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ThreeDseparationplot

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part of the DircPlayground

Calculation of the Separationpower in dependence of momentum and angle

The dependence of N(sigma) from the momentum p and the angle theta is calculated and displayed with Mathematia:

1. Momentum Dependence

Plot Number of sigma in dependence of momentum p:

• Number of sigma:
  

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The plot represents the Numbers of sigmas two particles are separated depending on the mometum with

• "sigma" = 0.01 is the resolution of a single photon track
• "sigma/sqrt(nph)" gives the resolution of a track with
  • nph = 16 is a typical number of produced photons
• Kaon = 493.68 MeV
• pionn = 139.57
• refractiv index n=1.47

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2. Angle Dependence

The number of produced photons denpends on the pathlength in the radiator which depends again on the incident angle.

See also

http://www.gae.ucm.es/~emma/docs/tesina/node4.html

Pathlength:

(see PathLength, Aida Galoyan))with: Angle psi:

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Pathlength of a partice in the radiator of the barrel:

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Number of measured Cherenkov photons:

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Detected Cherenkov photons:

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Number of sigma in dependence of momentum and theta angle:

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Number of sigma in dependence of momentum p (500-5000MeV/c) and angle theta:

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Number of sigma in dependence of momentum p (2000-4000MeV/c) and angle theta:

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Example on the treatment on the Phase Space Plots

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(Presented in the PidtagMeeting07). On the Example pbar p to phi phi (find the full set of Phasespaceplots on VrvsMeeting11) it is shown which fraction of produced kaons can be separated from pions with the help of the Barrel Dirc. First one sees all the kaons produced, secondly the kaons in the solid angle and the lower threshold (of the Kaon detection) of the Cherenkov detector and last but not least all the kaons over the limit of numbers of sigma separation beeing 4. The latter conditions is done for the two track resolutions "sigma" (track) = 10 mrad and 30 mrad. It shows that we loose with a bad track resolution for higher monenta a not minor amount of kaons (meaning having a not sufficient resolution to separate them from pions) in the angular region of the Barel DIRC. Remark: The calculations are peliminary and the separation limit arbitrary.

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Cut momentum and theta angle:

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Cut momentum and theta angle and number of sigma larger 4:

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With a track resulution of 10 mrad:

With a track resolution of 30 mrad:

-- GeorgSchepers - 29 Nov 2007