Lumped Element Kinetic Inductance Detectors

Kinetic Inductance Detectors (KIDs) provide a promising solution to the problem of producing large format arrays of ultra sensitive detectors for astronomy. Traditionally KIDs have been constructed from superconducting quarter-wave resonant elements capacitively coupled to a co-planar feed line [1]. Photon detection is achieved by measuring the change in quasi-particle density caused by the splitting of Cooper pairs in the superconducting resonant element. This change in quasi-particle density alters the kinetic inductance, and hence the resonant frequency of the resonant element. This arrangement requires the quasi-particles generated by photon absorption to be concentrated at positions of high current density in the resonator. This is usually achieved through antenna coupling or quasi-particle trapping. For these detectors to work at wavelengths shorter than around 500 μm where antenna coupling can introduce a significant loss of efficiency, then a direct absorption method needs to be considered. One solution to this problem is the Lumped Element KID (LEKID), which shows no current variation along its length and can be arranged into a photon absorbing area coupled to free space and therefore requiring no antennas or quasi-particle trapping. This paper outlines the relevant microwave theory of a LEKID, along with theoretical and measured performance for these devices.      

Noise and Sensitivity of Aluminum Kinetic Inductance Detectors for Sub-mm Astronomy

Kinetic inductance detectors are based upon high Q superconducting resonators. We have measured the electrical Noise Equivalent Power (NEP) of 100 nm thick 1/4λ coplanar waveguide Aluminum resonators at 100 mK using phase readout and radius readout. We find that the phase NEP is independent of the Q factor of the resonator, limited by excess noise in the KID and given by NEP at 100 Hz. It increases with roughly f ^−0.5 at lower frequencies. The amplitude NEP is strongly Q factor dependent, limited by the setup noise, nearly frequency independent and as low as NEP for a high Q resonator (Q=454.000). For lower Q resonators the amplitude NEP increases to values equal to or even larger than the phase readout.      

Clean Beam Patterns with Low Crosstalk Using 850 GHz Microwave Kinetic Inductance Detectors

We present modeling of distributed \(\lambda \) /4 microwave kinetic inductance detectors (MKIDs) showing how electromagnetic cross coupling between the MKID resonators can occur at frequencies corresponding to the microwave readout signal ( \(\sim \) 4–8 GHz). We then show system beam pattern measurements in the reimaged focal plane of a 72 detector array of lens–antenna coupled MKIDs at 850 GHz, which enables a direct measure of any residual optical crosstalk. With use of transmission line bridges we see no residual cross coupling between MKIDs and hence low crosstalk down to the \(-\) 30 dB level, with near Gaussian shape (limited by reimaging optics) to \(-\) 10 dB level.     

Millimeter-Wave Polarimeters Using Kinetic Inductance Detectors for TolTEC and Beyond

We examine the dynamics of a one-dimensional harmonically trapped Bose–Einstein condensate (BEC), induced by the addition of a dimple trap whose depth oscillates with time. For this purpose, the Lagrangian variational method (LVM) is applied to provide the required analytical equations. The goal is to provide an analytical explanation for the quasiperiodic oscillations of the BEC size at resonance, that is additional to the one given by Adhikari (J Phys B At Mol Opt Phys 36:1109, 2003). It is shown that LVM is able to reproduce instabilities in the dynamics along the same lines outlined by Lellouch et al. (Phys Rev X 7:021015, 2017). Moreover, it is found that at resonance the energy dynamics display ordered oscillations, whereas at off-resonance they tend to be chaotic. Further, by using the Poincare–Lindstedt method to solve the LVM equation of motion, the resulting solution is able to reproduce the quasiperiodic oscillations of the BEC.     

