Polarization Angle Calibrationby the Wiregrid rotation

Osamu Tajima (KEK)Presented by Hogan Nguyen (FNAL)

Osamu’s Idea to Optimize All Modules Simultaneously in a Compact Footprint

The first sparse grid to showproof-of-principle

The current grid: -motorized -no position encoding (sorry) -protection cover not shown

Sparse Wiregrid on the Deck !

Q1 U1 U2 Q2

Fitting PDFf(t; A0, A1, A2, w, d1, d2) = A0 + A1 cos(wt – d1) + A2 cos(2wt – d2)

d2 polarization angleA2 demod gain (* w was treated as common fixed parameter for all the horns,

its value is obtained from central horn fitting)

Wiregrid was rotated counter clockwise (look sky from the module)

Relative Angles

(degree)

00 64.60 +/- 0.22 +/- 2.75 +/- ? 108.25 +/- 0.23 +/- 2.75 +/- ? 17.77 +/- 0.23 +/- 2.75 +/- ? -32.67 +/- 0.24 +/- 2.75 +/- ?01 80.67 +/- 0.23 +/- 2.75 +/- ? 125.42 +/- 0.25 +/- 2.75 +/- ? 36.07 +/- 0.25 +/- 2.75 +/- ? -14.41 +/- 0.23 +/- 2.75 +/- ?02 78.37 +/- 0.27 +/- 2.75 +/- ? 118.28 +/- 0.27 +/- 2.75 +/- ? 28.10 +/- 0.26 +/- 2.75 +/- ? -15.24 +/- 0.23 +/- 2.75 +/- ?03 71.87 +/- 0.24 +/- 2.75 +/- ? 114.86 +/- 0.26 +/- 2.75 +/- ? 23.90 +/- 0.25 +/- 2.75 +/- ? -23.72 +/- 0.23 +/- 2.75 +/- ?04 61.87 +/- 0.26 +/- 2.75 +/- ? 106.70 +/- 0.26 +/- 2.75 +/- ? 17.00 +/- 0.27 +/- 2.75 +/- ? -35.70 +/- 0.25 +/- 2.75 +/- ?05 70.40 +/- 0.27 +/- 2.75 +/- ? 112.57 +/- 0.27 +/- 2.75 +/- ? 24.54 +/- 0.26 +/- 2.75 +/- ? -25.59 +/- 0.27 +/- 2.75 +/- ?06 69.50 +/- 0.26 +/- 2.75 +/- ? 112.29 +/- 0.25 +/- 2.75 +/- ? 22.01 +/- 0.24 +/- 2.75 +/- ? -28.53 +/- 0.27 +/- 2.75 +/- ?07 59.27 +/- 0.24 +/- 2.75 +/- ? 106.16 +/- 0.26 +/- 2.75 +/- ? 16.52 +/- 0.26 +/- 2.75 +/- ? -35.05 +/- 0.26 +/- 2.75 +/- ?08 68.80 +/- 0.27 +/- 2.75 +/- ? 112.66 +/- 0.27 +/- 2.75 +/- ? ------ +/- ------ +/- ----- +/- -28.03 +/- 0.27 +/- 2.75 +/- ?09 75.65 +/- 0.24 +/- 2.75 +/- ? 118.06 +/- 0.25 +/- 2.75 +/- ? 25.85 +/- 0.25 +/- 2.75 +/- ? -22.50 +/- 0.26 +/- 2.75 +/- ?10 66.97 +/- 0.26 +/- 2.75 +/- ? 109.04 +/- 0.28 +/- 2.75 +/- ? 20.36 +/- 0.27 +/- 2.75 +/- ? -30.00 +/- 0.27 +/- 2.75 +/- ?11 68.23 +/- 0.25 +/- 2.75 +/- ? 112.69 +/- 0.26 +/- 2.75 +/- ? 24.92 +/- 0.26 +/- 2.75 +/- ? -27.25 +/- 0.23 +/- 2.75 +/- ?12 69.70 +/- 0.27 +/- 2.75 +/- ? 113.20 +/- 0.25 +/- 2.75 +/- ? 23.87 +/- 0.25 +/- 2.75 +/- ? -25.81 +/- 0.28 +/- 2.75 +/- ?13 54.66 +/- 0.27 +/- 2.75 +/- ? 97.83 +/- 0.27 +/- 2.75 +/- ? 8.98 +/- 0.26 +/- 2.75 +/- ? -42.24 +/- 0.26 +/- 2.75 +/- ?14 63.47 +/- 0.25 +/- 2.75 +/- ? 108.16 +/- 0.25 +/- 2.75 +/- ? 16.24 +/- 0.25 +/- 2.75 +/- ? -32.22 +/- 0.23 +/- 2.75 +/- ?15 55.24 +/- 0.21 +/- 2.75 +/- ? 110.73 +/- 0.25 +/- 2.75 +/- ? -3.13 +/- 0.22 +/- 2.75 +/- ? -38.93 +/- 0.22 +/- 2.75 +/- ?

