energy Resolution with 4 different calibration constants(1st config, energy-dependent inter-module correction)

  14. Energy Resolution with 4 different alibration constants(1st config., energy-dependent inter-module correction) Table of s/E - - - - - - - - - - - - - - - - - - - - - - - - Fit results with - - - - - - Unit of s/E and s is per cent. - - • Problem 1 : Why no calibration case shows the smallest s/E in E >= 4 GeV ? • Problem 2 : Why constant term is so large in all the cases ?

  15. Linearity with 4 different calibration constants(1st config, energy-dependent inter-module correction) Problem 3 : What is the cause of this non-linearity? Energy-dependent (or over-estimate of) inter-module correction ? Also it could be due to the temperature variation ? Of course the MPPC saturation effect should be considered, too.

  16. Problem 4 : Bumps on Longitudinal Shower Shape No calibration (but with inter-module correction) 1st configuration 1 GeV center injection c.c. from Mean c.c. from Asymm. G. • Some bumps observed, even after the calibration. • Bump on layer-6 looks like over-correction, but others are not… • Currently no idea how to solve.

  17. Appendix : A sign of strip response non-uniformity(1st configuration, c.c. from mean value) Injecting position : X and Y layers show different level of outputs due to non-uniformity of the strip response.

  18. Summary • Several types of MIP calibration methods are examined, but none of them seems to be perfect. • There are several problems found : • Effort on calibration do not improve s/E • sconstant is not small (2~3 %) • Non-linearity • Bumps on the longitudinal shower curve • I personally suspect all of these problems are linked to almost one origin, the MIP calibration and the inter-module correction. • More study is necessary, but what we should do for the preliminary result toward coming workshops ?

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