X-KIDs high resolution X-ray spectroscopy with Kinetic Inductance Detectors

Transcription

1 X-KIDs high resolution X-ray spectroscopy with Kinetic Inductance Detectors Andrea Giachero University and INFN of Milano Bicocca INFN CSN5, Grant for Young Researcher November, 24th Rome

2 X-KIDs Project: synopsis Goal: develop a new scalable microcalorimeter technique based on absorber-coupled MKID detectors, for X-rays spectrometry suitable for future synchrotron light sources. Innovation: use MKID detectors in a thermal equilibrium mode as pure calorimeters to detect X-ray photons, instead of the classical non-equilibrium mode (athermal mode). Tasks: 1. Design and optimization of the detector layout (resonator geometry); 2. Devices production and characterization; 3. Development of a multiplexed readout (array of detectors); Units: 1. INFN Unit of Milano-Bicocca (PI); 2. INFN Unit of Genova; 2

3 Synchrotron light source Synchrotron radiation (SR) is electromagnetic radiation emitted when a high energy beam of charged particles (electrons) is deflected by a magnetic field; SR is emitted over a wide range of the electromagnetic spectrum, from Infra-red to hard X-rays; Booster ring X-rays beamline (monocromator) Any desired radiation wavelength can be produced; linear electron beams magnets experimental stations (samples) SR is very intense, and has extremely high brightness; SR region Possibility of examining extremely small samples (structure and proprieties); Ability to follow chemical and biological reactions in real-time (time resolved); Detection techniques: X-ray absorption spectroscopy (XAS); X-ray fluorescence (XRF). 3

4 Analytical techniques X-ray absorption spectroscopy (XAS) Measure of the X-ray absorption coefficient as a function of incident X-rays energy. X-ray fluorescence (XRF) Emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by bombarding with high-energy X-rays; Applications Amorphous solids and liquid systems; Solid solutions; Doping and ion implantation materials for electronics; Local distortions of crystal lattices; Organometallic compounds; Metalloproteins Metal clusters; Catalysis; Vibrational dynamics in solutions; Speciation of elements Liquid water and aqueous solutions; Synchrotron Radiation: a super microscope for new research opportunities into the structure and properties of matter. Detector with very strict requirements in energy and time resolution, in efficiency over a wide energy range, in counts rate and number of pixel, will be needed in the near future. 4

5 Detectors: Current Status Wavelength Dispersive Spectrometers (WDS) suited for low-energy (long-wavelength) Wavelength converted into a dispersion angle, which corresponds to a position on the focal plane; Dispersive elements: transmission gratings, reflection gratings and Bragg crystals; Detector: Charge Coupled Devices (CCD) and Position-Sensitive Detectors (PSD) Resolving Power E/ E = ( ) Efficiency (10 20) % Speed limitation for time-resolved applications; Energy Dispersive Spectrometers (EDS) better for the high-energy (short-wavelength) Incident X-ray photons cause ionization in a solid state detector, producing an electrical charge, which is amplified and recorded; Typical Detectors: Silicon Lithium Si(Li) or Silicon Drift Detectors (SDD) Resolution E = ( ) 5.89 KeV (Mn K ) E/ E = (5 100) Efficiency 100 % 5

6 Detectors: Low temperature detectors (LTD) To overcome the limitation in energy resolution of semiconductor X-ray detectors Microcalorimeters E. Fiorini and T. Niinikoski NIM 224 (1984) 84 S. H. Moseley, J. C. Mather, D. McCammon J. Appl. Phys. 56 (1984) 1257 Weak thermal link: connecting the absorber to a thermal reservoir, to cool the absorber back to its starting point; Phonon Sensor: the active part that converts the excitation into an electrical signal; Energy Absorber: the sensitive part where the incident radiations deposit their energy. The X-ray microcalorimeter works by sensing the heat generated by X-ray photons when they are absorbed and thermalized in a very low heat capacity element. Sensors Absorber Very low thermal capacity (small size, T < 100 mk); High stopping power (high Z material); Si or Ge Thermistors; Transition Edge Sensors (TES); Metallic Magnetic Calorimeter (MMC); Superconducting Tunnel Juction (STJ); Microwave Kinetics Inductance Detector (MKIDs); 6

