First results from the HAYSTAC axion search

The axion is a well-motivated cold dark matter (CDM) candidate first postulated to explain the absence of $CP$ violation in the strong interactions. CDM axions may be detected via their resonant conversion into photons in a "haloscope" detector: a tunable high-$Q$ microwave cavity maintained at cryogenic temperature, immersed a strong magnetic field, and coupled to a low-noise receiver. This dissertation reports on the design, commissioning, and first operation of the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC), a new detector designed to search for CDM axions with masses above $20$ $\mu\mathrm{eV}$. I also describe the analysis procedure developed to derive limits on axion CDM from the first HAYSTAC data run, which excluded axion models with two-photon coupling $g_{a\gamma\gamma} \gtrsim 2\times10^{-14}$ $\mathrm{GeV}^{-1}$, a factor of 2.3 above the benchmark KSVZ model, over the mass range $23.55 < m_a < 24.0$ $\mu\mathrm{eV}$. This result represents two important achievements. First, it demonstrates cosmologically relevant sensitivity an order of magnitude higher in mass than any existing direct limits. Second, by incorporating a dilution refrigerator and Josephson parametric amplifier, HAYSTAC has demonstrated total noise approaching the standard quantum limit for the first time in a haloscope axion search.Comment: Ph.D. thesis. 346 pages, 58 figures. A few typos corrected relative to the version submitted to ProQues

Baseline characteristics of the study patients and nodules.

<p>Baseline characteristics of the study patients and nodules.</p

Histopathological results of pulmonary nodules.

<p>Histopathological results of pulmonary nodules.</p

Receiver operator characteristic curves for the four risk prediction models.

<p>Receiver operator characteristic curves for the four risk prediction models.</p

Distribution of the probability of malignancy according to the four risk prediction models.

<p>Distribution of the probability of malignancy according to the four risk prediction models.</p

Decision curve analysis for the four risk prediction models.

<p>Decision curve analysis for the four risk prediction models.</p

Study patients.

<p>Study patients.</p

Decision analysis using the ACCP and BTS thresholds in 242 confirmed nodules.

<p>Decision analysis using the ACCP and BTS thresholds in 242 confirmed nodules.</p