Microwave Kinetic Inductance Detectors

for X-ray Science

Antonino Miceli FNAL Research Techniques Seminar

April 24, 2012

Outline Why Superconducting Detectors?

– Detector Requirements– Applications

Overview of MKIDs MKID activities at Argonne MKID resonator readout

Acknowledgements Tom Cecil (XSD Staff) Orlando Quaranta (Post-doc) Lisa Gades (XSD Staff) Outside Collaborators:

– Professor Ben Mazin (UCSB)– MSD/UChicago TES Team (Novosad et al)– CNM Cleanroom Staff

Superconductors Detectors for X-ray Detector R&D

Energy dispersive semiconductor detectors have almost reached their theoretical limits– e.g., Silicon Drift Diodes have energy resolution ~ 150 eV at 6 keV

Limited R&D on spectroscopic detectors– Only effort is Silicon array detector of Peter Siddons (BNL) and Chris

Ryan (Australia)• Using silicon arrays to achieve large collection solid angles for

fluorescence experiments.

Leverages local facilities and existing projects.– ANL’s Center for Nanoscale Materials for device fabrication– Many groups with thin film deposition experience– Superconducting Transition Edge Sensors for UChicago’s SPTpol

• ANL’s Material Science Division

Detector Requirements

Solid angle coverage– Pixel area and sample-detector distance

Count-rate– Need lots of pixels (i.e. multiplexing) if you going to deal

with superconducting detectors, which tend to be slow Peak-to-background ratio

– Maximize charge collection – Minimum of 1000:1 – Limits overall sensitivity

Energy resolution– Depends on applications (1-50eV at 6 keV)

Applications for superconducting x-ray detectors?

X-ray Inelastic Scattering– Access wide range of excitations.– Superconducting detectors allows

broadband and efficient measurement compared to crystal analyzers (i.e., wavelength dispersive spectrographs).

X-ray Fluorescence – Fluorescence line overlap in complex

biological samples– Fluorescence Tomography

• Needs pixelated energy-dispersive detectors

White-Beam Diffraction (ED-XRD)– Versus angle-dispersive diffraction

• Using monochromatic incoming beam and area detector

– Complex sample environments (e.g., high-pressure cells)

Competing with x-ray spectrographs (like astronomers…)

Quasiparticle detectors

Use small Superconducting Energy Gap Break Cooper Pairs Use Cooper Pairs as detection mechanism (like electron hole pairs

in a semiconductor)

Cooper Pair

Semiconductor Energy Gap: ≈ 1 eVSuperconductor Energy Gap: ≈ 1 meV

How to measure change in quasiparticle number?

Microwave Kinetic Inductance Detectors Quasiparticle generated by x-ray causes an

inductance increase (i.e., “kinetic inductance”)– Measure inductance change in a LC resonating

circuit

Multiplexing: Lithographically vary geometric inductance/resonant frequency…

DL s

DR s

Observables….

1024 pixels demonstrated in 2011 People are contemplating 10k pixels now

• Limited by room temperature electronics

What has been shown already for x-rays?

62eV

Mazin et al 2006

MaterialAtomic

Number Z

Transition Temperature

Theoretical Energy Resolution at 6 keV

Attenuation Length at 6 keV

Lead 82 7.2 Kelvin 3.53 eV 1.86 mmTantalum 73 4.5 Kelvin 2.79 eV 1.79 mm

Tin 50 3.7 Kelvin 2.53 eV 2.60 mmIndium 49 3.4 Kelvin 2.43 eV 2.77 mm

Rhenium 75 1.7 Kelvin 1.72 eV 1.31 mmMolybdenum 42 .92 Kelvin 1.26 eV 2.94 mm

Osmium 76 .66 Kelvin 1.07 eV 1.18 mm

MKIDs @ Argonne for synchrotrons The goal is moderate energy resolution (< 20eV) with good count rate

capabilities (> 200kcps) (i.e., ~200-500 pixels) Leverages Argonne’s micro/nano-fab facilities (CNM) and superconductivity

expertise (MSD); Astronomical TES bolometer program(MSD & UChicago). Three Main Aspects:

1. Device Fabrication Fabrication is completely in-house Relatively “simple”… patterning of metal (deposition, photolithography, etching)

Film quality is very important! Initially aim a simple device, then progress to more complex designs (e.g., membrane-

suspended) Dedicated deposition system on order.

2. Cryogenics and Device Characterization We are mostly limited by how fast we can test devices.

3. Readout electronics Initially the analog readout for characterization. Digital FPGA-based array readout in the near future.

Anatomy of an MKID – Our work (one design)

1 pixel

15 pixels2 mm

First x-ray pulses at APS in January 2012!