Design and Testing of Kinetic Inductance Detectors Made of Titanium Nitride

To use highly resistive material for Kinetic Inductance Detectors (KID), new designs have to be done, in part due to the impedance match needed between the KID chip and the whole 50?Ω readout circuit. Chips from two new hybrid designs, with an aluminum throughline coupled to titanium nitride microresonators, have been measured and compared to a TiN only chip. In the hybrid chips, parasitic temperature dependent box resonances are absent. The dark KID properties have been measured in a large set of resonators. A surprisingly long lifetime, up to 5.6?ms is observed in a few KIDs. For the other more reproducible devices, the mean electrical Noise Equivalent Power is $5.4 \times 10^{-19}\ \mathrm{W}\sqrt{\mathrm{Hz}}$ .     

Kinetic Inductance Phonon Sensors for the Cryogenic Dark Matter Search Experiment

An important challenge faced by phonon-mediated detectors for the next generation of dark matter detectors (>100 kg) is to instrument large target mass at low cost, while maintaining the large background suppression offered by the combination of phonons and ionization (or scintillation) measurement. Kinetic inductance phonon sensors, operating far below the superconducting transition temperature, offer an interesting solution to this scaling problem. They do not critically depend on the uniformity of T _c and their resonant-cavity readout is easy to multiplex. We are studying a microstrip (two parallel planes) transmission line architecture that may offer the additional advantage of a separation of functions: the main detector is just covered by an unpatterned aluminum film and the number of quasi-particles created in it by athermal phonons are sensed by a second film, which has been independently patterned and is mounted a few microns away from the detector. We present current results on the responsivity and noise of large area (∼33 mm²) microstrip kinetic inductance phonon sensors.      

Design and Characterisation of Titanium Nitride Subarrays of Kinetic Inductance Detectors for Passive Terahertz Imaging

We report on the investigation of titanium nitride (TiN) thin films deposited via atomic layer deposition (ALD) for microwave kinetic inductance detectors (MKID). Using our in-house ALD process, we have grown a sequence of TiN thin films (thickness 15, 30, 60 nm). The films have been characterised in terms of superconducting transition temperature \(T_\mathrm{c}\), sheet resistance \(R_\mathrm{s}\) and microstructure. We have fabricated test resonator structures and characterised them at a temperature of 300 mK. At 350 GHz, we report an optical noise equivalent power \(\hbox {NEP}_\mathrm{opt} \approx 2.3\times 10^{-15}~\hbox {W}/\sqrt{\hbox {Hz}}\), which is promising for passive terahertz imaging applications.     

A Comparison of Fundamental Noise in Kinetic Inductance Detectors and Transition Edge Sensors for Millimeter-Wave Applications

Kinetic inductance detectors (KIDs) show promise as a competitive technology for astronomical observations over a wide range of wavelengths. We are interested in comparing the fundamental limitations to the sensitivity of KIDs with that of transition edge sensors (TESs) at millimeter wavelengths, specifically over the wavelengths required for studies of the Cosmic Microwave Background (CMB). We calculate the total fundamental noise arising from optical and thermal excitations in TESs and KIDs for a variety of bath temperatures and optical loading scenarios for applications at millimeter wavelengths. Special consideration is given to the case of ground-based observations of 100 GHz radiation with a 100 mK bath temperature, conditions consistent with the planned second module of the QUBIC telescope, a CMB instrument Battistelli (Astropart Phys 34:705, 2011). Under these conditions, a titanium nitride KID with optimized critical temperature pays a few percent noise penalty compared to a typical optimized TES.     

熟化甘薯片微波真空干燥特性及其动力学

研究熟化甘薯片微波真空干燥过程中微波功率密度(0.6,0.75,1,1.5,3 W/g)和相对压力(0,-20,-40,-60,-80 kPa)对其干燥特性的影响,通过建立动力学模型来预测熟化甘薯片微波真空干燥过程中的水分变化。研究结果表明:在不同微波功率密度下,将初始干基含水率为1.61的熟化甘薯片进行干燥,所需时间为22~95 min,明显少于同等试验条件下的热风干燥;且熟化甘薯片的微波真空干燥过程包含有升速、恒速和降速三个阶段;随着相对压力的降低,干燥速率逐渐增大,但相对压力低于-60 kPa后,再次降低压力对于干燥速率影响不显著。熟化甘薯片的微波真空干燥动力学模型满足Page模型。本研究可为实现熟化甘薯片的高效干燥及品质保证提供新思路,为相关设备的开发提供理论依据。     

