Measurement of the hyperfine structure of antihydrogen in a beam

A measurement of the hyperfine structure of antihydrogen promises one of the best tests of CPT symmetry. We describe an experiment planned at the Antiproton Decelerator of CERN to measure this quantity in a beam of slow antihydrogen atoms.Comment: 5th International Symposium on Symmetries in Subatomic Physics (SSP2012), Groningen (The Netherlands), June 18 to 22, 201

First measurement of kaonic helium-3 X-rays

The first observation of the kaonic 3He 3d - 2p transition was made using slow K- mesons stopped in a gaseous 3He target. The kaonic atom X-rays were detected with large-area silicon drift detectors using the timing information of the K+K- pairs of phi-meson decays produced by the DAFNE e+e- collider. The strong interaction shift of the kaonic 3He 2p state was determined to be -2+-2 (stat)+-4 (syst) eV.Comment: Accepted for publication in Phys. Lett.

Low-energy kaon-nucleon/nuclei interaction studies at DAΦNE (SIDDHARTA and AMADEUS experiments)

The DAΦNE electron-positron collider at the Laboratori Nazionali di Frascati of INFN has made available a unique-quality low-energy negative-kaons “beam”. The SIDDHARTA experiment used this beam to perform unprecedented precision measurements on kaonic atoms, while the AMADEUS experiment plans to perform in the coming years precision measurements on kaon-nuclei interactions at low-energies, in particular to study the kaonic nuclei. The two experiments are briefly presented in this paper

Measurements of the strong-interaction widths of the kaonic 3He and 4He 2p levels

The kaonic 3He and 4He X-rays emitted in the 3d-2p transitions were measured in the SIDDHARTA experiment. The widths of the kaonic 3He and 4He 2p states were determined to be Gamma_2p(3He) = 6 \pm 6 (stat.) \pm 7 (syst.) eV, and Gamma_2p(4He) = 14 \pm 8 (stat.) \pm 5 (syst.) eV, respectively. Both results are consistent with the theoretical predictions. The width of kaonic 4He is much smaller than the value of 55 \pm 34 eV determined by the experiments performed in the 70's and 80's, while the width of kaonic 3He was determined for the first time.Comment: Accepted in Phys. Lett.

Kaonic3He and4He measurements in the SIDDHARTA experiment at the DAΦNE collider

The SIDDHARTA collaboration measured kaonic 3 He and 4 He 3d → 2p X-rays with gaseous targets at the DAΦNE e + e − collider. The 2p -state strong-interaction shifts and widths were precisely determined by using 144 high-resolution silicon drift detectors. The shift of K −4 He is in good agreement with theoretical calculations and consistent with the recent experimental result of KEK-PS E570. The shift of K −3 He is also determined for the first time. The newly determined widths are in agreement with optical model calculations

Progress and perspectives in the low-energy kaon-nucleon/nuclei interaction studies at the DAΦNE collider

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Structural reconstruction of cobalt and ferrocene-based metal-organic framework during electrochemical oxygen evolution reaction

Metal-organic frameworks (MOFs) are increasingly being investigated as electrocatalysts for oxygen evolution reaction (OER) due to their unique modular structures that present a hybrid between molecular and heterogeneous catalysts, featuring well-defined active sites. However, many fundamental questions remain open regarding the electrochemical stability of MOFs, structural reconstruction of coordination sites, and the role of in situ-formed species. Here we report structural transformation of a surface-grown MOF containing cobalt nodes and 1,1’-ferrocenedicarboxylic acid linkers (denoted as CoFc-MOF) during OER in alkaline electrolyte. Ex situ and in situ investigations of CoFc-MOF film suggests that the MOF acts as a pre-catalyst and undergoes a two-step restructuring process under operating conditions to generate a metal oxyhydroxide phase. The MOF-derived metal oxyhydroxide catalyst, supported on nickel foam electrodes, displays high activity towards OER with an overpotential of 190 mV at a current density of 10 mA cm–2. While this study demonstrates the necessity of investigating structural evolution of MOFs in electrocatalysis, it also shows potential of using MOFs as precursors in catalyst design