Campuses:
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| imagerteleconnotes20171003 [2017/10/03 13:57] – wenxx181 | imagerteleconnotes20171003 [2017/10/10 12:55] (current) – hanany | ||
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| - | ====== Telecon | + | ====== Telecon |
| - | Attending: | + | Attending: |
| __Agenda: | __Agenda: | ||
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| * Imager + Spectrometer (Karl) {{: | * Imager + Spectrometer (Karl) {{: | ||
| * Focal plane + noise model (Karl) {{: | * Focal plane + noise model (Karl) {{: | ||
| - | * optical system (Qi) {{:: | + | * optical system (Qi) {{:: |
| * Scan parameters (Shaul (for Kris)) | * Scan parameters (Shaul (for Kris)) | ||
| __Notes:__ | __Notes:__ | ||
| + | |||
| + | Imager + Spectrometer (Karl) | ||
| + | * mini-PIXIE, 20 cm mirrors, 10x38x48 FTS | ||
| + | * Same boresight angle | ||
| + | * Share same cooling system | ||
| + | * mass of mini-PIXIE, ~20 kg in total, barrel contributes most of it. | ||
| + | * detector assembly is < 1kg | ||
| + | * Imager focal plane mass: not known yet. **A/I** Brian to ping Roger. | ||
| + | * with Open Dragone | ||
| + | * same boresight as Imager, although not necessary | ||
| + | * quite small, fits easily | ||
| + | * with Cross Dragone | ||
| + | * boresights don't match, but scan pattern does (beta is same in both cases) | ||
| + | * Al: it’s okay. There will be some time delay between imager and spectrometer scans, but it does not matter much. | ||
| + | * Boresight and spin axis | ||
| + | * It’s not required to have boresight along the spin axis. PIXIE did plan to align with spin axis,allows fitting of Q/U of each pixel before moving to next pixel. | ||
| + | * It’s okay to not do this. The current main driver is the sky coverage. | ||
| + | * FTS box is not required to be with optical tubes, it can be anywhere as long as an optical path exists. | ||
| + | * The detectors can even be on the Imager focal plane. | ||
| + | * Tradeoffs: | ||
| + | * question of cost, might limit imager size | ||
| + | * Current primary costs: cooling, | ||
| + | * marginal costs when increasing | ||
| + | * Aside: | ||
| + | * Check Open Dragone fit, to see if there is conflict between mirrors and cone. **A/I** UMN to check. | ||
| + | * structural issues with support for mirrors? | ||
| + | * Brian: JPL is working on this question. | ||
| + | |||
| + | Noise Model (Karl) | ||
| + | * Biggest change: safety factor → 2 | ||
| + | * Squid is the largest contribution | ||
| + | * Using 3.5 pA/ | ||
| + | * Roger: all these numbers are fine. | ||
| + | * Cross check between Karl and Roger. | ||
| + | * bunching noise, a factor of 2 | ||
| + | * bunching noise does not contribute too much, ~15%; all other are same | ||
| + | * **A/I** Karl, track down 2 in bunching noise. | ||
| + | * Richard’s correction on Coma | ||
| + | * more detectors at high frequencies, | ||
| + | * can weight CMB frequencies more heavily. | ||
| + | * Can optimize edge taper | ||
| + | * including correlated photon bunching noise from CMB (correctly) and mirrors (incorrectly, | ||
| + | * Next step: Karl to implement full correct calculation for mirrors. | ||
| + | * best mapping speed is near 2 F lambda. | ||
| + | |||
| + | Optics (Qi) | ||
| + | * New cross-dragone with +/- 10 deg FOV | ||
| + | * f/4.5, 1m aperture, requires deployable shields. | ||
| + | * deployable shields should be V-grooves as well. leave design to thermal engineers. Just put place-holder in current model | ||
| + | * both cross dragones' | ||
| + | * total sensitivity is better than Open dragone (baseline) | ||
| + | * assumes full telescope is 4 K | ||
| + | * also number of detectors is larger. | ||
| + | * How does larger f-number give better sensitivity? | ||
| + | * **A/I** Karl/Qi to sort out scaling of focal plane with f-number. | ||
| + | |||
| + | Scan delayed to next week. | ||
| + | |||