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Over the past few decades, tetrafluoroethane (TFE, R134a Freon)-based gases have been widely used in the operation of phenolic resistive plate chambers (RPCs) in many high-energy experiments. However, TFE has a high global warming potential (GWP); therefore, a search for new eco-friendly gases to replace traditional TFE-based ones is now unavoidable. In this research, we present cosmic-ray test results of a prototype RPC for the SHiP (search for hidden particles) experiment using 1.6- and 1.4-mm-thick RPC electrodes containing mixtures of various gases, including 1,3,3,3-tetrafluoropropene (HFO1234ze), CO2, iC4H10 and SF6. We compare the performance data gathered with these new gas mixtures with those gathered with a traditional TFE-based gas used for RPCs in compact muon solenoid (CMS) and a toroidal LHC apparatus (ATLAS) experiments. The addition of CO2 to the HFO1234ze-based gas was found to be fairly effective in reducing the working-point high voltage (HVWP) for RPC operation. The results of our experiments lead us to the conclusion that adding 40% CO2 or less, when combined with HFO1234ze-based gas, is conducive to reliable detector performance for SHiP single-gap phenolic RPCs.

The main goals of the Search for Hidden Particles (SHiP) experiment are to observe hidden particles and to run a high-statistics study of tau neutrino events. Two different types of resistive plate chambers (RPCs) will be used in the future SHiP experiment: one for triggers to select the decayed muons emitted via tau neutrino interactions and one for precision time measurements of charged particles, which are expected from the decays of hidden particles. In the present research, we constructed and tested a prototype RPC module to study the fundamental detector performance of the muon trigger RPCs in the tau neutrino detector of the SHiP experiment. The required detector characteristics, such as the intrinsic noise rate, the time response, and the spatial resolution, were proven through the test of the present prototype detector with cosmic muons.

In this paper, we introduce a novel on-chip capacitive sensor design and a motion estimation method for measuring multi-axis out-of-plane tilting motion of a micro-stage that is used for in situ calibration of an integrated MEMS gyroscope. On-chip sensing and motion estimation is critical for this application, since precision in measuring high frequency tilting motion of the micro-stage determines how accurately an on-stage MEMS gyroscope can be calibrated in the field with respect to this motion. To obtain decoupled sensing signals from multi-axis out-of-plane tilting motion, a capacitive sensing layout with high off-axis signal rejection capability is introduced. With the proposed design specifications and range of tilting motion, a dual axis capacitive sensor model is developed, and simulation results show that the sensor is able to reject more than 99.90% of the off-axis signal. The sensor also permits detection of perturbations to stage geometry due to ambient temperature variation through the effects of nonlinear behavior on signal timing. To measure tilting motion with the obtained sensing signal, a motion estimator with extended Kalman Filter (EKF) is also developed. With assistance of a laser Doppler vibrometer (LDV), experiments are performed to identify the parameters of the motion estimator and validate its performance. The experimental results demonstrate a 286 ppm error in scale factor calibration of a commercial MEMS gyroscope by the micro-stage with moderate temperature variation.

We report record-high performance from a fused-silica micro Precision Shell Integrating (PSI) gyroscope. The PSI gyroscope uses a fused-silica resonator with a diameter of 1 cm and a mechanical quality factor (Q) of 5.2 million. The gyroscope has an angle random walk (ARW) of 0.00016 deg/√hr and short-term in-run bias instability of 0.0014 deg/hr without any temperature compensation. This performance for such a small shell gyroscope compares well with the larger mHRG and HRG devices reported previously. This performance, in a device this small, is achieved by optimizing the fabrication of the shell resonator so it provides high Q, large mass, high frequency resonance, and low as-fabricated frequency mismatch.

This paper reports the design, fabrication technology and initial testing results of an all fused-silica 3D shell (hemispherical) resonator and capacitive drive/sense electrodes made from a second shell, for use in high-performance gyroscopes. A single fused-silica shell is patterned to form multiple electrodes that follow the curvature of the shell resonator. 10 mm diameter Shell resonator is then integrated inside a larger Shell electrode (SiS). Our approach enables, for the first time, the fabrication of curved electrodes at the micro-scale. The SiS device provides large overlap area and nearly uniform gap with large capacitance for better frequency tuning capability, reduced operating voltages, improved capacitive sensitivity and reduced temperature sensitivity as compared to other electrode architectures. Successful fabrication and testing of two prototype SiS devices are demonstrated. Quality factor as high as of 0.4 Million and frequency split as low as 1.3 Hz is obtained at operating frequency of ~ 6000 Hz.

