Cryogenic Particle Detectors Instrumentation Frontier Community Meeting (CPAD) Argonne National Laboratory - Jan 9-11, 2013 Blas Cabrera - Spokesperson SuperCDMS Physics Department Stanford University (KIPAC) and SLAC National Accelerator Center (KIPAC) References: LTD13 (2009) - SLAC http:/ /ltd-13.stanford.edu LTD14 (2011) - Heidelberg http:/ /ltd-14.uni-hd.de LTD15 (2013) - Caltech June 24-28, 2013 1
TES sensors invented by DOE HEP program Original motivation was search for Dark Matter funded by DOE HEP at Stanford + NIST SQUIDs Breakthourgh in 1995 when Kent Irwin suggested voltage bias negative feedback Rapidly implemented in CDMS Dark Matter Rapidly implemented in x-ray astrophysics and materials studies at NIST, Goddard and beyond Implemented in CMB by Adrian Lee in 1996 Implemented in IR-optical-UV sensors in 1998 DOE HEP should take credit for these spin offs CPDA - Cryogenic Particles Detectors Page 2 Blas Cabrera - Stanford University
Original Motivation: Neutrinos & Dark Matter ! - wanted better resolution for large mass ! - now for CMB & IR-Optical-Xray ! - for Cosmic Frontier & Intensity Frontier Thermal detectors with NTD Ge sensors (T) Thermal sensors with doped semiconductors (T) Superconducting Tunnel Junctions (E) Superconducting Transition Edge Sensors (T) Superconducting Kinetic Inductance Devices (E) CPDA - Cryogenic Particles Detectors Page 3 Blas Cabrera - Stanford University
WIMP Search Sensitivity past future x10 5 yrs courtesy of Vuk Mandic CPDA - Cryogenic Particles Detectors Page 4 Blas Cabrera - Stanford University
Discrimination strategies ~10% ~ % 1 0 % 0 1 CPDA - Cryogenic Particles Detectors Page 5 Blas Cabrera - Stanford University
Intrinsic Resolution Phonon and Ions (CDMS, EDELWEISS) Scintillation and Ions/Phonons (XENON, CRESST) Quanta E 0 % E quanta N e /keV N N /keV Noise amp Δ E e-FWHM Δ E N-FWHM Phonons 100% 1 meV 1000000 1000000 0.1 keV 0.1 keV 0.1 keV Ions 10% 1 eV 300 100 1 keV 1 keV 3 keV Photons 1% 10 eV 10 1 0.01 keV 1 keV 10 keV CPDA - Cryogenic Particles Detectors Page 6 Blas Cabrera - Stanford University
NaI -> HPGe -> µcalorimeters Cryogenic Sensors For High-precision Safeguards Measurements weblink CPDA - Cryogenic Particles Detectors Page 7 Blas Cabrera - Stanford University
Scope of Cryogenic Detectors Sub-Kelvin Sensor types Transition Edge Sensors (T) Kinetic Inductance Detectors (E) Metallic Magnetic Calorimeters (T) Novel detection techniques Technologies Micro-fabrication with superconducting materials Cryogenics using dilution refrigerators and ADRs Multiplexing, SQUIDs, readout, & data analysis Particle absorbers & antennas: physics & design considerations CPDA - Cryogenic Particles Detectors Page 8 Blas Cabrera - Stanford University
Large TES arrays progressing 1,280-pixel SQUID TDM multiplexer for the SCUBA-2 weblink MUX chip has 32 columns each with 40 multiplexed SQUIDs 50 X 50 mm 2 CPDA - Cryogenic Particles Detectors Page 9 Blas Cabrera - Stanford University
Detectors and Physics Detector Physics Insulators - Debye heat capacity ~ T 3 at low temperature Conductors - Fermi liquid theory ~ T at low temperature Semiconductors - electrons & holes ~ 1eV excitation Superconductors - quasiparticles ~ 1meV excitation Magnetism - paramagnetism and diamagnetism Science applications Neutrino mass experiments (IF) Dark matter searches (CF) Alpha & beta spectroscopy, mass spectroscopy, heavy ions, and neutrons X-ray & gamma spectroscopy in atomic, nuclear, astrophysics & other fields UV-optical-IR single photon detection Bolometers in mm / sub-mm wave for astrophysics, THz applications (CF) CPDA - Cryogenic Particles Detectors Page 10 Blas Cabrera - Stanford University
Calorimeter Principle particle Thermal relaxation time: thermometer Thermal conductance t absorber weak thermal link : phonons electrons spins thermal bath tunneling states quasi particles CPDA - Cryogenic Particles Detectors Page 11 Blas Cabrera - Stanford University
Semiconducting Thermistors R T Si – ion-implanted (P,B) Ge NTD ( Neutron-Transmutation-Doped) High impedance device particle I bias Thermistor + JFET - 100 K CPDA - Cryogenic Particles Detectors Page 12 Blas Cabrera - Stanford University
Superconducting Transition Edge Sensor (TES) R self regulated working point T Materials Mo/Cu Electro-thermal feedback K. D. Irwin, Appl. Phys. Lett. 66 , 1945 (1995) Ir/Au V W X-ray heat input: TES R TES goes up shunt I joule heating decreases fast response time SQUID t CPDA - Cryogenic Particles Detectors Page 13 Blas Cabrera - Stanford University
