PMT absolute calibration using the Rayleigh scattering in Nitrogen air

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PMT absolute PMT absolute calibration using the calibration using the Rayleigh scattering in Rayleigh scattering in Nitrogen air Nitrogen air ICRR ICRR N.Sakurai N.Sakurai , M.Fukushi , M.Fukushi ma ma Utah University L.Wiencke Utah University L.Wiencke

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PMT absolute calibration using the Rayleigh scattering in Nitrogen air. ICRR N.Sakurai , M.Fukushima Utah University L.Wiencke. Motivation. Absolute calibration  :  Laser energy can be measured by energy meter preciously. Rayleigh scattering is well understood. - PowerPoint PPT Presentation

Transcript of PMT absolute calibration using the Rayleigh scattering in Nitrogen air

  • PMT absolute calibration using the Rayleigh scattering in Nitrogen airICRR N.Sakurai, M.FukushimaUtah University L.Wiencke

  • MotivationAbsolute calibrationLaser energy can be measured by energy meter preciously.Rayleigh scattering is well understood.So, we can obtain the precious number of scattering photons by Rayleigh scattering and it can be used for PMT Q.E.xC.E. calibration.

  • Absolute calibration using N2 laser (CRAY)

  • System overview

  • ComponentsLight source(Laser Science VSL-337ND-S)N2 laser lambda337.1nmEmax=300uJPulse width
  • PMT(H7195PX)Size of photo cathode60mm phiHPK provides their calibration data. (Only 25 phi @center)Both of the errors of HPK Q.E. and C.E. are 10%.)

  • Scattering regionPure N2 gas (99.9995%) is introduced.Flow rate is 5 10 litter/minutes Temperature and pressure is monitoredby environmental data logger.1 hour after of N2 flow start, calibration isstarted.

  • Rayleigh scattering refractive index(1.0002936 for stp N2) wavelength (337.1nm)Fk Correction factor for anisotropy of non-spherical molecules(1.03679 for N2)

    For stp N2, H.Naus and W.Ubachs, Opt lett, 25 5 347 2000

  • Calculation of # of photon in PMTNpulse: # of photon in each laser pulseWhen 1.0uJ, 1.697x1012photonNmol : # density of moleculeA : Acceptance of PMT (include dir. dependence)l: Length of scattering region

  • Polarization of laser beamThe angle of polarizer is changed and then laser energy is measured.Within +-5%

  • Laser energy cross checkglasslaserPyro (Accuracy = +-5% )Si (Accuracy = +-5% )

  • Calculation of # of photo-electron N0 : # of events below thresholdN : # of events above threshold: average of # of P.E.

  • Absolute calibration of PMT1# of photon from Si det.Nphoton=0.500.03

    # of P.E. from PMT.Npe=0.0930.01Q.E.C.E=0.180.02(Data provided by HPK Q.E.C.E.=0.190.03)

  • Absolute calibration of PMT2# of photon from Si det.Nphoton=0.50 0.03

    # of P.E. from PMT.Npe=0.110.01Q.E.C.E=0.210.02(Data provided by HPK:Q.E.C.E.=0.210.03)

  • Error estimation (very preliminary)Calibration of energy meter5%Polarization of beam0.5%Acceptance calculation2%Scattering calculation3%Reflection inside of box2%Geomagnetic field 5%Reproducibility of 1 p.e.10% # of Photon# of P.E.

  • SummaryPMT absolute calibration method using Rayleigh scattering by pure gas is developing. (obtained almost same result as HPK)Energy of laser is measured by two calibrated energy probes (Pyro-electric and Si), and two are consistent with 7%.The measured Q.E.xC.E. is consistent with HPK result.This system will be useful to measure Air fluorescence yield by well calibrated PMT. (Difference is only electron or photon.)