Biography:

In the past Y. Ban has collaborated on articles with H. Kukimoto and T. Ahmed. One of their most recent publications is Selective area control of material properties in laser-assisted MOVPE of GaAs and AlGaAs. Which was published in journal Journal of Crystal Growth.

More information about Y. Ban research including statistics on their citations can be found on their Copernicus Academic profile page.

Y. Ban's Articles: (28)

Selective area control of material properties in laser-assisted MOVPE of GaAs and AlGaAs

AbstractSelective are controls of carrier concentrations in GaAs and alloy compositions in AlGaAs have been studied by selectively irradiating the substrate with an ArF excimer laser during MOVPE growth. At substrate temperatures ranging from 600°C to 800°C, the growth rate is not influenced by the laser excitation, although surface morphology is remarkably improved at lower temperatures. An increase or decrease of carrier concentration in the selectively irradiated area of GaAs epitaxial layer is achieved. It is also demonstrated that the Al content of AlGaAs layers is higher in the irradiated area than in the unirradiated area.

First measurement of the deep-inelastic structure of proton diffraction

AbstractA measurement is presented, using data taken with the H1 detector at HERA, of the contribution of diffractive interactions to deep-inelastic electron-proton (ep) scattering in the kinematic range 8.5 < Q2 < 50GeV2, 2.4 × 10−4 < Bjorken-x < 0.0133, and 3.7 × 10−4 < χp < 0.043. The diffractive contribution to the proton structure function F2(x,Q2) is evaluated as a function of the appropriate deep-inelastic scattering variables χp, Q2, β (= χχp) using a class of deep-inelastic ep scattering events with no hadronic energy flow in an interval of pseudo-rapidity adjacent to the proton beam direction. the dependence of this contribution on χp is measured to be χp−n with n = 1.19 ± 0.06 (stat.) ± 0.07 (syst.) independent of β and Q2, which is consistent with both a diffractive interpretation and a factorisable ep diffractive cross section. A first measurement of the deep-inelastic structure of the pomeron in the form of the Q2 and β dependences of a factorised structure function is presented. For all measured β, this structure function is observed to be consistent with scale invariance.

A direct determination of the gluon density in the proton at low x

AbstractA leading order determination of the gluon density in the proton has been performed in the fractional momentum range 1.9 · 10−3 < xg/p < 0.18 by measuring multi-jet events from boson-gluon fusion in deep-inelastic scattering with the H1 detector at the electron-proton collider HERA. This direct determination of the gluon density was performed in a kinematic region previously not accessible. The data show a considerable increase of the gluon density with decreasing fractional momenta of the gluons.

Rapid communications in experimental high-energy physicsElastic and inelastic photoproduction of J/ψ mesons at HERA

AbstractResults on J/ψ production in ep interactions in the H1 experiment at HERA are presented. The J/ψ mesons are produced by almost real photons (Q2 ≈ 0) and detected via their leptonic decays. The data have been taken in 1994 and correspond to an integrated luminosity of 2.7 pb−1. The γp cross section for elastic J/ψ production is observed to increase strongly with the center of mass energy. The cross section for diffractive J/ψ production with proton dissociation is found to be of similar magnitude as the elastic cross section. Distributions of transverse momentum and decay angle are studied and found to be in accord with a diffractive production mechanism. For inelastic J/ψ production the total γp cross section, the distribution of transverse momenta, and the elasticity of the J/ψ are compared to NLO QCD calculations in a colour singlet model and agreement is found. Diffractive ψ′ production has been observed and a first estimate of the ratio to J/ψ production in the HERA energy regime is given.

Rapid communications in experimental high-energy physicsPhotoproduction of D∗± mesons in electron-proton collisions at HERA

AbstractAt the electron-proton collider HERA the inclusive D∗± meson photoproduction cross section has been measured with the H1 detector in two different, but partly overlapping, kinematical regions. For the first, where 〈Wγp〉 ≈ 200 GeV and Q2 < 0.01 GeV2, the result is σ(γp → ccX) = (13.2 ± 2.2−1.7 −4.8+2.1 +9.9) μb. The second measurement for Q2 < 4 GeV2 yields σ(γp → ccX) = (9.3 ± 2.1−1.8 −3.2+1.9 +6.9) μb at 〈Wγp〉 ≈ 142 GeV and σ(γp → ccX) = (20.6 ± 5.5−3.9 −7.2+4.3 +15.4 μb at 〈Wγp〉 ≈ 230 GeV, respectively. The third error accounts for an additional uncertainty due to the proton and photon parton density parametrizations. Differential cross sections are presented as a function of the D∗± transverse momentum and rapidity. The results compare reasonably well with next-to-leading order QCD calculations. Evidence for diffractive photoproduction of charm quarks is presented.