7 Detector: LTD WDS & EDS The spectral resolving power of the EDS is about few orders of magnitude worse than that of a WDS but the efficiency is around 100%. EDS: WDS: Example: TES Based (Goddard) Limit to energy resolution: rms statistical fluctuation of internal energy E (CkBT2) 1.5 kev E/ E 1200 E = 6 kev E/ E kev E/ E % E/ E = (5 100) 100 % E/ E = ( ) (10 20) % General Features Good energy and time resolution (pile-up); High detection efficiency; Large dynamic range in both energy and intensity. The microcalorimeter approach combines the simultaneous detection capabilities of EDS with the high spectral resolution of WDS. 7

8 Microwave Kinetic Inductance Detector (MKID) Incident photons change the surface impedance of a superconductor through the Kinetic Inductance Effect. Proposed for the first time in 2003, P. K. Day et al. Nature 425 (2003) 817. The resonance dip becomes broader and shallower due to an increase of Rs (dissipation); τ The resonance frequency is shifted to lower value due to an increase of Ls (Kinetic inductance) Quasi-particle recombine after τqp; Pair-breaking radiation (Eγ > 2 ) creates quasi particle density (nqp); Quasi-particle increase changes the surface impedance (Z S); Non-equilibrium mode (athermal mode) A resonant circuit lithographed in a thin film is used to sense L S and RS; To monitor the resonant circuit, it is continuously excited with a microwave signal. 8

9 Read out: homodyne detection method Forward transmission coefficient Frequency and Amplitude shifts related with the radiation detected Homodyne detection: in radio technology mixing with a Local Oscillator (LO) with same frequency as the signal to be detected. Simultaneous readout in the same line can be accomplished by tuning each pixel to a different resonant frequency with lithography during device fabrication; A comb of probe signals can be sent into the device, and room temperature electronics can measure the changes in amplitude and phase without significant cross talk; Possibility to couple many resonators to the same readout-line, which enables the possibility to create arrays of thousand pixels, with a simple readout (Frequency-Division Multiplexing, FDM); Possibility to use software-defined radio (SDR) techniques commonly used in modern wireless communications; 9

10 MKIDs: present and future Superconducting Microwave Microresonators have demonstrated their scalability operating in a non-equilibrium mode (athermal mode, i.e. as quasi-particle detectors) in several instruments: MUSIC, P. R. Maloney et al. Proc. of SPIE 7741 (2010) 77410F; IRAM, A. Monfardini et al. The Astroph. J. Supp. Series 194 (2011) 24; ARCONS, B. A. Mazin et al., Optics Express 20 (2012) 1503; MAKO, L.J. Swenson, et al. Proc. SPIE Int. Soc. Opt. Eng (2012) 84520P; sub-mm radiometry Recently proposed also for particle detectors applicable to rare-events search: Dark matter, D.C. Moore et al. App. Phys. Lett. 100 (2012) ; Neutrinoless double beta decay, S. Di Domizio et al. J. Low Temp. Phys 176 (2014) 917; Direct measurement of the neutrino mass, M. Faverzani et al. J. Low Temp. Phys 167 (2012) 1041; Advantages The natural multiplexing capability The simple fabrication process Very good time resolution read out up to thousand detectors using a single pair of coaxial cables and single HEMT amplifier (recent US proposal for 10'000 pixels) reduction in complexity at the cryogenic level; single or few layers of thin film; one orders of magnitude better than a CCD MKIDs will be very relevant for the future development of multipixel detector arrays 10

