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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 design and performance of a tracking detector, discussing sensor sizes, stave arrangements, and acceptance losses. Wei and Tonko debated extending the stable period for a service hybrid, with Tonko cautioning against making changes without reviewing the entire system. Hansheng and Satoshi discussed sensor dimensions and the need for more channels, with Satoshi noting the current order of full-size and half-size sensors. Zakaria presented an unexpected acceptance loss for negative particles in the windmill stave configuration, attributing it to the stave tilt and magnetic field effects. Simone Mazza clarified that the current design had moved away from the windmill layout to a flat stave arrangement, which should mitigate the asymmetry issue. The group also briefly discussed a workshop at UCSC, tentatively setting the dates for March 3rd to 5th and considering logistics like catering and room arrangements.
Next steps
- Satoshi: Ask the simulation team to clarify whether the active length (32 mm) is used in the simulation for the 33 mm physical sensor.
- Satoshi: Wait for and follow up on the answer from Hamamatsu regarding moving the wire bonding part closer to the edge of the strip.
- Zakaria: Redo the acceptance study using the current (non-windmill) baseline design with bent tracks.
- hansheng: Talk to Andy today about his new stave design idea and its implications for the Z direction acceptance.
- Satoshi: Push Andy to provide an official answer or input regarding his new stave design idea.
- Simone Mazza: Finalize and send out the details for the workshop at UCSC, scheduled for March 3rd to 5th.
- Simone Mazza: Plan the logistics for the workshop, including room booking (likely the free department room) and catering or lunch arrangements.
Summary
Service Hybrid Design specifications
The team discussed extending the service hybrid's stable length from 50 to 55 millimeters, with Tonko expressing concerns about making changes without considering the overall system impact. Hansheng and Satoshi discussed sensor specifications, with Hansheng proposing a 37mm sensor to recover full acceptance, while Satoshi explained that adding the required channels would be challenging due to existing constraints at the 8th channel. The conversation also touched on the active length of sensors and the need for more compact arrangements with 144 staves at 50mm width.
Sensor Specifications and Acceptance Results
Satoshi explained the specifications of the sensors, including the number of states and sensor width, and confirmed the order of 200 full-size sensors and 20 half-size sensors. He discussed ongoing efforts to modify the sensor design, including requests to Hamamatsu regarding marker placement and wire bonding, though some modifications were deemed impossible due to dedicated areas. Zakaria presented unexpected results from acceptance measurements, finding that negative particles (kaons and pions) have lower acceptance rates (95-95.1%) compared to positive particles (99.5%), potentially due to stave tilt geometry.
Particle Acceptance in Magnetic System
Zakaria presented a study on particle acceptance in a magnetic system, using a method similar to Yobo from Hawaii University. The study found that positive pions and kaons maintained approximately 99.5% acceptance, while negative particles experienced higher losses, particularly at low momentum (22% for pions and 26% for kaons between 0.2-0.3 GeV). The analysis revealed that track curvature through the magnetic field causes this difference, with negative particles being more affected due to opposite bending directions compared to positive particles. A simple model confirmed these findings, showing 20-27% loss at low momentum and decreasing with increasing momentum.
Windmill Design Modification Discussion
The team discussed changes to the windmill design, with Simone Mazza explaining that they had moved away from the windmill configuration to a flat stave design due to construction constraints. Simone Mazza noted that while the windmill design showed issues with curved tracks, the new flat stave design should be more symmetric and less prone to acceptance problems. Satoshi raised concerns about the new design not working effectively for the Z direction, and the team agreed to wait for input from Andy regarding material budget and acceptance studies. Hansheng committed to discussing the Z direction coverage requirements with Andy that day.
UCSC Workshop Planning Meeting
Simone Mazza and Satoshi agreed to hold the workshop at UCSC from March 3rd to 5th, with an expected attendance of 20-30 people. They discussed logistics including catering options, with Simone Mazza suggesting either using department funds or implementing a workshop fee to cover lunch costs, as the campus location requires organized catering rather than allowing participants to leave for meals. The group decided to use a department room as it would be free, though not ideal, and agreed on a workshop fee of around $100-200 to cover costs.
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