arXiv subjects
Publications and source records attributed to H. Themann.
We firstly report an axion haloscope search with toroidal geometry. In this pioneering search, we exclude the axion-photon coupling $g_{a\gamma\gamma}$ down to about $5\times10^{-8}$ GeV$^{-1}$ over the axion mass range from 24.7 to 29.1 $\mu$eV at a 95\% confidence level. The prospects for axion dark matter searches with larger scale toroidal geometry are also considered.
We review a recent letter published in Phys. Rev. Lett. $\textbf{116}$, 161804 (2016) of which the main argument is that the mode dependent magnetic form factors at axion haloscopes depend on the position of the cavity inside the solenoid while the corresponding electric form factors do not. We, however, find no such dependence, which is also equivalent to the statement that the electric and corresponding magnetic energy stored in the cavity modes are the same regardless of the position of the cavity inside the solenoid. Furthermore, we extend the statement to the cases satisfying $\vec{\nabla}\times\vec{B}_{\rm external}=0$, where $\vec{B}_{\rm external}$ is a static magnetic field provided by a magnet at an axion haloscope. Two typical magnets, solenoidal and toroidal, satisfy $\vec{\nabla}\times\vec{B}_{\rm external}=0$, thus the electric and corresponding magnetic energy stored in the cavity modes are always the same in both cases. The energy, however, is independent of the position of the cavity in axion haloscopes with a solenoid, but depends on those with a toroidal magnet.
The Daya Bay reactor antineutrino experiment is designed to make a precision measurement of the neutrino mixing angle theta13, and recently made the definitive discovery of its nonzero value. It utilizes a set of eight, functionally identical antineutrino detectors to measure the reactor flux and spectrum at baselines of 300 - 2000m from the Daya Bay and Ling Ao Nuclear Power Plants. The Daya Bay antineutrino detectors were built in an above-ground facility and deployed side-by-side at three underground experimental sites near and far from the nuclear reactors. This configuration allows the experiment to make a precision measurement of reactor antineutrino disappearance over km-long baselines and reduces relative systematic uncertainties between detectors and nuclear reactors. This paper describes the assembly and installation of the Daya Bay antineutrino detectors.