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--- imagerteleconnotes20171003 [2017/10/03 13:51] – kyoung
+++ imagerteleconnotes20171003 [2017/10/10 12:55] (current) – hanany
@@ Line 1: / Line 1: @@
-====== Telecon 20170926 ======
+====== Telecon 20171003 ======
-Attending:  \\
+Attending:  Al, Roger, Jacques, Jeff F., Shaul, Karl, Qi, Ranajoy, Brian \\
 __Agenda:__
@@ Line 7: / Line 7: @@
    * Imager + Spectrometer (Karl) {{:pico_and_pixie_20171003.pdf|Spectrometer Slides}}
    * Focal plane + noise model (Karl) {{:pico_fdm_noise_model_status_20171003.pdf|Noise model slides}}
-   * optical system (Qi)
+   * optical system (Qi) {{::crossdragone_d100cm_f4.5_fov10deg_10032017.pdf|}}
    * Scan parameters (Shaul (for Kris))
 __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,  telescope,  readout, and detectors
+      *  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/rt(Hz).  **A/I** Karl checking with Hannes at NIST about proper number to quote.
+  * Roger: all these numbers are fine.
+  * Cross check between Karl and Roger.  noise matches except for:
+    * 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.  Possibly polarization related.
+  * Richard’s correction on Coma
+    * more detectors at high frequencies, for both Open and Cross Dragone
+    * can weight CMB frequencies more heavily.
+  * Can optimize edge taper
+    * including correlated photon bunching noise from CMB (correctly) and mirrors (incorrectly, but with factor of 2)
+      * Next step: Karl to implement full correct calculation for mirrors.
+    * best mapping speed is near 2 F lambda.  Current Open Dragone pixels are at 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' focal planes view sky after 1 reflection off tertiary
+  * total sensitivity is better than Open dragone (baseline)
+    * assumes full telescope is 4 K
+    * also number of detectors is larger.  3k for Open, 7k and 11k for new crossed designs.
+  * How does larger f-number give better sensitivity?  Opposite what is normally said.  From CORE, increasing f-number gave no benefit since pixels grew at same rate focal plane grew.
+    * **A/I** Karl/Qi to sort out scaling of focal plane with f-number.
+Scan delayed to next week.

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