Session Q45: Advances in Detectors and Their Electronics

Probing fluid-cells-substrate nanoscale interactions using digital holographic interferometry and WiMTiP sensor

Measuring surface deformation is of great interest in areas including physics, material science, surface engineering, and biology. Among many, non-intrusive optical methods have advantages. We proposed a new method for measuring nano-deformation by combining a wrinkle-free nm thin film in polymer (WiMTiP) nano-strain sensor and Mach-Zehnder interferometry. A nm-thick smooth reflective thin film embedded in a polymer matrix acts as a flexible mirror and subsequently reflects a collimated coherent light to form the perturbed objective beam. It interferes with the unperturbed reference beam to form an interferogram. Any stress acting on the sensor deforms the embedded flexible mirror as changes in fringe spacings and subsequently encodes the deformation. To extract the deformation from interference pattern, a novel integration method, a.k.a. local-growing omni-directional integration is introduced whereby multiple integration paths with various lengths are generated to perform path integrations. Three applications will be discussed including the wetting of sessile water droplets over functional surfaces, the evaporation of droplets on soft surfaces, and cancer cell detection using WiMTiP microfluidic platform.

    

Direct Detection for Dark Field X-ray Microscopy

The recent development of a US based dark field x-ray microscopy technique has opened up investigation into mesoscopic interactions in a myriad of materials. Even with high efficiency optics, some diffracted signals are often too weak to detect using the current scintillation based methods of imaging. We present here an amorphous-Se detector with small pixel size and high efficiency detection in the hard x-ray energy regime of 15 keV and beyond. Resolution, exposure times and feature detection capabilities are reported and compared against current optical detection methods.   

Low Power Kinetic Inductance Traveling wave parametric amplifiers

A quantum-limited amplification chain is attractive for any application that requires the detection of faint electromagnetic signals. Reading out arrays of superconducting resonators, calls for large bandwidth amplifiers in addition to having the lowest possible noise. At millikelvin temperatures, Kinetic Inductance Traveling-Wave Parametric Amplifiers (KI-TWPAs) working in 3-wave-mixing (3WM) and fabricated from a 20 nm thick NbTiN film have shown to operate close to the quantum limit [1]. However, they still require fairly high pump power, and the pump must be isolated from the device under test by components that unavoidably insert loss, thereby degrading the noise performance of the chain. An amplifier functioning with a lower pump power would necessitate fewer of these nefarious isolating components. One solution is to use thinner superconducting films, because the nonlinearity of the kinetic inductance increases with decreasing film's thickness. In this contribution, we report the design and the first characterization results of a 3WM KI-TWPA based on NbTiN films with a thickness less than 20 nm.   

Positron Charge Sensing Using Two-Dimensional Materials

Traditionally, Positron Annihilation Spectroscopy (PAS) uses the detection of 511 keV photons that are emitted following a positron and an electron collision and annihilation. We aim to extend the utility of PAS by using charge-sensing devices. We fabricate sensitive field-effect transistors based on two-dimensional materials such as graphene, which are used as sensitive charge probes. Our devices measure the accumulated positive charge caused by the annihilation events in the solid and can be used in the future as tools for the study of positrons in solids [1,2].

We utilized a high-mobility double-gated graphene field-effect transistor to measure the accumulated charge created by positron annihilation in its back-gate. I will describe the use of graphene devices under DC, reaching a positron current sensitivity of 1.2 fA/√Hz, <!--[if gte msEquation 12]> lang=EN-US style='font-size:12.0pt;font-family:"Cambria Math",serif;
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mso-bidi-theme-font:major-bidi;mso-ansi-language:EN-US'> style='mso-bidi-font-style:normal'>Hz detected over 20 min [1]. I will also describe our RF devices, reaching a sensitivity of 0.01 fA/√Hz, corresponding to ~100 positrons/sec. In these RF graphene-based devices, the graphene is coupled to a waveguide and is integrated as an RF resonator, where annihilation events are detected through changes in the graphene RF reflection coefficient S11. It is designed for charge-detection of positrons in micro-second time-resolution, aiming to detect single positron annihilation events. Using a table-top ²²Na positron source, we demonstrate the utility of two-dimensional layered materials as probes for the charging dynamics of positrons in solids. In the future, we intend to integrate these devices inside the SPOT-IL slow positron beam [3, 4], built at the Hebrew University of Jerusalem.   

