Statistical tools for analysis of the performance of a high resistance measurement bridge

Il rapporto tecnico descrive l’utilizzo delle varianze di Allan e della densità di potenza spettrale per individuare le sorgenti di rumore che si possono riscontrare nel funzionamento del ponte di Wheatstone modificato di alta resistenza di tipo commerciale. Lo studio è stato condotto osservando le misure di corrente del detector del ponte in funzione del tempo di integrazione del medesimo. Da un’analisi preliminare dei dati ottenuti sono stati individuate le principali sorgenti di rumore del sistema in corrispondenza dei tempi di integrazione del detectorThe technical report exploits the use of Allan variances and the spectral power density to analyze the performance of the high resistance measurement Wheatstone modified bridge of commercial type. The study was performed by observing the current measurements of the bridge detector as a function of its integration time. From a preliminary analysis of the data obtained, the main sources of noise of the system have been identified in correspondence with the integration times of the detector

Practical quantum realization of the ampere from the electron charge

One major change of the future revision of the International System of Units (SI) is a new definition of the ampere based on the elementary charge \emph{e}. Replacing the former definition based on Amp\`ere's force law will allow one to fully benefit from quantum physics to realize the ampere. However, a quantum realization of the ampere from \emph{e}, accurate to within $10^{-8}$ in relative value and fulfilling traceability needs, is still missing despite many efforts have been spent for the development of single-electron tunneling devices. Starting again with Ohm's law, applied here in a quantum circuit combining the quantum Hall resistance and Josephson voltage standards with a superconducting cryogenic amplifier, we report on a practical and universal programmable quantum current generator. We demonstrate that currents generated in the milliampere range are quantized in terms of $ef_\mathrm{J}$ ($f_\mathrm{J}$ is the Josephson frequency) with a measurement uncertainty of $10^{-8}$. This new quantum current source, able to deliver such accurate currents down to the microampere range, can greatly improve the current measurement traceability, as demonstrated with the calibrations of digital ammeters. Beyond, it opens the way to further developments in metrology and in fundamental physics, such as a quantum multimeter or new accurate comparisons to single electron pumps.Comment: 15 pages, 4 figure

The Telecommunications and Data Acquisition Report

Archival reports are given on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA), including space communications, radio navigation, radio science, ground-based radio and radar astronomy, and the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, supporting research and technology, implementation, and operations. Also included is TDA-funded activity at JPL on data and information systems and reimbursable DSN work performed for other space agencies through NASA. In the search for extraterrestrial intelligence (SETI), implementation and operations for searching the microwave spectrum are reported. Use of the Goldstone Solar System Radar for scientific exploration of the planets, their rings and satellites, asteroids, and comets are discussed

NBS monograph

From Abstract: "This is a tutorial Monograph describing various aspects of time and frequency (T/F). Included are chapters relating to elemental concepts of precise time and frequency; basic principles of quartz oscillators and atomic frequency standards; historical review, recent progress, and current status of atomic frequency standards; promising areas for developing future primary frequency standards; relevance of frequency standards to other areas of metrology including a unified standard concept; statistics of T/F data analysis coupled with the theory and construction of the NBS atomic time scale; an overview of T/F dissemination techniques; and the standards of T/F in the USA. The Monograph addresses both the specialist in the field as well as those desiring basic information about time and frequency.

The Ionospheric Continuous-wave E-region Bistatic Experimental Auroral Radar (ICEBEAR)

The Sun drives many atmospheric processes on Earth through solar electromagnetic radiation, the solar wind, and the solar magnetic field. These solar phenomena interact with a region around the Earth where plasma can be formed, the ionosphere. This region is located 60–1000 km above the surface of the Earth, and is of interest to many scientists and engineers due to the interaction between radio waves and plasma. Variations in the ionospheric plasma density can cause disruptions to GPS signals and radio communications. Attempts have been made to measure the ionospheric plasma properties through the use of rockets, satellites, and remote sensing instrumentation. One of the issues with measuring the ionosphere, specifically the lower altitudes of the ionosphere, is that it is expensive to do in situ. Rockets are required for in situ measurements at altitudes of 90–150 km (the E-region of the ionosphere). Rocket launches are expensive, so more efficient remote methods of measuring the E-region are typically used. This includes radars utilizing radio waves to scatter from the ionospheric plasma. From the scattered signal, plasma properties can be derived to provide insight into the physical processes occurring. The Ionospheric Continuous-wave E-region Bistatic Experimental Auroral Radar (ICEBEAR) was developed to probe the E-region of the ionosphere using this mechanism. Through the use of modern radar hardware and techniques, it was possible to obtain simultaneously high temporal (down to 0.1 s) and spatial (≈ 1.5 km) resolution images of ionospheric plasma density perturbations over a 600 km × 600 km field of view. The radar operates at 49.5 MHz and transmits a continuous-wave, pseudo random noise, phase modulated code to obtain these images. The radar is bistatic, with both transmitter and receiver being located in Saskatchewan, Canada, and operated by the University of Saskatchewan. The radar was designed with future improvements in mind, where each transmitter and receiver antenna are individually controlled/sampled. This Ph.D. dissertation describes the dynamics of the ionosphere, the design and construction of ICEBEAR, and presents some preliminary results, exhibiting the exciting modern capabilities of the system

