Low Noise Equivalent Power TES Bolometers for FIR Space Applications
Staff: Peter Ade
Postdocs: Rashmi Sudiwala, Dimitry Morozov
Collaborators: Stafford Withington, David Goldie (University of Cambridge), Neil Trappe, Stephen Doherty (NUI, Maynooth, Ireland)
A 388 pixel TES array developed in a previous study.
Future space missions such as SPICA, CoRE, and FIRI must achieve performance levels far beyond those achieved with the bolometric detectors of Planck and Herschel. Achieving ultra-sensitive instruments, with sensitivity limited by astrophysical backgrounds rather than the thermal emission of the telescope, requires reducing the telescope temperature from the 40 – 60 K achieved with passive cooling, to around 5 K which requires active cooling. This background reduction permits detector sensitivities to be reduced from ~ 10-17 to ~ 10-19 W/√Hz – a factor of 100 more sensitive. In addition the number of detectors needs to increase from 10’s to 100’s of pixels to make efficient use of cold large apertures in space. Both of these requirements can be achieved with Transition Edge Superconducting (TES) detectors operating at temperatures < 100 mK. We are collaborating with the Cambridge University Detector Physics Group and the National University of Ireland, Maynooth, on an ESA-funded programme to advance this TES technology to a level where it can be considered as mature and therefore offer a credible detector capability for future FIR astronomy missions. We are also working with SRON who are developing critical-path sub-systems for the SAFARI instrument proposed for SPICA.
A prototype FIR 4x4-element horn array.
Key issues that are being explored in this research work are:
- An understanding of the physics of the TES devices to identify the sensitivity limits that are possible and to consider issues such as response time, optical efficiency, and spectral response.
- Detailed electromagnetic and optical modelling to establish optimum designs for coupling the telescope power onto the pixels. To this end we are exploring the use of individual horn feeds for the detectors and how best to arrange absorbers on the detectors.
- Development of fabrication and packaging technologies for the horn plates, which is crucial to this concept which needs to be scalable to provide efficient coupling for detector arrays of ~1000 pixels.
- Strategies to control straylight and protect the ultra-sensitive elements from electromagnetic interference (EMI).
- A range of optical measurements, in both low and high background radiant backgrounds, to characterise the spectral and spatial response and to measure the performance parameters of these ultrasensitive arrays.
This project is funded by the European Space Agency Core Technology Programme (CTP).