https://pfspipe.ipmu.jp/jira This file is an XML representation of an issue en-us 8.3.4 803005 13-09-2019 https://pfspipe.ipmu.jp/jira/browse/PIPE2D-377 DRP 2-D Pipeline <p>Measure the cross-talk coefficients using very saturated arc lines.  We can also do this using enough darks (as was done for HSC using Yagi-san's cosmic ray-based algorithm), but I suspect that the saturation trails are good enough.</p> PIPE2D-377

Measure PFS cross-talk coefficients

Bug Normal Done Done price rhl Tue, 26 Feb 2019 14:28:55 +0000 Mon, 4 Jan 2021 20:23:08 +0000 Fri, 26 Jun 2020 18:57:24 +0000 0 5 <p>Neven: To accurately measure the coefficients we need to request more focused data from LAM with sufficient exposures to reveal the saturation trails. Neven will look into this.</p> <p>Just an FYI: when I looked at this a long time ago, the crosstalk was bi-polar. The per-amp signals from the preamp to the ADC are differential twisted pairs, so that crosstalk can go either way. Should be stable for assembled cryostats....</p> <p>The data that are available for this ticket:</p> <p>12922 - 12960 the set of Neon data:<br/> unsaturated data, exptime=15 sec with attenuator at 240<br/> saturated data, exptime=15 sec with no attenuator <br/> saturated data, exptime=100 sec with no attenuator <br/> saturated data, exptime=300 sec with no attenuator </p> <p>Robert recommended to work with saturated, ``bleeding'' data to easily identify which fibers crosstalk to where and to get good signal. Jim notes that this is only valuable if you know what is the flux in overexposed lines. In order to do that one would need to estimate flux from unsaturated exposures and then multiply by ratio of exposure time and take into account suppression by attenuator. Attenuator values have been deduced in <a href="https://pfspipe.ipmu.jp/jira/browse/PIPE2D-323" title="Effects of attenuator on the flux for the LAM data" class="issue-link" data-issue-key="PIPE2D-323"><del>PIPE2D-323</del></a> (see the coefficients in the Figures there).</p> <p>Using the LSST tool, <tt>measureCrosstalk.py</tt> on <tt>visit=12922..12951</tt> (the unsaturated data, which gives the best S/N), I get 2-3 sigma detections of the some of the crosstalk coefficients.</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java"> measureCrosstalk INFO: Coefficients: [[ 0.00000000e+00 1.44343314e-04 -1.94648110e-05 -3.16576757e-06 1.42585166e-04 8.77068742e-05 2.74841033e-04 1.67585129e-03] [ 1.25909573e-04 0.00000000e+00 1.67928265e-05 3.45523513e-05 1.35091439e-04 9.84909784e-05 1.21150915e-04 1.19224918e-04] [-3.17470112e-05 -2.45970878e-05 0.00000000e+00 3.19747371e-04 8.55176186e-05 7.86037490e-05 5.40274705e-05 7.14990747e-05] [ 2.50621597e-05 -6.37933866e-08 2.38304929e-04 0.00000000e+00 1.27087420e-04 2.85813672e-04 5.63632930e-05 9.70012043e-05] [ 1.15817631e-04 1.68083658e-04 1.64138619e-04 2.31510116e-04 0.00000000e+00 8.75362020e-05 4.00934223e-05 -1.93203887e-05] [ 1.18028176e-04 1.32240646e-04 1.25063758e-04 1.97395566e-04 1.74431858e-04 0.00000000e+00 1.02643426e-04 -1.42276876e-05] [ 1.72953616e-04 2.18197252e-04 3.94008151e-04 1.52665016e-04 1.58990340e-04 1.40468474e-04 0.00000000e+00 1.64068726e-04] [ 1.21380063e-03 1.64559446e-04 6.32526717e-05 8.29588462e-05 -3.57388853e-05 -2.21135579e-05 1.80654883e-04 0.00000000e+00]] measureCrosstalk INFO: Errors: [[ nan 9.91449488e-05 9.59764293e-05 9.13887925e-05 8.65858747e-05 9.88380634e-05 1.06215986e-04 5.50728524e-04] [9.51092006e-05 nan 9.34346172e-05 8.84959009e-05 8.87283604e-05 9.10020608e-05 8.01342321e-05 8.08069526e-05] [1.01827194e-04 1.00470643e-04 nan 1.04412786e-04 1.12072987e-04 1.05188803e-04 8.17734108e-05 8.59935826e-05] [9.88750107e-05 9.80467812e-05 9.92097339e-05 nan 1.03731429e-04 5.95550635e-04 7.89797268e-05 8.79871077e-05] [7.20556418e-05 8.66447008e-05 1.05128216e-04 9.71880945e-05 nan 9.30918904e-05 8.16232277e-05 7.48949533e-05] [7.40533360e-05 8.87360584e-05 8.47910414e-05 2.74526799e-04 9.22506442e-05 nan 8.18406988e-05 8.51190489e-05] [9.79577817e-05 1.00221820e-04 9.54559218e-05 9.06347123e-05 1.00276600e-04 1.07225656e-04 nan 1.23933671e-04] [1.95971646e-04 9.59757526e-05 8.57987689e-05 9.65587824e-05 1.04003899e-04 1.05910200e-04 1.08329492e-04 nan]] </pre> </div></div> <p>I ended up using quartz exposures, as that provides a lot of target pixels (the full height of the image, rather than just a few discrete points). I'm not perfectly happy with the result (there are some small residuals remaining), but it does a decent job and this provides a tool to make solid measurements in the future. Some thought needs to go into selecting a particular set of fibers that minimises the overlap between traces and crosstalk for the various amplifiers.</p> <p>This is based on <a href="https://pfspipe.ipmu.jp/jira/browse/PIPE2D-472" title="Strategy for determining traces from non-odd/even high-density fiber data" class="issue-link" data-issue-key="PIPE2D-472"><del>PIPE2D-472</del></a>, so that needs to be reviewed first.</p> <p>Merged to master.</p> Relates PIPE2D-376 Development Rank 0|02qprv:ck Reviewers hassan Sprint 2DDRP-2021 A Story Points 3.0