First results of a search for neutrinos from collapsing stars with the LVD at Gran Sasso

AbstractThe Large Volume Detector (LVD) in the Gran Sasso underground Laboratory is a multipurpose detector consisting of a large volume of liquid scintillator interleaved with limited streamer tubes. In this paper we discuss its power to study low energy cosmic neutrinos. The results show that the first LVD tower (368 tons of liquid scintillator) is well suited to detect neutrinos from gravitational stellar collapses within all of our Galaxy over a wide range of burst duration (up to a few hundred seconds). No burst candidates have been observed in the first two months of data taking.

Absolute stereochemistry of yohimbine and reserpine☆

AbstractThe absolute configurations of yohimbine and reserpine based upon the optical rotation studies, but no chemical proof, have been indicated by formulae I and II respectively. In this paper, the Prelog's asymmetric synthesis is applied with success to yohimbine(I) and methyl reserpate(IV), thereby providing evidence for the correctness of the formulae. Furthermore, yohimbine is directly correlated with dihydrocorynantheane(XVII) of known absolute stereochemistry, conclusively establishing the absolute stereochemistry of a number of yohimbine alkaloids.

GEM based detector for future upgrade of the CMS forward muon system

AbstractIn view of an upgrade of the CMS experiment, the GEM for CMS collaboration is performing feasibility studies on employing Triple-GEM detectors for the high-η region (1.6–2.4) of the CMS endcaps. A detailed review of the development and characterization of the CMS full-size prototype baseline detector will be presented. GEMs have excellent spatial and time resolution, high rate capability and radiation hardness, they are an appealing option for simultaneously enhancing muon tracking and triggering capabilities in the high-η region. The GEM for CMS collaboration has studied the performance of small and full-size prototype detectors during several test beam campaigns in order to validate new technologies and techniques in view of a mass production for CMS experiment. Results from measurements with x-rays and from test beam campaigns at the CERN SPS will be shown from both small and large prototypes.

Overview of large area triple-GEM detectors for the CMS forward muon upgrade

AbstractIn order to cope with the harsh environment expected from the high luminosity LHC, the CMS forward muon system requires an upgrade. The two main challenges expected in this environment are an increase in the trigger rate and increased background radiation leading to a potential degradation of the particle ID performance. Additionally, upgrades to other subdetectors of CMS allow for extended coverage for particle tracking, and adding muon system coverage to this region will further enhance the performance of CMS.Following an extensive R&D program, CMS has identified triple-foil gas electron multiplier (GEM) detectors as a solution for the first muon station in the region 1.6<|η|<2.2, while continuing R&D is ongoing for additional regions.

Measurement of χc2 production in two-photon collisions

AbstractThe production of the χc2 charmonium state in two-photon collisions has been measured with the Belle detector at the KEKB e+e− collider. A clear signal for χc2 → γJ/ψ, J/ψ → ℓ+ℓ− is observed in a 32.6 fb−1 data sample accumulated at center-of-mass energies near 10.6 GeV, and the product of its two-photon decay width and branching fraction is determined to be Γγγ(χc2)B(χc2→γJ/ψ)B(J/ψ→l+l−)=13.5±1.3(stat.)±1.1(syst.)eV.

Measurement of the oscillation frequency for B0–B0 mixing using hadronic B0 decays

AbstractThe oscillation frequency of B0–B0 mixing (Δmd) has been measured using 29.1 fb−1 of data collected with the Belle detector at KEKB. This measurement is made through the distributions of the proper decay time difference of B pairs in events tagged as same- and opposite-flavor decays. In each event, one B is fully reconstructed in a flavor-specific hadronic decay mode, while the flavor of the other is extracted through a likelihood calculated from the b-flavor information carried in its final decay products. We obtain Δmd=(0.528±0.017±0.011)ps−1, where the first error is statistical and the second error is systematic.

Search for the electric dipole moment of the τ lepton

AbstractWe have searched for a CP violation signature arising from an electric dipole moment (dτ) of the τ lepton in the e+e−→τ+τ− reaction. Using an optimal observable method and 29.5 fb−1 of data collected with the Belle detector at the KEKB collider at s=10.58 GeV, we find Re(dτ)=(1.15±1.70)×10−17 ecm and Im(dτ)=(−0.83±0.86)×10−17 ecm and set the 95% confidence level limits −2.2×10−17

Measurements of the mass and full-width of the ηc meson

AbstractIn a sample of 58 million J/ψ events collected with the BES II detector, the process J/ψ→γηc is observed in five different decay channels: γK+K−π+π−, γπ+π−π+π−, γK±K0Sπ∓ (with K0S→π+π−), γφφ (with φ→K+K−) and γpp̄. From a combined fit of all five channels, we determine the mass and full-width of the ηc to be mηc=2977.5±1.0(stat.)±1.2(syst.) MeV/c2 and Γηc=17.0±3.7(stat.)±7.4(syst.) MeV/c2.

