Production of technical parts for Mechanical Engineering field is very important. There are many conditions which the produced parts have to satisfy. Very important for functional parts are accuracy ...of final parts. This accuracy could be evaluated in different ways. For example it can be evaluated shape accuracy or dimensional accuracy. This paper is focused to Fused Deposition Modelling (FDM) technology which is used for Additive Manufacturing process. The parts in additive manufacturing are produced directly from virtual model and digital file which could be obtained by direct modelling with CAD software of by 3D scanning. Published paper deals realized research where the full factor experiment was prepared and measured shape and dimensional accuracy of produced specimens. There are designed two types of specimens with different shapes and dimensions. Digital models are processed with different different 3D printer settings. Measured values are evaluated by statistical methods.
The Brewer-Dobson circulation (mainly meridional circulation) is very important for stratospheric ozone dynamics and thus for the overall state of the stratosphere. There are some indications that ...the meridional circulation in the stratosphere could be longitudinally dependent, which would have an impact on the ozone distribution. Therefore, we analyse here the meridional component of the stratospheric wind at northern middle latitudes to study its longitudinal dependence. The analysis is based on the NCEP/NCAR-1 (National Centers for Environmental Prediction and the National Center for Atmospheric Research), MERRA (Modern Era-Retrospective Analysis) and ERA-Interim (European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis Interim) reanalysis data. The well-developed two-core structure of strong but opposite meridional winds, one in each hemisphere at 10 hPa at higher northern middle latitudes, and a less pronounced five-core structure at 100 hPa are identified. In the central areas of the two-core structure the meridional and zonal wind magnitudes are comparable. The two-core structure at 10 hPa is almost identical for all three different reanalysis data sets in spite of the different time periods covered. The two-core structure is not associated with tides. However, the two-core structure at the 10 hPa level is related to the Aleutian pressure high at 10 hPa. Zonal wind, temperature and the ozone mixing ratio at 10 hPa also exhibit the effect of the Aleutian high, which thus affects all parameters of the Northern Hemisphere middle stratosphere. Long-term trends in the meridional wind in the "core" areas are significant at the 99% level. Trends of meridional winds are negative during the period of ozone depletion development (1970-1995), while they are positive after the ozone trend turnaround (1996-2012). Meridional wind trends are independent of the sudden stratospheric warming (SSW) occurrence and the quasi-biennial oscillation (QBO) phase. The influence of the 11-year solar cycle on stratospheric winds has been identified only during the west phase of QBO. The well-developed two-core structure in the meridional wind illustrates the limitations of application of the zonal mean concept in studying stratospheric circulation.
In the forward end-cap of the Belle II spectrometer, particle identification is provided by a proximity focusing RICH detector with an aerogel radiator (ARICH). The ARICH’s primary function is to ...effectively distinguish between pions and kaons in the momentum range of 0.5GeV/c to about 4GeV/c, as well as to contribute to identification of low-momentum leptons. Since its operation began, Belle II has collected over 420fb−1 of data. Based on this large data sample, studies of several effects that impact the performance of the ARICH detector were carried out. In this paper, we present a comparison of the observed Cherenkov ring image and detector particle identification performance in the measured data and detector simulation. Furthermore, we highlight recent efforts aimed at enhancing the ARICH’s performance by taking into account the effects of particle decay in flight and scattering in materials before the detector, as well as by refining the probability density function used for particle identification likelihood evaluation.
Test of the Hamamatsu MPPC module S11834 as a RICH photon detector Korpar, S.; Tahirović, E.; Križan, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Letnik:
766
Journal Article
Recenzirano
In our previous studies, we have shown that silicon photo-multipliers can be used as single photon detectors in a RICH counter (Korpar et al., 2009, 2010 1 and 2). Their main advantage with respect ...to the classical photo-multiplier tubes is the operation in high magnetic fields, while their disadvantage is a relatively high dark count rate. Recently, Hamamatsu made commercially available sensors with a rather low dark count rate ( approximately 0.1 MHz/mm super(2)) and with a larger active area, offering a possibility for a much better signal-to-noise ratio. We have designed, constructed and tested a module with Hamamatsu 88 channel S11834 MPPCs. To increase the geometric acceptance, light concentrators have been employed. In the present contribution we discuss the results of studies of the light concentrator design optimization and of the detector module response to fast light pulses. Also presented are the results of RICH prototype tests in a test beam.
We present a search for lepton-flavor-violating τ decays into three leptons (electrons or muons) using 782 fb−1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. ...No evidence for these decays is observed and we set 90% confidence level upper limits on the branching fractions between 1.5×10−8 and 2.7×10−8.
