Search results for "ABT"
showing 10 items of 190 documents
Observation of charmonium pairs produced exclusively in $pp$ collisions
2014
A search is performed for the central exclusive production of pairs of charmonia produced in proton-proton collisions. Using data corresponding to an integrated luminosity of $3{\rm\ fb}^{-1}$ collected at centre-of-mass energies of 7 and 8 TeV, $J/\psi J/\psi$ and $J/\psi\psi(2S)$ pairs are observed, which have been produced in the absence of any other activity inside the LHCb acceptance that is sensitive to charged particles in the pseudorapidity ranges $(-3.5,-1.5)$ and $(1.5,5.0)$. Searches are also performed for pairs of P-wave charmonia and limits are set on their production. The cross-sections for these processes, where the dimeson system has a rapidity between 2.0 and 4.5, are measu…
Search for CP violation in D (+/-) -> (KSK +/-)-K-0 and D-s(+/-) -> K-S(0)pi(+/-) decays
2014
A search for \CP violation in Cabibbo-suppressed $D^{\pm}\rightarrow K^0_{\mathrm{S}} K^{\pm}$ and $D^{\pm}_{s}\rightarrow K^0_{\mathrm{S}} \pi^{\pm}$ decays is performed using $pp$ collision data, corresponding to an integrated luminosity of 3~fb$^{-1}$, recorded by the LHCb experiment. The individual $CP$-violating asymmetries are measured to be \begin{eqnarray*} \mathcal{A}_{CP}^{D^{\pm}\rightarrow K^0_{\mathrm{S}} K^{\pm}} & = & (+0.03 \pm 0.17 \pm 0.14) \% \mathcal{A}_{CP}^{D^{\pm}_{s}\rightarrow K^0_{\mathrm{S}} \pi^{\pm}} & = & (+0.38 \pm 0.46 \pm 0.17) \%, \end{eqnarray*} assuming that $CP$ violation in the Cabibbo-favoured decays is negligible. A combination of the measured asymmet…
Evidence for Increased neutron and proton excitations between 51−63 Mn
2015
The hyperfine structures of the odd-even 51−63Mnatoms (N=26 −38) were measured using bunched beam collinear laser spectroscopy at ISOLDE, CERN. The extracted spins and magnetic dipole moments have been compared to large-scale shell-model calculations using different model spaces and effective interactions. In the case of 61,63Mn, the results show the increasing importance of neutron excitations across the N=40subshell closure, and of proton excitations across the Z=28shell gap. These measurements provide the first direct proof that proton and neutron excitations across shell gaps are playing an important role in the ground state wave functions of the neutron-rich Mn isotopes. publisher: Els…
Nuclear charge radii of 62−80Zn and their dependence on cross-shell proton excitations
2019
Nuclear charge radii of 62−80Zn have been determined using collinear laser spectroscopy of bunched ion beams at CERN-ISOLDE. The subtle variations of observed charge radii, both within one isotope and along the full range of neutron numbers, are found to be well described in terms of the proton excitations across the Z=28 shell gap, as predicted by large-scale shell model calculations. It comprehensively explains the changes in isomer-to-ground state mean square charge radii of 69−79Zn, the inversion of the odd-even staggering around N=40 and the odd-even staggering systematics of the Zn charge radii. With two protons above Z=28, the observed charge radii of the Zn isotopic chain show a cum…
Simulation studies of the laser ablation ion source at the SHIPTRAP setup
2020
Hyperfine interactions 241(1), 46 (2020). doi:10.1007/s10751-020-01708-0
High-resolution spectroscopy of gaseous $^\mathrm{83m}$Kr conversion electrons with the KATRIN experiment
2020
In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous $^\mathrm{83m}$Kr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The results obtained in this calibration measurement represent a major commissioning milestone for the upcoming direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the full KATRIN beamline. The KATRIN main spectrometer's excellent energy resolution of ~ 1 eV made it possible to determine the narrow K-32 and L$_3$-32 conversion electron line widths with an unprecedented precision of ~ 1 %.
The nuclear magnetic moment of 208Bi and its relevance for a test of bound-state strong-field QED
2018
Physics letters / B 779, 324 - 330 (2018). doi:10.1016/j.physletb.2018.02.024
Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers
2017
Collinear laser spectroscopy was performed on Zn (Z=30) isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N=33–49, allowed the measurement of nuclear spins for the ground and isomeric states in odd-A neutron-rich nuclei up to N=50. Exactly one long-lived (&
A test of charge-parity-time invariance at the atto-electronvolt scale
2017
We developed a novel fast measurement procedure for cyclotron frequency comparisons of two individual particles in a Penning trap, which enabled us to compare the charge-to-mass ratio of the proton and the antiproton with a fractional precision of 69 parts per trillion. To date this is the most precise test of charge-parity-time invariance using baryons. Our measurements were performed at cyclotron frequencies of about 30 MHz, which means that charge-parity-time symmetry holds at the atto-electronvolt scale.
Characterization of softwood and hardwood lignoboost kraft lignins with emphasis on their antioxidant activity
2014
Fractionation of softwood and hardwood LignoBoost kraft lignins, using sequential extraction with organic solvents of increasing hydrogen-bonding ability (dichloromethane, n-propanol, and methanol), was carried out. Using SEC, analytical pyrolysis, FTIR and UV/VIS spectroscopy, and chemical analytical methods, four fractions were obtained and characterized in terms of their yield, composition, functionality, lignin structural features, and antioxidant properties. In tests with free radicals (ABTS●+, DPPH●, O2●-) and the ORAC (oxygen radical absorbance capacity) assay, the high radical scavenging capacity of the lignin’s soluble fractions was demonstrated. The antioxidant activity of the fra…