detector physics group at the cavendish laboratory click to edit master title style detector and...

Detector Physics Groupat the

Cavendish Laboratory

Click to edit Master title styleDetector and Optical Physics Group


Transition Edge Sensor Bolometers

D. J. Goldie,M. D. Audley, D. M. Glowacka, V. N. Tsaneva, S. Withington.

TES Bolometers: CMB Workshop Cambridge July 2009



DPG activities

•DPG capabilities

•Optical modelling•Electromagnetics•Thermal behaviour•Device modelling •Fabrication (Transition Edge Sensors (TESs), Kinetic Inductance Detectors, SIS tunnel junctions, SQUIDs..•Characterization•Detector packaging

•This talk•TESs for CMB polarization experiments




ClOVER TEAM

•Cambridge – M. D. Audley, B. Barker, M. Brown, M. Crane, D. Glowacka, D. Goldie, K. Grainge, A. Lasenby, H. Stevenson, D. Titterington, V. Tsaneva, S. Withington

•Cardiff – P.A.R Ade, P. G. Calisse, W. Gear, w. Grainger, P. Hargrave, J, House, K. Isaac,, B. Kiernan, P. Mauskopf, S. Parsley, G. Savini, R. V. Sudiwala, C. Tucker, R. Tucker, I. Walker, M. Whitehead, J. Zhang

•Manchester – L. Piccirillo, P. Diamond, A. Galtress, V. Haynes, P. Leahy,

S. Lewis, B. Maffei, L. Martinis, S. Melhuish, G. Pisano, R. Watson,

•Oxford – M. Brock, P. Cabella, P. Ferreira, P. Grimes, B. Johnson, M. Jones, W. Lau, J. Leech, D. O’Dea, C. North, D. Sutton, A. Taylor, G. Yassin

•NIST- K. D. Irwin

•UBC- M. Halpern




Key Features of CLOVER

• Two telescopes measuring polarization of CMB:• LF: 97 GHz• HF: combined 150 and 220 GHz focal plane

LF: 96 horns => 192 finline-coupled detectors at 97 GHz

• Focal Plane: hexagonal array of horns, two polarizations per horn

• Detectors: Bolometers with superconducting transition edge sensors (TES)

• Readout: Time-division SQUID multiplexer (NIST, UBC)

• Sensitivity: limited by unavoidable photon noise (2.2x10-17 W/√Hz)

HF: 192 horns => 192 4-probe OMTs in mixed 150/220 GHz focal plane

• Operating Temperature: 100 mK (active control of bath temperature)




• CLOVER needs high-performance polarimetry

Why Microstrip-coupled TESs?

• TES design can be optimised separately and doesn’t have to change

if the array architecture changes

• Can include planar band-pass filters, phase shifters, modulators etc.

=> simple detector becomes multi-function integrated circuit

• Calibration

• Flexibility: RF absorption is separated from the bolometer




•Finline-coupled detector, uses a rectangular-waveguide to finline to superconducting microstrip transition.

Waveguide probes

Grounding ring

Low frequency Mid- and high frequency

ClOVER TES Detector Designs

•Polarization-sensitive detector, which uses probes suspended on a SiNx membrane in a circular waveguide.




TESs for ClOVER

•Mo-Cu TESs•500 nm SiNx support and thermal isolation•Tc 200 mK•Tbath 100mK




ClOVER Science-Grade Detectors

Tc: 190 mK

Power handling: 11 pW

30 chips per wafer




Slotline coupled to microstrip

•Detail of the slotline-microstrip transition

•Single metalization layer for critical dimensions

•Oxford design




Response of LF Detector to BB Illumination

IV Curves for different black-body temperatures

3

5

7

9

11

13

15

17

19

0 0.2 0.4 0.6 0.8 1 1.2

V (mV)

I (m

A)

34 K

30 K

25 K

20 K

15 K

10 K

5 K

1 K

•Blackbody Illuminator•Two low-pass filters define band•Conical radiator•Heat sunk to 1K stage




Linearity at Fixed Bias




Excess noise reduction

G/4

3G/4

JohnsonG2

•Current noise mainly from Johnson and thermal sources alone.•Little excess noise.

• Dark NEP at 200 mK:1.75x10-17 W/√Hz

with G= 172 pW/K




Effect of Dielectric Loading by Substrate

100% and

89%

efficiency100 μm

225 μm




Focal-Plane Module for ClOVER




LF Detector Module with OMTs

•Could already populate an 8*8 array




ClOVER HF CHANNEL

•150 and 220 GHz channels use probes suspended on SiNx membrane across circular waveguide

•Cardiff rf design

•Power from opposite probes combined onto a single TES




Fully processed wafer with 150 GHz devices

Four-probe OMT for HF instrument




Four-probe OMT for HF instrument




Power Multiplexing

Nb1

Ins1

Nb2

Ins3Nb3




Response of Four-Probe OMT to Illuminator

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 5 10 15 20 25 30

TBB (K)

Pd

etec

ted

(p

W)




Materials Characterization I

•K. Rostem et al. J Low Temp Phys (2008) 151: 76–81

•Johnson noise thermometry•Thermal conductance studies•Crucial for next generation low background TESs




Materials Characterization II

•Heat capacity measurements•Major implications for TES dark noise •D. J. Goldie et al. J. Appl. Phys. 105, 074512 2009




Materials Characterization III

•Lab on a chip 1st generation•Wideband measurements of microstrip losses

•K. Rostem et al. J. Appl. Phys. 105, 084509 2009




Materials Characterization IV

•Lab on a chip 2•Thermal conductance

•How to make low G close-packed arrays?

•Low G TESs for low power applications




Optical Modelling

•Bolometer reception patterns

•Reduced pixel size

•C. N. Thomas, S. Withington




Summary ClOVER TESs

•Highly developed process route for microstrip coupled TESs

•High optical detection efficiency for both finline and probe-coupled designs

•Satisfy ClOVER requirements for dark NEP, power handling and response time

•Packaging-shielding complete

•Integrated with time division MUX




The FUTURE

•Recently kicked-off ESA TRP Cardiff/SRON/Maynooth/RAL•Next generation TESs for space missions •Far-IR TES detectors•Ultra-low noise CMB B-mode detectors

•ClOVER a significant legacya significant opportunity

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