Development and testing of antenna and subsystems for MIST, a 21-cm global signal experiment to study the cosmic dawn epoch of the universe
Bibliographic record
Abstract
The epoch when the first stars in the Universe were born is an unsolved mystery in cosmology. Observations of this time are possible only through measurements of the redshifted 21-cm neutral hydrogen line, which are fundamental to our understanding of the Universe. The epoch known as the Cosmic Dawn can be probed by making 21--cm brightness temperature measurements averaged spatially across the sky, and the glow of the first stars is expected to cause a spectral absorption feature in this global signal. The EDGES experiment in 2018 reported an absorption feature centered at 78~MHz, with 0.5 K in depth; this absorption feature can be interpreted as being a detection of the global signal. RFI contamination, strong foreground emissions from the Milky Way (~10^3 K), ionospheric effects, and instrumental systematics are the biggest challenges to overcome experimentally, representing the primary limitations in obtaining a high-fidelity detection, and therefore new independent measurements are necessary. This thesis focuses on the development of MIST and Mini-MIST, new experimental efforts for detecting the global signal. These instruments will be installed in northern Chile and at the McGill Arctic Research Station (MARS), two of the most radio quiet sites on Earth. Because the measurement is limited by systematics, rather than statistical error, the primary challenge is precise design and characterization of MIST subsystems. The ultimate goal involves distinguishing the signal from Galactic foreground emission, which requires rigorously calibrating the instrument to approximately 1 part in 10^4. This thesis presents the development of a variety of MIST subsystems, including antenna design, readout electronics characterization, data acquisition, software development, and environmental monitoring of soil conductivity and permittivity. With our efforts, MIST and Mini-MIST will provide invaluable, independent measurements of the Cosmic Dawn signal
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".