Post on 12-Sep-2021
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Low Temperature Detectors
for Astrophysics
Cryocourse 2011 Philippe Camus
CNRS, Institut Néel, Grenoble
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PLAN
Introduction
LTD overview
Selected applications
What is a good detector ?
It is a device that converts a physical quantity into
an electrical signal…
High efficiency
Sensitivity (high Signal/Noise)
Calibration
Compatible with electronics
Fabrication (arrays)
=> don’t reduce it to the physical principle…
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Why using low temperatures ?
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Photons : mm & sub mm, X-rays (1-10 keV)
Matter : Mass spectrometry, heavy ion, a particles, b particles,…
Astroparticles : Neutrinos, Dark Matter (WIMPs)
LTDs Overview :
Selected topics
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Calorimeter principle
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Phonons
Electrons
Spins
Tunneling states
Quasi-particles
particle
thermal bath
absorber
weak thermal link
thermometer
Calorimeter or Bolometer ?
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C decrease with T !
The absorber depends on the application
Needs a good thermometer
Fundamental thermal noise
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Poissonian statistics
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The energy resolution is given by the readout electronics
Temperature measurement
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A resistive thermometer
needs to dissipate some
power
Look for high sensitivity (A)
Essential to be close to the
fundamental Johnson noise
NTD-Ge / Doped Si / NbSi
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VRH systems
Neutron transumation
doped Germanium
Doped silicum Si:P:B
Amorphous alloys
(excess noise !?) A = -3…-15
Large resistance adjustment (kW-GW)
TES
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Sharp resistance variation at transition
(A = 50…1000)
Strong electro-thermal feedback
(Pj = V2/R)
Voltage – biased
Pure metal (W), bi-layer Mo/Cu, Mo/Au,
Ir/Au, Ti/Au or alloys NbSi
Low impedance (mW)
Needs a detailed understanding
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Agreement on the TES-mirocalorimeter model after several
years (K.Irwin…)
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Metallic Magnetic Calorimeter
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dc SQUID H
Au:Er Au:Yb
Ag:Er
Bi2Te3:Er
PbTe:Er
LaB6:Er
Non dissipative thermometer
Contactless
State of the art
for X-ray energy resolution
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Bolometer version
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Low fluxes => low-g
Low freq. => low temperature
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Kinetic Inductance Detectors
Principle proposed by J.Zmuidsinas (Caltech, 2002)
Measure QP generated in superconducting films
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F0
f
S21 [dB
]
F [GHz]
Light Dark
Superconducting
film
1 2
R(Psky) L(Psky)
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/4 CPW resonator Lumped Element Kinetic Inductance Detector
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0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.501E-22
1E-21
1E-20
1E-19
1E-18
1E-17
1E-16
1E-15
1E-14
1E-13
101
102
103
104
105
106
107
108
109
1010
NE
P
[W
/H
z]
T/Tc
NEP Nqp
[
nse
c]
or
Nq
p
# quasiparticles quasiparticle lifetime
100 nm Al 6 GHz /4 CPW resonator
Looking for the best materials (Al, Ta, TiN, TaN…)
A very active field of research in the next years
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Making Arrays
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Multiplexing techniques : put several signals into a single line ?
Time division
Frequency division
Code division
Amplifier noise
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High Impedance Temporal MUX
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Rb = 10MW
Cint = 1nF
fRC = 16Hz
N = 8
F = 256Hz
Eamp = 1.6nV/Hz 1/2
Low Impedance Temporal MUX
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Nyquist LC filter
BW 20 Hz, MUX 8:1
KIDs frequency multiplexer
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Selected Applications
The neutrino mass
LTD in space : Planck/Herschel mission
and future
Dark matter search by cryogenic
methods
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Neutrino mass
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Mibeta calorimeter
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FWHM +
pile-up ..
Cryogenic detectors in Space :
the Planck / Herschel missions
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Launched in May 2009
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4K
1.6K
0.1K
NTD-Ge sensor, NEP = 10-17 W/Hz1/2 @ 100mK
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ARCHEOPS
MAXIMA BOOMERANG
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End of mission in January 2012
After Planck…
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Mapping the CMB polarization
Information on the inflation phase
Needs an increased number of detectors (52 => 10000)
CORE Concept (ESA) Focal plane at 50 mK
Herschel Detectors
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PACS Instrument 256 pixels arrays (300mK)
Integrated MUX with CMOS
After Herschel
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Low g design for 70 pW, 50mK
SPICA Concept (JAXA)
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Detecttion of WIMPs by the nuclear recoil (energy
deposition) WIMPs energy
WIMP ross section (very low…)
Cryogenic detectors provide best WIMP limit.
Already sensitive to SUSY models
Threshold and resolution ok
Future gains in sensitivity will depend on
improvements on different backgrounds
discrimination : R&D !!
Improve the mass :
EDW-II 40 kg for sw-n 10-8 pb
EURECA 1 ton for sw-n 10-10 pb
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Mesure simultanée
Chaleur @ 17 mK avec
thermomètre Ge/NTD
Ionisation @ qq V/cm avec
electrodes Al
Identification Evt par evt du type de
recul
Q=Eionisation/Erecul
Q=1 pour recul electronique
(radioactivité ambiante)
Q0.3 pour recul nucléaire
(Wimps et neutron)
Center electrode Guard ring
7 cm
m=320g
Fiducial volume(≈ 55%)
Heat
Ionization
guard Ionization
center
Thermometer
(Ge NTD)
Reference electrode
Center electrode
Guard
Electrodes
Ge crystal
discrimination g/n > 99.9% pour Er> 15keV
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Structure : 10 tonnes Blindage Pb : 35 tonnes Blindage PE : 35 tonnes
Pour qq kg de détecteurs…
EURECA 1T
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‘4K’ electronics
‘100K’ electronics
‘300K’ electronics
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Heat is a nice way of detecting particles…
But other “channels” are often used and needed:
charge and light, for instance (ionization, scintillation).
Thermometer
Charge collector
Semiconductor
Light detector
Thermometer
Scintillator
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60 µm hole
Sintered silverCopper box
Vibrating Wires
(5 µm and 13 µm)
Density of quasiparticles measured directly by damping
of micro vibrating wire
ULTIMA detectors (Godfrin et al.)
Conclusion
LTD are essential for high sensitivity
instruments in astrophysics
Wide range of techniques and application
Progress in manufacturing make them
ready for applications in other fields of
science and industry
Needs a low-temperature cryogenics
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References
• Ch. Enss (edt),
Cryogenics Particle Detection,
Springer (2005)
• LTD Conferences (1987-2011)
http://ltdorg.kip.uni-heidelberg.de/
• DRTBT
http://www-ecole-drtbt.grenoble.cnrs.fr/
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