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LAT Commissioning Receivers (LATCRs)

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Jeff McMahon

U. Chicago and FNAL

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Motivation

  • CMB-S4 must operate such that everything works immediately once we commission
  • Doing this requires testing
    • The performance of the combination of the telescope and receiver must be validated and verified
      • E.g., end-to-end noise, beams, and on-systematics including ground pickup and mitigation of signals from constellations of satellites
      • This enables corrective actions to be taken before the receiver is deployed
        • Software integration, sidelobe issues, scan pattern, etc.
    • The optics tube designs must be verified and validated as a unit, in North America
      • E.g., Noise, scattering, beam effects, bands
      • This enables corrective actions to be taken before deployment

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Requirements

Proposal

  • We need three commissioning cameras (LATCR)
    • One for the SPLAT
    • One for the ChiLATs
    • One for optics tube validation in North America
  • LATCR requirements
    • ≥4 optics tubes per cryostat to enable the test of each band during commissioning
    • FTS, variable load, beam mapper, etc for NA lab tests. Consider adding vibration tester.
    • Design the system to facilitate all tests. Requirements for what should be validated must be agreed upon early.
  • Adapt the LATR design to realize a cryostat that holds ≥4 optics tubes
  • This cryostat should be capable of cooling to operating temperature in ~4 days, and warm in ~2 to ensure rapid turn arounds for testing and debugging
  • Develop test equipment for NA performance verification and validation (See Johanna’s talk after this)

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Heritage and starting points

SO LATR tester (Chicago)

  • Test cryostat for SO LATR tubes
  • Measurements of Beams, efficiency, bands, etc are starting soon
  • https://arxiv.org/abs/2102.02129

Modcam: CCAT commissioning camera (Cornell)

  • Commissioning camera
  • test cryostat for new instrument modules
  • https://arxiv.org/abs/2012.10411

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Next steps for the LATCR

  • Agree to requirements for the testing and commissioning programs
  • Develop the commissioning camera design
  • Develop the testing and calibration infrastructure required by this program