A multi-reflection time-of-flight mass spectrometer (MR-TOF) will be a critical component for quickly removing radioactive contaminants produced at the future “N = 126 factory” addition to ATLAS at ...Argonne National Laboratory (ANL). This unique thermalized ion beam facility will employ multi-nucleon transfer reactions to produce very neutron-rich isotopes relevant to the astrophysical r-process. Ion beams produced at this facility will include isobaric contaminants, while precision measurements of such rare isotopes typically require highly purified samples. Hence, to tackle this issue an MR-TOF has been built and commissioned at the University of Notre Dame in an off-line test setup comprising a thermionic source and a Bradbury-Nielsen gate (BNG) to create the ions bunches to be purified. Resolving power above 30,000, with a corresponding efficiency of 35%, has been achieved. Most of the ion beam losses could be the result of the large radial divergence of ion bunches produced by the BNG, hence greater efficiency and resolving power are expected once the MR-TOF is connected to an radiofrequency quadrupole (RFQ) cooler and buncher at ANL.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We report precision determinations of the beam-normal single spin asymmetries (A_{n}) in the elastic scattering of 0.95 and 2.18 GeV electrons off ^{12}C, ^{40}Ca, ^{48}Ca, and ^{208}Pb at very ...forward angles where the most detailed theoretical calculations have been performed. The first measurements of A_{n} for ^{40}Ca and ^{48}Ca are found to be similar to that of ^{12}C, consistent with expectations and thus demonstrating the validity of theoretical calculations for nuclei with Z≤20. We also report A_{n} for ^{208}Pb at two new momentum transfers (Q^{2}) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the Z≤20 nuclei. These data confirm our basic understanding of the underlying dynamics that govern A_{n} for nuclei containing ≲50 nucleons, but point to the need for further investigation to understand the unusual A_{n} behavior discovered for scattering off ^{208}Pb.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
In this work, we report a precise measurement of the parity-violating asymmetry $A_{\rm PV}$ in the elastic scattering of longitudinally polarized electrons from $^{48}{\rm Ca}$. We measure $A_{\rm ...PV} =2668\pm 106\ {\rm (stat)}\pm 40\ {\rm (syst)}$ parts per billion, leading to an extraction of the neutral weak form factor $F_{\rm W} (q=0.8733$ fm$^{-1}) = 0.1304 \pm 0.0052 \ {\rm (stat)}\pm 0.0020\ {\rm (syst)}$ and the charge minus the weak form factor $F_{\rm ch} - F_{\rm W} = 0.0277\pm 0.0055$. The resulting neutron skin thickness $R_n-R_p=0.121 \pm 0.026\ {\rm (exp)} \pm 0.024\ {\rm (model)}$~fm is relatively thin yet consistent with many model calculations. The combined CREX and PREX results will have implications for future energy density functional calculations and on the density dependence of the symmetry energy of nuclear matter.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
We report a precision measurement of the parity-violating asymmetry A PV in the elastic scattering of longitudinally polarized electrons from 208 Pb . We measure APV=550±16(stat)±8(syst) parts per ...billion, leading to an extraction of the neutral weak form factor FW(Q2=0.00616 GeV2)=0.368±0.013 . Combined with our previous measurement, the extracted neutron skin thickness is Rn−Rp=0.283±0.071 fm. The result also yields the first significant direct measurement of the interior weak density of 208 Pb: ρW0=− 0.0796 ± 0.0036 ( exp ) ± 0.0013 ( theo ) fm−3 leading to the interior baryon density ρb0 = 0.1480 ± 0.0036 ( exp ) ± 0.0013 ( theo ) fm −3. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
We report a precision measurement of the parity-violating asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A_{PV}=550±16(stat)±8(syst) parts ...per billion, leading to an extraction of the neutral weak form factor F_{W}(Q^{2}=0.00616 GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R_{n}-R_{p}=0.283±0.071 fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ_{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo) fm^{-3} leading to the interior baryon density ρ_{b}^{0}=0.1480±0.0036(exp)±0.0013(theo) fm^{-3}. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
A series of data samples was collected with the Belle II detector at the SuperKEKB collider from March 2019 to June 2022. We determine the integrated luminosities of these data samples using three ...distinct methodologies involving Bhabha (\(e^+e^- \to e^+e^-(n\gamma)\)), digamma (\(e^+e^- \to \gamma\gamma(n\gamma)\)), and dimuon (\(e^+e^- \to \mu^+ \mu^- (n\gamma)\)) events. The total integrated luminosity obtained with Bhabha, digamma, and dimuon events is (426.52 \(\pm\) 0.03 \(\pm\) 2.48)~fb\(^{-1}\), (427.32 \(\pm\) 0.03 \(\pm\) 2.56)~fb\(^{-1}\), and (424.84 \(\pm\) 0.04 \(\pm\) 3.88)~fb\(^{-1}\), where the first uncertainties are statistical and the second are systematic. The resulting total integrated luminosity obtained from the combination of the three methods is (426.88 \(\pm\) 1.93)~fb\(^{-1}\).
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