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Access type: UnknownSubject: search.filters.subject.Analytical Chemistry (journal)

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    Fabrication and luminescence properties in Yb–Tb co-doped a-SiCO thin films
    (VBRI Press, 2020-07-24)
    Amorphous silicon oxycarbide (a-SiCxOy) single doped with Yb3+ and co-doped with the couple Tb3+ - Yb3+ thin films were grown on crystalline silicon substrates by rf magnetron sputtering. The elemental composition in at. % is determined by energy dispersive spectroscopy and fourier transform infrared spectroscopy allows to investigate the chemical properties of the host. The concentration of Yb in the single doped sample was 3.5% and for the codoped samples (Yb, Tb) were (3%, 0.9%), (3.5%, 0.6%) and (4%, 0.6%), respectively. Post-deposition annealing treatments were made in order to induce optical activation of the rare earths. Conversion or absorption of high energy photons were analyzed by photoluminescence spectroscopy. The photoluminescence spectra show that for a given temperature range in the thermal annealing process, as well as for the appropriate rare earth concentrations the activation of Yb3+ and Tb3+ is enhanced. A strong reduction of the Tb3+ emission in contrast to the Yb3+ emission in the a-SiCxOy,:Tb:Yb samples at annealing temperature at 500°C suggests a energy transfer from Tb3+ to Yb3+ ions. Copyright © 2018 VBRI Press.
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    First Measurement of A = 4 Hypernuclei and Antihypernuclei at the LHC
    (American Physical Society, 2025)
    In this Letter, the first evidence of the 4/Λ H ̅ⅇ antihypernucleus is presented, along with the first measurement at the LHC of the production of (anti)hypernuclei with mass number A = 4, specifically (anti) 4/Λ H and (anti) 4/Λ He. In addition, the antiparticle-to-particle ratios for both hypernuclei (4/Λ H ̅/4/Λ H = and 4/Λ H ̅ⅇ = 4/Λ Hⅇ) are shown, which are sensitive to the baryochemical potential of the strongly interacting matter created in heavy-ion collisions. The results are obtained from a data sample of central Pb-Pb collisions, collected during the 2018 LHC data taking at a center-of-mass energy per nucleon pair of √ˢɴɴ = 5.02 TeV. The yields measured for the average of the charge-conjugated states are found to be [0.78 ± 0.19(stat) ± 0.17(syst)] × 10⁻⁶ for the (anti) 4/Λ H, and [1.08 ± 0.34(stat) ± 0.20(syst)] × 10⁻⁶ for the (anti) 4/Λ He, and the measured antiparticle-to-particle ratios are in agreement with unity. The presence of (anti) 4/Λ H and (anti) 4/Λ He excited states is expected to strongly enhance the production yield of these hypernuclei. The yield values exhibit a combined deviation of 3.3σ from the theoretical ground-state-only expectation, while the inclusion of the excited states in the calculations leads to an agreement within 0.6σ with the present measurements. Additionally, the measured (anti) 4/Λ H and (anti) 4/Λ He masses are compatible with the world-average values within the uncertainties.
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