Jonathan R. Tedeschi

Single-electron detection and spectroscopy via relativistic cyclotron radiation

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Although first derived in 1904, cyclotron radiation from a single electron orbiting in a magnetic field has never been observed directly. We demonstrate single-electron detection in a novel radio-frequency spectrometer. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta electron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay end point, and this work demonstrates a fundamentally new approach to precision beta spectroscopy for future neutrino mass experiments.

Design considerations for high-Q bandpass microwave oscillator sensors based upon resonant amplification

A series of microwave resonant oscillator sensors were designed and characterized using bandpass planar and volumetric electrical resonators having loaded quality factor (Q) values in the range of 2 to 20. The use of these resonators in positive feedback circuits yielded sensor Q-factors of up to 2 × 107, demonstrating Q-factor amplifications on the order of 106. It is shown that the Q-factor amplification can be increased in a positive feedback system through the selection of feedback loop group delay, allowing use of resonators with lower static, loaded Q-factor values. A low-frequency electromagnetic interference sensing application is demonstrated for two resonant oscillator configurations, showing considerable frequency sensitivity to 45 kHz emitters.

Wide-bandwidth, wide-beamwidth, high-resolution, millimeter-wave imaging for concealed weapon detection

Active millimeter-wave imaging is currently being used for personnel screening at airports and other high-security facilities. The cylindrical imaging techniques used in the deployed systems are based on licensed technology developed at the Pacific Northwest National Laboratory. The cylindrical and a related planar imaging technique form three-dimensional images by scanning a diverging beam swept frequency transceiver over a two-dimensional aperture and mathematically focusing or reconstructing the data into three-dimensional images of the person being screened. The resolution, clothing penetration, and image illumination quality obtained with these techniques can be significantly enhanced through the selection of the aperture size, antenna beamwidth, center frequency, and bandwidth. The lateral resolution can be improved by increasing the center frequency, or it can be increased with a larger antenna beamwidth. The wide beamwidth approach can significantly improve illumination quality relative to a higher frequency system. Additionally, a wide antenna beamwidth allows for operation at a lower center frequency resulting in less scattering and attenuation from the clothing. The depth resolution of the system can be improved by increasing the bandwidth. Utilization of extremely wide bandwidths of up to 30 GHz can result in depth resolution as fine as 5 mm. This wider bandwidth operation may allow for improved detection techniques based on high range resolution. In this paper, the results of an extensive imaging study that explored the advantages of using extremely wide beamwidth and bandwidth are presented, primarily for 10-40 GHz frequency band.

Three-dimensional millimeter-wave imaging for concealed threat detection in shoes

This paper describes a study performed at the Pacific Northwest National Laboratory which investigated the use of active millimeter-wave radar imaging to perform threat detection in non-divested shoes. The purpose of this study was to determine the optimal imaging system configuration for performing this type of task. While active millimeter-wave imaging systems have proven to be effective for personnel screening, the phenomenology associated with imaging within a heterogeneous medium, such as a shoe, dictates limits for imaging system parameters. Scattering, defocusing, and multipath artifacts are significantly exaggerated due to the high contrast index of refraction associated with the boundary at the air and shoe interface. Where higher center-frequency and bandwidth result in much improved lateral and range resolution in the body scanning application, smaller wavelengths are significantly defocused after penetrating the sole of the shoe. Increased bandwidth, however, is essential for the shoe scanning application as well. Obtaining fine enough depth resolution is critical in separating the scattering contribution of each layer of the shoes in range to isolate possible threats embedded within the sole. In this paper, the results of a study to optimize the following imaging system parameters are presented: antenna illumination beamwidth, antenna polarization, transceiver bandwidth, and physical scanning geometry.

Fully polarimetric differential intensity W-band imager

We present a novel architecture based upon a Dicke-switched heterodyne radiometer architecture employing two identical input sections consisting of horn and orthomode transducer to detect the difference between the horizontal (H) and vertical (V) polarization states of two separate object patches imaged by the radiometer. We have constructed and described previously a fully polarimetric W-band passive millimeter wave imager constructed to study the phenomenology of anomaly detection using polarimetric image exploitation of the Stokes images. The heterodyne radiometer used a PIN diode switch between the input millimeter wave energy and that of a reference load in order to eliminate the effects of component drifts and to reduce the effects of 1/f noise. The differential approach differs from our previous work by comparing H and V polarization states detected by each of two input horns instead of a reference load to form signals ΔH and ΔV from adjacent paired object patches. This novel imaging approach reduces common mode noise and enhances detection of small changes between the H and V polarization states of two object patches, now given as difference terms of the fully polarimetric radiometer. We present the theory of operation, initial proof of concept experimental results, and extension of the differential radiometer to a system with a binocular fore optics that allow adjustment of the convergence or shear of the object patches as viewed by the differential polarimetric imager.

Passive fully polarimetric W-band millimeter-wave imaging

We present the theory, design, and experimental results obtained from a scanning passive W-band fully polarimetric imager. Passive millimeter-wave imaging offers persistent day/nighttime imaging and the ability to penetrate dust, clouds and other obscurants, including clothing and dry soil. The single-pixel scanning imager includes both far-field and near-field fore-optics for investigation of polarization phenomena. Using both fore-optics, a variety of scenes including natural and man-made objects was imaged and these results are presented showing the utility of polarimetric imaging for anomaly detection. Analysis includes conventional Stokes-parameter based approaches as well as multivariate image analysis methods.

Wideband archimedean spiral antenna for millimeter-wave imaging array

This paper discusses the design of a wide-bandwidth, wide-beamwidth, cavity-backed Archimedean spiral antenna for use in 10–40 GHz holographic radar imaging arrays. Simulated and measured performance characteristics are presented along with millimeter-wave radar images obtained with the antenna arrays for security screening applications.

Project 8 Phase III Design Concept

We present a working concept for Phase III of the Project 8 experiment, aiming to achieve a neutrino mass sensitivity of

Results from the Project 8 phase-1 cyclotron radiation emission spectroscopy detector

2~\mathrm{eV}

New Improvements to Millimeter-Wave Body Scanners

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