Fe-55 and Cd-109

1 micron WSi2 (XSD)

Inductor/Absorber

Capacitor

Detector Testing

Be window (x-ray transparent)

Cryostat

Microwave Electronics

Cryostat Cryogen Free ADR T = 100 mK for 2 days 3-4 hour recycle time

Microwave Electronics Vector Network Analyzer IQ mixing

Control & Data Analysis Software

Inside the cryostat…

LNA Stainless Steelcoax

NbTi (superconducting)coax

Attenuator

Sample box@ 60 mK

m-metal shield

0.5K stage

60 K stage

4 K stage

VNA

Measure the transmission through the device (S21)– Wide range of frequency: 0.3 - 20 GHz– Easily identify resonators:

• Resonance frequencies, Quality Factors (Qr, Qc, Qi)

– Cannot measure pulses nor noise

Signal Generators

IQ MixerVariableattenuator

IQ mixing (Pulses and Noise)– Homodyne mixing– Demodulate to 0 Hz (DC) and monitor for

changes in Re(S21) and Im(S21) (i.e., I & Q)– Amplitude = sqrt(I2 + Q2)– Phase= arctan(Q/I)

IQ Mixer

IQ Fitting and parameter extraction

Frequency (GHz)

Real (S21)

Imag

(S21

)

Pulses

Pulse fitting– Decay Time -> Quasiparticle life time– Phase pulse height -> Energy of the incident photon– The signal in phase is larger than amplitude

Phase

I &

Q

Amplitude

Time (ms)

Tungsten Silicide MKIDs

We have been searching for dense materials for x-rays.

WSix is a material with low Tc, high kinetic inductance fraction and good quality factors. – Similar to Titanium Nitride– Maybe also be interesting for optical MKIDs.

arXiv:1203.5064v1

Optical MKIDs (Mazin et al) -- Spectrophotometry

Mazin et al., Optics Express 2012

R=E/ΔE=16 at 254 nm

Limited by LNA/power handling/Q

A readout for large arrays of Microwave Kinetic Inductance Detectors (McHugh, Mazin et al, arXiv:1203.5861v1)

How to readout 1024 MKIDs….

Another technology – Transition Edge Sensors

TES have the best energy resolution (not Fano limited) However, TES require relatively complex cryogenic electronics which

makes multiplexing difficult.– Limited to 200 pixels right now.

Also, larger pixel means slower response….

TES are evolving towards MKID/resonator readout “Microwave SQUIDs”

Eventually would like a wideband, quantum-limited LNA for MKIDs (i.e., don’t need SQUID anymore)– Josephson parametric amp (J. Gao et al)

• arXiv:1008.0046v1– Kinetic Inductance parametric amp

(P. Day et al)• arXiv:1201.2392v1

Superconducting microwave resonant circuits for the detection of photons from microwaves through gamma rays, Irwin, K.D., et al. Microwave Symposium Digest (MTT), 2011 IEEE MTT-S International , vol., no., pp.1-4, 5-10 June 2011

B. Mates et al ApL 2008 (NIST)

Conclusions

Superconducting detector development has started at the APS. – Testing infrastructure (cryo, electronics, analysis software) is complete. – Now focusing on device fabrication and iterating on designs

MKIDs are a path towards high count rates and higher solid angle coverage. – Has the potential to provide a very unique capability (detector/instrument) for

the APS.

MKIDs are a relatively young technology and there is room for R&D.

Thank you!

The End

Extra Slides

Comparison of Silicon Drift Diode, MAIA, TES and MKID

Area Sensor-Window Distance

Energy Resolution @ 6keV

Max Count rate (per pixel)

P/B ratio

Energy Range

State of maturity

Silicon Drift

Diode40mm2 5mm

250eV 250kHz5000:1

(?) < 20keVCommercia

lly Available175eV 100kHz

MAIA 1mm2 x 384 5mm 250eV 20kHz per pixel 5000:1

(?)< 20keV Semi-

commercial??

NIST TES0.14 mm2 per pixel

(256+ pixels)

1 cm3eV @ 6keV

18eV @ 40keV70eV @ 100keV

10-100 Hz/pixel (256+ pixels) ?? 300eV –

100keVSemi-

commercial

MKIDs 0.14 mm2 per pixel 1 cm 60eV (2006)

2eV is theoretical limit4000Hz/pixel(256+ pixels) ?? 300eV-

100keV R&D+

Silicon Drift Diodes

Commercially available– E.g., Vortex 4-pixel SDD (4 x 40mm2)

Performance of single pixel SDDs (measured)– Mn Ka FWHM ~ 250 eV (Max Count rate ~ 250 kHz per pixel)– Mn Ka FWHM ~ 175 eV (Max Count rate ~ 100 kHz per pixel)

SDD have reached their limits of energy resolution. Only improvement to be made is more pixels to increase total

count rate throughput and solid angle collection.– Thus, the MAIA detector (BNL/Australia)!

