We report the first measurement of discrimination between low-energy helium recoils and electron recoils in liquid xenon. This result is relevant to proposed low-mass dark matter searches which seek to dissolve light target nuclei in the active volume of liquid-xenon time projection chambers. Low-energy helium recoils were produced by degrading α particles from ^{210}Po with a gold foil situated on the cathode of a liquid xenon time-projection chamber. The resulting population of helium recoil events is well separated from electron recoils and is also offset from the expected position of xenon nuclear recoil events.
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http://dx.doi.org/10.1103/PhysRevLett.132.111801 | DOI Listing |
Sci Adv
January 2025
Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA.
P2X receptors (P2XRs) are adenosine 5'-triphosphate (ATP)-gated ion channels comprising homomeric and heteromeric trimers of seven subtypes (P2X1-P2X7) that confer different rates of desensitization. The helical recoil model of P2XR desensitization proposes stability of the cytoplasmic cap sets the rate of desensitization, but timing of its formation is unclear for slow-desensitizing P2XRs. We report cryo-electron microscopy structures of full-length wild-type human P2X4 receptor in apo closed, antagonist-bound inhibited, and ATP-bound desensitized states.
View Article and Find Full Text PDFCommun Phys
December 2024
C. N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, NY 11794 USA.
Solid-state detectors with a low energy threshold have several applications, including searches of non-relativistic halo dark-matter particles with sub-GeV masses. When searching for relativistic, beyond-the-Standard-Model particles with enhanced cross sections for small energy transfers, a small detector with a low energy threshold may have better sensitivity than a larger detector with a higher energy threshold. In this paper, we calculate the low-energy ionization spectrum from high-velocity particles scattering in a dielectric material.
View Article and Find Full Text PDFJ Inorg Biochem
March 2025
Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, 80126 Napoli, Italy. Electronic address:
The design of protein-metal complexes is rapidly advancing, with applications spanning catalysis, sensing, and bioremediation. We report a comprehensive investigation of METPsc1, a Miniaturized Electron Transfer Protein, in complex with cadmium. This study elucidates the impact of metal coordination on protein folding and structural dynamics across temperatures from 100 K to 300 K.
View Article and Find Full Text PDFJ Phys Chem A
December 2024
Radboud University Nijmegen, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
In molecular beam scattering experiments, an important technique for measuring product energy and angular distributions is velocity map imaging following photoionization of one or more scattered species. For studies with cold molecular beams, the ultimate resolution of such a study is often limited by the product detection process. When state-selective ionization detection is used, excess energy from the ionization step can transfer to kinetic energy in the target molecular ion-electron pair, resulting in measurable cation recoil.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
We present first-principles molecular dynamics simulations of oxygen difluoride impinging upon the monohydrogenated Si{001}(2 × 1) surface. Adsorption occurred in fewer than 10% of our computed trajectories, but in each reactive case the initial step involved partial dissociation to yield an adsorbed fluorine atom and a free oxygen monofluoride radical. In one trajectory, the adsorbed fluorine atom displaced a hydrogen atom into an unusual Si-H-Si bridge position, consistent with three-centre two-electron bonding.
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