11 X-KIDs project: objectives of the proposal Goal: develop a new scalable microcalorimeter technique based on absorber-coupled MKID detectors, operating in thermal quasi-equilibrium mode (also known as thermal-mode), and suitable for X-rays detection; Starting point: three years project Development of Microresonator Detectors for Neutrino Physics funded by Fondazione Cariplo (grant International Recruitment Call 2010, ref ) at the University of Milano Bicocca (NuKIDs). Devices designed to operate in non-equilibrium mode and tested with low energy X-ray sources collimated in an small area around the center of the inductor. The developed detectors are not able to resolve a monochromatic energy, due to various effects: contact between the inductor and the substrate, slow diffusion of the quasiparticles in the film. M. Faverzani et al J. Low Temp. Phys 176 (2014)

12 X-KIDs project: Thermal Mode Preliminary plot from NuKIDs project The responsivity of a MKID is related to the dσ/dnqp where σ is the complex conductivity; In non-equilibrium mode the excess quasiparticles dσ/dnqp is due to an external pair breaking; A temperature change can produce an identical increase of quasiparticle population of an external pair-breaking, J. Gao et al. J. Low Temp. Phys. 151 (2008) 557; The effect of a small variation in temperature leads to a change in the surface impedance LS. The amplitude and phase shifts of S21 depends on the increase in equilibrium thermal quasiparticle population due to the bath temperature variation. devices with critical temperature low enough (Tc < 500 mk); Very sensitive if the sensitivity improves as the TC is lowered (δf 1/TC2); low energy gap ; slower recombination time τqp (i.e. low G-R noise); operating at very low temperature to minimize the absorber thermal capacity (T Tc /4); Thermal equilibrium mode (thermal mode) 12

13 X-KIDs project: Thermal Mode (cont'd) Energy resolution: theoretically limited only by thermodynamic fluctuations across the thermal weak: ΔERMS (CkBT2) for a metal absorber (i.e. Gold) 200 μm 200 μm 2 μm working at T = 50 mk, it is possible to have resolution around 1 ev. Time resolution: for quality factors around Q 104: resonator response time of τr = Q/2πfres fres = (1 6) GHz range, rise time around 1μs or less is achievable; Two-Level System (TLS) noise: due to surface layer of defects on the metalization or substrate using a proper design the it can be substantially reduced to negligible value, O. Noroozian et al. AIP Conf. Proc., 1185 (2010) ; Constrains Amplifier noise: negligible if: δdets21 > δamps21 δdets21: fluctuations due to the detector response; δamps21: fluctuations due to the HEMT amplifier. Requirement satisfied if (paper in preparation): Low amplifier noise temperature: Tn= 2.5 K available in commerce; Low critic temperature: Tc < 500 mk achievable using Ti/TiN multilayer; Kinetic inductance fraction: α > 0.5 achievable using Ti/TiN multilayer; Qtot/QiQc 1/4 (called critical coupled condition) achievable with proper design; 13

14 X-KIDs project: Involved research Units Microresonator design: Unit of Milano-Bicocca exploiting a consolidated collaboration with a JPL/Caltech group headed by P. K. Day; Film production: Unit of Milano-Bicocca in collaboration with the Micro ElectroMechanical Systems (MEMS) of the Bruno Kessler Foundation (FBK, Trento, Italy); Read-out and Multiplexing: Units of Milano-Bicocca and Genova jointly involved; Data handling and analysis: Units of Milano-Bicocca and Genova jointly involved; Cryogenics: Unit of Milano-Bicocca, cryogenics laboratory jointly supported by INFN and University through a specific agreement 14

