A growing range of medical treatments and diagnostic procedures use radioactive sources. The strength of these sources is often measured using ionisation chambers whose output is an electrical current in the range from picoamperes (10-12 A) to microamperes (10-6 A). Robust, traceable calibration of the electrical current readout is vital for validating the stability and… Read More

Scientists at e-SI-Amp partner Physikalisch-Technische Bundesanstalt (PTB) have developed a stable current amplifier for the sub-picoampere measurement range. The low noise and stability makes direct current measurements with uncertainties of less than 10 attoamperes (1 attoampere = 10-18 A) readily achievable. The “ultrastable low-noise current amplifier” (ULCA) enables traceable measurement and generation of small currents… Read More

KRISS and NPL have demonstrated robust operation of a gallium arsenide tunable-barrier single-electron pump operating with 1 part-per-million accuracy at a temperature of 1.3 K and a pumping frequency of 500 MHz. NPL and KRISS scientists showed that the current from a gallium arsenide electron pump was still accurately quantised at the level of 1… Read More

Researchers from the Laboratoire National d’Essais (LNE) have developed a quantum current standard able to generate currents of values in a range from microamperes (10-6 A) to milliamperes (10-3 A) accurately linked to the elementary charge with a targeted relative uncertainty of 10 parts in a billion. This breakthrough relies on an error-free application of… Read More

A new accuracy record in measurements on single-electron pumps has been demonstrated by PTB. 0.16 µA/A of relative combined uncertainty was reached within less than 1 day of measurement time. Robustness tests of pump operation on the sub-ppm level revealed good stability of tunable-barrier pumps against variations in the operating parameters. Single-electron (SE) pumps are promising… Read More

The Conference on Precision Electromagnetic Measurements is the most important conference in the field of electrical metrology. Held every two years, it brings together representatives from National Measurement Institutes, Universities and Industry to discuss state of the art measurement techniques and issues surrounding the measurement system. The conference in 2016 was held in Ottowa, Canada.  A significant… Read More

At a microscopic level, electrical current is most often described as a flow of charged particles. While the size of an electrical current can therefore be quantified using a ‘particle flow rate’, this is not the way that the base unit of electrical current in the International System of units (SI) the ampere is presently defined. Instead,… Read More