• Speed and resolution are inverse proportional. Controllable thermal conductance to bath (“G”)

SiN membrane geometry

Phonon-Coupled MKIDs -- Single Photon Emission CT -- SPECT

SPECT Imaging (for animals) Patrick La Riviere thinks phonon-coupled MKIDs might be good for this. Also interesting for high-energy x-ray applications

Sunil Golwala et al

Current Status of MKID Research at APS II

Exploring various detector configurations– Quasiparticle Trapping Tradition Configuration

• 60eV resolution and 4000cps per pixel proven in 2006• 30eV should be “easily” possible

– More is understood about noise sources• 2eV is theoretical limit at 6keV

– Lump-element design (WSix) No charge diffusion High Peak-to-Background

– Phonon-Coupled Large pixels and thick silicon (or other dielectric material for absorption

Silicon Absorber (1mm)

SiN membrane

Resonator

Inductor/Absorber

Capacitor

• Pump-probe XAS w/o mono• 3eV at 7keV• 80Hz with 40 pixels (256 possible today)

• 80Hz * 256 = 20kHz (TDM)• 80Hz * 1000 = 80kHz (CDM) This starts to

be very interesting for RIXS/XES/XANES

MKIDs – Readout Scheme

Multiplexing is main advantage of MKIDs over STJs and TES

Should be able to readout

~4000 pixels

MKID Array readout

Room temperature electronics– Transfer complexity from cryogenic electronics (TES & SQUIDs) to room temperature. – Scalable system

Array size limitation is room temperature electronics (512 is practical today)– Riding on Moore’s Law for room temperature microwave integrated circuits developed

for the wireless communications industry.

X XIQ Mixer

Low Pass

Filters

16-bit D/A

16-bit D/A

14-bit A/D

14-bit A/D

FPGA-based IQ demodulation (Xilinx

SX95T RF Engines

Channel Core)

GHz Synthsizer

Quasiparticle Generation – A Cascade Process

Incoming Photon absorbed, ionizing atom and releasing inner-shell electron1. First Stage: Rapid energy down-conversion (electron-electron interactions secondary

ionization and cascade plasmon emission) e.g. 10keV photoelectron down-conversion to a thermal population of electrons and holes at a

characteristics energy ~ 1eV takes 0.1 ps (Kozorezov et al ) 1st stage ends when electron-phonon inelastic scattering rate dominates electron-electron

interactions.

2. Second Stage: ~ 1eV down-convert to large number of Debye energy phonons Energy of phonon distribution exceeds energy of electron distribution Debye energy of superconductors is larger than SC gap energy Phonons with energy > 2 D will generate quasiparticles.

Finally, we have a mixed distribution of quasiparticle and phonons:• Nqp ~ Ephoton/D

• But scaled down because large percentage of photon energy stays in the phonon system• For Tantalaum, 60% energy resides in qp system. (Kurakado) (Efficiency h)

• Nqp = hh /n D

• At 6keV and Ta absorber, D = 0.67 meV 5 Million qp!!

Phonon Trapping

Dominant phonon loss mechanism for Ta and Al is through the substrate. – Copper Pair breaking phonons Mean Free path ~ 50nm

Effective quasiparticle lifetime is lengthened by phonon trapping. – Acoustic match between superconducting film and substrate.

Thus thicker films or membrane-suspended absorbers.

Two major classes of Superconducting Detectors

Thermal Detectors (i.e., Transition Edge Sensors) Quasiparticle Detectors

Transition-Edge Sensors (TES)

1/e response time = 100 μs - 1 ms

Kent Irwin, NIST

Transition-Edge Sensors (TES)

TES have the best energy resolution (not Fano limited) However, TES require relatively complex cryogenic electronics which

makes multiplexing difficult.– Limited to 200 pixels right now.

Also, larger pixel means slower response….

Irwin & Ullom, NIST

TES array at NSLS (NIST U7A)

Commissioned at NSLS this year…. Waiting for results…

Gamma-Ray TES Array (NIST + Los Alamos)

Resolution 25 eV at 100 keV for 1 mm2 20eV at 40keV for 1 mm2

70 eV at 100 keV for 2 mm2

Count Rate 10Hz/pixel (now) 25Hz/pixel (soon)

Pixels 256 (now) 1024 (soon)