Overview:

The project undertaken by our team focussed on the HERA collider at the DESY laboratory in Hamburg. HERA was built in order to study the structure of the photon at the smallest distances available, and to investigate the strong and Electro-weak interactions of particle physics. A group at U.C.L. built a major part of the ZEUS general-purpose detector at HERA and has been working on physics analysis since the start of the experiment.

Aims of the Project:

Our group was commissioned to analyse data from the ZEUS experiment at HERA. By searching through a series of high energy Electro-proton scattering events, the group sifted out those events where a low angle photon has collided with the proton and produced high-energy jets of particles (jet photoproduction). The group then calculated how much of the photon's energy went into the collision. This information was then used to count the number of events where the photon appears to have structure. The purpose of this web page is to present these results in a visually stimulating manner, along with an explanation of the results and an illustration of the events themselves and examples of real collisions.

Project Methodology:

Information Collection:

Two members of our group were assigned to the collection of information. In order to fulfil the group objectives, they were required to understand the basic kinematics of jet photoproduction, as well as something about the strong interaction (Quantum Chromodynamics or QCD). They also had to obtain information about the HERA accelerator and the ZEUS detector, which collected the data we were analysing. This information governed the analysis and the selection devised, as well as providing material for a final presentation.

Data Analysis Software:

Accessing the data required the use of some ZEUS software packages. Two members of our group were assigned to learn hoe to run these packages and understand the results. They were also required to use some CERN software (called the "root" package) in order to carry out their analysis and to make plots. To use the "root package required some knowledge of the programming language c++.

Final Presentation:

The final presentation was the responsibility of all the group members. Various packages exist to display our data, including a Java-based event display, which can be used to display the events themselves.