We report on patterning of miniaturized gold (Au) based micro-hotplates reaching high temperature at lower power consumption than ever reported using aerosol jet printing. Efficient heating (i.e. ...~12 °C/mW) was achieved by reducing the effective heating area and the thickness of the polyimide substrate. Au nanoparticles solution was used for printing heaters of two different sizes, i.e. 500 × 500 μm2 and 150 × 150 μm2. These double meander heaters were patterned on a 50 μm-thick polyimide substrate implementing 5 μm-thick membranes using laser etching. Finite element simulations were used to optimize the thermal design of the devices. They exhibit a power consumption at 250 °C of 39 mW and 22 mW for the larger and smaller heater design, respectively. These results indorse the significance of aerosol jet printing process at high resolution to realize high temperature and power efficient micro-hotplates on foil for applications such as; in portable gas and chemical sensors, thermal metrology and mapping, localized heating, thermal actuators and microfluidics etc.
A theoretical description of the convection-diffusion process in a homogeneous system enabling estimation of diffusion coefficients employing commercially available Y-junction microchannel is ...presented. A detailed numerical analysis based on finite volumes and finite differences, namely the explicit, implicit and Crank-Nicolson method, was performed and analyzed on the same domain in order to verify the proposed models. All numerical approaches provided stable solutions with certain numerical variations depending on the number of iterations defined by the mesh density. In addition, the method was validated with measurements of diffusion coefficients of some selected components in the short Y-junction microchannel. Benefits and possible pitfalls of this estimation method are discussed. Key words: diffusion coefficient, microfluidic device, Y-junction microchannel, mathematical model, numerical methods
The mechanisms by which carbon nanotubes nucleate and grow are still poorly understood. Understanding and mathematically describing the process is crucial for its optimization. This paper reviews ...different models which have been proposed to explain carbon nanotube growth in the chemical vapor deposition process. The review is divided into two sections, the first section describes some nucleation, growth and termination simulations based on molecular dynamics, and the second section describes some mathematical models based on transport and kinetics theories. Key words: Carbon nanotubes, CVD, growth simulations, kinetics
Global decay chain vertex fitting at Belle II Krohn, J.-F.; Tenchini, F.; Urquijo, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2020, Letnik:
976, Številka:
C
Journal Article
Recenzirano
Odprti dostop
In this paper we report the implementation of a global vertex fitting algorithm within the Belle II analysis software environment, which was originally developed for BaBar (Hulsbergen, 2005). We ...explore the impact of global vertex fitting algorithms for flavour physics analyses with the Belle II detector at the SuperKEKB e+e− collider, such as in the reconstruction of final states with neutral particles, and in fits with geometrical constraints from SuperKEKB’s nano-beam interaction region. The algorithm is compared to the standard vertex fitting algorithm employed by the Belle experiment. We have developed the fitting framework to utilise the EIGEN library for linear algebra operations, reducing the computation time for vertex fitting operations by an order of magnitude over previous methods. This has a significant impact on physics analysis computing efficiency, where vertex fitting over large combinations of final state particles is one of the most CPU intensive operations at Belle II.
The Full Event Interpretation Keck, T.; Abudinén, F.; Bernlochner, Florian U. ...
Computing and software for big science,
12/2019, Letnik:
3, Številka:
1
Journal Article
Odprti dostop
The full event interpretation is presented: a new exclusive tagging algorithm used by the high-energy physics experiment Belle II. The experimental setup of Belle II allows the precise measurement of ...otherwise inaccessible
B
meson decay modes. The Full Event Interpretation algorithm enables many of these measurements. The algorithm relies on machine learning to automatically identify plausible
B
meson decay chains based on the data recorded by the detector. Compared to similar algorithms employed by previous experiments, the Full Event Interpretation provides a greater efficiency, yielding a larger effective sample size usable in the measurement.
