We investigate two- and three-electron spin blockade in three vertical quantum dots (QDs) coupled in series. Two-electron spin blockade is found in a region where sequential tunneling through all QDs is forbidden but ...
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We investigate two- and three-electron spin blockade in three vertical quantum dots (QDs) coupled in series. Two-electron spin blockade is found in a region where sequential tunneling through all QDs is forbidden but tunneling involving virtual hopping through an empty QD is allowed. It is observed only for the hole cycle with a distinct bias threshold for access to the triplet state. Three-electron spin blockade involving the quadruplet state is observed for nonequibilium conditions where sequential tunneling is allowed and the triplet state is accessible. Our results shine light on the importance of the nonequibilium conditions to obtain sufficient population of triplet and quadruplet states necessary for spin blockade.
The 18Ne(α,p)21Na reaction provides a pathway for breakout from the hot CNO cycles to the rp process in type-I x-ray bursts. To better determine this astrophysical reaction rate, the resonance parameters of the compo...
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The 18Ne(α,p)21Na reaction provides a pathway for breakout from the hot CNO cycles to the rp process in type-I x-ray bursts. To better determine this astrophysical reaction rate, the resonance parameters of the compound nucleus 22Mg have been investigated by measuring the resonant elastic scattering of 21Na+p. An 89 MeV 21Na radioactive ion beam was produced at the CNS Radioactive Ion Beam Separator and bombarded an 8.8 mg/cm2 thick polyethylene target. The recoiled protons were measured at scattering angles of θc.m.≈175∘ and 152∘ by three ΔE-E silicon telescopes. The excitation function was obtained with a thick-target method over energies Ex(22Mg) = 5.5–9.2 MeV. The resonance parameters have been determined through an R-matrix analysis. For the first time, the Jπ values for ten states above the α threshold in 22Mg have been experimentally determined in a single consistent measurement. We have made three new Jπ assignments and confirmed seven of the ten tentative assignments in the previous work. The 18Ne(α,p)21Na reaction rate has been recalculated, and the astrophysical impact of our new rate has been investigated through one-zone postprocessing x-ray burst calculations. We find that the 18Ne(α,p)21Na rate significantly affects the peak nuclear energy generation rate and the onset temperature of this breakout reaction in these phenomena.
We measured and analysed the electronic transport properties of a single-walled carbon nanotube (SWCNT) network on which the nanotubes were deposited by an ink-jet method. The SWCNT network showed an Ohmic behaviour d...
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Intensity modulated radiation therapy (IMRT) requires the determination of the appropriate multileaf collimator settings to deliver an intensity map. The purpose of this work was to attempt to regulate the shape betwe...
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Intensity modulated radiation therapy (IMRT) requires the determination of the appropriate multileaf collimator settings to deliver an intensity map. The purpose of this work was to attempt to regulate the shape between adjacent multileaf collimator apertures by a leaf sequencing algorithm. To qualify and validate this algorithm, the integral test for the segment of the multileaf collimator of ARTS was performed with clinical intensity map experiments. By comparisons and analyses of the total number of monitor units and number of segments with benchmark results, the proposed algorithm performed well while the segment shape constraint produced segments with more compact shapes when delivering the planned intensity maps, which may help to reduce the multileaf collimator's specific effects.
The properties of the orbitally excited (L=1) Bs0 states are studied by using 1.0 fb−1 of pp collisions at s=7 TeV collected with the LHCb detector. The first observation of the Bs2*(5840)0 meson decaying to B*+K− i...
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The properties of the orbitally excited (L=1) Bs0 states are studied by using 1.0 fb−1 of pp collisions at s=7 TeV collected with the LHCb detector. The first observation of the Bs2*(5840)0 meson decaying to B*+K− is reported, and the corresponding branching fraction measured relative to the B+K− decay mode. The Bs1(5830)0→B*+K− decay is observed as well. The width of the Bs2*(5840)0 state is measured for the first time, and the masses of the two states are determined with the highest precision to date. The observation of the Bs2*(5840)0→B*+K− decay favors the spin-parity assignment JP=2+ for the Bs2*(5840)0 meson. In addition, the most precise measurement of the mass difference m(B*+)−m(B+)=45.01±0.30(stat)±0.23(syst) MeV/c2 is obtained.
