Differences

This shows you the differences between two versions of the page.

--- imagerteleconnotes20170911 [2017/09/11 12:48] – hanany
+++ imagerteleconnotes20170911 [2017/09/19 13:51] (current) – hanany
@@ Line 1: / Line 1: @@
 ====== Telecon 20170911 ======
-Attending: \\
+Attending: Al, Shaul, Amy, Brad, Julian, Brian, Roger, Bill, Jacques, Jeff \\
 __Agenda:__
   * New Permanent Telecon Time: Tuesday 2 pm
   * White noise and focal plane model {{::pico_noise_open_v_crossed_20170911.pdf|Noise model status}}  (Karl)
     * Focal plane size comparison {{:fov_comparison_09112017.pdf|}} (Qi)
   * White noise comparison; 1/f noise (Roger, Jeff)
+    * TDM noise :{{::Noise_for_CMB_Probe_v2.pdf|TDM noise Study}}
+    * 1/f noise summary : {{::flicker_noise_CMB_probe.pdf| 1/f noise Study}}
 __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, diffraction, spillover may need study with GRASP.
+        * 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.  Hex packing assumed
+  * 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.  Also lower sidelobes.
+    * may need to consider diffraction pattern on primary of open.  Does primary need to be oversize?  How much?  A GRASP calculation could be done.
+Focal plane sizes (Qi)
+  * Past report said DLFOV for Open/Crossed ~ 75%.  This was stop at primary.
+  * 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.
+/f noise and TDM (Roger)
+  * presentation tied up in JPL release procedure.  Should be shared with 1 week.
+  * 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.  Need a very low G and low T_bath helps achieve this.
+    * little to no 1/f input from readout developers yet.
+    * total instrument 1/f compiled from various deployed sources
+    * how low has been achieved?  Unclear, most experiments use modulators or focus on higher l science.
+    * 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?  This is a critical component.
+      * what 1/f knee is needed?  if 1 RPM need 16 mHz.
+      * 1 RPM is fast.  Past experiments are 0.5-1 RPM.
+      * Large broadband HWP is not possible.  Need to address/understand 1/f.
+      * (Jacques) 1/f not terrible problem if uncorrelated.  only reduces low l sensitivity.
+        * 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.  "Space is easy."

User Tools

Differences

Page Tools