Horns and receivers for an HI Intensity mapping experiment.

UoM administered thesis: Master of Science by Research

  • Authors:
  • Ian Evans

Abstract

In studying the evolution of the early Universe, cosmologists have looked for ways to measure the Universe's scale size as it evolved. One method is to examine the size of Baryon Acoustic Oscillations (BAO), remnants of pressure waves present in the universe before recombination. To this point studies of BAOs have focused on a visual survey of galactic spacing as a measure of BAO size. An alternative approach is to measure the statistical distribution of neutral hydrogen. This can be measured at radio frequencies. The BINGO project (Baryon acoustic oscillations In Neutral Gas Observations) is a cosmological telescope designed with the intention of making these measurements. BINGO will require a front end (horns and receiver) with a stability that allows detection of the BAO signal. This dissertation first examines the response of the horns, using an innovative foam platelet design, to changes in compression. It will show that, while there is a problem with changes in the insertion loss as a response to compression, these issues can be calibrated away. In the second part the methods and python code used in testing the stability of a single channel receiver are outlined with a particular focus on the efficacy of three analogue to digital converters. Then, the single line receiver is replaced with a correlation receiver and their stabilities are evaluated and compared as are the stability of three different types of LNAs (Low noise amplifiers). Finally, the stability of COLFETs, cold-reference loads for use in radiometer calibration, are evaluated compared to using room temperature loads and LNAs. It will be shown that the COLFETs have a similar stability to LNAs. As a result, it will be difficult to decide whether the correlation receiver's reference source should be COLFETs or sky reference horns.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
Award date1 Aug 2018