Tagpid/Pandatagpid TpC (compare)

**Tracking:** The TPC is discussed as a solution for the outer tracking within the target spectrometer. The required momentum resolution is ~1%, the required vertex resolution ~150um in the xy plane and < 1cm in z direction.

**PID:** In the momentum range below ~1GeV and above ~2GeV the TPC provides information for particle identification within the target spectrometer. Especially for particles with momenta below ~1GeV this is of great help for the overall PID performance and to supplement the information from the barrel DIRC.

**General:** 3D tracking device - charged particles ionize detector gas - electric field along cylinder axis separates positive gas ions from electrons - primary electrons drift towards readout anode - gas amplification done by several GEM foils - ungated, continuous operation mode due to HESR beam properties - intrinsic ion feedback suppression by GEM foils - continuous data readout within PANDA DAQ - parallel online data reduction and processing (including tracking)

**PID:** performed via measurement of mean energy loss per track length (dE/dx), described by Bethe-Bloch-formula, in combination with (obligatory) momentum measurement - PANDA TPC offers to do ~50-100 (fluctuating) energy loss measurements per track - truncated mean algorithm used to get rid off Landau tail and to calculate mean

**Geometry:** inner radius: 15cm, outer radius: 42cm, length: 150cm, gas volume: 700l, 2 separate chambers (due to beam pipe)

**Material budget:** ~1.5% X/X0

**Detector gas:** Ne/CO2 (90/10, maybe admixture of CH4), gas gain: several 1000

**Operation:** drift field: 400V/cm, 2x2mm pads (100000)

Data were generated based on an event generator which shoots p, K, pi, mu and e (plus antiparticles) isotropically through the TPC. All tracks come from the IP, with momenta between 0.2 and 4GeV/c. Tracks are divided into 6mm pieces, for each the energy loss is calculated resulting in 50-100 measurements depending on track length. Upper 40% are discarded and mean dE/dx calculated (truncated mean). The spread of the these dE/dx values for certain p bins is fitted with a Gaussian and the dE/dx resolution is defined as the corresponding sigma.

The separation power between two particles is defined as: 2*|I1 - I2| / (sigmaI1/I1 + sigmaI2/I2), where I stands for the dE/dx of the respective particle. A constant dE/dx resolution was assumed.

Note: For all the simulation results shown here the gas density value was a factor of 1.5 to high. Therefore we expect the performance to be a bit worse. For example the dE/dx resolution will change from ~5% to ~7%. Simulations will be repeated with the new PANDA framework as soon as possible.

-- QuirinWeitzel - 10 May 2006

I | Attachment | Action | Size | Date | Who | Comment |
---|---|---|---|---|---|---|

png | PIDoverview.png | manage | 132.2 K | 18 May 2006 - 16:15 | QuirinWeitzel | dE/dX curves for PANDA TPC |

png | TPC_Geom.png SeparationPower.png | manage | 318.2 29.8 K | 15 19 May 2006 - 15:14 07:50 | QuirinWeitzel | Separation Power of PANDA TPC geometry from simulation |

png | TPC_Geom.png | manage | 318.2 K | 15 May 2006 - 15:14 | QuirinWeitzel | TPC geometry from simulation |

png | dEdxResolution.png | manage | 20.6 K | 19 May 2006 - 07:49 | QuirinWeitzel | dE/dE Resolution for PANDA TPC |

png | tpc-gem_principle.png | manage | 35.7 K | 15 May 2006 - 14:44 | QuirinWeitzel | GEM-TPC working principle |

Revision r4 - 18 May 2006 - 16:14 - QuirinWeitzel

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