Quantifying Light Loss in the Tagger
Microscope for the GlueX Experiment
Christine Ploen
Advised by Dr. R. Jones
JLab and the Physics Dept., University of Connecticut, Storrs, CT 06268

The Tagger Microscope in the Search for Gluons
The Standard Model predicts the existence of an exotic meson, coined the Gluon.
The LHC at Cern has confirmed gluons’ existence, but the GlueX experiment seeks to produce them in large numbers for analysis for the first time.
The Tagger Microscope catches scattered high-energy electrons in a scintillating fiber array.
Fiber optics transmit the signal to electronics at which the energy and pulse time are recorded.

Damaged Fibers Lose Light

New ‘Untouched’ Fibers

Processed Fibers

Some fiber bundles are performing well; others transmit little to no light.
Goal: fabricate at least 9 more bundles each yielding 20% more light to replace low performing bundles at JLab now.

Goal: Critique our procedures and materials by examining old fibers.
Photos have given qualitative data.
Next step: determine actual photon yield of processed fibers.

Top and Bottom Left: Light Guide recently cut from spool shows exceptional clarity under laser light. (MFR Saint Gobain BCF-98).

Top and Bottom Right: The appearance of many surface imperfections in illuminated light guide. (Previously processed light guide. MFR: Saint Gobain BCF-98).

Testing Improves Methodology

Better Fibers Now
Double-Clad Materials: Original bundles used single clad fibers due to supplier error. Subsequent fibers are double-clad, which improves light transmission.
No Straightening: 1st Generation fibers were straightened before they were assembled into bundles. We have eliminated straightening to reduce stress on fibers.
Improved Bending: 1st Generation fibers were bent in a hot water tank. Rapid cooling and mineral deposits likely damaged the fibers. Procedure altered to bend fibers in hot air with more gradual temperature changes.

The Dark Box

Acknowledgements
Many thanks to Dr. Richard Jones, James McIntyre, Ann Marie Carroll, Liana Hotte, Aaron Khan, Andrew Sampino, and others involved in the GlueX Experiment at UConn.
Photo Credits: Images used with permission from http://zeus.phys.uconn.edu/wiki/index.php/

This pulsed laser testing apparatus uses electronic components identical to those in the tagger microscope at JLab. With it, we can determine the performance of any fiber in any bundle.