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Calibration Device for Scintillators (view source)
Revision as of 18:09, 28 June 2012
, 18:09, 28 June 2012no edit summary
===Project Proposal===
===Project Proposal===
The confinement of quarks and gluons within the hadron has been declared one of the top ten physics mysteries of the century. Quarks, along with leptons, are the smallest known building blocks of our universe, however scientists have yet to isolate one. Quarks and anti-quarks exist only in bundles known as hadrons, bound tightly together by the force-carrier particles gluons. The reason for the massive strength of such bonds remains unknown, and open for exploration. The field of Quantum Chromodynamics designates such a force the “Color Force”, further explaining that quarks and gluons carry a “color charge” (Red, Blue, Green, AntiRed, AntiBlue, or AntiGreen). As quarks and gluons frantically interact and transfer color charges, the net color of any given hadron remains colorless. When quarks pull away, the color force merely stretches and grows stronger, forever confining the quarks and gluons. The color force is a fundamental interaction, the source of even the strong interaction, and thus an understanding of the gluonic field would unveil an entirely new realm of physics that is driving the world around us.
The GlueX Experiment, centered in Jefferson Lab, Virginia, is devoted to understanding the gluonic field by mapping the spectrum of the exotic hybrid meson. When the gluonic field is excited, hybrid mesons (hadrons composed of quark-antiquark pair and valence gluon) with exotic JPC quantum numbers are produced and these can be an indirect probe of the gluonic field. The experiment utilizes a particle accelerator to direct a 12 GeV electron beam at a diamond wafer, splitting it into a 9 GeV linear polarized photon beam and 3 GeV electron beam via coherent bremsstrahlung radiation. Known as photoproduction, this process produces virtual vector mesons, some with exotic JPC. The photon beam enters the solenoid detector, where the meson decays are analyzed and reconstructed. The scattered electrons, bent by a magnetic field, travel through a tagger microscope guided by optical fibers. Because bend radius corresponds to energy, the fiber paths indicate energy level. Silicon photomultiplier sensors are then able to “tag” the electrons with an initial momentum, and associate an energy with the corresponding photon. This tagger microscope provides important information for meson reconstruction that must be accurate. There is not, however, a current means for ensuring this.
For my research I will be designing and building a calibration device for the tagger microscope. The device will consist mechanically of a metal track with two flanged timing pulleys at each end and a timing belt connecting them. A cart will be pulled horizontally by the belt, which is driven by a Lin-Engineering 1.8 degree stepper motor. The motor is controlled by a program which I have written in LabVIEW, along with a DAQ card, R208 microstep driver, and quadrature rotary encoder. Extending down from the moving cart will be a light pulser that will hover over the fiber bundles and flash light to calibrate them. More specifically, two methods are being explored for light distribution: (1) Waveshifting fibers and (2) Mylar reflection. Waveshifting fibers, which when placed over the fiber bundles would illuminate only to UV light, would be effective but costly. Mylar reflection, in which a laser diode uses the mylar mirror to reflect light into the fiber bundles, would be cheaper but includes problems such as refraction, interference, and the fibers’ narrow window of light acceptance. I am currently writing a Matlab program to explore the feasibility of this second method.
A mechanized calibration device is a small, but instrumental, element of the GlueX experiment. Unable to access the microscope while it’s running, we nevertheless need to know that we can trust its results. The results of this experiment are expected to increase the knowledge of Quantum Chromodynamics by several orders of magnitude. The scope includes energy advances, as an understanding of the confinement of antiquarks could help us harness antimatter. From here, the potential extends from renewable energy to space travel. But fundamentally, this experiment seeks to expose an unknown element of physics, and I hope to contribute.
== Previous Work ==
== Previous Work -- John Turner ==
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=== Ideas ===
=== Ideas ===