2020 Winter - 2021 Spring
Contents
Hall work
- Water level sensor installation
- Total: 2 days. 1 day testing + 1 day installation
- Darkening leak check
- Total: 1 day
- Modification on vent exit to reduce FPGA temperature
- Total: 3 days. 1 day diagnose, 1 day test and 1 day installation. Excluding time for designing time.
- DIRC Diffuser seal issue
- Total: 2 days. 1 day test and 1 day installation. Excluding time for water seal test
- Contaminated mirror replacement in north upper OB
- Total: 1 days. Uninstall + Disassembly: 1 day; mirror removal + setting up clean area, mirror gluing+ curing: 3 days; silicone seal + cleaning + assembly: 1 days; installation: 1 day. Excluding time for water seal test
- Inspect the south lower OB
- 1 day
- If mirror problem, adding 6 more days for mirror replacement.
- South box module c2r18 over current limit diagnosis work
Non Hall Work
- Testing spare DIRC modules
- Control and operation
- Alarm modification strategy
- Resolving (double checking) DIRC hole in occupancy before run starts
- Dis-entangle DIRC interlock and interlock reset from FCAL and CCOM
- Individual (stand alone) SiPM TDA offset
- Tile FPGA voltage regulation issue.
- Recover loan-out (Duke SOLID group) MOROC chips
Not-to-forget items
- Re-activate tile-temperature alarm for the south box c2r18
- Including south box c2r18 fiber verification back into the DAQ starting procedure
2020 October DIRC Work Planning
By December 2020, DIRC would have been operational for one whole year. There is a list of work/improvement/maintenance items need to be completed/addressed before the next GlueX-2 running period. A full list of such items can be found in the following link: https://halldweb.jlab.org/wiki/index.php/2020_Winter_-_2021_Spring
Among these items, there are three items which need to be addressed. It is crucial for the DIRC detector owner Justin Stevens and detector on-call assistance Wenliang (Bill) Li to gain access to the accelerator site after current run period as users, to complete the suggested work. We would like to submit a request to gain access to the accelerator site and have it approved as soon as possible.
Note that Item 1 and 2 should be scheduled as soon as the current run period ends. The scheduling of item #3 will require the detailed evaluation of the outcome of item #2 and consultation with Tim and Eugene.
Detailed work description, required personnel and equipment are listed below:
Item #1 (Highest priority) Debuging/repairing DIRC South Box PMT module c2r18.
Personnel: Bill for hardware replacement and darkbox re-sealing; Justin for signal verification.
Estimated days: 1
Equipment required: fix height platform, 2-inch wide electrical tape, LV power supply and cables.
Task description: unseal the South (lower) DIRC dark box; disassemble the c2r18 PMT mounting brackets; replacing the FPGA board; signal verification (by Justin) and reseal dark box. Note that this work does not require two people to work within six feet of each other, therefore no PPE is required.
This work item should be scheduled as soon as the run ends.
Item #2 (High priority) North (Upper) and South (Lower) mirror box inspection and re-sealing the LED diffusers with RTV
Personnel required: 3. Keith and Bobby for unmounting the backplates, Bill/Justin for assembling the LED-diffuser.
Estimated days: 2
Procedure: water from both DIRC boxes will be drained and dried with purge pure N2. Keith and Bobby will remove of the backplate of both DIRC boxes, a care inspection will be performed to examine if water seep into the mirror and protector. As the backplates are removed, the LED fiber with diffuser will be dismounted and resealed with RTV (24 hours curing time). Note that unmounting the backplates require two people to work together within 6 feet distance, PPE is required; Re-sealing diffuser doesn't require two people to with within 6-feet.
This work item should be scheduled as soon as the run ends and after item #1 is completed.
Item #3 Mirror replacement work.
Personnel required: 2-4 (Bill/Justin + three techs support). At different stages of this work, different number of personnel are needed. The exact number are given at specific stage.
Equipment required: JLG lift, power platform, clean room in the Hall, four long work benches and two four-deck rolling equipment shelves.
PPE: face masks (to be purchased), powder-free gloves (to be purchased), hazard suits.
Estimated days: ~10 days (for both boxes)
Steps:
0. As mentioned above, this item requires the assessment of the mirror inspection results (from item #2), available time and available personnel, etc. One must hold a detailed discussion session among detector owner (Justin), engineer (Tim) and hall leadership (Eugene) after the completion of item #2, to decide how and when to proceed this item. The procedure given below is only for referencing purpose. Note that if both boxes required mirror replacement, then these steps will be repeated.
1. Disassembly stage: Uninstall + Disassembly. At this stage, two technicians (Bobby + Keith) are required and they will work within 6 feet of each other. Unmount the backplate (if mounted), and remove the mirror box from the optical box. Duration estimated: 1 day
2. Old mirror removal/ New mirror preparation. Here Keith and Bobby will work within six-feet to dissemble mirror boxes in pieces. Bill will assist to lay the dissembled pieces to the long work benched and shelves.
Keith will remove the effected mirror with the metal string (alone). Pre-cut mirror and protector will be glued, sealed and taped to the strong-back, here Bill will assist Keith within six feet.
Estimated mirror removal + setting up clean area, mirror gluing+ curing: 3 days
3. Assembly and installation
The cleaning, assembly and installation of the mirror box will take 1 day.
During the assembly stage, Bobby and Keith will assemble the mirror box with the assistance from two spotters from different angles. All within 6 feet distance.
During the installation stage (inserting mirror box back to the optical box), Bobby and Keith will work within 6 feet
Voltage Regulation Related Work Performed by Chris and Nick
- HV Power controller regulation issue.
- This issue manifests itself in the form of sudden HV drop to the HV for a PMT module, the module refuses to re-ramp and give over current limit error. Additionally, the problem module will affect HV read back from other modules. Such event is documented in the following log entry: https://logbooks.jlab.org/entry/3830391
- Broken connectors in the north HV distribution box
- Through out operation, a number of north box HV connectors have failed from the north (upper) distribution box, we should address these broken connectors.
- Make 3 feet extensions to the HV cables which are 5 feet short, so that we can properly strain relief the cable bundle. This should significantly reduce the number of the broken connectors during the run period.
Note that these works doesn't required two people to work into 6-feet distance, therefore now PPE is required. The first work item may required a quick access to the Hall and the second item will required coordination with Tim and should be scheduled after the planned mirror inspection workshop (November or later).
