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QCAL upgrade plan

QCAL upgrade plan. E. Santovetti KLOE General meeting 10-11 October 2002. Current situation Efficiency, resolution, Background occupancy Electronic noise Future intervention PM test and selection Replacement of ~ 10 PM Electronic upgrade. Efficiency.

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QCAL upgrade plan

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  1. QCAL upgrade plan E. Santovetti KLOE General meeting 10-11 October 2002 • Current situation • Efficiency, resolution, Background occupancy • Electronic noise • Future intervention • PM test and selection • Replacement of ~ 10 PM • Electronic upgrade

  2. Efficiency MIP detection Efficiency vs ch (efficiency of the single channel !) Average ch. efficiency = 97 % Actual detection eff. > 99 % Photon efficiency from KL +-0 (70 MeV) ~ 85 % QCAL A QCAL B E. Santovetti KLOE GM 10-11 October 2002

  3. MIP signal amplitude MIP signal amplitude vs ch # After HV equalization the response remains very inhomogeneous The Magnetic field (5.2T) reduces the signal amplitude by 60% ADC counts bad PM ch. number E. Santovetti KLOE GM 10-11 October 2002

  4. QCAL B Ch. 9 QCAL A Ch. 9 E(MeV) E(MeV) QCAL A Ch. 8 QCAL B Ch. 11 E(MeV) E(MeV) MIP signal amplitude/2 bad channel The threshold (3 or 50 ADC counts) cuts evidently the signal ! good channel E. Santovetti KLOE GM 10-11 October 2002

  5. Efficiency 1-eff. Efficiency and signal amplitude show a clear correlation 1/Amp. (ADC ch-1) E. Santovetti KLOE GM 10-11 October 2002

  6. Background and time resolution (from KL +-0 events) Time resolution for photons ~ 2.4 ns Background occupancy ~ 0.3 ( t = 200 ns, all QCAL) Dt (ns) E. Santovetti KLOE GM 10-11 October 2002

  7. Electronic noise The electronic noise is very high ! correlated with the magnetic field ADC affected low frequency (few MHz) correlated with the machine TDC and ADC affected higher frequency EMC level E. Santovetti KLOE GM 10-11 October 2002

  8. Future plan Replacement of the worst (~ 10) photomultipliers - preliminary test to check if there is an improvement Replacement of the all 32 HV divider - HV decupling capacitor in the divider Possible redesign of the FE electronics - differential amplifier (lower noise) ? E. Santovetti KLOE GM 10-11 October 2002

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