Three instrument advances resolve residual antineutrinos from a shut-down reactor, three-dimensional molecular orbitals with a table-top light source, and three field-tuned phases of an exciton condensate.
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Residual antineutrinos from a shut-down reactor were counted
The Double Chooz collaboration has made the first quantitative measurement of residual antineutrino flux that continues after the reactor cores at France's Chooz B plant are shut down. The flux comes from partly burnt fuel still inside the cores and from spent fuel held in nearby cooling pools. A detector 400 metres from the cores, filled with more than 30 cubic metres of liquid scintillator, counted 106 ± 18 candidate events in 17.2 days of reactor-off data, a signal at 5.9 sigma. Detailed simulations that model the decay activities of fission products and the best available neutrino spectra predicted 88 ± 7 events; the measured count agrees with that prediction. Anthony Onillon and Thierry Lasserre of the Max Planck Institute for Nuclear Physics in Heidelberg led the work. The Max Planck Institute announced the result on 4 August, and the measurement was published in Physical Review Letters. The collaboration's preprint describing the same measurement was posted to arXiv in October 2025. The reactor-monitoring and nuclear-safeguards use the team highlights remains a proposed application rather than a demonstrated capability.[1]
A table-top light source carried molecular orbitals into three dimensions
Separately, Wiebke Bennecke, Matthijs Jansen and Stefan Mathias of the University of Göttingen combined ultrafast momentum microscopy with a table-top, spectrally tunable high-harmonic extreme-ultraviolet source and an algorithm that rebuilds three-dimensional information from sparse, undersampled data. That combination gave the first three-dimensional photoemission orbital tomography experiment, imaging the frontier orbitals of a PTCDA molecule adsorbed on a pristine silver (110) surface. Photoemission orbital tomography was defined in 2009, and its three-dimensional form had until now required long measurements at large synchrotron facilities. The reconstruction algorithm carries much of the new approach: it lowers how much sampling is required. The measurement supplies electron momentum and the algorithm supplies the missing half, so the three-dimensional image is a reconstruction constrained by measurement rather than a free invention. The team presents femtosecond time-resolved orbital imaging as an opening rather than a completed result. The paper appeared in Nature Communications on 19 June; the university announced it on 4 August.[2]
A weak field moved an exciton condensate through three phases
A third instrument path, led by Feng Wang of Berkeley Lab and the University of California, Berkeley, reported evidence for two-component exciton Bose-Einstein condensates in an electron-hole bilayer built from molybdenum diselenide, hexagonal boron nitride and tungsten diselenide. Magneto-optical spectroscopy inside a dilution refrigerator distinguishes three condensate phases with different spin-valley polarisations. At zero magnetic field the many-body ground state is a coherent superposition of two intravalley exciton flavours. At a weak critical field it turns through a first-order quantum phase transition into a two-component intervalley condensate, and at high fields into a fully polarised single-component condensate. The condensate signatures form a dome in density-temperature space and persist up to about 1.8 kelvin. The authors present this as evidence for the equilibrium condensation that had remained elusive, not as a closed question. The paper appeared in Nature on 10 June; Berkeley Lab announced it on 4 August. Taken together, the three developments show instruments and reconstruction methods now registering residual reactor antineutrinos after shutdown, three-dimensional molecular orbitals with a table-top light source, and an exciton condensate moving through three field-tuned phases—each previously hard to resolve with the same clarity.[1], [2], [3]
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