15 X-KIDs project: Previous Experience of the PI 1. CUORE ( present) Development of the the RAD (Radiation Array Detector) detector arrays; Design and development of the data acquisition system (Ph.D. period); Design and development of the readout electronics; Coordinator of the CUORE Slow Control System CUORE-SCS (since June 2012); 2. MKIDs R&D (2012 May 2015) Development of Microresonator Detectors for Neutrino Physics (funded by Fondazione Cariplo (grant International Recruitment Call 2010, ref ) Detector development and characterization; Development of the readout and data acquisition system; Data analysis. 3. HOLMES ( present) Development of Transition Edge Sensor (TES) for the direct measurement of the neutrino mass using the electron capture (EC) decay of 163-Holmium. Coordinator of the read-out and multiplexing systems; Detector development and characterization; Data analysis. ERC Advanced Grant n

16 X-KIDs project: Microresonator design CPW (feedline) Resonator geometry: lumped element form: two interdigitated capacitors (IDC) connected with a coplanar strip (CPS) transmission line that works as inductor; IDC CPS (inductor) Sensitive part One end of the resonator is shorted to ground while the other end is capacitively coupled to a coplanar waveguide (CPW) used as feedline; Absorber Geometry optimized to minimize the TLS noise; Si2N3 membrane Designed and simulated with Sonnet ; TM Metal Absorber: thermally coupled with the inductive part and suspended Si2N3 membrane: Absorbers with a very high stopping power are needed in order to avoid loss of energy and to keep the thermal capacity as low as possible. A thickness of 5 μm of Gold provides a stopping power close to 100% radiation of energies up to 6 kev and 45% at 20 kev; IDC Preliminary geometry design Microresonator arrays (2 8) will be fabricated with the aim of optimizing the detector design and the fabrication procedures; At the end of the project a larger detector array (16 16?) will be realized and tested ; 16

17 Titanium nitride (TiN), has been recently investigated as superconducting material, and has shown very good performances for KIDs, M. R. Vissers et al. App. Phys Lett. 97 (2010), ; TiN properties: High resistivity in the normal state; Large fraction of kinetic inductance (α 0.5); very high quality factors (Qi = ); Using multilayer of pure Ti and stoichiometric TiN (Ti:TiN) the critical temperature TC is tunable in the ( ) K temperature range (proximity effect); Ti:TiN Features Good reproducibility for the target TC; Critical temperature uniformity across the wafer <%1 (from the edge and to the center); Plots from A. Giachero et al. J. Low Temp. Phys. 176 (2014) 155 X-KIDs project: Film production A. Giachero et al. J. Low Temp. Phys. 176 (2014)

18 X-KIDs project: Film production (cont'd) Preliminary plots from NuKIDs project Very low Tc High df/dt gradient Preliminary measurements show that Ti/TiN multilayers devices with very low critical temperature (Tc = 640 mk) have a high df/dt gradient at very low working temperature; This behavior makes this film a natural candidate to exploit microresonators in thermal quasiequilibrium mode; Film with lower critical temperature (Tc < 500 mk) already produced; All the the devices will be produced by the Micro ElectroMechanical Systems (MEMS) of the Bruno Kessler Foundation (FBK, Trento, Italy); 18

19 X-KIDs project: Read-out and Multiplexing ROACH ADC/DAC IF Readout system similar to the one developed at the University of Santa Barbara for the ARCONS experiment, Sean McHugh et al. Rev. of Sci. Instr. 83 (2012) ; Open architecture computing hardware ROACH (Reconfigurable Open Architecture Computing Hardware) as FPGA process board and the DAC/ADC and IF boards, developed for the MUSIC experiment, as digitizer and up/down converter; 19

20 X-KIDs project: Cryogenics The Cryogenics Laboratory of the Physics Department of Milano-Bicocca University hosts many facilities and infrastructures which are jointly run by INFN and University through a specific agreement; Fully equipped for low temperature radiation detector testing (vacuum and low temperature instrumentation, calibration sources, electronic instrumentation, data acquisition systems, control instrument, computing systems and data storages); The project will be hosted in an existing Oxford Kelvinox MX40 cryostat: power of 40 μw at 100 mk and a base temperature of 25 mk; Cryostat fully equipped for performing measure on low temperature detector; A microwave readout lines is already installed and only few updates will be needed to fulfill the project technical requirements 20

