We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of ($22\pm 3$) tonne day. Above $\sim 0.4{\mathrm{keV}}_{ee}$, we observe $<1\text{event}/(\text{tonne}\mathrm{day}{\mathrm{keV}}_{ee})$, which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses $m_{\chi }$ within $3–6\mathrm{GeV}/c^2$, DM-electron scattering for $m_{\chi }>30\mathrm{MeV}/c^2$, and absorption of dark photons and axionlike particles for $m_{\chi }$ within $0.186–1\mathrm{keV}/c^2$.

Direct dark matter detection experiments based on a liquid xenon target are leading the search for dark matter particles with masses above $\sim 5\mathrm{GeV}/c^2$, but have limited sensitivity to lighter masses because of the small momentum transfer in dark matter-nucleus elastic scattering. However, there is an irreducible contribution from inelastic processes accompanying the elastic scattering, which leads to the excitation and ionization of the recoiling atom (the Migdal effect) or the emission of a bremsstrahlung photon. In this Letter, we report on a probe of low-mass dark matter with masses down to about $85\mathrm{MeV}/c^2$ by looking for electronic recoils induced by the Migdal effect and bremsstrahlung using data from the XENON1T experiment. Besides the approach of detecting both scintillation and ionization signals, we exploit an approach that uses ionization signals only, which allows for a lower detection threshold. This analysis significantly enhances the sensitivity of XENON1T to light dark matter previously beyond its reach.

We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of $6.3\times {10}^{-42}{\mathrm{cm}}^2$ at $30\mathrm{GeV}/c^2$ and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator.

We present the first measurement of nuclear recoils from solar B 8 neutrinos via coherent elastic neutrino-nucleus scattering with the XENONnT dark matter experiment. The central detector of XENONnT is a low-background, two-phase time projection chamber with a 5.9 t sensitive liquid xenon target. A blind analysis with an exposure of 3.51 t × yr resulted in 37 observed events above 0.5 keV, with ( 26.4 − 1.3 + 1.4 ) events expected from backgrounds. The background-only hypothesis is rejected with a statistical significance of 2.73 σ . The measured B 8 solar neutrino flux of ( 4.7 − 2.3 + 3.6 ) × 10 6 cm − 2 s − 1 is consistent with results from the Sudbury Neutrino Observatory. The measured neutrino flux-weighted CE ν NS cross section on Xe of ( 1.1 − 0.5 + 0.8 ) × 10 − 39 cm 2 is consistent with the Standard Model prediction. This is the first direct measurement of nuclear recoils from solar neutrinos with a dark matter detector. Published by the American Physical Society 2024

This paper investigates the thermal behavior of axial flux synchronous permanent-magnet machines (AFSPMMs) through a 3-D thermal-magnetic finite-element analysis (FEA). This paper offers a systematic approach to magnetothermal FEA. The considered axial flux machine is wound on a soft magnetic compound core. The computation of thermal field is performed via a coupled thermal and fluid-dynamical model based on FEA, where the thermal sources are obtained from a DC current flow model and a magnetostatic model. This paper includes an overview of the finite-element method (FEM) model implementation. Simulation results are presented, and, to validate the model, the simulated surface temperature rise of the motor parts is compared by experimental data.