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==Project Abstract==

==Project Abstract==

The GlueX experiment is designed to probe the mechanisms of confinement of quarks and gluons inside hadrons. Quantum chromodynamics (QCD) is the accepted theory of the nuclear strong force which explains the interactions of the quarks and gluons that compose hadrons. Quarks and gluons are subatomic particles which never live in isolation, but are always bound inside composite objects called hadrons. Gluons are the force that holds quarks together inside hadrons is the gluon field. Different hadrons are distinguished by a unique set of quantum numbers for J (spin), P (parity), and C (charge conjugation) and flavor. Hadrons come in two types: mesons existing in their simple state of bound quark/antiquark, and baryons in simplest form of three quarks. Mesons consist of only two fermions, and provides a unique opportunity for studying strong-interacting physics. Such an opportunity is analagous to the hydrogen atom in classical physics.  

The GlueX experiment is designed to probe the mechanisms of confinement of quarks and gluons inside hadrons. Quantum chromodynamics (QCD) is the accepted theory of the nuclear strong force, which explains the interactions of the quarks and gluons that compose hadrons. Quarks and gluons are subatomic particles which never live in isolation, but are always bound inside composite objects called hadrons. Gluons create the force that holds quarks together inside hadrons. Hadrons come in two types: mesons existing in their simple state of bound quark/antiquark pairs and baryons in their simplest form of three quarks. Mesons consist of only two fermions, and provide a unique opportunity for studying strong-interacting physics. Such an opportunity is analogous to the hydrogen atom in classical physics.

The idea of confinement was proposed as a way to explain how quarks and gluons are the elementary particles of which the nucleus is made, even though isolated quarks and gluons have never been observed in an experiment. The proposal of quark confinement states that an infinite amount of energy is required to isolate a quark outside of a hadron. One of the predictions of QCD is that the gluonic field inside hadrons will have an independent degree of freedom from the quarks, and will be capable of being independently excited. The energies and mode structures of the excitations can give important information regarding the configuration of the gluonic fields, which ultimately give rise to confinement. The GlueX experiment searches for mesons with internal gluon excitations, called "exotic mesons". GlueX will map exotic mesons by protucing them with photon-proton collisions and subsequently measuring their quantum numbers by studying the angular distributions of their decay particles. Ultimately, if GlueX is successful it will be the first time that such exotic mesons have been observed experimentally.

One fundamental hypothesis in the field of strong-interaction nuclear physics is confinement, which explains how quarks and gluons are the elementary particles of which the nucleus is made, even though isolated quarks and gluons have never been observed in an experiment. Confinement implies that an infinite amount of energy is required to isolate a quark outside of a hadron. One of the predictions of QCD is that the gluonic field inside hadrons has an independent degree of freedom from the quarks, and is capable of being independently excited. The energy and mode structure of the excitations give important information regarding the configuration of the gluonic fields, which ultimately lead to confinement.

The GlueX experiment will generate a photon beam beginning with a 12gev electron beam from the CEBAF accelerator at Jefferson National Laboratories. GlueX will subsequently use the coherent bremsstrahlung technique to linearly-polarize this photon beam. The photon beam will then pass through a solenoid-based hermetic detector which is being designed to collect data on meson production and decay. Using the tagged bremsstrahlung technique, electromagnetic radiation is produced by the deceleration of electrons inside a component called the radiator. After they emerge from the radiator, a magnetic spectrometer called the "tagger" will measure the remaining energy of the electrons. The energy in the photon beam is thus "tagged" by the energy of the beam minus the energy of the electrons measured in the tagger.  

The GlueX experiment searches for mesons with internal gluon excitations, called “exotic mesons.” The experiment will map these mesons by producing them with photon-proton collisions and subsequently measuring their quantum numbers by studying the angular distribution of their decay particles. The GlueX experiment will generate a photon beam beginning with a high-energy electron beam from the US Department of Energy’s Thomas Jefferson National Accelerator Facility, using the process of coherent bremsstrahlung. Coherent bremsstrahlung refers to electromagnetic radiation produced by the deceleration of electrons inside a diamond crystal. After the electrons emerge from the diamond, their energies are measured in a magnetic spectrometer called the “tagger”, which “tags” the energy of the photons produced in the diamond as the difference between the pre- and post-bremsstrahlung electron energies.  

This project concerns the design andconstruction of the electron detectors that measure the energy and timing of the electrons in the tagger. A prototype for the tagging detectors - colloqually known as the "microscope" - is currently being designed and constructed at UConn. The entire prototype will be complete in December 2009 and will be tested during early 2010 in an electron beam at Jefferson National Laboratory in Virginia.

The tagger is a major component in the engineering design of GlueX. Members of the nuclear physics group at UConn have received funding from the US Department of Energy for the design and prototyping of electron detectors for the tagger. The design goals of this project include selection of optical fibers and waveguides for the electron detectors, the mechanical design and machining of a light-sealed case to contain the detectors, and the development of techniques for gluing them and mounting them on a precise remote-controlled alignment rail system. A prototype of the tagging fiber detector is currently being constructed, and will be tested at the Thomas Jefferson National Accelerator Facility in January 2010.

 

During the fall 2008 semester, a huge development in the project is the finalization of a design for the “skeleton” framework that will both support and contain the electronic, optical, and mechanical components of the microscope. To do this, TurboCad drafting software was used to create ANSI-standardized renderings of the different pieces that will ultimately come together to form the skeleton. The idea for a skeleton framework for the actual microscope box was decided on as a way to conserve weight in the final design. The final design must also be light-sealed and durable, and the contents of the box must be easily accessible for routine maintenance. All of these specific considerations were taken into account when designing the tagger microscope's skeleton (and complete box), and all of the details of this work are described below.

==Summary Fall 2008 Work==

==Summary Fall 2008 Work==