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| imagerteleconnotes20180131 [2018/01/31 13:50] – kyoung | imagerteleconnotes20180131 [2018/02/01 13:40] (current) – kyoung | ||
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| ====== Telecon 20180131 ====== | ====== Telecon 20180131 ====== | ||
| - | Attending: | + | Attending: |
| - | Notes by : \\ | + | Notes by : Karl/ |
| === Agenda=== | === Agenda=== | ||
| - | * Preparing the next Teamx-I | + | * {{:: |
| - | * Report | + | * Report |
| - | * Cleaned up focal plane | + | * Cleaned up focal plane {{:: |
| * GRASP {{:: | * GRASP {{:: | ||
| | | ||
| + | | ||
| + | === Notes === | ||
| + | |||
| + | Preparing the next Teamx-I -- By learning from previous one. | ||
| + | * response from TeamX, 90 slides on sub-systems. | ||
| + | * Section summaries in presentation. No cost discussion today. 15 pages in each sub-system. | ||
| + | * Need to do homework on some items before next TeamX | ||
| + | * Systems: | ||
| + | * I&T will be analyzed in next teamX, was not analyzed here. Still marked as weakness due to complexity. | ||
| + | * telescope systems at various temperatures (40 K, 4 K, 100 mK) make testing the end to end alignment challenging. | ||
| + | * Will continue discussion with Bill J. and Tomo next week. | ||
| + | * Definition: OGSE, optical ground support equipment. Testing equipment that doesn' | ||
| + | * Future threats: add “cost of cooler” | ||
| + | * FP and detectors | ||
| + | * Str: TES have ground based heritage. detector 1/f shown to be acceptable. future options for MKIDS. | ||
| + | * Roger will lead 1/f story for final report. Tomasso is running gain variation and per rotation calibration options (assuming 10 mHz 1/f knee) | ||
| + | * General comment: detector 1/f isn't the only important 1/f term. Other issues (temperature stability) may dominate. | ||
| + | * Only modulation is sky rotation and scan speed. | ||
| + | * Weak + future threat: Impact of cosmic rays. | ||
| + | * Jeff Fillipini has looked into this. As has Roger. | ||
| + | * Work to reduce impact is also being done at Berkeley. | ||
| + | * Hannes: What about optical coupling? | ||
| + | * This hasn't been finalized. | ||
| + | * Electronics | ||
| + | * Weak: Temperature limits. | ||
| + | * TeamX assumed what is currently used. but would used space qualified electronics, | ||
| + | * Amy: TeamX usually gives reports to science teams, not reviewers. | ||
| + | * Optics: | ||
| + | * Weakness: maturity of mechanical and thermal design of focal plane. | ||
| + | * this work is in progress for next TeamX | ||
| + | * Thermal: | ||
| + | * 3HE, testing for MIRI was expensive. even if those tests done for PICO, < $1M so ignore it. | ||
| + | * Cost is large. $900M for cooling, 50% of instrument cost. This is largest thermal risk point. | ||
| + | * Mechanical: | ||
| + | * Strength: scalable, simple, nothing radical | ||
| + | * Weakness: optics alignment complex. | ||
| + | * Address by pointing out WMAP and Planck have done this successfully, | ||
| + | * Configuration | ||
| + | * Threat: No volume margin for primary mirror inside the shade | ||
| + | * Shaul: this is being worked on, should have some margin by next TeamX | ||
| + | |||
| + | Focal Plane V4 (Karl) | ||
| + | * simpler focal plane, 2 wafer sizes. | ||
| + | * roughly 1000 more detectors at high frequency. | ||
| + | * FP could go further out in X, | ||
| + | * Current reflectors need to be larger if we increase focal plane; but we can increase focal plane with current strehl limits. | ||
| + | * Central wafer issues: | ||
| + | * multi- and mono band pixels coexist | ||
| + | * insufficient bond pads for number of bolos on this wafer. | ||
| + | * 4000 bolos on 4" wafer. | ||
| + | * We are assuming 100 um per bond pad. 4 inch wafer. | ||
| + | * 2 mm between tiles, may be too small. For EBEX, ~5 mm. **Karl** to check | ||
| + | * Roger to get spacing number from recent BICEP arrays | ||
| + | * Kris: We need to think about how pixels are aligned to scan direction and how this impacts map making. | ||
| + | * are we making single detector maps? multi detector maps? do pixels need to follow the same path on the sky as a neighbor? | ||
| + | * This may require slight rotations of the focal plain. | ||
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