ZEUS Experiment
John J. Ryan, Ph.D.
ZEUS
ZEUS is a Deep Inelastic Scattering experiment
at HERA, in Hamburg, Germany.
It is a big experiment. I followed primarily two working groups:
the Structure Function Group and the Diffractive Group.
My personal analysis interests are in studying Hadronic Final States,
in hopes of improving our understanding of the full process of
Hadronization.
Physics
I am hoping to draw on the efforts and information from E665, the
Fermilab Muon Scattering experiment, as well as ZEUS, to gain a
better understanding of the whole process of Final State Hadron production.
From my investigations in E665, I have some ideas about Fragmentation
which the ZEUS detector is beautifully constructed to test.
The ``Current Jet'' is just blossumed out like a flower in the detector,
because of the asymmetric boost.
And in case you've gotten complacent in running so many Monte Carlo
models, I'll continue to remind you that QCD does NOT address the
formation of Final State Hadrons; it assumes that the process can be
factorized into a stage of Fragmentation of the color flux tube and a
stage of Hadronization, in which the quark-sets are ``dressed'' into
real, observable hadrons. This last stage has been fit to data from many
experiments, so the agreement between the Monte Carlos and measurements
should not be misinterpreted as justifications for the models of the
first stage.
Detector
I worked on several technical aspects, in an effort to
better understand the ZEUS detector. I studied the characteristics of
the noise in the Uranium Calorimeter and developed a set of
elimination criteria to reduce its effects on physics analyses.
The goal was to use the Energy Imbalance information
to improve the position resolution of clusters in the Calorimeter.
I also expended quite some effort in improving the
matching of charged tracks to calorimeter clusters and in mapping
correction functions for smearing and inefficiencies in acceptance and energy
reconstruction, in an energy and position dependent way.
Ideally, I wanted to be able to subtract the charged energy,
using tracking, from calorimeter clusters, in order to reconstruct
neutral energy simultaneously in the final state.
There is some great physics here which has not been done before.
It is, however, an ambitious task.
Software Management
I spent quite a lot of time on issues of Software Management
in ZEUS. I arrived in the collaboration just as the Offline Group was
investigating migrating away from the old system, based on Patchy and
CMZ from CERN, to some system based on CVS.
I had had some experience
with these issues and efforts at M.I.T. on the PHOBOS Experiment,
so I offered some help. I wrote a program in lex and yacc to
convert Patchy card-files into a directory structures of files; my
expert knowledge of Patchy from my graduate student days finally paid
off, I guess. In the end, I personally converted about 80% of the ZEUS
software out of Patchy format.
The second part of this Software Management scheme was to
implement a working environment based on GNU Make. The system was finally quite elaborate, yet extremely flexible.
The modern system employs the C-PreProcessor to handle the
machine dependent program segments and the inclusion of header files.
The building of the libraries and the executables is managed by
GNU Make. The Version control is handled by CVS.
I wrote a great deal of
documentation on this system, including a ``User's Guide'' and a
``Manager's Guide,'' as well as the 93 page ``Reference Manual.''
These can be found on the ZSMSM Home Page:
The ZEUS Scheme of Modern Software Management (ZSMSM)
Object-Oriented analysis
In addition, I worked on my longer term goals of
developing an Object-Oriented analysis environment. I
implemented Classes for detector objects such as vertices, tracks and
calorimeter clusters and their lower-level components, as well as
physics objects like particles and event kinematics.
I performed my studies of track-to-calorimeter matching using these
objects.
Last modified: Mon Sep 20, 1999