\subsection{Calorimeter Energy Reconstruction}

The IPP group is a strong participant in the understanding and
utilisation of the CDF calorimeter systems. This work fits well with
our previous experience on CDF-I and ZEUS, and meshes with our
activities on the ATLAS calorimeter. In terms of physics aims, our
work has two main themes: understanding the jet energy
scale in order to make a precision measurement of the top mass, and
understanding the $\met$ performance in order to study
non-Standard-Model signatures involving neutral penetrating particles.

The understanding of the jet-energy scale and resolution has been
the most important factor in the initial measurements of the top-quark
mass in Run II of the Tevatron. Our group has been involved in many
areas related to jets. Spreitzer is responsible for the jet
reconstruction software development and maintenance. A recently
graduated student (Arguin) and Sinervo have developed
the jet-energy corrections for the underlying event and multiple
interactions per bunch crossing.  We have also developed a technique
to study the response of low-$p_T$ jets using photon-jet balancing, a
method in which the photon undergoes conversion and is detectable by
the tracking system. Finally, we have applied this to the measurement
of the top quark mass, constraining the energies of the two
light-quark
jets in top decay to the $W$ boson mass, to produce the single
most precise measurement of the top quark mass as of September 2005.
In related work, Sabik and Savard have studied the tracking efficiency
in the core of jets, an essential part of the understanding of the
absolute energy scale, another key ingredient to top quark mass
measurements.

A typical search for non-Standard-Model physics involving missing
energy is the search for evidence of superpartner production. The most
critical aspect of such a search is a reliable understanding of both
the resolution functions and systematic uncertainties of the hadron
calorimeter system. MacQueen worked full time on these
issues for two years, with Orr providing supervision, as part of his
service work. More recently Spreitzer, with supervision from Savard,
has taken over these efforts as part of their interest in searches
for new physics in high $\met$ events. 
%
% There was stuff in here about the beam offset and plug energy
% cleanup, but they are old now. We need something more recent. Pierre?
%
Currently, we are working on filter code to clean up
$\met$ \ data samples.  This is mainly pattern recognition studies to
remove spurious $\met$ \ due to beam halo from upstream machine
components.  Snihur, who has considerable experience in CDF data
validation in general and jet reconstruction in particular, continues
to provide oversight in the area of calorimeter data validation.