Observation of the decays B0→K+π−π0 and B0→ρ−K+

AbstractWe report the observation of B0 decays to the K+π−π0 final state using a data sample of 78 fb−1 collected by the Belle detector at the KEKB e+e− collider. With no assumptions about intermediate states in the decay, the branching fraction is measured to be (36.6−4.3+4.2±3.0)×10−6. We also search for B decays to intermediate two-body states with the same K+π−π0 final state. Significant B signals are observed in the ρ(770)−K+ and K*(892)+π− channels, with branching fractions of (15.1−3.3−1.5−2.1+3.4+1.4+2.0)×10−6 and (14.8−4.4−1.0−0.9+4.6+1.5+2.4)×10−6, respectively. The first error is statistical, the second is systematic and the third is due to the largest possible interference. Contributions from other possible two-body states will be discussed. No CP asymmetry is found in the inclusive K+π−π0 or ρ−K+ modes, and we set 90% confidence level bounds on the asymmetry of −0.12

Measurement of cross sections for D0D¯0 and D+D− production in e+e− annihilation at s=3.773GeV

AbstractThe cross sections for D0D¯0 and D+D− production at 3.773 GeV have been measured with BES-II detector at BEPC. These measurements are made by analyzing a data sample of about 17.3 pb−1 collected at the center-of-mass energy of 3.773 GeV. Observed cross sections for the charm pair production are radiatively corrected to obtain the tree level cross section for DD¯ production. A measurement of the total tree level hadronic cross section is obtained from the tree level DD¯ cross section and an extrapolation of the Ruds below the open charm threshold.

Study of J/ψ→ωK+K−

AbstractNew data are presented on J/ψ→ωK+K− from a sample of 58M J/ψ events in the upgraded BES II detector at the BEPC. There is a conspicuous signal for f0(1710)→K+K− and a peak at higher mass which may be fitted with f2(2150)→KK¯. From a combined analysis with ωπ+π− data, the branching ratio BR(f0(1710)→ππ)/BR(f0(1710)→KK¯) is <0.11 at the 95% confidence level.

Spectra of prompt electrons from decays of B+ and B0 mesons and ratio of inclusive semielectronic branching fractions

AbstractWe present spectra of prompt electrons from decays of neutral and charged B mesons. The results are based on 140 fb−1 of data collected by the Belle detector on the ϒ(4S) resonance at the KEKB e+e− asymmetric collider. We tag ϒ(4S)→BB¯ events by reconstructing a B meson in one of several hadronic decay modes; the semileptonic decay of the other B meson is inferred from the presence of an identified electron. We obtain for charged and neutral B mesons the partial rates of semileptonic decay, to electrons with momentum greater than 0.6GeV/c in the B rest frame, and their ratio b+/b0=1.08±0.05±0.02, where the first and second errors are statistical and systematic, respectively.

Measurement of branching fractions for the inclusive Cabibbo-favored K¯∗0(892) and Cabibbo-suppressed K∗0(892) decays of neutral and charged D mesons

AbstractThe branching fractions for the inclusive Cabibbo-favored K¯∗0 and Cabibbo-suppressed K∗0 decays of D mesons are measured based on a data sample of 33 pb−1 collected at and around the center-of-mass energy of 3.773 GeV with the BES-II detector at the BEPC collider. The branching fractions for the decays D+(0)→K¯∗0(892)X and D0→K∗0(892)X are determined to be BF(D0→K¯∗0X)=(8.7±4.0±1.2)%, BF(D+→K¯∗0X)=(23.2±4.5±3.0)% and BF(D0→K∗0X)=(2.8±1.2±0.4)%. An upper limit on the branching fraction at 90% C.L. for the decay D+→K∗0(892)X is set to be BF(D+→K∗0X)<6.6%.

Study of the J/ψ decays to ΛΛ¯ and Σ0Σ¯0

AbstractUsing 58 million J/ψ events collected by the BES-II detector at the BEPC, the decays J/ψ→ΛΛ¯ and Σ0Σ¯0 are analysed. The branching fractions are measured to be Br(J/ψ→ΛΛ¯)=(2.03±0.03±0.15)×10−3 and Br(J/ψ→Σ0Σ¯0)=(1.33±0.04±0.11)×10−3. The angular distribution is of the form dNdcosθ=N0(1+αcos2θ), with α=0.65±0.11±0.03 for J/ψ→ΛΛ¯ and α=−0.24±0.19±0.07 for J/ψ→Σ0Σ¯0.

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