Fast Neutron Scintillation from Ga2O3 Crystals for Radiation Detection

Gallium oxide (Ga₂O₃) is a newly emerged ultrawide bandgap (4.9 eV) semiconductor with many applications in deep UV optoelectronics, extreme condition radiation detection and power switching devices. While Ga₂O₃ can be grown via molecular beam epitaxy, it can also be grown from melt using Bridgman technique, thus lower the cost.  The large bulk of Ga₂O₃ crystal is particularly suitable for radiation detection. However, a direct optical observation of fast neutron scintillation from Ga₂O₃ crystal is in short supply.

We report fast neutron scintillation from furnace grown bulk Ga₂O₃ crystal. We conducted our experiment at Los Alamos Neutron Science Center (LANSCE) 4FP60R beamline with neutron energy 1 -- 800 MeV. We used a fiber coupled optical spectrometer to observe scintillation spectrum, and we located a spectral peak at 365 nm wavelength. We used a PI-MAX 4 intensified camera from Princeton Instruments to directly image scintillation photon emission pattern, and we observed bright scintillation images. Comparative calibration showed that the scintillation efficiency was approximately 30,000 photons per MeV. We are conducting further data analysis on neutron energy dependent scintillation efficiency.   

    

Author not Attending

We present characterization studies of scintillating tiles with signals read out using silicon photomultipliers (SiPMs) for use in a high-granularity calorimeter in the future Electron-Ion Collider. Using cosmic rays, we study the light yield and timing resolution of various SiPM-on-tile configurations and geometries. We have also mounted a collimated radiation source and LED to 2D stage stepper motors to study the signal uniformity within a tile, and the cross-talk between adjacent cells. In addition, we tested a 3D printed frame structure for its ability to isolate signals between cells. I will summarize the present status and plans for R&D on SiPM-on-tile technology for the EIC and discuss the resulting physics performance that it can yield.   

Superconducting nanowire resonators with circular cross-section.

We report on a significant advance in implementing vibrating nanowire resonators as mechanical probes in helium superfluids as bolometers, thermometers and detectors of turbulence. Nanomechanical resonators produced lithographically typically have a flat, rectangular cross-section. Sharp edges result in velocity enhancement for potential flow reducing the operational velocity before exceeding the critical velocity. A circular cross-section can operate at higher velocities and allows for a robust description of the flow dynamics. The wires are made by drawing multifilament superconducting cables through a series of diamond dies to the desired diameter. The filaments of the cable are isolated by etching the copper matrix and then transported to a desired location to form an electro-mechanical resonator. We have characterised superconducting nano-mechanical vibrating wire resonators with diameters in the range from 200 nm to 1 µm and lengths of up to 2 mm. The nanowires have been tested in superfluid helium-4, superfluid helium-3 and helium-3 gas. We have measured critical temperatures and critical currents for varying diameters of the wires. Resonant frequencies are typically in the range of 1-20 kHz and the contact resistance between a nanowire and an aluminium bond wire has been measured to be no more than 30 mOhm. In our current work these wires will be used as probes within a superfluid helium-3 dark matter detector.

    

Potential for Open-charm Meson Measurements at Jefferson Laboratory

The inner structure of the proton and heavy nuclei, even in the high Bjorken-x valence region, is not well understood and the root of many open questions in nuclear physics. The study of exotic meson production, such as open-charm production from charmonium, experimentally tests our understanding of hadron structure. Using Monte Carlo simulations and hadronization models we estimate acceptance rates for certain open-charm production events for various detector geometries. For example, the CEBAF electron-ion collider at Jefferson Lab is a candidate to observe such events, especially after the upcoming high energy upgrade. We also explore the potential benefits that a muon (and neutral hadron) forward calorimeter system would bring to these studies by tagging muons and neutrons from charmed baryons. We present a possible design and simulated performance of the implementation of such as system in a cost effective method with plastic scintillator and silicon photomultiplier readout. Such a design is also applicable to the upcoming Electron Ion Collider which will open new avenues of discovery.   

