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BTOF demonstrator/mechanics meeting
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US/Pacific
Description
https://ucsc.zoom.us/j/98299273347?pwd=HHm9tGM6hD7aZaIVWWaF16ueAT3gVu.1
Quick recap
The meeting focused on updates and discussions related to the design and assembly of the TOF stavelets and service hybrids. Simone Mazza provided an update on the gluing and wire bonding studies for sensor attachment, and the group discussed the possibility of using removable adhesives to allow for sensor replacement. The conversation then shifted to the mechanical design of the stavelets, with Dan presenting envelope drawings to clarify the available space for the service hybrid, which was confirmed to be 20 centimeters. The group debated the length and width requirements for the stavelets, with Tonko and others seeking precise dimensions. The discussion also covered thermal management, with options like thermal pads and screws being considered for securing the service hybrid. Tonko presented updated power consumption calculations for the stave, which showed an increase due to IR drop and LDO losses. Elke emphasized the need for a documented, version-controlled record of all design parameters and power numbers. The conversation ended with an agreement to reconvene later.
Next steps
- Simone Mazza: Send a few stavelets and the models for the mock-up jig to Brookhaven for practice.
- Simone Mazza: Complete the wire bonding study on the sensors using the silver epoxy and report the results.
- Simone Mazza: Design the stavelet width (target 39mm) in collaboration with the ASIC designer.
- Dan: Recirculate the full drawing of the TOF envelope and attach it to the meeting agenda.
- Dan: Update the simulation study to include a 7.5mm spacing between sensors for the ADA coverage analysis.
- Tonko: Prepare detailed slides explaining the power calculation (IR drop, LDO loss) for the next meeting.
- Rachid: Attend the global grounding scheme meeting and provide feedback to the BTOF team.
- Andy (jung196): Finish the study on the pseudorapidity coverage and report findings.
- Hansheng: Check the fit of the two-layer stave design within the TOF envelope, considering the inner radius constraint.
- Tonko and Wei: Evaluate the feasibility of the service hybrid design within the 20cm allocated space, considering connector and FPC requirements.
Summary
Sensor Stabilization and Wire Bonding
Simone Mazza provided an update on the stabilized sensor work, reporting that studies on glue support for sensor wire bonding are underway using B-component silver epoxy, with wire bonding tests planned to assess failure rates. Rachid raised concerns about the difficulty of removing sensors with silver epoxy and suggested exploring thermally activated epoxy alternatives, with Simone Mazza agreeing to investigate removal methods and offering to send samples to Brookhaven for practice. The team discussed stave length requirements, with Tonko confirming they can currently provide 52mm (option A) or potentially 50mm (option B) stave length, though longer lengths are still needed for the 5cm wide service hybrid design.
TOF and Symbol Detector Alignment
Dan presented the envelope model for TOF and symbol detectors, explaining that about a year ago they intentionally aligned the centers of the two detectors to be shared between the subsystems, despite being slightly offset from the IP. Elke clarified that this misalignment with the IP is a feature of EPIC and not unique to this design. The discussion revealed that while the original design had asymmetric splits due to engagement ring support, the current support system with GST and Trace Rails allows for symmetric splits, and the centers of both TOF and symbol detectors are now intentionally aligned.
Sensor System Stave Dimensions Discussion
The team discussed the dimensions and placement of staves and service hybrids within the sensor system. They confirmed that each stave would have 20 centimeters reserved for electronics at the edge, including space for connectors, power, and readout boards. While Jung suggested the possibility of splitting apart the service hybrid into separate components for power connections, Tonko indicated this would require additional drawings to evaluate. The discussion concluded with Jung asking for an update on the sensor coverage discussion, but the transcript ended before this topic was addressed.
Stave Thickness Design Modification
The team discussed reducing the stave thickness to 5 centimeters, which increases the number of staves per tray from 120 to 144, though some tracking accuracy is sacrificed. Simone Mazza noted that simulation studies need to be updated to reflect the actual detector design including stave thickness and GST components, rather than assuming zero thickness sensors. The team identified the need for further studies on pseudorapidity coverage and correlations using standard candles like D star to better understand the impact of the 60% drop in low momentum tracks.
Hybrid Service Configuration Review
The team reviewed a slide presentation about hybrid service configuration, focusing on stavelet dimensions and technical specifications. Dan presented the default configuration with seven stavelets at 50 millimeter width and 1.3 meter length, including a 5-millimeter clearance between staves and sectors for safe integration and assembly. The discussion included plans for a carbon fiber shell to enclose each sector and potentially pump in dry nitrogen for temperature control and protection against dust and debris.
Tablet Component Design specifications
The team discussed the dimensions of a tablet/stave component, with Simone Mazza confirming that a 39mm height specification would be acceptable rather than the previously shown 40mm. Rachid proposed using thermally conductive epoxy glue to attach the service hybrid to the stave, though there was debate about whether screws would be more reliable for long-term reliability, particularly in radiation environments. The discussion also covered thermal management options for both the upper readout board and lower power board, with various approaches including thermal pads and 3D printed standoffs being considered.
Thermal Management and Power Design
The team discussed thermal management and power considerations for the readout board design. Tonko explained that the power board generates significantly more heat than the readout board, and the team agreed on the need for proper airflow, particularly dry air, for cooling. Rachid raised concerns about grounding issues for the carbon fiber stave and suggested developing a grounding scheme to avoid potential shorts and grounding loops that could affect the sensitive ASICs and preamps. Dan proposed a potential design modification to reduce the height of power boards by placing them on one side of the stave instead of both sides, which could create space for additional sensors.
Detector System Power Requirements Discussion
The team discussed power consumption calculations for the detector system, with Tonko explaining that the total power requirement increased to 65 watts due to IR drops and LDO losses, requiring approximately 17 amps total current. Dan presented sensor spacing modifications to accommodate the service hybrid, reducing spacing by 1mm between adjacent sensors. The group agreed that power requirements need to be properly documented in a centralized location, with Satoshi taking the lead to create a comprehensive Word document that can be version controlled and posted to Zenodo for tracking changes and updates.
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