HyCal Repairs, Testing, and Upgrades
This page will have information about the repairs, tests, and upgrades of HyCal that are necessary for the running of PRad II, the Hidden Sector Search experiment, and the π 0 Transverse Form Factor experiment.
HyCal Cable Upgrades in Hall B
As a part of the HyCal upgrades, the cables that attach to the computing crates needed to be changed to LEMO connectors for use in the Flash Analog-to-Digital Converters (FADC) boards that will be used in the crates for the upcoming experiments. These cables need to be removed from their original boards and refitted with the proper end connectors. Following this, each of the cables needed to be tested and fixed if there were any issues. This was done by utilizing a modified 32-pin connector at the end that will lead to HyCal that completed the circuit between cables that were opposite one another and one that paired cables that were next to each other. These linked cable then had a voltage of 5V sent through them to see if there were any issues in carrying the signal. In the case of lone cables or where a pair failed a terminator would be used on one cable and the same 5V signal would be sent to confirm which cables did not work. There were a total of 60 bundles of 32, 27, and 25 cables to test. The current status of this work can be views on the following spreadsheet PDF (Cable Testing Check Sheet). Two cables were found to not function properly and needed to be re-soldered to their boards that will connect to HyCal and 3 of those boards needed their 32-pin connectors replaced due to them cracking or being otherwise unusable.
After testing each of the cables, the cables were then re-bundled into groups of 16. The labeling was done to preserve the previous numbering scheme and adding an extra identifier after a period. For example the sub-bundles of 16 made from board 10.3 would be labeled 10.3.1 and 10.3.2 respectively. Bundle X.Y.1 would always have cables 1-16 and bundle X.Y.2 would always have the rest (depending on whether the original bundle had 32, 27 or 25 cables to begin with). These will then be used to map to the DAQ system for the new experiments with the new boards.
Meeting Update Slides for this Project
HyCal Cable Upgrade Project Pictures
Contributors
- Aruni Nadeeshani (Mississippi State University)
- Buddhiman Tamang (Mississippi State University)
- Erik Wrightson (Mississippi State University)
- Mark Taylor (JLab Fast Electronics Group)
Special Thanks
- Thanks also goes out to the Hall B staff that helped with moving the floor grates to give better access to the cables.
This work was done in the Summer of 2024. THIS WORK IS ONGOING.
HyCal Optical Fiber and Connection Repairs
The optical fibers, plexiglass connectors, and light blocking coverings necessary for the Light Monitoring System (LMS) to send control signals to the HyCal modules required repairs to have all ~2000 modules in proper working order. These fibers can be used to test the various modules as well as be used as a control signal during experimentation and calibration. HyCal was brought to the ESB at JLab where an ePAS approval needed to be filed for the work as it involved clear UV-activated glue for securing the optical components to each module.
Initially, a map was made for the outer lead glass (PbGlass) and central lead-tungstate (PbWO4) where the various repairs that needed to be done could be noted. Those working on creating this map were also asked to create a duplicate that just included information for the location of temperature sensors to that could then be used for updating the digital mapping in the DAQ for the new experiments and upgraded wiring system seen in HyCal Cable Upgrades in Hall B. This temperature sensor map can be seen in the two following spreadsheets ( PbGlass Temperature Sensor Map and PbWO4 Temperature Sensor Map). Each of these two maps have one mapping showing using a (Row.Column) notation and one using the digital notation from the PRad Geant4 simulator. This form of double mapping was also kept for the optical repairs spreadsheet.
Once the maps were created and it was clear which modules needed to be repaired, the materials and ePAS approval were obtained the repairing and replacing the optical connections could begin on September 5, 2024. The current status of these repairs can be seen in the following PDF version of the repair mapping spreadsheets ( PbGlass Optical Fiber Repair Map and PbWO4 Optical Fiber Repair Map). Please see this PDF for more detailed procedures of this process. The 12 fibers in the central region of HyCal needed to be applied by feeding the fibers through a tungsten absorber that and this follows a similar procedure just with that caveat.
Repair of Crystals Beneath the Tungsten Absorber
The central 12 PbWO4 crystals of HyCal surround a fitting for the beam to pass through the calorimeter. These crystals allow for an extremely tight angular coverage that makes HyCal so useful in experiments that require high precision at low angles like the PRad experiments. Mounted in this beam pipe fitting and covering the 12 crystals is a tungsten absorber. The optical fibers for the covered crystals must fed through holes on the absorber and then have a plexiglass optical donut connector affixed to the fiber and then attached to the crystals with UV activated glue. An extra challenge in this process is that the absorber when slid into its final position only has a very small gap from the crystals with the optical donuts needing to fit into pre-drilled holes within the absorber, but these holes are slightly smaller than the openings to the crystals. This necessitates a more precise placement of the connectors. Initially this difference was not quantified, so those working on the detector in person at the time (Aruni, Buddhiman, and Erik) consulted with Ashot Gasparian about the best way to go about figuring this out. With Ashot's advice, an impression was taken of one of the holes and then used to compare to the crystal openings and it was ensured that the alignement centered the holes above the crystal openings. As long as the optical donuts were placed in the center of each crystal with a tolerance of a few millimeters then the absorber would be able to be successfully seated. This was successfully done on September 26th, 2024.
HyCal Optical Fiber and Connection Repair Project Pictures
Contributors
- Aruni Nadeeshani (Mississippi State University)
- Buddhiman Tamang (Mississippi State University)
- Erik Wrightson (Mississippi State University)
- Yuan Li (Shangdong University) [Damage Mapping Portion of this Project]
- Eugene Pasyuk (Jefferson Lab)
- Ashot Gasparian (North Carolina A&T State University)
Special Thanks
- Thanks goes out to the Hall B staff that helped with setting up the ESB space.
- Thanks goes out to Alexander Somov from Hall D for providing training and the materials for using the UV-activated glue.
- Thanks also goes out to Morgan Cook from the Hall B staff for helping us with setting up the ePAS for this work.
This work began in late August 2024 and will be completed in September of 2024. THIS WORK IS ONGOING.
