Reference Instrument (DSR final)
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Band center in GHzNotes
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Latest update: 4/22/2019.
20273993145225278
Please email John Ruhl and Zeesh Ahmed with additions/updates/corrections
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Property
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Beam fwhm (arcminutes)10.07.45.12.21.41.00.9https://cmb-s4.org/wiki/images/Lat-noise-190311.pdf
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Fractional bandwidth (nu_h - nu_l)/nu_center0.250.220.460.380.280.270.16
20GHz: https://cmb-s4.org/wiki/index.php/File:Band_def_v1.99.png . Others, Charlie Hill memo, https://drive.google.com/file/d/0B6iVmnB52dnCVkxwNHJtRWR1R3dXR3J1T0FOajlkUHhGM2lj/view?usp=sharing
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Lower band edge 17.524.030.075.5125.0195.0255.5
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Upper band edge22.530.048.0110.5165.0255.0300.5
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optical efficiency (CMB to detector)0.150.120.210.110.180.260.3Charlie Hill email to JR, 7/23/2019.
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Poptical (pW) (observing mode)0.240.21.11.182.58.610.1
S4_SO_V3_goalSensitivity_assumptions_20190507_3.pdf (Atacama; PWV=1mm, el=50deg)
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Psat (pW)0.720.63.33.547.525.830.3"
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Poptical looking into 400K test (w/ LAT optical efficiency)
4.13.920.921.239.886.274.6pW
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Poptical looking into 400K test (w/ 75% optical efficiency)
212575145166249186pW (in a test cryostat)
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Detector typeTES: AlMn (100mK) + series Al (160mK)DSR 4.5.1
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Detector base temperature100 mK
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Detector TES transition temperature (AlMn)160 mK DSR 4.5.1
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Dark NEP
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NET_CMB CDT (scaling from BICEP, ACT, SPT)2141772242383207471281 (this is CDT, needs update) single detector, uK_cmb*s^1/2
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NET_CMB SOv3 goal (calculation)3253872473053858542077S4_SO_V3_goalSensitivity_assumptions_20190507_3.pdf
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NET correlation factor 0.30.050.250.020.10.02
Need reference. (NET_array = NET_detector/[(N_detector)^.5 (1 - correlation_factor)^.5]
) may be reduced in NEQ/U for arrays with alternating Q & U detectors (but not NET)
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Number of detectors per optics tube1603203203460346037443744DSR Table 4-13
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Number of hex wafers per optics tube33331 hex per wafer
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Number of pixels per hex wafer2040432.5468added 6/26/2020, for convenience
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Number of detectors per hex wafer408080865865936936That this is an odd number at 93 and 145 GHz is... disturbing.
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Number of 3-rhomboid wafers per optics tube11113 rhomboids per wafer and 3 per focal plane
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Number of detectors per 3-rhomboid wafer408080865865936936(per wafer, divide by 3 to get the number per rhomboid)
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Number of hex wafers +3*rhomboids/optics tube 4444228
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Readout
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MUX typeTDM
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MUX factor64same as used in AdvACT HF array
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Mux modules per optics tube310109117
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Wide field survey (Chile) LATs
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Number of optics tubes in one LAT02125
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Number of wafers in one LAT084820Matches DSR Table 4.22, one modification76
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Number of detectors in one LAT06406404152041520187201872060880
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Total number of detectors per LAT121760
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Mux modules per LAT0201308585
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Data sampling rate (in Hz, 4 bytes/sample)400
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Data rate per LAT (Gibps @ 4 bytes/sample) 1.45Gibi = 2^30
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Data compression0.35
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Data rate per LAT (Gibps, compressed)0.51Gibi = 2^30
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Data rate per LAT (TebiBytes/day)5.36Tebi = 2^40
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De-lensing survey (Pole) LAT
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Number of optics tubes in one LAT12124
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Number of wafers in one LAT484816Matches DSR Table 4.2276
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Number of detectors in one LAT1606406404152041520149761497657296
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Total number of detectors per LAT114432
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Mux modules per LAT3201308468
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Data sampling rate (in Hz, 4 bytes/sample)400
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Data rate per LAT (Gbps @ 4 bytes/sample) 1.36
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Data compression 0.35
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Data rate per LAT (compressed) 0.481.36
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Data rate per LAT (TBytes/day, compressed)5.0414.39
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LAT totals (2xChile + 1xPole)
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Wafers required42414456
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Total wafers228
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Chile (2 LATs) detector count01280128083040830403744037440
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Detector count160192019201245601245605241652416
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Total detectors357952511184
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Optics
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Primary mirror type - large apertureSegmented
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optics tubes per telescope - large apertureSingle cryostat with 19 optics tubes
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Lens materialSilicon, with diameter < 46cm
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Lens temperatures4.5K, 1.2K, 1.2K
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Lens AR coat technologyDiced silicon multi-layer AR coating
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f/# at focal plane2.04from Gallardo's calculations for SO ID11 design
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Horn typeSmooth wall spline profile
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Horn diameter (mm)2618.35.34from Charlie Hill memo. 20GHz from Niemack.
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Spillover on cold stop0.720.510.750.570.350.2DSR Table 4-8. (these are loss numbers on stop)
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Cold stop temperature1 K
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Window0.5 inch thick UHMWPEDSR Table 4-8
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300K filterIRB (27u)DSR Table 4-16 and 4-8
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80K filtersIRB (40u) + Alumina (2mm thick)LPE = "low pass edge"
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40K filterIRB (300u)IRB = "Infrared blocker, metal mesh"
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4K filtersIRB(660u) + LPE(800u)LPE cutoffs are for 90/150 optics tubes, still need to spec for others.
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1K filterLPE (1470u)
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100 mK filterLPE (1610u)
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Polarization modulationDetector differencing
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Cryogenics (per LAT receiver)
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FPU cooling technologyLD400 Dilution (25mW at 1K, 400uW at 100mK)DSR Table 4-14
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Pulse tube #1Cryomech PT90 (80K, 90W) - quantity = 2DSR Table 4-14
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Pulse tube #2Cryomech PT420 (40K, 55W + 4K, 2W) - quantity = 2DSR Table 4-14
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Telescope scan rate60arcminutes per second on sky (DSR table 4-3)
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FWHM beams per second6.08.111.827.342.960.066.7
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Three times FWHM beams/sec18.024.335.381.8128.6180.0200.0sample rate estimate
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Signal bandwidth (approx)9.012.217.640.964.390.0100.0Hz
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