We present the first measurements of absolute branching fractions of Ξc0 decays into Ξ−π+, ΛK−π+, and pK−K−π+ final states. The measurements are made using a dataset comprising (772±11)×106 BB¯ pairs ...collected at the ϒ(4S) resonance with the Belle detector at the KEKB e+e− collider. We first measure the absolute branching fraction for B−→Λ¯c−Ξc0 using a missing-mass technique; the result is B(B−→Λ¯c−Ξc0)=(9.51±2.10±0.88)×10−4. We subsequently measure the product branching fractions B(B−→Λ¯c−Ξc0)B(Ξc0→Ξ−π+), B(B−→Λ¯c−Ξc0)B(Ξc0→ΛK−π+), and B(B−→Λ¯c−Ξc0)B(Ξc0→pK−K−π+) with improved precision. Dividing these product branching fractions by the result for B−→Λ¯c−Ξc0 yields the following branching fractions: B(Ξc0→Ξ−π+)=(1.80±0.50±0.14)%, B(Ξc0→ΛK−π+)=(1.17±0.37±0.09)%, and B(Ξc0→pK−K−π+)=(0.58±0.23±0.05)%. For the above branching fractions, the first uncertainties are statistical and the second are systematic. Our result for B(Ξc0→Ξ−π+) can be combined with Ξc0 branching fractions measured relative to Ξc0→Ξ−π+ to yield other absolute Ξc0 branching fractions.
We report the first observation of the Ξc(2930)0 charmed-strange baryon with a significance greater than 5σ. The Ξc(2930)0 is found in its decay to K-Λc+ in B-→K-Λc+Λ¯c- decays. The measured mass and ...width are 2928.9±3.0(stat.)-12.0+0.9(syst.) MeV/c2 and 19.5±8.4(stat.)-7.9+5.9(syst.) MeV, respectively, and the product branching fraction is B(B-→Ξc(2930)0Λ¯c-)B(Ξc(2930)0→K-Λc+)=1.73±0.45(stat.)±0.21(syst.)×10-4. We also measure B(B-→K-Λc+Λ¯c-)=4.80±0.43(stat.)±0.60(syst.)×10-4 with improved precision, and search for the charmonium-like state Y(4660) and its spin partner, Yη, in the Λc+Λ¯c- invariant mass spectrum. No clear signals of the Y(4660) nor its spin partner are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of (772±11)×106BB¯ pairs collected at the Υ(4S) resonance by the Belle detector at the KEKB asymmetric energy electron–positron collider.
We report the results of a search for the rare, purely leptonic decay B^{-}→μ^{-}νover ¯_{μ} performed with a 711 fb^{-1} data sample that contains 772×10^{6} BBover ¯ pairs, collected near the ...ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic B-meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of B(B^{-}→μ^{-}νover ¯_{μ})=(6.46±2.22±1.60)×10^{-7} or a frequentist 90% confidence level interval on the B^{-}→μ^{-}νover ¯_{μ} branching fraction of 2.9,10.7×10^{-7}.
We present a particle vertex fitting method designed for B factories. The presented method uses a Kalman Filter to solve a least squares estimate to globally fit decay chains, as opposed to ...traditional methods that fit each vertex at a time. It allows for the extraction of particle momenta, energies, vertex positions and flight lengths, as well as the uncertainty estimates of these quantities. Furthermore, it allows for the precise extraction of vertex parameters in complex decay chains containing neutral final state particles, such as \({\gamma}\) or \(K^0_L\) , which cannot properly be tracked due to limited spatial resolution of longitudinally segmented single-layer crystal calorimeters like the Belle II ECL. The presented technique can be used to suppress combinatorial background and improve resolutions on measured parameters. We present studies using Monte Carlo simulations of collisions in the Belle II experiment, where modes with neutrals are crucial to the physics analysis program.
Phys. Rev. D 99, 112006 (2019) We report measurements of the production cross sections of charged pions,
kaons, and protons as a function of fractional energy, the event-shape variable
called thrust, ...and the transverse momentum with respect to the thrust axis.
These measurements access the transverse momenta created in the fragmentation
process, which are of critical importance to the understanding of any
transverse momentum dependent distribution and fragmentation functions. The low
transverse momentum part of the cross sections can be well described by
Gaussians in transverse momentum as is generally assumed but the
fractional-energy dependence is non-trivial and different hadron types have
varying Gaussian widths. The width of these Gaussians decreases with thrust and
shows an initially rising, then decreasing fractional-energy dependence. The
widths for pions and kaons are comparable within uncertainties, while those for
protons are significantly narrower. These single-hadron cross sections and
Gaussian widths are obtained from a $558\,{\rm fb}^{-1}$ data sample collected
at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB
asymmetric-energy $e^+ e^-$ collider.
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