We present a measurement of form-factor-independent angular observables in the decay B0→K*(892)0μ+μ−. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb−1, collected by the ...
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We present a measurement of form-factor-independent angular observables in the decay B0→K*(892)0μ+μ−. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb−1, collected by the LHCb experiment in pp collisions at a center-of-mass energy of 7 TeV. Four observables are measured in six bins of the dimuon invariant mass squared q2 in the range 0.1
The result of a search for the decay Bc+→Bs0π+ is presented, using the Bs0→Ds−π+ and Bs0→J/ψϕ channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to ...
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The result of a search for the decay Bc+→Bs0π+ is presented, using the Bs0→Ds−π+ and Bs0→J/ψϕ channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 1 fb−1 taken at a center-of-mass energy of 7 TeV, and 2 fb−1 taken at 8 TeV. The decay Bc+→Bs0π+ is observed with significance in excess of 5 standard deviations independently in both decay channels. The measured product of the ratio of cross sections and branching fraction is [σ(Bc+)/σ(Bs0)]×B(Bc+→Bs0π+)=[2.37±0.31 (stat)±0.11 (syst)−0.13+0.17(τBc+)]×10−3, in the pseudorapidity range 2<η(B)<5, where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the Bc+ lifetime. This is the first observation of a B meson decaying to another B meson via the weak interaction.
A measurement of the CP asymmetry in B+→K+μ+μ− decays is presented using pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, recorded by the LHCb experiment during 2011 at a center-of-mass en...
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A measurement of the CP asymmetry in B+→K+μ+μ− decays is presented using pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, recorded by the LHCb experiment during 2011 at a center-of-mass energy of 7 TeV. The measurement is performed in seven bins of μ+μ− invariant mass squared in the range 0.05
Measurements of neutral current cross sections for deep inelastic scattering in e+p collisions at HERA with a longitudinally polarized positron beam are presented. The single-differential cross-sections dσ/dQ2, dσ/d...
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Measurements of neutral current cross sections for deep inelastic scattering in e+p collisions at HERA with a longitudinally polarized positron beam are presented. The single-differential cross-sections dσ/dQ2, dσ/dx and dσ/dy and the reduced cross section σ˜ are measured in the kinematic region Q2>185 GeV2 and y<0.9, where Q2 is the four-momentum transfer squared, x the Bjorken scaling variable and y the inelasticity of the interaction. The measurements are performed separately for positively and negatively polarized positron beams. The measurements are based on an integrated luminosity of 135.5 pb−1 collected with the ZEUS detector in 2006 and 2007 at a center-of-mass energy of 318 GeV. The structure functions F˜3 and F3γZ are determined by combining the e+p results presented in this paper with previously published e−p neutral current results. The asymmetry parameter A+ is used to demonstrate the parity violation predicted in electroweak interactions. The measurements are well described by the predictions of the Standard Model.
Measurements of charm mixing parameters from the decay-time-dependent ratio of D0→K+π− to D0→K−π+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb−1 of integrated l...
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Measurements of charm mixing parameters from the decay-time-dependent ratio of D0→K+π− to D0→K−π+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb−1 of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP ) symmetry, the mixing parameters are determined to be x′2=(5.5±4.9)×10−5, y′=(4.8±1.0)×10−3, and RD=(3.568±0.066)×10−3. Allowing for CP violation, the measurement is performed separately for D0 and D¯0 mesons yielding AD=(−0.7±1.9)%, for the direct CP-violating asymmetry, and 0.75<|q/p|<1.24 at the 68.3% confidence level, for the parameter describing CP violation in mixing. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation.
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