This paper reports measured results for a fused-silica precision shell integrating (PSI) micro gyroscope employing out-of-plane drive/sense transduction mechanism. The PSI gyroscope is made with a 5 mm radius shell resonator operating in $n=2$ wine-glass mode at a frequency ( $f_{n=2}$ ) of 5.803 kHz with as-fabricated frequency split ( $\Delta f$ ) of 2.1 Hz. Large and reasonably uniform capacitance (∼0.25 pF) is achieved with flat surface electrodes. The gyroscope is operated in the force-rebalance mode by interfacing with an ultra-low-noise transimpedance amplifier (TIA). Near-navigation grade angle random walk (ARW) of $0.0062\ \deg/\sqrt{\mathrm{h}}\mathrm{r}$ , in-run bias instability (BI) of 0.027 deg/hr and scale factor of 158 mV/deg/s without any temperature compensation are achieved.

This paper presents a modular and generic micromachined oven-control system for use with miniature micro-electro-mechanical system (MEMS) transducers. The micro-oven-controlled off-the-shelf commercial six-axis MEMS inertial measurement unit (IMU), Invensense MPU-6050, provides the lowest reported temperature-induced root of sum of squares bias errors of 62.71°/h and 1.920 mg from -40°C to 85°C for three-axis gyroscopes and three-axis accelerometers, respectively. The micro-oven control system provides thermal isolation from the surrounding environment using a micro-machined isolation platform, vacuum-sealing, and a metal package. In addition, a CMOS temperature sensor, a proportional-integral-derivative-based temperature control scheme, and least mean square and random forest compensation algorithms are utilized to reduce temperature-induced bias drifts of IMUs. The most stable axes achieve peak-to-peak bias drifts of 12.78°/h and 665.2 ug during a thermal-cycle test for gyroscopes and accelerometers, respectively. The oven's heater power consumption is

In the past several decades, many studies have been conducted to search for non-baryonic dark matter, such as weakly interactive massive particles (WIMPs). In the search for WIMPs, charged particles incident on the detector are background particles because WIMPs are neutral. Charged particles originate from various sources, such as cosmic rays and laboratory materials surrounding the main detector. Therefore, a veto that discriminates charged particles can improve the particle-detection efficiency of the entire experiment for detecting WIMPs. Here, we investigate in the thickness range of 1 mm to 5 mm, the optimal thickness of a polystyrene scintillator as a chargedparticle veto detector. We found that 3-mm-thick polystyrene provides the best performance to veto charged particles and the charged-particle background in the search for the WIMP signal. Furthermore, we fabricated 3-mm-thick and 5-mm-thick polystyrene charged particle veto detectors that will be used in an underground laboratory in the search for WIMP dark matter. After exposing those detectors are the actual beam line, we compared the rate of charged particles measured using those detectors and the rate simulated through a Monte Carlo simulation.

High energy cosmic rays are one of the biggest concerns for a detector used in space and manned spaceflight, along with the swift development of the high energy experiments in space and spaceflight enterprise, the research of shielding materials against high energy cosmic rays has become increasingly important. In this study, firstly we defined a simple detector in the form of human body, some shielding materials and the geometry of shielding structure, then we comprehensively considers the radiation shielding properties of various materials together with the consideration of mass problems of shielding materials. The radiological protection capability of materials against certain higher energy cosmic ray was appraised from the perspectives of radiation dose. The results concluded under the same level of mass of shielding materials, it is advantageous to employ the composites and non-metal materials as shielding materials than using metal or alloy. For practical application, the cabin wall of spaceship is usually consisted with multi-layers. The calculation result shows that a multi-layers cabin wall that has low density layer-high density layer-low density layers structure has a more ideal shielding effect.

For the several decades, the non-baryonic dark matter has been searched in many ways and by many research teams. Non-baryonic dark matter is known as a weakly interaction and neutral particle. In the direct detection ways, it is not easy to identify a non-baryonic dark matter from other particles, such as gamma ray and neutron, due to its electric neutrality. So, the identification of neutral particle is an essential part for the direct detection method of dark matter in a cosmic ray free laboratory with a detector made of radioactive free materials. A pulse shape discrimination (PSD) method was introduced more than fifty years ago. And it has been used by various elementary particle experiments. We need a more precise PSD method to detect directly dark matter interacting rarely. We can see the primary and the secondary signals in the scintillation produced by an elastic scattering between an incident particle and a target atom. The primary signal is composed of the scintillations from an excitation process of target nuclear and an ionization process of target atom while the secondary signal is composed of scintillation from ionization process, only. The ratio of scintillations from excitation and ionization processes gives the clue to identify the neutral particles. Here, we introduce an improved way to separate the primary signal into the scintillations induced by excitation and ionization processes through the elastic scattering between a target atom and a non-baryonic dark matter. This separation of primary signal can provide a big hint to identify a non-baryonic dark matter.

