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| private:teleconsnotes20170614 [2017/06/14 18:20] – atrangsr | private:teleconsnotes20170614 [2017/06/19 06:14] (current) – hanany |
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| | ====== Telecon Notes 20170614 ====== |
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| Attendance: Julian, Lloyd, Raphael, Al, Amy, Kris Gorski (for his presentation only) | Attendance: Julian, Lloyd, Raphael, Al, Amy, Kris Gorski (for his presentation only) |
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| **EPIC** scan strategy has large bore angle / good polarization scan angles / quickly covers the sky. But it required large sun shields and reduced the power per area from the solar arrays. **CORE** survey is a compromise that addresses some of the engineering challenges associated with the EPIC strategy, has a 120deg opening angle ring - donut on the sky precessing elliptically. Some similarities to WMAP but somewhat better crossing angles on each pixel. A scan strategy similar to **Planck** but with more continuous precession (less discrete) would be notably better than Planck. Kris also considering a **"fantasy idea"** - spacecraft spins with spin angle along Sun axis (simple, maximal power, maximal shaded volume for optics) and does not precess - instead add a moving mirror to optics. BEAST an example. But don't know about emissivity as a function of angle (large angles), and polarization propagation through such a system. Amy to arrange a meeting with a JPL optics expert to discuss these things. | **EPIC** scan strategy has large bore angle / good polarization scan angles / quickly covers the sky. But it required large sun shields and reduced the power per area from the solar arrays. **CORE** survey is a compromise that addresses some of the engineering challenges associated with the EPIC strategy, has a 120deg opening angle ring - donut on the sky precessing elliptically. Some similarities to WMAP but somewhat better crossing angles on each pixel. A scan strategy similar to **Planck** but with more continuous precession (less discrete) would be notably better than Planck. Kris also considering a **"fantasy idea"** - spacecraft spins with spin angle along Sun axis (simple, maximal power, maximal shaded volume for optics) and does not precess - instead add a moving mirror to optics. BEAST an example. But don't know about emissivity as a function of angle (large angles), and polarization propagation through such a system. Amy to arrange a meeting with a JPL optics expert to discuss these things. |
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| Comment: it would be good to explore the other limiting case - beams 90deg to Sun line - slow to cover entire sky, but good angles for Q and U, and may be good for spectrometer, Kris asked Julian about simulating many pixels - Julian says have emulated 1,000+ pixels. Some discussion about half wave plate - haven't closed the door on this, but Amy doesn't think its likely a good fit in cost and risk for the single imaging telescope design (perhaps for smaller telescopes). Comment **need to define metrics by which we want to evaluate scan strategy options**. Al notes spectrometer and imager treat 1/f drifts in time domain very differently. In spectrometer they don’t effect large angle pixel to pixel comparison the way they would in an imager. Kris notes he's willing to call in again if invited. | Comment: it would be good to explore the other limiting case - beams 90deg to Sun line - slow to cover entire sky, but good angles for Q and U, and may be good for spectrometer, Kris asked Julian about simulating many pixels - Julian says have emulated 1,000+ pixels. Some discussion about half wave plate - haven't closed the door on this, but Amy doesn't think its likely a good fit in cost and risk for the single imaging telescope design (perhaps for smaller telescopes). Kris also wants to know how effectively polarization angles can be aligned and varied for current technologies, and what we know about correlated noise on multi-wafer experiments. Comment: need to define metrics by which we want to evaluate scan strategy options. Al notes spectrometer and imager treat 1/f drifts in time domain very differently. In spectrometer they don’t effect large angle pixel to pixel comparison the way they would in an imager. Kris notes he's willing to call in again if invited. |
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| **Raphael has slides "Theory update and plan"** | **Raphael has slides "Theory update and plan"** |
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| ** Possible topics for next week's agenda** | ** Possible topics for next week's agenda** |
| * Al talking about complementary spectrometer and SuperPIXIE (he's not sure if he'll be available to do this) | * Al talking about complementary spectrometer and SuperPIXIE (he's not sure if he'll be available to do this) |
| * Discussion about adding working groups (per Lloyd's idea, Shaul's follow up email) | * Discussion about adding working groups (per Lloyd's idea, Shaul's follow up email) |
| * Discuss study schedule (per Amy's email and uploaded PDFs) | * Discuss study schedule (per Amy's email and uploaded PDFs) |
| * Detector and readout tech selection - perhaps Jeff could summarize discussion between himself, Roger (at JPL), and Amy, and path forward | * Detector and readout tech selection - perhaps Jeff could summarize discussion between himself, Roger (at JPL), and Amy, and path forward |