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BTOF demonstrator/mechanics meeting
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Description
https://ucsc.zoom.us/j/98299273347?pwd=HHm9tGM6hD7aZaIVWWaF16ueAT3gVu.1
Quick recap
The meeting focused on the development and assembly of stave components for a detector project, with participants discussing 3D printed jigs, component fitting issues, and assembly strategies. Simone Mazza and Grigory presented challenges with their current 3D printed components, including loose fits and threading issues, while Grigory explained these were due to printer misalignment issues that have since been resolved. The team debated different approaches to stave assembly, with Aidan Tiernan advocating for a modular approach where components are added step-by-step with testing at each stage, while Simone Mazza expressed concerns about timeline constraints and funding limitations for implementing such a complex assembly process. Sushrut shared thermal simulation results for stave cooling designs, showing temperature gradients across sensors, and the team discussed power distribution solutions including the possibility of multiple DC-DC converters on the power board to account for voltage drops across the stave length.
Next steps
- Grigory: Send the 3D model files to Simone Mazza's team so they can 3D print the jig components locally.
- Grigory: Cross-check the thread specifications for the jig components with Dorian to ensure compatibility.
- Sushrut: Rerun the thermal simulations for the stave with updated chip configuration and power dissipation data before the upcoming review.
- Sushrut: Update the finite element simulation results to reflect the correct cooling temperature boundary conditions (e.g., +5C glycol cooling) and document the expected temperature gradients across the sensor.
- Team (likely Sushrut/Simone): Obtain and incorporate the final chip design and power dissipation numbers from Fermilab (expected in Sylvia's TIC meeting) into the thermal simulations.
- Grigory and Simone Mazza: Discuss offline and finalize the design for the vacuum jig/fixture (including vacuum distribution and hole pattern) to hold the interposer flat during assembly.
- Team: Start test assemblies using current 3D printed jigs and document precision/tolerances achieved, as input for future QC procedures and database requirements.
- Team: Once final sensor, ASIC, and hybrid designs are available, converge on the detailed stave design (including component placement and cooling tube layout) and perform FEA analysis to optimize cooling and mechanical parameters.
Summary
3D Printing Component Issues Discussion
Simone and Grigory discussed issues with 3D-printed components, including loose parts and tight threads. Grigory explained that some surface imperfections were due to printer issues, specifically a misaligned Z-axis rod, which he has since fixed. They agreed that Grigory would send the model files to Simone's team for local 3D printing to avoid shipping complications. The team also identified threading issues with nozzles, which Grigory suggested could be addressed by either 3D printing new threads or tapping the existing ones.
Component Assembly and Alignment Strategies
The team discussed technical aspects of component assembly and alignment. Grigory explained his approach to threading components, while John suggested using a soldering iron for a more secure connection. Simone Mazza clarified that the current design assumes 128 channels, though future iterations will likely change to 32 channels. The group discussed alignment strategies for FPC (Flexible Printed Circuit) components, with Grigory proposing a simple solution using a larger aluminum fixture with pins to achieve proper positioning without needing to redesign the FPC.
Carbon Fiber Assembly Process Planning
The team discussed assembly processes for components, focusing on how to connect and align carbon fiber with interposer and other components using jigs with pins and specific tolerances. Simone Mazza explained the plan to first assemble and glue one side of the stave, then the other side, before joining them together, with a separate jig for gluing the top and bottom halves. The group addressed concerns about precision tolerances, with Grigory and Simone Mazza explaining that while current 3D printed jigs have coarse tolerances, they aim to achieve hundreds of microns or better precision using proper jigs and smart scope measurements for quality control.
Three-Component System Design Discussion
Grigory presented a design for a three-component system including a vacuum component, holder, and interposer, with Simone Mazza suggesting modifications for better vacuum distribution. The team discussed positioning precision requirements, with Grigory explaining the 150 micron target for sensor overlap, while Sushrut clarified that gantries would be used for stave assembly with dowel pins for precise positioning. Rachid raised questions about modular assembly, leading to a discussion about the benefits of modular approach versus full stave assembly, with Rachid advocating for a step-by-step component installation process that has been successfully implemented in previous projects.
Carbon Fiber Staves Proposal Discussion
Rachid presented a detailed proposal for building carbon fiber staves based on lessons learned from the Atlas project, suggesting a modular approach where components could be tested and replaced individually before final assembly. He proposed using a design similar to Atlas's but with modifications, including potentially gluing components rather than co-curing them, and emphasized the importance of proper component placement and testing at each stage. Elke cautioned that setting up new facilities was not in the original plan due to funding constraints, and emphasized the need for a full cost analysis. The team discussed potential manufacturing capabilities at various institutions including Asuka in Japan and Purdue.
Carbon Fiber Stave Design Review
The team discussed the stave design, focusing on carbon fiber and honeycomb structures for cooling. Sushrut presented existing prototypes and thermal simulations for both mini and full stave lengths, including experimental validation using silicon heaters. The current design shows hotspot temperatures at 10°C with +5°C glycol cooling, though there was some confusion about the temperature scale. Sushrut confirmed they would rerun the thermal simulations with the new configuration for an upcoming review, while noting that power requirements for the new four-chip design were still uncertain pending information from Fermilab's TIC meeting.
Sensor Temperature and Module Design
The team discussed sensor temperature gradients and their impact on performance. Simone Mazza clarified that temperature changes of 1-2 degrees Celsius across a sensor are not significant, as meaningful effects only occur at around 10 degrees. The group also debated the merits of building modules with components mounted on the FPC versus using silicon modules, with Rachid advocating for the FPC approach due to its lower risk and parallel processing capabilities. Simone Mazza requested a more detailed presentation from Rachid on the FPC loading process to better understand the proposed approach and compare it to previous implementations.
Power Distribution Optimization Strategy
The team discussed optimizing power distribution by adding multiple low-voltage lines from the power board to address voltage drops across the stave, with Simone Mazza suggesting a solution involving multiple DC-DC converters on the power board. Takashi provided updates on design considerations and space constraints for implementing this solution. The group also explored the possibility of using eight chips in one FPC instead of four to reduce the number of traces needed, though Simone Mazza noted he was still awaiting a clear answer from Fermilab on this option.
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