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Agenda of the 15th EVOmeeting, GSI, 25.04.2008

  • "Why do we need a Disc DIRC at PANDA?", presentation Klaus Föhl

  • discussion

  • next meeting

Results and Decisions

  • Do we need a Disc DIRC at PANDA? - Particle Multiplicities and Analysis Chain
    • The Scottish groups applied for funds in Scotland to build a Disc DIRC for PANDA [1, 2]. In the PID TAG Klaus Föhl presented his contribution to their report and the answers they gave to demands of the referee [3]. Both are helpful examples for the process that all the PID detectors have to undergo. Klaus Föhl showed that the physics need for a Disc DIRC was demanded. Later on this need was demonstrated via the evaluation of Physic books channels that Bertram Kopf were coordinating. In this simulations the performance of the Disc DIRC could be switched to be worse or even completely off. The latter showed drastically worse efficiency and relative background reduction.
    • This got very clear in the presentation of Klaus Götzen [4]. He reported about his analysis with the full simulation with the old frame work of the Channel he is responsible for (pp →> DsDs0*(2317)).
    • Further points of Klaus Föhls talk:
      • From symmetry considerations (pattern recognition and analysis) the disc should have a 128fold symmetry meaning 128 edges (for each focussing element one). He showed the Analysis chain with
        • DPM generated events (&manual list)
        • particle tracking with GEANT4 to DIRC
        • photon propagation in disc (PHYSICA)
        • photon pattern analysis (PHYSICA)
      • Analyzed had been multi particle events, closely emitted decay products (phi->K+K-) and the sensitivity to noise.
      • Different simulations he did with this chain changing the parameters "numbers of channels" and "pixel size" exhibit that the chosen numbers of 128 channels and 1.5mm pixel (focussing resolution around 1mm) are most reasonable.

  • Map of Separation Power and Mis Identification [5, 6]
    • Klaus Götzen demonstrated that the Map of Mis Identification (in logarithmic scale for the z-coordinate) gives more or less the same information as the separation power.
    • The trapping fraction of the DIRC detectors newly went into the Fast Simulation as an important fact since it describes the lost of Cherenkov photons that do not have the right angle (Cherenkov angle + dip angle) to fulfil the conditions for total internal reflection. Thus it describes the resolution loss which goes directly into the separation power. Even more it causes holes in the map off separation where, for instance, the protons are to slow at 90 degree entrance angle into the barrel DIRC to have a large enough Cherenkov cone for internal reflection. Klaus put two animated gifs to the PID TAG Wiki that evince the influence of the particle mass and also of the magnetic field on the DircTrappingFraction.

  • Both parts of the meeting were very helpful example how to work in the PID TAG and how to evaluate our detectors.
    • The report for the Disc DIRC strongly supported by well organized simulation work made clear what task we still have to do.
    • The Map of Separation Power with all the effects included is a very important tool to be used by all the members of the PID TAG.

  • After the meeting Quirin Wetzel sent a status report for the TPC concerning the simulations to the dE/dx in the TPC done by his coworker Viola:
    • She includes the TPC into the PANDAROOT using Geant3 (since there are still some problems with Geant4). She already reconstructs likelihoods for various particle hypotheses. Thus she has the complete reconstruction chain. The next steps to do are systematic studies of the full parameter space (momentum and angle). The same time she makes studies for the influence of the gas.

  • The next meeting should take place in about three weeks after this meeting.

  • and Everybody should read the report from Glasgow.

References: Presentations and Reports

-- GeorgSchepers - 24 Apr 2008

I Attachment Action Size Date Who Comment
MicrosoftPowerPoint-PidTag080421.ppt.pdfpdf MicrosoftPowerPoint-PidTag080421.ppt.pdf manage 772 K 2008-04-25 - 09:47 KlausGoetzen Separation and MisID map - pdf (K.Goetzen)
PidTag080421.pptppt PidTag080421.ppt manage 1 MB 2008-04-25 - 09:48 KlausGoetzen Separation and MisID map - ppt (K.Goetzen)
STFC_PPRP_DIRC.pdfpdf STFC_PPRP_DIRC.pdf manage 2 MB 2008-04-25 - 14:51 GeorgSchepers report to the Disc DIRC, scottish groups
STFC_VP_DIRC.pdfpdf STFC_VP_DIRC.pdf manage 8 MB 2008-04-25 - 14:50 GeorgSchepers praesentation, Bjoern Seitz
discstudies_080407_update.pdfpdf discstudies_080407_update.pdf manage 908 K 2008-04-25 - 13:46 KlausGoetzen Glasgow Studies DsDs0 w/ + w/o Disc DIRC
evo20080425.klausfoehl.pptppt evo20080425.klausfoehl.ppt manage 606 K 2008-04-25 - 15:06 UnknownUser talk Klaus Foehl
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