New zwitterionic bisulfite compounds of aldehydes, such as pyridine-2-carbaldehyde
(1)
and qunoline-2-carbaldehydes
(2)
, were for the first time spectroscopically characterized and structurally ...studied. In the crystal structures, molecules
1
and
2
are connected
via
intermolecular OH⋯−O
3
S and NH
+
⋯−O
3
S interactions to form hydrogen-bonded chains. The oxidation of a solution of
2
in dimethyl sulfoxide with atmospheric air afforded quinaldil
(3)
and quinaldoin
(4).
In the crystalline state, compound
4
exists as the enediol tautomer formed by strong intramolecular hydrogen bonds.
Complexes {(NMe
2
H
2
)Ln(TDA)(HCOO) ∙ 0.5H
2
O)} are prepared by the solvothermal synthesis in a water–dimethylformamide (1 : 1) system from a mixture of 1,2,3-triazole-4,5-dicarboxylic acid (H
3
...TDA), NaOH, and Ln(NO
3
)
3
(Ln = Eu, Gd). The crystal structure of the europium complex is determined by X-ray structure analysis (CIF file CCDC no. 1939689). This compound is shown to be the ionic metal-organic framework, where the cavities in the anionic structure of Eu(TDA)(HCOO)
–
are partially occupied by the dimethylammonium cations and water molecules. The study of the luminescence spectra of the gadolinium derivative gives the energy of the triplet level of the H
3
TDA ligand (~25 300 cm
–1
), the value of which makes it possible to efficiently sensitize the luminescence of rare-earth metal ions, in particular, Eu
3+
. The decay kinetics and the emission and excitation spectra of the heterometallic derivatives {(NMe
2
H
2
)Gd
1 –
x
Eu
x
(TDA)(HCOO) ∙ 0.5H
2
O)} are studied. The dilution of europium with gadolinium results in a substantial decrease in the concentration quenching of the europium luminescence and an increase in the observed lifetimes of the excited state of Eu
3+
.
We present a search for charged Higgs bosons in top quark decays. We analyze the e+jets, μ+jets, ee, eμ, μμ, τe and τμ final states from top quark pair production events, using data from about 1 fb−1 ...of integrated luminosity recorded by the DØ experiment at the Fermilab Tevatron Collider. We consider different scenarios of possible charged Higgs boson decays, one where the charged Higgs boson decays purely hadronically into a charm and a strange quark, another where it decays into a τ lepton and a τ neutrino and a third one where both decays appear. We extract limits on the branching ratio B(t→H+b) for all these models. We use two methods, one where the tt¯ production cross section is fixed, and one where the cross section is fitted simultaneously with B(t→H+b). Based on the extracted limits, we exclude regions in the charged Higgs boson mass and tanβ parameter space for different scenarios of the minimal supersymmetric standard model.
We report observation of the electroweak production of single top quarks in ppover collisions at sqrts=1.96 TeV based on 2.3 fb(-1) of data collected by the D0 detector at the Fermilab Tevatron ...Collider. Using events containing an isolated electron or muon and missing transverse energy, together with jets originating from the fragmentation of b quarks, we measure a cross section of sigma(ppover --> tb + X, tqb + X) = 3.94 + or - 0.88 pb. The probability to measure a cross section at this value or higher in the absence of signal is 2.5 x 10(-7), corresponding to a 5.0 standard deviation significance for the observation.
We present a measurement of the W boson mass using data corresponding to 4.3 fb(-1) of integrated luminosity collected with the D0 detector during Run II at the Fermilab Tevatron pp collider. With a ...sample of 1,677,394 W → eν candidate events, we measure M(W) = 80.367 ± 0.026 GeV. This result is combined with an earlier D0 result determined using an independent Run II data sample, corresponding to 1 fb(-1) of integrated luminosity, to yield M(W) = 80.375 ± 0.023 GeV.
In this work, the results of the measurements of characteristics of 40-cm and 2-m scintillation counters irradiated by a particle beam with a momentum of 7 GeV/c from the accelerator of the Institute ...for High Energy Physics are presented. The scintillators used in counters are BC-404 and BC-408 scintillators. The counters are viewed from both ends by R1828-01 photomultiplier tubes. The PMT signal spectra are well described by a convolution of the Landau and Gaussian distributions. Their width is determined mainly by fluctuations of ionization energy losses. The time distributions of the signals obey the Gaussian law. For the 40-cm counter, the time resolution is σ(
T
) = 88 ps; for the 2-m counter, it varies from 120–160 ps in its center to ~100 ps near the end.
The muon system of the Run II DØ detector Abazov, V.M.; Alkhazov, G.; Baldin, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2005, Letnik:
552, Številka:
3
Journal Article
Recenzirano
We describe the design, construction, and performance of the upgraded DØ
muon system for Run II of the Fermilab Tevatron collider. Significant improvements have been made to the major subsystems of ...the DØ
muon detector: trigger scintillation counters, tracking detectors, and electronics. The Run II central muon detector has a new scintillation counter system inside the iron toroid and an improved scintillation counter system outside the iron toroid. In the forward region, new scintillation counter and tracking systems have been installed. Extensive shielding has been added in the forward region. A large fraction of the muon system electronics is also new.
Though 2-arylperimidines have never been used in iridium(III) chemistry, the present study on structural, electronic and optical properties of
-unsubstituted and
-methylated 2-(2-thienyl)perimidines, ...supported by DFT/TDDFT calculations, has shown that these ligands are promising candidates for construction of light-harvesting iridium(III) complexes. In contrast to
-H perimidine, the
-methylated ligand gave the expected cyclometalated μ-chloro-bridged iridium(III) dimer which was readily converted to a cationic heteroleptic complex with 4,4'-dicarboxy-2,2'-bipyridine. The resulting iridium(III) dye exhibited panchromatic absorption up to 1000 nm and was tested in a dye-sensitized solar cell.
We measure the charge asymmetry A ≡ (N++ - N--)/(N++ + N--) of like-sign dimuon events in 6.1 fb-1 of pp collisions recorded with the D0 detector at a center-of-mass energy square root(s) = 1.96 ...TeV at the Fermilab Tevatron collider. From A we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.009 57 ± 0.002 51(stat) ± 0.001 46(sys). It differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(-0.6)(+0.5)) × 10(-4), and provides first evidence of anomalous CP violation in the mixing of neutral B mesons.
We present the first measurement of the integrated forward-backward charge asymmetry in top-quark-top-antiquark pair (tt) production in proton-antiproton (pp) collisions in the lepton+jets final ...state. Using a b-jet tagging algorithm and kinematic reconstruction assuming tt + X production and decay, a sample of 0.9 fb(-1) of data, collected by the D0 experiment at the Fermilab Tevatron Collider, is used to measure the asymmetry for different jet multiplicities. The result is also used to set upper limits on tt+X production via a Z' resonance.
PDF
