Emily Kuhn successfully defends thesis, “Calibration Instrumentation for the Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX)”

five people posing for a photo.
March 4, 2022

On March 4, 2022, Yale Physics and Wright Lab graduate student Emily Kuhn successfully defended the thesis “Calibration Instrumentation for the Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX)”.  (Advisor: Laura Newburgh)

Kuhn explained,  ”We know very little about dark energy—which is surprising considering that it makes up roughly 70% of our universe and is causing our universe to expand at an accelerating rate. We can learn more about dark energy by measuring the universe’s size as a function of time during specific periods of our cosmic history. One experiment seeking to make such a measurement is HIRAX, which is a new radio telescope based in South Africa that I worked on for my Ph.D. In particular, I focused on several calibration projects for HIRAX, including DIY-ing a 600L cryostat to measure noise properties of antennas and assembling a drone system to measure the telescope beam properties. 

This fall, Kuhn will join the NASA Jet Propulsion Laboratory (JPL) as a a NASA Postdoctoral Program (NPP) fellow to continue working on instrumentation for 21cm radio cosmology experiments.

Thesis Abstract:

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a 21 cm neutral hydrogen intensity mapping experiment to be deployed in the Karoo Desert in South Africa. It aims to improve constraints on the dark energy equation of state through measurements of large-scale structure at high redshift, while doubling as a state-of-the-art fast radio burst (FRB) detector. This dissertation focuses on two aspects of the HIRAX instrument characterization: (1) optimizing the signal-to-noise of antennas, through the design and implementation of a custom test-bed for determining the noise temperature of radio antennas operating between 400-800MHz, and (2) mapping the HIRAX telescope beam pattern with a custom drone calibration system. The work described is critical to HIRAX’s development, both by informing final antenna design and providing the tools to generate beam maps that will factor into all cosmological analysis.

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