Physical Principles of Low Temperature Detectors: Ultimate Performance Limits and Current Detector Capabilities

The rapid development of low temperature thermal detectors since the early 1980s has resulted in remarkable improvements in the sensitivity and precision of many types of measurements. We will discuss the operating principles of these detectors in the most general possible terms. We will try to show how the physics of some popular thermometer systems introduces performance limits, and how the different figures of merit and optimizations that result affect various applications.      

Test beam results of Current Injected Detectors (CID) irradiated up to 5×10 1 MeV neq/cm

Two full size strip detectors were investigated in this study: one with p⁺ strips (p⁺/n⁻/n⁺) and another with n⁺ strips (n⁺/p⁻/p⁺). Both detectors, are made of magnetic Czochralski silicon (MCz-Si) and irradiated to S-LHC fluencies, were tested with 225 GeV muon beam in the CERN H2 area. The Current Injected Detector (CID) sensors were operated in a cooling box capable of providing a −53 °C temperature. Results indicate a relative charge collection efficiency (CCE) at 5×10¹⁵ n_eq/cm² above 30% in irradiated p⁺/n⁻/n⁺ CID detector at 600 V bias voltage. The signal to noise ratio of this CID module was about eight and a forward current of 30 μA was needed for detector biasing. In standard reverse bias, the same detector could not provide a sufficiently large signal for particle tracking purposes. A p-type (n⁺/p⁻/p⁺) sensor was irradiated to a fluence of 2×10¹⁵ n_eq/cm² and measured under the same test beam conditions. According to the theory of CIDs developed by the CERN RD39 Collaboration, this detector module could be biased up to only 230 V due to the low irradiation fluence. The CCE at 230 V was 35% in CID operation and 20% when reverse biased.     

A Millimeter and Submillimeter Kinetic Inductance Detector Camera

We present results from a demonstration camera using Microwave Kinetic Inductance Detectors (MKIDs) (Day et al. in Nature 425, 817–821, [2003]) at the Caltech Submillimeter Observatory. The focal plane consists of 16 two-color (240 and 350 GHz) pixels. Each pixel is a phased-array of slot dipole antenna whose output power is coupled to MKIDs via in-line color-defining bandpass filters. A prototype software-defined radio system was used to read out up to four MKIDs simultaneously. We obtained maps of Jupiter, Saturn, and G34.3 and demonstrated sensitivities of approximately 1 Jy s^1/2 and 10 Jy s^1/2 in the two bands, respectively, limited by detector noise due to a low-efficiency optical train. We anticipate that a second engineering run in 2008 with a 36-element, 4-color array and an optimized optical train will be background limited at 240, 270, 350, and 400 GHz. We are undertaking the construction of a full-size MKID camera with 576 four-color spatial pixels and using 2304 MKIDs readout by an expanded software-defined radio system.      

ZnO基紫外探测器的研究进展与关键技术

近年来,ZnO基紫外探测器由于其优异的光电特性,已成为紫外探测领域研究中的新热点之一。介绍了近年来国内外不同结构类型的ZnO基紫外探测器的研究状况,并对影响探测器性能的ZnO的光电导特性、薄膜微结构、掺杂、金半接触等关键技术进行了探讨,指出推动ZnO紫外探测器实用化进程的关键在于制备高质量的掺杂薄膜以及进一步提高器件的量子效率。     

Fast algorithm for track segment and hit reconstruction in the CMS Cathode Strip Chambers

In this note, we propose an algorithm for fast and efficient track segment reconstruction in Cathode Strip Chambers used by the Compact Muon Solenoid experiment for muon detection in the forward direction. The algorithm is designed to be CPU-efficient and is targeted for High Level Trigger (HLT, online reconstructed events pre-selection) purposes. The segment finding efficiency and the spatial resolution attainable with the proposed algorithm as well as the required CPU time are benchmarked using the Cosmics Muon data and found to surpass the HLT requirements.     

