The new track extrapolation package of the ATLAS tracking software in a case study of a high precision $ W $ mass measurement

The desired precision of 25 MeV for the W mass with the ATLAS detector is planed to be achieved by using the leptonic decay channel of the $ W $: $ W \rightarrow l\nu $, where $ l=e,\mu $. As the longitudinal momentum of the neutrino can not be measured, the measurement is done using the transverse momentum of lepton and neutrino, which is calculated through a recoil method.

Results from CDF and D0 have shown that an unprecise knowlegde of the total lepton energy and momentum scale is the dominating source of uncertainty of the W mass measurement. The knowledge of the lepton mass scale requires a deep understanding of the material in the ATLAS Inner Detector with a uncertainty of about 1% which is of an order of magnitude better than in any comparable high energy physics experiment so far. In addition the magnetic field map has to be known with a precision of 0.1%. This also requires tracking algorithms to process this detailed input. The methology on how to achieve such a detailed description and its correct treatment including energy loss and multiple scattering effects during track extrapolation will be presented.

In addition, results from the ATLAS Combined Testbeam 2004 using the new extrapolation scheme will be included into the presentation.

-- AndreasSalzburger - 30 Jun 2005

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Topic revision: r2 - 2007-11-07 - TWikiGuest
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