We search for lepton-flavor-violating τ→ℓV0 decays, where ℓ is an electron or muon and V0 is one of the vector mesons ρ0, ϕ, ω, K⁎0 and K¯⁎0. We use 854 fb−1 of data collected with the Belle detector ...at the KEKB asymmetric-energy e+e− collider. No evidence for a signal is found in any decay mode, and we obtain 90% confidence level upper limits on the individual branching fractions in the range (1.2–8.4)×10−8.
Using 605 fb(-1) of data collected at the Upsilon(4S) resonance we present a measurement of the inclusive radiative B-meson decay channel, B-->X(s)gamma. For the lower photon energy thresholds of ...1.7, 1.8, 1.9, and 2.0 GeV, as defined in the rest frame of the B meson, we measure the partial branching fraction and the mean and variance of the photon energy spectrum. At the 1.7 GeV threshold we obtain the partial branching fraction BF(B-->X(s)}gamma)=(3.45+/-0.15+/-0.40)x10(-4), where the errors are statistical and systematic.
First measurements of beam backgrounds at SuperKEKB Lewis, P.M.; Jaegle, I.; Nakayama, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2019, Letnik:
914
Journal Article
Recenzirano
Odprti dostop
The high design luminosity of the SuperKEKB electron–positron collider is expected to result in challenging levels of beam-induced backgrounds in the interaction region. Properly simulating and ...mitigating these backgrounds is critical to the success of the Belle II experiment. We report on measurements performed with a suite of dedicated beam background detectors, collectively known as BEAST II, during the so-called Phase 1 commissioning run of SuperKEKB in 2016, which involved operation of both the high energy ring (HER) of 7 GeV electrons as well as the low energy ring (LER) of 4 GeV positrons. We describe the BEAST II detector systems, the simulation of beam backgrounds, and the measurements performed. The measurements include standard ones of dose rates versus accelerator conditions, and more novel investigations, such as bunch-by-bunch measurements of injection backgrounds and measurements sensitive to the energy spectrum and angular distribution of fast neutrons. We observe beam–gas, Touschek, beam–dust, and injection backgrounds. As there is no final focus of the beams in Phase 1, we do not observe significant synchrotron radiation, as expected. Measured LER beam–gas backgrounds and Touschek backgrounds in both rings are slightly elevated, on average three times larger than the levels predicted by simulation. HER beam–gas backgrounds are on average two orders of magnitude larger than predicted. Systematic uncertainties and channel-to-channel variations are large, so that these excesses constitute only 1–2 sigma level effects. Neutron background rates are higher than predicted and should be studied further. We will measure the remaining beam background processes, due to colliding beams, in the imminent commissioning Phase 2. These backgrounds are expected to be the most critical for Belle II, to the point of necessitating replacement of detector components during the Phase 3 (full-luminosity) operation of SuperKEB.
Test of the HAPD light sensor for the Belle II Aerogel RICH Yusa, Y.; Adachi, I.; Dolenec, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2017, Letnik:
876
Journal Article
Recenzirano
The Aerogel Ring-Imaging Cherenkov detector (ARICH) is being installed in the endcap region of Belle II spectrometer to identify particles from B meson decays by detecting the Cherenkov ring image ...from aerogel radiators. To detect single photons, high-sensitive photon detector which has wide effective area (∼70mm × 70mm), a Hybrid Avalanche Photo Detector (HAPD), has been developed in a collaboration with Hamamatsu K.K. The HAPD consists of hybrid structure of a vacuum tube and an avalanche photodiode (APD). It can be operated in 1.5T magnetic field of the spectrometer and withstands the radiation levels expected in the Belle II experiment. There are two steps of electric pulse amplification: acceleration of photo-electron in electric field in the vacuum tube part and electron avalanche in the APD part resulting in total gain of order 105. For the ARICH, we use 420 HAPDs in total. Before installing them, we performed quality assessment studies such as measurements of dark current, noise level, signal-to-noise ratio and two-dimensional scan with laser illumination. We also measured quantum efficiency of the photocathode. During the HAPD performance tests in the magnetic field, we observed very large signal pulses which cause long dead time of the readout electronics in some of the HAPDs. We have carried out a number of studies to understand this phenomenon, and have found a way to mitigate it and suppress the degradation of the ARICH performance. In this report, we will show a summary of the HAPD performance and quality assessment measurements including validation in the magnetic field for all of the HAPDs manufactured for the ARICH in the Belle II.
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