First Results from

Thermal Kinetic Inductance Detectors:

Highly Multiplexible Bolometric

MKIDs for X-ray Spectroscopy

G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Department of Physics, University of California, Santa Barbara, CA 93106, USA

LTD-16, Grenoble, July 21, 2015

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Why TKIDs for X-ray detection?

TKIDs

Thermal Kinetic Inductance Detectors (TKIDs):

· single pixel energy resolution an utilize frequency domain multiplexing

· usable in a big energy / wavelength range

· can utilize frequency domain multiplexing

· no read noise

· ……… promising as

X-ray detectors!

TKID vs. TES:

TES: · impressive energy resolution

· high time resolution

· multiplexing is complex and

challenging

TKID: · comparable time resolution

· much easier to multiplex

· energy resolution: …..

ideal where spatial resolution is required!

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

TKID design

TKIDs

Many X-ray photons would penetrate the

superconductor

Microcalorimeter: inductor & absorber on

a free floating Si3N4 membrane

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

TKIDs

TKID design

: sub-stoichiometric TiNx

Many X-ray photons would penetrate the

superconductor

Microcalorimeter: inductor & absorber on

a free floating Si3N4 membrane

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

TKIDs

TKID design

: sub-stoichiometric TiNx

: Si3N4 (etched with XeF2)

Many X-ray photons would penetrate the

superconductor

Microcalorimeter: inductor & absorber on

a free floating Si3N4 membrane

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

TKIDs

TKID design

: sub-stoichiometric TiNx

: Si3N4 (etched with XeF2)

: absorber (Ta or Au)

Many X-ray photons would penetrate the

superconductor

Microcalorimeter: inductor & absorber on

a free floating Si3N4 membrane

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

TKIDs

TKID design

: sub-stoichiometric TiNx

: Si3N4 (etched with XeF2)

: absorber (Ta or Au)

Many X-ray photons would penetrate the

superconductor

Microcalorimeter: inductor & absorber on

a free floating Si3N4 membrane

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

TKIDs

TKID design

: sub-stoichiometric TiNx

: Si3N4 (etched with XeF2)

: absorber (Ta or Au)

: Nb feedline & ground plane

Mushroom shaped absorbers planned,

current simple absorbers just to reduce

prototype complexity.

Bridges: 0.25 x 2 µm2 cross section

140 µm long

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Single photon pulses

Data analysis

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Single photon pulses

Data analysis

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Analysing max. pulse height doesn’t work.

Data analysis

140 150 160pulse max. [degrees]

no

. o

f e

ve

nts

140 150 160pulse max. [degrees]

no

. o

f e

ve

nts

pulse maximum [degrees]

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Data analysis

Pulse rise time depends on absorption location.

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Why fit pulses?

Pulse fitting

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse fitting

Why fit pulses?

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse fitting

Why fit pulses?

free parameters in pulse model: photon arrival time rise time

fall time max. membrane temperature

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse model: resonance frequency over T

Pulse fitting

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse model: phase shift over frequency

Pulse fitting

as measured

after feedline subtraction

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse model: assumed temperature behaviour

Pulse fitting

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse fitting

Pulse model: assumed temperature behaviour

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse fitting

Pulse model: assumed temperature behaviour

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse model construction

Pulse fitting

base temperature

increased temperature

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Pulse fitting

Pulse model construction

Resolution of 75 eV at 5.9 keV, despite significant design flaws in first TKID prototype

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Energy resolution still restrained by saturation

Achieved energy resolution

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Resonator saturation

Interaction between thermal design and critical temperature

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Resonator saturation

Interaction between thermal design and critical temperature

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Resonator sensitivity

Resonator saturation

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Wrong thermal design

Resonator saturation

too small heat capacity ΔTmembrane = 150 – 200 mK

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Wrong thermal design + high sensitivity = saturation

Resonator saturation

Simple extrapolation: We should be able to resolve

below 10 eV at 5.9 keV by eliminating saturation.

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

How to eliminate saturation?

eliminating saturation:

reduce Qi:

reduces best achievable resolution

increase TiNx Tc:

reduces best achievable resolution

reduces heat capacity

increase measurement temperature:

already near upper limit

increases noise

reduce membrane heat capacity:

issues with Au absorber but

reduces best achievable resolution

…..

measure below resonance frequency:

Resonator saturation

eliminating saturation:

reduce Qi:

reduces best achievable resolution

increase TiNx Tc:

reduces best achievable resolution

reduces heat capacity

increase measurement temperature:

already near upper limit

increases noise

reduce membrane heat capacity:

issues with Au absorber but

reduces best achievable resolution

…..

measure below resonance frequency:

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

How to eliminate saturation?

Resonator saturation

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Measurement below resonance.

driving a TKID below resonance frequency:

Resonator saturation

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

No longer saturated but still high sensitivity.

Resonator saturation

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

More challenging data analysis.

Work in progress.

Δf = 0 kHz Δf = -140 kHz

Δf = -540 kHz Δf = -340 kHz

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel

Many thanks to:

Everybody involved

Mazin group at UCSB:

Ben Mazin

Seth Meeker Matt Strader

Paul Szypryt Alex Walter Clint Bockstiegel

Giulia Collura

Thermal Kinetic Inductance Detectors for X-Ray Spectroscopy G. Ulbricht, B.A. Mazin, P. Szypryt, A. B. Walter, C. Bockstiegel