Thermal Kinetic Inductance Detectors for CMB Polarimetry Roger
1,2 O’Brient ,
2 Steinbach ,
1 Minutolo ,
Bryan James Lorenzo Hien Anthony Turner1, Albert Wandui2, Jonas Zmudizinas2 1NASA Jet Propulsion Laboratory, 2California Institute of Technology
Relevance to CMB Stage 4: • • • •
1,2 Bock ,
Collaboration aspires to deploy ~500,000 detectors SQUID multiplexing could do this, but at significant cost and risk KIDs and TKIDs simplify instrument design, reducing risk TKIDs offer calibration and extra design parameters to optimize beyond KIDs
Prototype:
Measured performance:
• • • •
•Noise calibrated with heater •White region is photon limited for 150GHz band and higher at South Pole •Likely limited by amplifier and electronic noise- latest design fixes a coupling inefficiency
Started with dark tests and integrated heaters for stimulation Heaters will provide calibration in future design Five devices on a line with differing leg Gs Schematic:
Advantages of TKIDs over other detectors: • Simple integration- few wire-bonds at cryogenic stages • High multiplexing factors- in principle ~500 • More design parameters than traditional KIDs: • Separate absorber and inductor • Inductor volume • Bolometer leg G • Bolometer island temperature (in addition to Tc and Tbath) • The fundamental noise is G-noise from the legs, which we can control through simple geometry and well calibrated recipes • Drop in compatible with commonly used antenna-coupled bolometer designs • Integrated heaters provide calibration
1 Nguyen ,
• Photo:
•Low frequency noise is common mode •After removal, flat to less than 100mHz •Bolometer G and τ consistent with expectations:
• Most recent versions include integrated ground plane and dielectric for antennas and microstrip feeds.
•τ~5ms (no electrothermal feedback)
Sensitivity Model q
q
Next Designs:
Software Defined Radio Readout:
• 150mm diameter dark (no antennas) wafer with CPW feed, study yield and recipes developed to optimize.
• Schematic of GPU accelerated software radio readout
@xqp @xqp @xqp @T (⌫, T )(T ) S⌘ = = @Popt @Nqp @T @Popt 2Qi G(T )T 2 | x | ⇤ 2 N EP⇤ = • NEP: S2 2 (GT ) 2 2 2 N EP N EPT LS,amp / (GT ) GR / Vsc
Send data to USRP
Upload data in GPU
Download data to RAM
• Detects thermalized phonons instead of directly detecting photons • Responsivity:
Process received data
Get data from USRP
Send data to user API
10Gb Ethernet
To cryostat
Download data to RAM
Generate transmission data
Live plotting
cryostat
Storage
From cryostat
• Demodulated VNA scan:
A/e
ADC units
DAC clock
Signal after cryostat
ik(f1 ,f2 )t2
Detector S21
DAC units
Signal before the cryostat
ADC clock
Contact: Roger O’Brient:
[email protected] Bryan Stenibach:
[email protected] James Bock:
[email protected]
• Modes of operation: • Traditional comb of tones • Chirp faster than resonator ring-down time, listen to ringdown, PPF and FFT.
• Antenna-coupled bolometers • Prototype will contain four pixels, two polarizations each • All fed by common transmission line (red) • Calibration heaters wired in series (blue) • Generalizes to arbitrarily large arrays • Total wire count: 6
