Related papers: Improved Calibration of Instruments for Small Dire…
We performed calibrations of four different commercial picoammeters using the Ultrastable Low-noise Current Amplifier (ULCA) as a calibrator current source operated in the range between 1 femtoampere and 1 microampere. The results allow the…
A standard method for picoammeter calibrations is the capacitor charging technique, which allows generating traceable currents in the sub-nA range. However, its accuracy is limited by the ac-dc differences of the capacitances involved. The…
An interlaboratory comparison of small-current generation and measurement capability is presented with the ultrastable low-noise current amplifier (ULCA) acting as travelling standard. Various measurements at direct currents between 0.16 nA…
An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current…
In this paper, we present a programmable Ultra Low DC Current Source (ULCS) developed at T\"UB\.ITAK UME. The output current range is from 1 fA up to 100 pA with 100 aA resolution and is directly traceable to DC voltage, capacitance and…
New technology, the ultrastable low-noise current amplifier and the electron pump, provide new methods for making traceable measurements of small DC electric currents. We review four traceability routes for small current measurements and…
An ultrastable low-noise current amplifier (ULCA) has been transferred between two laboratories, NPL and PTB, four times, with three of the transfers yielding a relative change in the trans-resistance gain of less than $2 \times 10^{-7}$.…
Modern commercial direct-current current transformers (DCCT) can measure currents up to the kA range with accuracies better than 1E-5. We discuss here a DCCT calibration method and its implementation with commercial instruments typically…
We describe a calibration setup for the transresistance of low-current amplifiers, based on the capacitance-charging method. The calibration can be performed in the current range of typical interest for electron counting experiments. The…
The capacitance-charging method is a well-established and handy technique for the generation of dc current in the 100 pA range or lower. The method involves a capacitance standard and a sampling voltmeter, highly stable devices easy to…
A programmable quantum current generator based on the application of Ohm's law to quantum voltage and resistance standards has demonstrated a realization of the ampere from the elementary charge with a $10^{-8}$ relative uncertainty [J.…
We compared the performance of a commercial ammeter and a home-made integrating electrometer in reading ionisation chamber currents less than 100 pA. The integrating electrometer charges a capacitor with the unknown current and measures the…
A low noise constant current source used for measuring the $1/f$ noise in disordered systems in ohmic as well as non-ohmic regime is described. The source can supply low noise constant current starting from as low as 1 $\mu$A to a few tens…
We present the design process and implementation of fully open-source, ultra-low noise programmable current source systems in two configurations. Although originally designed as coil drivers for Optically Pumped Magnetometers (OPMs), the…
We broach a seldom-discussed topic in precision metrology; how subtle errors in calibration processes are discovered and remedied. We examine a case study at the National Physical Laboratory (NPL), UK, involving the calibration of DC…
This manual is intended to help ALMA and other interferometer users improve images by recognising limitations and how to overcome them and deciding when and how to use self-calibration. The images provided by the ALMA Science Archive are…
We present the comparison of results from the generation and the measurement of direct currents in the pA range, performed with traceable state-of-the-art methods at highest accuracy. The currents were generated with the capacitor charging…
Atomic force microscopy (AFM) is an analytical surface characterization tool which can reveal a sample's topography with high spatial resolution while simultaneously probing tip-sample interactions. Local measurement of chemical properties…
Ionization chambers are essential for activity determinations in radionuclide metrology. We have developed a high-precision integrating-differentiating (int-diff) system for measuring small currents. It is anticipated to enhance the…
Characterizing the variability of the extragalactic sources used for calibration in the Atacama Large Millimeter/Sub-millimeter Array (ALMA) is key to assess the flux scale uncertainty of science observations. To this end, we model the…