Kinetic and wet oxidation of phenol catalyzed by non-promoted and potassium-promoted manganese/cerium oxide

The wet oxidation of organic compounds to CO2 and H2O has been shown to be a very efficient technique in the outflows treatment. This work focuses on the interaction of the chemical element potassium with the catalyst MnO2-CeO2 in the wet degradation of phenol. The reaction has been carried out in an autoclave with a controlled system of agitation, pressure, temperature and sampling of the liquid phase. The experiments were performed in the presence of the catalysts MnO2-CeO2 and K-MnO2-CeO2 in the following operational conditions: temperature of 130 degrees C, P = 20.4 atm, catalyst concentration in the range 1.5-5.0 g/L, initial phenol concentration of 0.5 g/L, initial pH varying between 6.8 and 8.5, and percentage of potassium in the catalyst MnO2-CeO2 ranging between 0% and 10%. Curves indicating the profile of conversion of total organic carbon show that the phenol degradation is favored when the potassium quantity is reduced. This behaviour is confirmed by BET analysis, whereby the catalyst presents larger specific area when compared to the percentages of other components. Regardless of the catalyst used in the phenol oxidation, the kinetic constant of reaction had the same order of magnitude for two parallel stages proposed by a first-order kinetic model.     

微波烧结SiC颗粒增强铝基复合材料

采用微波烧结的方法,在烧结温度分别为680℃,710℃,740℃,770℃,800℃制备了15％的SiCp／Al复合材料。探讨温度对材料的致密度和力学性能的影响。结果表明：致密度和材料硬度及冲击韧性随温度变化呈马鞍形,在770℃样品的密度和硬度及冲击韧性达到最佳值,分别为2．62g／cm3,42．6MPa,40J／cm2。结论：用微波烧结SiCp／Al复合材料可在短时间内使样品达到烧结致密化,缩短烧结时间,节约能源。     

Microwave characterization of laser ablated Y1Ba2Cu3O7−x thin films

In the present study we report the measurements of microwave surface resistance (R_s) of YBCO thin films on LaAlO₃ substrate as a function of temperature, thickness and magnetic field by microstrip resonator technique. The T_c(R = 0) of the films is 90 K and J_c > 10⁶ A/cm² at 77 K. The microwave surface resistance has been measured for films of various thicknesses. The value of R_s has been found to be initially decreased with increasing film thickness due to increase in number of defects. A minimum microwave surface resistance has been obtained for film thickness of about 300 nm. The increase of R_s with film thickness above 300 nm is possibly due to degradation of the film microstructure as observed with Atomic Force Microscopy. Temperature dependence of surface resistance has been studied for best quality films. The field induced variations of surface resistance are also investigated by applying dc magnetic field perpendicular to stripline structure and surface of the film. A general linear and square field dependence of R_s at low and high value of fields has been observed with critical field value of 0.4 T which confirms the microwave dissipation induced by flux flow in these resonators at 10 GHz frequency. The hysteresis of R_s in dc field observed for field value above critical field shows the higher value of surface resistance in decreasing field than in increasing field which is in agreement with one state critical model and is a characteristic of homogeneous superconductors.     

Microwave direct synthesis of MgB2 superconductor

Intermetallic compound superconductor MgB₂ was synthesized from spherical magnesium powder and lower purity amorphous boron powder by microwave direct heating. Powder X-ray diffraction (XRD) analysis indicates that the phases of the synthesis sample are MgB₂ (major phase) and a small amount of MgO. Scanning electron microscope (SEM) observation shows that the MgB₂ grain size is homogeneous and the particle size is about several hundreds of nanometers. The onset superconducting transition temperature of the MgB₂ sample measured by the temperature dependence of magnetization measurement is about 37.6 K. The critical current density J_c calculated according to the Bean model are about 2.0 × 10⁵ A/cm² at 20 K in self-field and 1.0 × 10⁵ A/cm² at 20 K in 1 T applied field.