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PRIMEX Targets. Objective: To obtain the “effective” number of 12 C atoms/cm 2 for the Primakoff analysis. See Primex Note 28, “Analysis of Primex Targets”, Philippe Martel and Rory Miskimen, for experimental details. Carbon target: Pyrolytic graphite, 9mm thick (5% RL) - PowerPoint PPT Presentation

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  • PRIMEX Targets

  • Objective: To obtain the effective number of 12C atoms/cm2 for the Primakoff analysisSee Primex Note 28, Analysis of Primex Targets, Philippe Martel and Rory Miskimen, for experimental details.

  • Carbon target: Pyrolytic graphite, 9mm thick (5% RL) Low porosity compared to graphite (1% versus 10%) Doesnt fragment, easier to machine than graphite Natural isotopic abundance, 98.89% Elemental analysis: Proton induced x-ray emission (72 elements) and Combustion (CHNO)Carbon 99.63%Aluminum .006%Hydrogen
  • Measuring rT for the carbon target: r measured using water displacement technique. Thickness measurements using a .05 mil accuracy micrometer.

  • Average the first 5 measurements, and use the error from the 3rd measurement: r = 2.1979 .0006 g/cm3

  • Block II:380.40380.50380.55380.50380.50380.40380.35(mils)

  • Target thickness (mil) = 380.4 0.1

  • Target impuritiesDefine an effective carbon areal densityNeff(Z=6) = 1.06585 x 1023 atoms/cm2This is about 0.1% higher than what you obtain by assuming everything in the target is carbon.

  • Beam absorption in the target Include this effect in the effective target thicknessThe NIST XCOM data base gives l=56.5 g/cm2 at 5.2 GeV. The estimated error in l is 1.5%. Neff(Z=6) = 1.04606 x 1023 atoms/cm2

  • Do we need to worry about magnetic scattering from 13C in the target? Conclusion: for our purposes 13C is equivalent to 12C

  • Neff(Z=6) = 1.0461 x 1023 atoms/cm2 0.05%The errors in each experimental parameter were propagated to find the total error in Neff.

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