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| imagerteleconnotes20170911 [2017/09/11 12:21] – created kyoung | imagerteleconnotes20170911 [2017/09/19 13:51] (current) – hanany | ||
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| ====== Telecon 20170911 ====== | ====== Telecon 20170911 ====== | ||
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| + | Attending: Al, Shaul, Amy, Brad, Julian, Brian, Roger, Bill, Jacques, Jeff \\ | ||
| __Agenda: | __Agenda: | ||
| - | * White noise and focal plane model (Karl) | + | |
| - | * Focal plane size comparison (Qi) | + | |
| - | * 1/f and TDM readout | + | * Focal plane size comparison |
| - | * Scan Angles (Kris) | + | * White noise comparison; |
| + | * TDM noise : | ||
| + | * 1/f noise summary : {{:: | ||
| __Notes:__ | __Notes:__ | ||
| - | | ||
| + | |||
| + | New telecon time. **Tuesdays 2 pm CDT** starting 9/19. | ||
| + | |||
| + | Noise model (Karl) | ||
| + | * Added multichroic pixels | ||
| + | * stop illumination changes with frequency | ||
| + | * Comments: | ||
| + | * **A/I** should set lowest band at 25 dB to be conservative. | ||
| + | * illuminations, | ||
| + | * Amy can look for person or software access at JPL. **A/I**: pending discussion with Shaul. | ||
| + | * 100 mK bath temperature added. | ||
| + | * effects low frequencies where phonon noise was dominate at 100 mK bath. | ||
| + | * Single detector NET, Open performs better, particularly at high frequency. | ||
| + | * DLFOV calculated. | ||
| + | * in F*lambda units, crossed diameter is 2x open diameter. | ||
| + | * pixels numbers added which satisfy DLFOV requirements. | ||
| + | * Final polarization weights are similar | ||
| + | * crossed is 0-20% better at most bands. | ||
| + | * open 5% better at only 3 bands. | ||
| + | * Discussion: | ||
| + | * Since roughly equal sensitivity open is probably preferred as focal plane is smaller, fewer detectors, less massive, easier to cool, overall cheaper. | ||
| + | * may need to consider diffraction pattern on primary of open. Does primary need to be oversize? | ||
| + | |||
| + | Focal plane sizes (Qi) | ||
| + | * Past report said DLFOV for Open/ | ||
| + | * DLFOV reduced for stop between primary and secondary on open dragone. | ||
| + | * Key points: | ||
| + | * stop location matters and reduces DLFOV. | ||
| + | * results consistent with and explain focal plane sizes in noise presentation. | ||
| + | |||
| + | 1/f noise and TDM (Roger) | ||
| + | * presentation tied up in JPL release procedure. | ||
| + | * brief summary of work done: | ||
| + | * TDM version of white noise calc in rough agreement with UMN numbers. | ||
| + | * Likely to need 100 mK bath temperature just so bolometers are build-able. | ||
| + | * little to no 1/f input from readout developers yet. | ||
| + | * total instrument 1/f compiled from various deployed sources | ||
| + | * how low has been achieved? | ||
| + | * Comments: | ||
| + | * SPIDER has a non-scanning data set which can be examined for 1/f levels. **A/I** Roger to follow-up. | ||
| + | * Niemack may have data on TDM showing 10 mHz 1/f knee. | ||
| + | * will the community doubt 1/f knee as low as needed is possible? | ||
| + | * what 1/f knee is needed? | ||
| + | * 1 RPM is fast. Past experiments are 0.5-1 RPM. | ||
| + | * Large broadband HWP is not possible. | ||
| + | * (Jacques) 1/f not terrible problem if uncorrelated. | ||
| + | * Gain changes and temperature stability are large problems. | ||
| + | * (Julian) making single detector maps is useful in dealing with 1/f, i.e. scan stratagey matters. | ||
| + | * Has pipeline to do large scale simulations. | ||