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High Energy Physics Seminar Abstract: Chris Ainsley
University of Pennsylvania
Department of Physics and Astronomy
High Energy Physics Seminar
An alternative determination of the LEP beam energy & Calorimetry for the ILC
Chris Ainsley
Cambridge University
Abstract
One of the principal objectives of the LEP II program was the precise
determination of the mass of the W boson. The resolution on the W mass was
greatly improved by employing kinematic fits, in which the constraints of
energy and momentum conservation were imposed. An accurate knowledge of
the LEP beam energy was therefore of paramount importance, since it set
the scale for the W mass measurement. Constrained kinematic fits will have
less applicability at the ILC because of beamstrahlung in the high
electric field densities of the colliding bunches. Nevertheless, excellent
jet-energy resolution will be a mandatory requirement for the ILC
detector, not least so that hadronic decays of Z and W bosons can be
distinguished effectively. This places stringent requirements on the
calorimetry.
In the first part of this talk, I will review a novel technique developed
to cross-check the standard LEP energy calibration through the use of
physics events of the type e+e- -> Z gamma with Z -> ffbar, an approach
that may well have a role to play at the ILC. I will then move on to
discuss how a highly granular calorimeter system for the ILC detector,
with the unprecedented ability to image showers, is being developed by the
CALICE collaboration, in the quest to achieve the ultimate in jet
energy-resolution.