21 X-KIDs project: Timeline and budget Main costs: Film FBK and Liquid Helium to run the experiments at cryogenics temperature; All the other instrumentations needed (cryostat, GHz synthesizer, Vector Network Analyzer, HEMT amplifier, the ROACH2 based system) are already present and usable at the INFN Cryonices laboratory of Milano-Bicocca 21

22 X-KIDs project: Synergy with other INFN projects What s special about Synchrotron Radiation? HOLMES What is so Synchrotron (ERC Advanced Radiation Grant?no ) Goal: measure the neutrino mass by deploying a large array (1000 pixels) of low temperature 163 Ho-implanted microcalorimeters sensed by Transition Edge Sensor (TES); The TESs detector will be readout by rf-squid exploiting the homodyne detection using a similar readout system (ROACH2 based) of this proposal; What s special about Synchrotron Radiation? What is so Synchrotron Radiation? ) CALDER (ERC Starting Grant no. Goal: develop cryogenic detectors based on superconducting resonators for the identification of rare events, such as double beta decay and dark matter interactions with ordinary matter; MKIDs detector will be readout a multiplexing system based on the homodyne detection using a similar readout system (ROACH2 based) of this proposal; The idea is to develop a common readout and multiplexing system, in terms of firmware and software tools, for control and preprocessing, usable for all the three research activities. 22

23 MKIDs: other applications The development of the KIDs technology in thermal and athermal represents by itself excellent research; In the recent What next? meeting in Rome, MKIDs has been proposed, in the working group New direction, as possible detector for future particle and astroparticle experiment; This is acknowledged by the European Research Council which founded two Starting Grants: Study of Terahertz Focal Plain Arrays (TFPA), Starting Grant no ; Cryogenic wide-area Light Detectors with Excellent Resolution (CALDER), Starting Grant no thermal athermal Kilo-pixel arrays of such devices may have a large impact in many frontier fields: Study of the THz bandwidth, largely unexplored both for astronomical and for ground based applications, S. Ariyoshi et al. Appl. Phys. Express 6 (2013) ; THz spectroscopy for bio-medical material and the homeland security; Hard X-rays ( KeV) band allowing passive isotope tracing analysis of nuclear fuel in reactor industry or in security sensing, T. Cecil et al. 37 (2012) 697; Single photon regime, quantum comunication and q-bit, S. Probst et al. arxiv: ; 23

24 Conclusion Synchrotron radiation-based techniques are nowadays currently used in various many fields of research; With the advent of high-brilliance synchrotron sources, X-ray detectors will need to perform at a far more demanding level than at present; Low temperature detectors are the most promising solution for very high energy and time resolution X-ray spectroscopy; MKIDs in thermal mode fulfill these requirements and allow the possibility to read a large amount of pixel at the same time (FDM); The goal of X-KIDs project is to develop a new scalable microcalorimeter detection technique based on absorber-coupled MKID detectors working in thermal mode; All the devices will be produced at the FBK exploiting Ti/TiN multilayers with very low critical temperature Tc; Within the two years a demonstrator 2 x 8 pixel arrays will be designed, fabricated, characterized and tested; In case of good performances a larger (or more) array will be designed; 24

25 X-KIDs high resolution X-ray spectroscopy with Kinetic Inductance Detectors Back-up Slides Andrea Giachero University and INFN of Milano Bicocca INFN CSN5, Grant for Young Researcher November, 24th Rome

26 NuKIDs: detector array 26

27 NuKIDs: non-resolving detector explanation 27

28 MKIDs: two-channel readout 28

29 HOLMES: rf-squid read-out DC biased TES (1 bias for all TESs); SQUID coupled with TES and a resonator circuit; Microwave rf-squid read out with flux ramp modulation (common flux line is inductively coupled to all the SQUIDs); Signal reconstructed by homodyne detection (IQ signal demultiplexing) and ramp demodulation; 29