Cold Electronics Develpment for the Next Generation Axion Dark Matter eXperiment

The Axion Dark Matter eXperiment - Extended Frequency Range (ADMX-EFR) is a next generation microwave cavity haloscope experiment, which will search for axionic dark matter at DFSZ sensitivities in the 2 - 4 GHz frequency range. Optimizing noise performance in the first stage cold electronics is critical for achieving high scan speeds at our target sensitivities. At Washington University, we are developing this first stage cold amplifier system needed to amplify an axion signal above the background electrical noise. We will discuss our efforts in designing a system that can improve scan speeds through vacuum squeezing and the flux pumped Josephson parametric amplifiers (JPAs) capable of achieving this.   

Author not Attending

Detecting relic neutrinos is a longstanding goal in fundamental physics. It is one of the predictions of the Standard Model that has not been yet confirmed. Additionally, it carries a photographic image of the early Universe, albeit from a much older epoch of neutrino decoupling.

The conventional approach to this problem is to search for the peak in the spectrum of electrons emitted in a beta-decay. Experimentally, this goal is extremely challenging as the required energy resolution is defined by the tiny neutrino masses (~10 meV).  While it seems possible to achieve a required energy resolution of the measuring apparatus, the intrinsic physics of the beta-emitting source imposes additional limitations. ??The current consensus is that sufficient statistics together with the clean spectrum could only be achieved if beta decayers are attached to a solid state substrate. If one wants to keep the energy resolution as high as the mass of the neutrino, one needs to account for the presence of the solid state environment.

This opens a whole new field of research in surface physics, both experimental and theoretical.  I will outline the main directions  and questions to be addressed  and their implications for the design of the full scale relic neutrino  experiment.   

Dynamic strain measurements in bulk acoustic resonators with stroboscopic x-ray diffraction microscopy

We report direct observation of gigahertz dynamic strain in a microfabricated bulk-acoustic wave device containing diamond nitrogen-vacancy (NV) centers using stroboscopic scanning hard X-ray diffraction microscopy at the Advanced Photon Source. Color centers, like the NV center, have emerged as an essential platform for quantum sensing and quantum networking. Static lattice strain can tune the spin and orbital Hamiltonians, whereas dynamic strain enables quantum control or hybrid coupling of color centers and a resonator. We image both static and dynamic strain in within an NV center-coupled acoustic resonator with picosecond temporal resolution and nanometer spatial resolution. Our experiments provide a direct view of the diamond strain environment in our devices, which sheds light on their behavior, limitations, and a pathway for improvements. We also correlate the direct strain measurements with spin measurements of the NV centers within these devices.   

Author not Attending

Vibrations induced from a pulse tube cryocooler have been shown to degrade coherence time on qubits, limit resolution on cryogenic microscopy, and limit base temperature of dilution refrigerators. Traditionally, vibration is decoupled from ultra-low temperature cryogenics using thermally conducting foils, braids, or wires. These isolation techniques have been shown to be insufficient for sensitive measurements. A novel vibration isolation platform is developed and installed in a Maybell dilution refrigerator that suspends the lower three stages of the dilution refrigerator off three sets of leaf springs and polymer ropes. The vibration performance is measured and compared to ANSYS simulations.   

An in-situ Strain Manipulation Stage

Complex transition metal oxides, because of their correlated d electrons, feature a rich phase diagram of interplay between spin, charge, and orbital degrees of freedom. It has been demonstrated that strain engineering is a powerful tool in the exploration of this phase diagram. However, the strain achievable by existing techniques is limited to either discrete/small ^[1][2] values or specific symmetries/directions ^[3][4]. Recent advances in strain tuning capabilities of freestanding oxide membranes have demonstrated the potential in realizing continuous control of strain in arbitrary symmetries ^[5][6]. In this work, we report our recent development of an in-situ mechanical manipulation stage and illustrate its capabilities with preliminary results of tuning prototypical oxides.

 

 

[1] D. G. Schlom et al., Annu. Rev. Mater. Res. 37, 589–626 (2007).

[2] C. R. Zhu et al., Phys. Rev. B, 88, 121301 (2013).

[3] K. Edalati, Adv. Eng. Mater. 21, 1800272 (2019).

[4] H. H. Kim et al., Science 362, 1040–1044 (2018).

[5] S. S. Hong et al., Science 368, 71 (2020).

[6] R. Xu et al., Nat. Commun. 11, 3141 (2020).