Abstract
The emphasis of this thesis is on cosmology experiments using a submillimetre
continuum array receiver. Divided into two parts, the thesis initially explores an astrophysical
model, followed by an experiment based on results of the model. The second
part deals with some of the design considerations for SCUBA, the Submillimetre Common
User Bolometer Array. The thesis touches on all aspects of a problem in astronomy:
the theoretical modelling, an observational experiment, and the development of instrumentation.
Part I deals with the astronomical question of gravitational lenses and the microwave
background. Simulations of an anisotropic submillimetre background due to
dusty primeval galaxies are presented, along with the observations that would result
when gravitational lensing by clusters of galaxies is considered. The experiment was
tried with the single pixel bolometer system on the James Clerk Maxwell Telescope and
it measured an upper limit on CBR anisotropy of ΔT/T < 4.6x10⁻³ (95% confidence)
towards the cluster Cl 2244 at the angular scale of 5". The small angular scale is due to
the aid of the cluster lensing effect.
The second part looks at the extensive design considerations for the feedhorn antennas
and the bolometer integrating cavities in SCUBA. Single mode optics optimizes
aperture efficiency and this is usually achieved by having a length of waveguide, but
analysis here shows that one can still have a single moded device without a waveguide.
A filter drum furthers SCUBA's capabilities by allowing the detector arrays to operate
at higher frequency wavebands, as well as the primary wavebands. At the higher frequencies
the feedhorns are overmoded, which is a case investigated in this thesis. The
SCUBA Project will have the horns fabricated by an outside contractor according to the
specifications derived in Part II.