The fabrication of shell resonators for vibratory gyroscopes is often accompanied by a split between drive and sense mode frequencies. To tune these frequencies and reduce the frequency split, a voltage can be applied between the shell and electrodes placed around it. This paper investigates electrostatic frequency tuning in shell resonators as a function of voltage, capacitive gap between the shell and electrode, electrode span angle and height, and electrode placement and configuration using a numerical approach. The results of this investigation show that conformal electrodes placed around the shell rim with a uniform gap provide the best tuning capability. Considering fabrication challenges and shell aspect-ratio, other electrode configurations might be more practical in some devices, although they have worse tuning capability.

We report a vacuum-packaged fused-silica (FS) micro birdbath shell resonator gyroscope (BRG) with near-navigation-grade in-run (evaluation duration $ day) bias stability of 0.0103 deg/h (at room temperature without temperature stabilization). The BRG utilizes a 5mm diameter birdbath (BB) resonator with $n=2$ wineglass mode $f=10.5436\ \mathrm{kHz}$ and original frequency split $(\Delta f)=6\ \text{Hz}$ :. The BRG is encapsulated in an LCC package and has an excellent $Q$ (1.54 million) and decay time constant $(r=46\ \mathrm{s})$ after near mode matching. The performance is believed to be limited by the noise from readout-and-control circuitry. The bias stability of this device is among the best reported values for micro-scale vibratory gyroscopes today.

This paper examines major contributions to error when calibrating a microelectromechanical system (MEMS) gyroscope using a miniature vibratory micro-stage. Calibration via this micro-stage has been previously introduced by the authors to provide a reference stimulus, allowing gyroscope scale factor to be calibrated repeatedly over time. This requires that the reference stimulus can be measured with extremely high accuracy. Scale factor calibration to errors a few hundred parts per million has been demonstrated. However, determination of limiting factors for calibration performance remains of great importance for future device improvement. In this paper, the gyroscope model, stage dynamics, and calibration approach are briefly described. Then, sensitivity of calibration errors to underlying stochastic and parameter identification errors is analyzed. Analysis results indicate that even when signal-to-noise ratio is sufficient to for high accuracy (

This paper presents the design and experimental results of a microvibratory actuation and sensing platform to provide on-chip physical stimulus for in situ calibration of long-term scale factor drifts in multiaxis microelectromechanical systems (MEMS) inertial sensors. The platform consists of a three degrees-of-freedom micromotion stage that can provide piezoelectric actuation for X / Y -tilting reference stimuli, compensation of undesired off-axis motion, integrated sensing of applied periodic stimulus, and electrostatic position lock-down for shock protection. A dual-axis MEMS gyroscope is mounted on top of the microplatform, and its electrical interconnects are provided through microfabricated highly flexible parylene cables with virtually zero-loading. The piezoelectric stage is measured to provide up to 280°/s angular ac excitation to a 25-mg inertial sensor payload at an expense of

This paper describes a generic, ultra-low-noise transimpedance amplifier (TIA) for capacitive MEMS sensors. The TIA obtains both very low input referred current noise (5.12 fA/VHz) and wide dynamic range (123 dB) by employing a digitally-controlled floating resistor, a voltage-and-temperature tolerant current generator, and low-noise operational amplifier (op-amp). The floating resistor allows the amplifier to obtain excellent output linearity and obtain a wide dynamic range. An integrated digital controller of the current generator lowers the TIA noise by reducing the amount of fluctuation in the resistance of the floating resistor by eliminating the transmission of control voltages for the floating resistor through a bonding pad. A beta-multiplier current reference circuitry with a resistor with low temperature coefficient of resistance (TCR) generates bias current with very low sensitivity to variations in supply voltage and temperature. A two-stage Miller-compensated op-amp with optimized transistor dimensions is designed. The prototype chip was fabricated using a 0.18 μm standard CMOS process with 1.8 V supply voltage. The circuitry is evaluated with a high performance vibratory MEMS gyroscope and excellent bias stability (0.04 deg/h) is measured.