Metallic Magnetic Calorimeter (MMC) M H dc SQUID T Au:Er Au:Yb Ag:Er Bi 2 Te 3 :Er main differences to resistive calorimeters: PbTe:Er non-contact readout no dissipation due to readout current LaB 6 :Er CPDA - Cryogenic Particles Detectors Page 14 Blas Cabrera - Stanford University
So what is intrinsic resolution for thermal detectors ? Heat capacity C at temperature T has energy CT The average energy per carrier ~ kT So there are N ~ CT / kT carriers ( ) rms kT So statistical thermal noise Δ E N = kT 2 C But we can detect smaller signal as shown CPDA - Cryogenic Particles Detectors Page 15 Blas Cabrera - Stanford University
Signal and Noise Energy fluctuation is not energy resolution 1 2 ⎛ 2 π f c ⎞ G Δ E = ✓ ◆ p f c = k B T 2 C ; ⎜ ⎟ ⎝ Δ f ⎠ 2 π C f 2 C McCammon CPDA - Cryogenic Particles Detectors Page 16 Blas Cabrera - Stanford University
Signal & Noise But finite thermalization time and amp noise Δ f so limited 1 2 ⎛ 2 π f c ⎞ G p Δ E = f c = k B T 2 C ; ⎜ ⎟ ⎝ Δ f ⎠ 2 π C CPDA - Cryogenic Particles Detectors Page 17 Blas Cabrera - Stanford University
Many ways to measure temperature (K α 1 / K α 2 for 55 Fe at 6 keV) Transition Edge Sensors (TES) Doped semiconductors - Si and NTD Ge Doped paramagnetism - MMC ( ) 1 4 ⎛ ⎞ 8 τ 0 1 4 k B T 2 C 4 ( ) rms = k B T 2 C 40 ( ) rms = ( ) rms = Δ E Δ E Δ E k B T 2 C ⎜ ⎟ α τ 1 ⎝ ⎠ α CPDA - Cryogenic Particles Detectors Page 18 Blas Cabrera - Stanford University
Non-equilibrium versus Equilibrium Detectors Non-equilibrium detectors have an energy gap which is much larger than kT and allows long-lived excitations which we count. photons from scintillator ( ~ 2% E total ) - phototubes to count photons e-h in a semiconductor ( ~ 30% E total ) - measure total charge quasiparticle (e’ s) in superconductor ( ~ 40% E total ) - measure STJ, KID or TES Equilibrium detectors are weakly coupled to thermal bath so thermal equilibrium is reached ( ) T T D ( ) C V N k 12 π 4 5 3 Insulators with Debye heat capacity Conductors with Fermi heat capacity C V = γ T + α T 3 electrons phonons CPDA - Cryogenic Particles Detectors Page 19 Blas Cabrera - Stanford University
Radiation interacting with Matter, e.g. Si Electron energy loss processes: 10 4 Ashley Si Stopping Power (eV/µm) For E K > 10 eV 10 2 loss e-e collisions Bethe-Bloch For E gap < E K < 10 eV 10 0 loss through e-h pair Vavilov production optical phonons 0 Z axis Depth (µm) For E opt < E K < E gap 10 -2 Si 60 keV 60 keV photon 20 photon optical phonon loss acoustic recoil 40 For E s < E K < E opt phonons 10 -4 electron recoil electron acoustic phonon loss 60 -20 0 20 -20 0 20 For E K < E s no loss, but X axis (µm) Y axis (µm) 10 -6 in E-field continual 10 -5 10 -3 10 -1 10 1 10 3 10 5 10 7 acoustic phonon Electron Energy (eV) emission with v drift CPDA - Cryogenic Particles Detectors Page 20 Blas Cabrera - Stanford University
Semiconductor diodes Along track of primary electron cloud of e-h some recombine close to track and are lost the rest separate in the E-field and move to opposite electrodes Excellent x-ray and gamma spectrometers Si diodes operate at 300K (gap 1.2 eV) Ge diodes operate at 77K (gap 0.7 eV) Energy resolution given by counting statistics N = E ε ε Si = 3.7 eV Number of e-h pairs but where N ≠ E E gap ε Ge = 3.0 eV and ( ) rms = ( ) rms ≠ ε Δ E ε F E Δ E N = ε E Also find but better ( ) rms = F ≈ 0.1 Δ E ε F E < E gap E < ε E where the Fano factor thus ( ) FWHM = 120 eV @ 6 keV Δ E Obtain for Si diodes CPDA - Cryogenic Particles Detectors Page 21 Blas Cabrera - Stanford University
Fano factor ‘crazy carpentry’ F = Var corr /Var Poisson Mean = 746.81; σ corr = 6.00; σ Poisson = 27.33; Fano = 0.048; 80 F always < 1 due to correlations 70 forced by energy 60 conservation. 50 Number of Events Simple example 40 has one type of excitations phonons excitation and 30 equal probability 20 Roosbroeck PR139, A1702 (1965) for any energy 10 partition at each 0 step in cascade. 0 100 200 300 400 500 600 700 800 900 1000 Number of Excitations CPDA - Cryogenic Particles Detectors Page 22 Blas Cabrera - Stanford University
Superconducting Tunnel Junction (STJ) S1 I S2 V 2 Δ thermal background non-thermal – fast detector specially suited for low-energy photons CPDA - Cryogenic Particles Detectors Page 23 Blas Cabrera - Stanford University
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