TES Bolometer Array with SQUID readout for Apex
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Transcript of TES Bolometer Array with SQUID readout for Apex
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QUANTENELEKTRONIK
TES Bolometer Array with SQUID readout for Apex
V. Zakosarenko, T. May, R. Stolz, H.-G. Meyer, Institute for Physical High Technology, Jena
E. Kreysa, W. Esch, Max Planck Institute for Radioastronomy, Bonn
The work is supported by the German BMBF under the contract No. 05 AA2PC1/3.
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QUANTENELEKTRONIK
Laboca
Project purpose: Large Bolometer Camera (Laboca) with 300 pixel for sub-millimeter rangefor Atacama Pathfinder Experiment (APEX) on array of 12m-telescopes in Chili , Atacama
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QUANTENELEKTRONIKBolometer Principles
Thermistor = transition edge sensor (TES)
Infrared power Peit T R I
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QUANTENELEKTRONIK
Electro Thermal Feedback
Transition edge sensor with voltage bias
Resi
stance
TemperatureT0
Working point
Tc
Rw
• The transition temperature Tc is slightly above the bath
temperature T0 .
• Due to the power dissipation PBIAS = VBIAS
2/RW = (TC-T0)/Gthe thermistor warms up to TC .
•The working point is stable: T R PBIAS T
Electro-Thermal Feedback (ETF)
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QUANTENELEKTRONIKSignal Response
)1(
1
)1(
1
iL
L
VP
IS
BIASi
)1()(
0iGT
PL BIAS
BIASi VS
1
)(log
)(log
Td
Rd
L>>1 ; << 1
Current response
Open loop gain Sharpness of the transition
10
L
Effective time constant
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QUANTENELEKTRONIKTES Bilayer
Proximity bilayer with TC~ 0.5K
Mo (60 nm)
Au-Pd (8 nm)
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QUANTENELEKTRONIK7-pixel Array
7-pixel array chip mounted in the Cu holder plate (1,5 cm x 1,5 cm)
Si waferSi N membrane ~1µm thick with Ti absorber film on the back side
Au ring
Nb wiring
Thermistor (TES)
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QUANTENELEKTRONIKSQUID current sensors
SQUID holder with 4 mounted current sensorsµ-metal shield
SQUID current sensor chip
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QUANTENELEKTRONIKMeasuring System
SQUID holder with 4 current sensors. The µ-metal shield is not installed.
Superconducting bolometer chamber (Al) with7-pixel horn array
3He stage with sorption pump (300mK)
1.5K pot of 4He cryostat
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QUANTENELEKTRONIKFirst Light
30m - radiotelescope of IRAM on Pico Veleta in Spain, Sierra Nevada.
Cryostat with TES bolometers in telescope cabin
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QUANTENELEKTRONIKFirst Results
0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3
1,0
1,5
2,0
RBIAS
= 90 mOhmChannel No.
1 2 3
Bol
omet
er S
igna
l, µA
Bias Current, mA
The whole system worked stable in the cabin.
But: bad weather (snow)
0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,360
70
80
90
100
110
120
RBIAS
= 90 mOhm
Channel No. 1 2 3
P, p
W
IBIAS
, mA
Response of the bolometers on the change of black body temperature (77K 300K)
Power calculated as IBIAS x RBIAS x Si
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QUANTENELEKTRONIKNext Step
LABOCA: Large Bolometer Camera: 300 pixel on 4 inch wafer
Laboca should be ready in the middle of the year 2005!
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QUANTENELEKTRONIKMultiplexing
Two possibility:
a)parallel readout 300 current sensors each in separate packaging, ~1250
wires to room temperature electronics, 300 FLL electronics. low risk (familiar way) mechanical complexity, thermal last, too expensive !
b) multiplexing 300 SQUID integrated on the wafer with bolometers, ~30
SQUID amplifier in separate packaging, ~200 wires to room temperature, 30 FLL electronics, and digital controller . less expensive new development (challenge !)
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QUANTENELEKTRONIKTime Domain MUX
Amplifier SQUID
TES
RBIAS
TES
RBIAS
TES
RBIAS
TES
RBIAS
Digital control bias switches
FLL electronics,
Sinch
TES bias
Active SQUID
Out
Feedback 1.5K 0.3K 300K
RESET
Bias
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QUANTENELEKTRONIKTest of the MUX Electronics
6 separate SQUIDs, SQUID-array as amplifier, the simplest FLL with two operational amplifiers
Sampling frequency 5 kHz Sampling frequency 100 kHz
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QUANTENELEKTRONIKIntegrated Bolometer
First samples are fabricated. Tests in the laboratory will be performed in the next weeks.
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QUANTENELEKTRONIKConclusions
•7 pixel TES bolometer array with SQUID readout shows stable operation in real environment in telescope cabin.
• 7 pixel TES bolometer array with integrated SQUID is ready for test.
•Time domain multiplexing operates. Optimization of bandwidth and noise figure is in progress.
•Great challenge to perform the proposed schedule.