arXiv subjects

Kameron Mehling

Publications and source records attributed to Kameron Mehling.

6 recordsLinked to original sources

arXiv2025

The Extreme Universe Observatory on a Super-Pressure Balloon II: Mission, Payload, and Flight

The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) is a pathfinder mission toward a space-based observatory such as the Probe of Extreme Multi-Messenger Astrophysics (POEMMA). The aim of POEMMA is the observation of Ultra High Energy COsmic Rays (UHECRs) in order to elucidate their nature and origins and to discover $\gtrsim$ 20 PeV very high energy neutrinos that originate from transient and steady astrophysical sources. EUSO-SPB2 was launched from W\=anaka New Zealand on May 13th, 2023 as a NASA Balloon Program Office test flight. The mission goals included making the first near-space altitude observations of the fluorescence emission from UHECR-induced extensive air showers (EASs) and making the first direct Cherenkov light emission from PeV cosmic rays traversing Earth's atmosphere. In addition, a Target of Opportunity program was developed for selecting and scheduling observations of potential neutrino sources as they passed just below the Earth's limb. Although a leaky balloon forced termination over the Pacific Ocean after 37 hours, data was collected to demonstrate the successful commissioning and operation of the instruments. This paper includes a description of the payload and the key instruments, pre-flight instrument characterizations in the lab and in the desert, flight operations and examples of the data collected. The flight was too short to catch a UHECR event via fluorescence, however about 10 candidate EAS events from cosmic rays were recorded via Cherenkov light.

astro-ph.HE↗

arXiv2025

Narrowline Laser Cooling and Spectroscopy of Molecules via Stark States

The electronic energy level structure of yttrium monoxide (YO) provides a long-lived, low-lying $^{2}\Delta$ state ideal for high-precision molecular spectroscopy, narrowline laser cooling at the single photon-recoil limit, and studying dipolar physics with unprecedented interaction strength. High-resolution laser spectroscopy of ultracold laser-cooled YO molecules is used to study the Stark effect in the A$^{\prime}\,^{2}\Delta_{3/2}\,J=3/2$ state. An immediate onset of the linear Stark effect is observed in the presence of weak applied electric fields due to the near degenerate $\Lambda$-doublet and the large electric dipole moment. By applying a small electric field the Stark insensitive state is spectroscopically isolated and the absolute transition frequency to the X$\,^2\Sigma^+$ electronic ground state is determined with a fractional frequency uncertainty of 9 $\times$ 10$^{-12}$. This electric field control is necessary to implement a quasi-closed photon cycling scheme that preserves parity. With this scheme the first narrowline laser cooling of a molecules is demonstrated, reducing the temperature of sub-Doppler cooled YO in two dimensions.

physics.atom-ph↗

arXiv2024

Collisions of Spin-polarized YO Molecules for Single Partial Waves

Efficient sub-Doppler laser cooling and optical trapping of YO molecules offer new opportunities to study collisional dynamics in the quantum regime. Confined in a crossed optical dipole trap, we achieve the highest phase-space density of $2.5 \times 10^{-5}$ for a bulk laser-cooled molecular sample. This sets the stage to study YO--YO collisions in the microkelvin temperature regime, and reveal state-dependent, single-partial-wave two-body collisional loss rates. We determine the partial-wave contributions to loss of specific rotational states (first excited $N=1$ and ground $N=0$) following two strategies. First, we measure the change of the collision rate in a spin mixture of $N=1$ by tuning the kinetic energy with respect to the p- and d-wave centrifugal barriers. Second, we compare loss rates between a spin mixture and a spin-polarized state in $N=0$. Using quantum defect theory with a partially absorbing boundary condition at short range, we show that the dependence on temperature for $N=1$ can be reproduced in the presence of a d-wave or f-wave resonance, and the dependence on a spin mixture for $N=0$ with a p-wave resonance.

physics.atom-ph↗

arXiv2022

Blue-Detuned Magneto-Optical Trap of Molecules

Direct laser cooling of molecules has reached a phase space density exceeding 10$^{-6}$ in optical traps, but with rather small molecular numbers. To progress towards quantum degeneracy, a mechanism is needed that combines sub-Doppler cooling and magneto-optical trapping (MOT) to facilitate near unity transfer of ultracold molecules from the MOT to a conservative optical trap. Using the unique energy level structure of YO molecules, we demonstrate the first blue-detuned MOT for molecules that is optimized for both gray-molasses sub-Doppler cooling and relatively strong trapping forces. This first sub-Doppler molecular MOT provides an increase of phase-space density by two orders of magnitude over any previously reported molecular MOT.

physics.atom-ph↗

arXiv2021

High Phase-Space Density of Laser-Cooled Molecules in an Optical Lattice

We report laser cooling and trapping of yttrium monoxide (YO) molecules in an optical lattice. We show that gray molasses cooling remains exceptionally efficient for YO molecules inside the lattice with a molecule temperature as low as 6.1(6) $\mu$K. This approach has produced a trapped sample of 1200 molecules, with a peak spatial density of $\sim1.2\times10^{10}$ cm$^{-3}$, and a peak phase-space density of $\sim3.1\times10^{-6}$. By adiabatically ramping down the lattice depth, we cool the molecules further to 1.0(2) $\mu$K, twenty times colder than previously reported for laser-cooled molecules in a trap.

physics.atom-ph↗

arXiv2019

UCIRC2: An Infrared Cloud Monitor for EUSO-SPB2

We describe the design and implementation of the University of Chicago Infrared Camera 2 (UCIRC2) built for monitoring cloud coverage during the EUSO-SPB2 flight (the second generation of the Extreme Universe Space Observatory on a Super Pressure Balloon). UCIRC2 uses two infrared (IR) cameras centered on 10$μ$m and 12$μ$m wavelengths to capture images of the clouds beneath EUSO-SPB2 in two bands spanning the thermal emission peak. Taken every minute, the IR images allow the determination of the height and coverage of clouds between the telescope and the ground. We discuss the design and construction of UCIRC2, including the techniques and design principles that make the module temperature and vacuum resilient. Additionally, we delineate the image reconstruction process and the pixel by pixel temperature calibration procedure. This paper will posit design and implementation suggestions for future ultra-high energy space telescopes.

astro-ph.IM↗