Data and systematic error analysis for the neutron electric dipole moment experiment at the Paul Scherrer Institute and Search for Axionlike Dark Matter

This thesis details work conducted as part of the experimental collaboration responsible for the neutron electric dipole moment (nEDM) experiment based at the Paul Scherrer Institute (PSI). The nEDM is a sensitive probe of a broad range of new CP violating physics beyond the standard model, however it remains elusive: while historic experiments since 1951 have increased in sensitivity by over six orders of magnitude, a nonzero nEDM is yet to be detected. Many theories of physics beyond the standard model predict neutron EDMs of a size that would be detectable by current and next generation experiments, and it has been said that measurements of the neutron EDM have ruled out more theories than any other experiment. One explanation of the smallness of the neutron EDM, the Peccei-Quinn theory, invokes a novel particle, the axion, which is also a credible dark matter candidate. The axion is yet to be detected. The work covers three main areas. First, contributions to the data analysis technique used to analyse the main dataset to produce a new world-leading limit on the neutron EDM. Second, an auxiliary measurement campaign to map the magnetic field within the experiment's magnetic shields is described, and the analysis of these datasets to provide corrections for several critical systematic effects is presented. Finally, a novel analysis of the data taken at a previous-generation nEDM experiment is used to derive the first experimental limits on the coupling of axion-like dark matter particles to gluons is described. These exclusions are up to 1000 times stronger than previous results for cosmologically interesting 10-22 eV axions

An AFM-SIMS Nano Tomography Acquisition System

An instrument, adding the capability to measure 3D volumetric chemical composition, has been constructed by me as a member of the Sánchez Nano Laboratory. The laboratory\u27s in situ atomic force microscope (AFM) and secondary ion mass spectrometry systems (SIMS) are functional and integrated as one instrument. The SIMS utilizes a Ga focused ion beam (FIB) combined with a quadrupole mass analyzer. The AFM is comprised of a 6-axis stage, three coarse axes and three fine. The coarse stage is used for placing the AFM tip anywhere inside a (13x13x5 mm3) (xyz) volume. Thus the tip can be moved in and out of the FIB processing region with ease. The planned range for the Z-axis piezo was 60 µm, but was reduced after it was damaged from arc events. The repaired Z-axis piezo is now operated at a smaller nominal range of 18 µm (16.7 µm after pre-loading), still quite respectable for an AFM. The noise floor of the AFM is approximately 0.4 nm Rq. The voxel size for the combined instrument is targeted at 50 nm or larger. Thus 0.4 nm of xyz uncertainty is acceptable. The instrument has been used for analyzing samples using FIB beam currents of 250 pA and 5.75 nA. Coarse tip approaches can take a long time so an abbreviated technique is employed. Because of the relatively long thro of the Z piezo, the tip can be disengaged by deactivating the servo PID. Once disengaged, it can be moved laterally out of the way of the FIB-SIMS using the coarse stage. This instrument has been used to acquire volumetric data on AlTiC using AFM tip diameters of 18.9 nm and 30.6 nm. Acquisition times are very long, requiring multiple days to acquire a 50-image stack. New features to be added include auto stigmation, auto beam shift, more software automation, etc. Longer term upgrades to include a new lower voltage Z-piezo with strain-gauge feedback and a new design to extend the life for the coarse XY nano-positioners. This AFM-SIMS instrument, as constructed, has proven to be a great proof of concept vehicle. In the future it will be used to analyze micro fossils and it will also be used as a part of an intensive teaching curriculum