We report the latest experimental results from a fused-silica Birdbath Resonator Gyroscope (BRG) with a quality factor of 419k and a resonant frequency of 9030 Hz. The BRG and its readout/control system achieve an angle random walk (ARW) of 0.00126 deg/√hr and a bias stability of 0.0391 deg/hr. These results were obtained using a force-rebalanced control architecture without temperature control or additional compensation. The ARW and bias stability are further improved by driving the resonator at displacements near 10% of the nominal electrostatic gap. The low gyroscope noise is attributed to a relatively large measured scale factor of 100 mV/deg/s.

This paper reports characterization of a micro actuation and sensing platform for on-chip scale factor measurement and calibration of generic MEMS inertial sensors. The platform has a unique 6-DOF-motion capability that is used to deliver calibration stimuli with minimum off-axis motion, simultaneous excitation of multiple calibration axes, and on-chip measurement of acceleration sensitivities of the tested IMU. The microsystem is demonstrated to provide rotational calibration references with less than 15–30 ppm short-term instability for characterization of scale factor of a commercial gyroscope load in its full sensing range.

A capacitive sensor design is introduced with an associated method for constructing a trusted threshold crossing angle (θ TH ) from the capacitance profile to perform precise measurement of the out-of-plane (X and Y) tilting angles of a 6 degree of freedom (DOF) piezoelectric actuation stage for in situ calibration of micro electromechanical (MEMS) gyroscopes. The capacitance vs. tilting angle relationship of the sensor is calibrated with the assist of an external Laser Doppler vibrometer (LDV) and a closed-form model of the sensor. The θ TH are extracted by detecting the crossing location of the reconstructed capacitance trajectories using measurement from LDV or on-chip capacitive sensor, the comparison shows close agreements. The experimental results demonstrate: (a) the on-chip capacitive sensor is able to track the tilting motion with high accuracy; (b) the θ TH extracted from on-chip capacitive sensor can serve as an invariant reference point for scale factor calibration of MEMS gyroscopes.

This paper introduces a digital pulse width modulation technique for MEMS oven-control system. The proposed method generates digital, pulse width modulated signals from analog signals produced by a proportional-integral-derivative controller. This technique, therefore, provides good digital properties, such as better design scalability and higher power efficiency. These advantages are confirmed with an oven-control system for a commercial 6-axis inertial measurement unit. As a result, the oven-control system is fabricated on a single printed circuit board measuring 42mm×42mm×10mm and the power efficiency is increased to 94.4%. The entire system shows ±1.8ppm frequency drift during a thermal-cycle test, from −40°C to 85°C with the rate of the change 1°C/min.

The performance of a commercial 6-axis (3-axis accelerometer and 3-axis gyroscope) MEMS inertial measurement unit (IMU) has been improved by a factor of >300x by utilizing a low-power ovenized microsystem. The IMU is thermally isolated from the external ambient by mounting it on a custom-designed micro-machined glass platform and packaging it in vacuum. In the present study, a microcontroller and voltage-controlled current source are assembled together with the thermally-isolated packaged IMU on a printed circuit board. The entire system is thermal-cycled over a temperature span from −40°C to 85°C. Both temperature control (i.e., ovenization) and compensation are used to reduce bias drift due to temperature change. The measured frequency drift of the IMU is improved by a factor of 950x and stabilized to ±2ppm, and the bias drift of the IMU is reduced to 60 °/hr for one of the gyroscope axes, and 1.7 mg for one of the accelerometer axes.

A 9-bit 110-MS/s pipelined-SAR ADC is proposed. To alleviate the design tradeoff between conversion rate and power consumption, the design adopts a voltage-mode open-loop amplifier and a time-interleaved SAR architecture with comparator sharing. The ADC simulated in a 65-nm CMOS technology achieves an ENOB of 8.63 bits near the Nyquist input frequency at the sampling rate of 110MS/s. The power consumption is 7.9mW, resulting in 181.3fJ/conversion-step of Figure of Merit (FoM).

Eu-doped In2O3 (EIO) thin films were deposited by radio-frequency magnetron sputtering on glass substrates with varying growth temperatures. All the EIO thin films showed a significant dependence on the growth temperature. From the figure of merit index data, the optimum growth temperature for depositing high-quality EIO thin films was found to be 300 degrees C. The ELO thin film deposited at 300 degrees C showed a highly preferential growth orientation along the (222) plane with an average particle size of 160 nm, bandgap energy of 3.94 eV, average optical transmittance of 65.2% in the wavelength range 450-1100 nm, and electrical resistivity of 2.5 x 10(-3) Ω cm. These results indicate that the electrical and optical properties of EIO thin films can be modulated by controlling growth temperature.