Analysis of noise temperature sensitivity for the design of a broadband thermal noise primary standard

A broadband primary standard for thermal noise measurements is presented and its thermal and electromagnetic behaviour is analysed by means of a novel hybrid analytical?numerical simulation methodology. The standard consists of a broadband termination connected to a 3.5mm coaxial airline partially immersed in liquid nitrogen and is designed in order to obtain a low reflectivity and a low uncertainty in the noise temperature. A detailed sensitivity analysis is made in order to highlight the critical characteristics that mostly affect the uncertainty in the noise temperature, and also to determine the manufacturing and operation tolerances for a proper performance in the range 10MHz to 26.5 GHz. Aspects such as the thermal bead design, the level of liquid nitrogen or the uncertainties associated with the temperatures, the physical properties of the materials in the standard and the simulation techniques are discussed

Investigation of the significance of the 'body effect' on sensitivity to metallic objects in a walk-through metal detector

An investigation has been carried out to determine the extent to which a walk-through metal detection system is affected by the capacitive and inductive coupling between candidates' bodies and the coil array-known as the 'body effect'. In this experiment both small and large items are investigated to determine ratio of the signal contribution from the candidate compared to the object, and a comparison is made between the response of a small object both with and without the candidate. Also an experiment is presented to demonstrate the inductive / capacitive nature of this signal. © 2013 Published under licence by IOP Publishing Ltd

High-resolution passive video-rate imaging at 350 GHz

We are developing a 350 GHz cryogenic passive video imaging system for use in standoff security applications. This demonstration system uses 800 photon-noise-limited superconducting transition edge sensor bolometers, read out using a time-division multiplexed readout system. It will image a 1 m x 1 m field of view at a standoff distance of 16 m to a resolution of approximately 1 cm at video frame rates (20 frames per second). High spatial resolution is achieved by the use of an f/2.0 Cassegrain optical system with 1.3 m primary mirror. Preliminary dark and optical testing of prototype detectors indicates that we can achieve a noise equivalent temperature difference (NETD) below 100 mK for the fully sampled 1 m x 1 m image at 20 frames per second. We report on the current status of development of this system

A 350-GHz high-resolution high-sensitivity passive video imaging system

We are developing a 350 GHz cryogenic passive video imaging system. This demonstration system uses 800 photon-noise-limited superconducting transition edge sensor bolometers. It will image a 1 m x 1 m area at a standoff distance of 16 m to a resolution of approximately 1 cm at video frame rates (20 frames per second). High spatial resolution is achieved by the use of an f/2.0 Cassegrain optical system with 1.3 m primary mirror. Preliminary testing of prototype detectors indicates that we can achieve a noise equivalent temperature difference (NETD) of 70 mK for the fully sampled 1 m × 1 m image at 20 frames per second