UMICH-2015: Instrumentation I break-out session 1

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Goals: (1) Identify requirements for CMB-S4 detectors and focal plane architectures; (2) Review status of existing technologies with particular attention to assessing positives, negatives with respect to systematic error mitigation; and (3) Identify work that needs to be done in order to complete maturation of candidate technologies, and begin discussion of how we will go about choosing focal plane design.

Please come prepared to describe a given focal plane architecture along the dimensions outlined below, and to debate whether or not these are the right dimensions. Are things missing? If you have a slide to add, please post it on the wiki. If you think of additional questions or topics for debate, please add those as well.



  1. TES Bolometers
  2. HEMT Amplifiers
  3. MKIDs

Array Architecture

  1. beam formation and sidelobes
  2. bandpass definition
  3. polarization selection strategy
  4. polarization modulation strategy

Advantages/Disadvantages, Systematic Mitigation Strategy

  1. sensitivity - photon-noise domination achieved for ground-based loading?
  2. fabrication complexity, yield, uniformity
  3. Scalability to order[500,000] detectors
  4. optical efficiency, cross-talk
  5. Technological readiness level

Required Work or Studies

  1. What is technological readiness?
  2. What are unknowns?
  3. What is timeline for development?

Slides for Discussion

Framing Thoughts on Array Requirements

Adrian Lee: Media:2015.09.22.Adrian.Lee.Detector.Requirements.S4.pdf
Charles Lawrence: Media:Detector_slide_CRL_09-21-2015.pdf

Detector and Array Architectures

Polarization-Sensitive Feed Coupled TES (Ed Wollacl): Media:NASA2015Wollack_CMBpol.pdf
Planar Antenna-Coupled TES (Jamie Bock): Media:S4_ann_arbor_jjb.pdf
Sinuous Antenna TES (Adrian Lee): Media:2015.09.22.Adrian.Lee.Sinuous.small.pdf
MKIDs for CMB (Brad Johnson): Media:2015_CMB-S4_meeting.pdf
MKIDs @ NIST/Stanford (Jason Austermann): Media:CMB-S4_Sept2015_MKID_slide_Austermann.pdf‎
GRIN/GRIM Lenslet Option (Jason Austermann): Media:CMB-S4_Sept2015_GRIN_slide_Austermann.pdf
silicon feedhorn-coupled TES polarimeters (Hannes Hubmayr): Media:Hubmayr_cmbs4_feedhorncoupled.pdf
HEMT noise (Charles Lawrence): Media:S4_HEMT_noise.pdf
HEMT scalability (Charles Lawrence): Media:Hemt_scalability.pdf



Charles: Suggests HEMTs at low-F and bolos at high frequencies overlapping at 120 GHz.

systematic errors: cross correlation between HEMTs and bolos looks at sys errors.

HEMTs don't need as much filtering and loss of signal.

Wollack: feedhorn coupled

best materials to couple the photons. Or else you will need to double the number of photons. Ed is using mono crystal silicon.

advocate of modulation and shielding

no modulator on chip - make it cheap and easy to make it.

Ed and Charles, it's hard to calibrate out effects since the signal is small.

for space in these detectors: some features for particle immunity. largely engineering details.


microstrip wiring to 300 GHz is difficult.

diff pointing is low but still need to de-project

scales well

beam quality is lower but if you had a modulator.

Phil: MKIDs noise and 1/f noise acceptable now at 150 GHz.

inexpensive to build and being done commercially now..


can increase the BW to 5:1

horns have mass but ok for ground.


$100 per module. for geostar 30-100 GHz.

TODO ITEM: calculate array number versus frequency and see how expensive.

defining bands is important....

inventory of systematics, crosstalk, beam formation

optics give low f/#

we've deployed 30,000 TES detectors, so 1 order apart.

then move to entire system.

studying tradeoffs with multichroric vs. single frequency.

what do to with KIDs to test them in the field.

optics give low f/#


Interaction with overall design is important.

We've deployed 30,000 detectors

Need to scale and also includes testing

Systematic errors Is polarization modulation occurring at the array or sky side of array? Affects beam performance requirements (differential pointing, ellipticity, gain, size)

Small telescopes-> simple arrays Large telescopes -> multichroic arrays

KIDs discussion in MUX


calculate array number versus frequency and see how expensive.

defining bands is important....

inventory of systematics, crosstalk, beam formation