Astronomical Instrumentation for CMB Observations

    Researchers in our department work on instrumentation for observing the cosmic microwave background

    QUBIC

    The Q and U Bolometric Interferometer for Cosmology (QUBIC) is a ground-based experiment that aims to detect faint primordial B-mode polarization anisotropies in the Cosmic Microwave Background – the so-called smoking gun of inflation. Systematic errors make ground-based observations of B modes at millimetre wavelengths very challenging and QUBIC mitigates these problems in a somewhat complementary way to other existing or planned experiments using the novel technique of bolometric interferometry. This technique takes advantage of the sensitivity of an imager and the systematic error control of an interferometer.  In QUBIC, a cold reflective optical combiner superimposes the re-emitted beams from 400 aperture feedhorns onto the focal plane. In the Department of Physics we have been involved in the modelling, design, and preliminary measurements of the optical components and we continue to work with the QUBIC collaboration on future upgrades.

    BISOU

    BISOU (Balloon Interferometer for Spectral Observations of the primordial Universe) is a balloon-borne pathfinder aiming to detect spectral distortions in the Cosmic Microwave Background (CMB) using a spectrometer. The CMB spectrum is nearly a perfect black body at a temperature of T = 2.7255 +/- 0.0006 K. Due to interactions in the very early Universe deviations from the ideal black body spectrum are called spectral distortions and can be used to probe the earliest epoch. BISOU will be developed by an international collaboration involving several laboratories in France, Italy, Ireland, the UK, the USA and Japan.

    At Maynooth University we are designing and verifying the optical system and detectors of BISOU. As it is a balloon experiment its optical design is very much constrained by volume and mass requirements within a small cryostat. A sketch of the optical design is shown below. The concept is based on a two input and output Fourier Transform Spectrometer design comparing the signal measured from the sky with a calibration source.

    More information at https://www.ias.universite-paris-saclay.fr/en/content/bisou

    Staff:

     
    Postgraduate Students:

    • A. Flood
    • S. Marwede
    • S. Doyle