Look sky from moduleSame definition as qpoint:array_061509.txt

Q1 U1 U2 Q2

stat. error syst. absolute angle (1/4 bolts pitch on the cryostat, conservatively)

Other syst. errors (possible bias, TP leakage, analysis methods etc.)

0 deg.

90 deg.

Comparison with Other Calibrations

Wiregrid Moon

Wiregrid TauA

Moon TauA

Syst. diff. in Q1 & Q2

Syst. diff. in Q1 & Q2

2-3 deg. Diff.in all diodes ?

Comparison with Other Calibrations (cont.)

Wiregrid Moon

Wiregrid TauA

Moon TauA

Syst. diff. in Q1 & Q2

Syst. diff. in Q1 & Q2

2-3 deg. Diff.in all diodes ?

Relative Demod Amplitude

RQ_0000 Q1 0.623 0.001 U1 0.758 0.002 U2 0.696 0.002 Q2 0.505 0.001 RQ_0001 Q1 0.615 0.002 U1 0.913 0.003 U2 0.538 0.002 Q2 0.679 0.002 RQ_0002 Q1 0.550 0.002 U1 0.641 0.002 U2 0.455 0.001 Q2 0.468 0.001 RQ_0003 Q1 0.673 0.002 U1 0.794 0.003 U2 0.818 0.003 Q2 0.422 0.001 RQ_0004 Q1 0.693 0.002 U1 0.807 0.003 U2 0.675 0.002 Q2 0.594 0.002 RQ_0005 Q1 0.795 0.002 U1 0.500 0.001 U2 0.860 0.002 Q2 0.553 0.001 RQ_0006 Q1 0.557 0.001 U1 0.858 0.002 U2 0.868 0.002 Q2 0.463 0.001 RQ_0007 Q1 0.707 0.002 U1 0.917 0.003 U2 0.645 0.002 Q2 0.704 0.002 RQ_0008 Q1 0.868 0.002 U1 0.999 0.003 U2 0.000 0.000 Q2 0.506 0.001 RQ_0009 Q1 1.000 0.002 U1 0.961 0.002 U2 0.908 0.003 Q2 0.806 0.002 RQ_0010 Q1 0.695 0.002 U1 1.022 0.003 U2 0.924 0.002 Q2 0.558 0.001 RQ_0011 Q1 0.726 0.002 U1 0.715 0.002 U2 0.527 0.001 Q2 0.518 0.001 RQ_0012 Q1 0.710 0.002 U1 0.957 0.002 U2 0.814 0.002 Q2 0.513 0.001 RQ_0013 Q1 0.730 0.002 U1 0.982 0.003 U2 0.837 0.002 Q2 0.655 0.002 RQ_0014 Q1 0.885 0.002 U1 0.896 0.003 U2 0.600 0.002 Q2 0.721 0.001 RQ_0015 Q1 0.827 0.002 U1 0.812 0.003 U2 1.058 0.002 Q2 0.574 0.002

Possible systematic error has not been estimated, yet

Ratio of Relative Demod Amplitude to Relative gain obtained from skydips (normalized to center horn Q1)

Q1 U1 U2 Q2

Q1 U1 U2 Q2

ratio ratio ratio ratio

deg.

deg.

Further Investigations are necessary to have conclusion• Most of them are lower than 1 while skydip uncertainty ~10% Demod TP differences ? TauA/skydip seems to have same tendency How about Moon demod/TP ?• Outer radius ratio seems to be small !? Wiregrid signal is not uniform on the array ? Difference of solid angles from wire to ground screen, or other reason ?

All Diodes average

Summary• We obtained Polarization angle and relative demod

gain (signal height) by the sparse wiregrid calibration• Polarization Angle

– Can be measured with less than 3 deg. accuracy while we have not finished all syst. error study

– Wiregrid Moon : Several deg. diff for Q1 and Q2– Wiregrid TauA : consistent while 2-3 deg. offsets

• Relative Demod Gain– Cross checks with other calibrations are important

Possible Syst. Error Sources• Due to the protection UHMW-PE cover, its rotation effect is

visible in total power clearlyIts systematic effect have to be estimatedFitting can be improved, too (e.g. leakage is taken into account)

• Wiregrid polarization signal is obtained from the reflection from all directions. However, top direction is sky temp.(10K) while both sides and bottom are 300K. It might make systematic for amplitude and pol. angle. These possible bias have to be estimated.

• Contribution from 300K depends on the focal plane position, so magnitude of polarization signal may depend on the position within the array

Following plots are Demod (w/ fitting curves) and TP

Demod

Total Power