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The project that I am working on with Dr. Jones and his UConn lab group is the mechanical design of the tagger microscope box. The tagger microscope is a critical part of the GlueX particle accelerator experiment being constructed and run at Thomas Jefferson National Accelerator Facility in Virginia. The GlueX project is overseen (and largely-funded) by the United States Department of Energy, but is executed by an international collaboration of physicists which includes students and faculty members from universities in the US, Canada, Chile, the United Kingdom, Greece, Armenia, and China.  

The project that I am working on with Dr. Jones and his UConn lab group is the mechanical design of the tagger microscope box. The tagger microscope is a critical part of the GlueX particle accelerator experiment being constructed and run at Thomas Jefferson National Accelerator Facility in Virginia. The GlueX project is overseen (and largely-funded) by the United States Department of Energy, but is executed by an international collaboration of physicists which includes students and faculty members from universities in the US, Canada, Chile, the United Kingdom, Greece, Armenia, and China.  

Overall, the GlueX experiment is designed to test the existence and effects of confinement in quantum chromodynamics. Quantum chromodynamics (QCD) is a theory of the atomic strong force which also encompasses the interactions of the quarks and gluons that compose hadrons. Quarks, gluons, and hadrons are all subatomic particles, the largest of them being the hadrons, which include protons and neutrons. Gluons are also important because they are the "glue" that modern researchers believe holds the subatomic particles in place. Quarks (as well as leptons) bind to the hadrons in an atom, and because of this a quark often blends in with its hadron during spectroscopy experiments. Quarks exist in quantum states, such that they are assgned quantum numbers for J (spin), P (parity), and C (charge conjugation). The modern understanding of quarks comes from extensive research and theory on the subject of mesons, which are essentially hadrons with integer spins that make them easier to study. Because of this it was possible to find that mesons are bound to both quarks and antiquarks in different states. In a similar area of research, the idea of confinement was developed as a subtheory of QCD that is based on the idea that a quark is infinitely inseparable from its hadron, because the large amount of energy required for the separation would be impossible to generate. Experimental physics has suggested that confinement is a viable and probable theory, and GlueX seeks to furhter define and identify its existence and qualities. In the GlueX experiment, the gluonic field which binds quarks together will be excited, with the hopes of  producing a spectrum of exotic mesons, which have quantum numbers that are impossibly suited to mesons within the quark model previously described. GlueX will map these exotic mesons by probing their corresponding hadrons (protons). Ultimately, if GlueX is successful it will be the first time that such exotic mesons have been observed experimentally, and will greatly bolster the theory of confinement in QCD.

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.  

Overall, the GlueX experiment will use the coherent bremsstrahlung technique to generate a linearly-polarized photon beam. This photon beam will pass through a solenoid-based hermetic detector which is being designed to collect data on meson production and decay. Using a bremsstrahlung technique is both useful and important because it produces electromagnetic radiation produced by the deceleration of charged particles, which in this case are the photons of the beam. As the GlueX photons decelerate, the radiation they emit will be targeted towards the microscope and a detector which will ultimately measure their energy. The final experiment will be contained in the newly-constructed Hall D at J-Lab sometime around 2014. The prototype for the tagger microscope that is being designed and constructed at UConn will be complete in 2009, and will be tested as soon as possible in another hall at J-Lab or a similar accelerator facility if J-Lab is unavailable. My work so far relates directly to this prototype.

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.

 

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.  

 

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.

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.

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.