We study the decay B+→K+K– π+ and investigate the angular distribution of K+K– pairs with invariant mass below 1.1 GeV / c2. This region exhibits both a strong enhancement in signal and very large ...direct CP violation. We construct a coherent sum model for the angular distribution of the S- and P-wave, and report the ratio of their amplitudes, the relative phase and the forward-backward asymmetry. We also report absolute differential branching fractions and direct CP asymmetry for the decay in bins of MK+K– and the differential branching fractions in bins of MK+π–. The results are based on a data sample that contains 772 × 106 $B\bar{B}$ pairs collected at the $Υ$(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e– collider. The result favors the presence of S- and D-waves in low MK+K– region to the detriment of a P-wave.
Using 980 fb−1 of data collected with the Belle detector operating at the KEKB asymmetric-energy e+ e− collider, we report the measurements of the masses, and the first measurements of the instrinsic ...widths, of the Σc ( 2455 )+ and Σc (2520)+ charmed baryons. We find M (Σc (2455)+) − M (Λc+) = 166.17 ± 0.0 5−0.07+0.16 MeV / c2, Γ (Σc (2455)+) = 2.3 ± 0.3 ± 0.3 MeV /c2, M ( Σc (2520)+) − M(Λc+) = 230.9 ± 0. 5− 0.1+ 0.5 MeV / c2, and Γ(Σc (2520)+) = 17.2− 2.1− 0.7+2.3+3.1 MeV / c2, where the uncertainties are statistical and systematic, respectively. These measurements can be used to test models of the underlying quark structure of the Σc states.
We report new measurements of the production cross sections of pairs of charged pions and kaons as a function of their fractional energies using various fractional-energy definitions. Two different ...fractional-energy definitions were used and compared to the conventional fractional-energy definition reported previously. The new variables aim at either identifying dihadron cross sections in terms of single-hadron fragmentation functions, or to provide a means of characterizing the transverse momentum created in the fragmentation process. The results were obtained applying the updated initial-state radiation correction used in other recent Belle publications on light-hadron production cross sections. In addition, production cross sections of single charged pions, kaons, and protons were also updated using this initial-state radiation correction. The cross sections are obtained from a 558 fb-1 data sample collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
We study hadronic transitions between bottomonium states using 496 fb−1 data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e− collider. We measure ...B(ϒ(4S)→π+π−ϒ(1S))=(8.2±0.5(stat)±0.4(syst))×10−5, B(ϒ(4S)→π+π−ϒ(2S))=(7.9±1.0(stat)±0.4(syst))×10−5, and B(ϒ(4S)→ηϒ(1S))=(1.70±0.23(stat)±0.08(syst))×10−4. We measure the ratio of branching fractions R=B(ϒ(4S)→ηϒ(1S))/B(ϒ(4S)→π+π−ϒ(1S))=2.07±0.30(stat)±0.11(syst). We search for the decay ϒ(1D31,2)→ηϒ(1S), but do not find significant evidence for such a transition. We also measure the initial-state radiation production cross sections of the ϒ(2S,3S) resonances and we find values compatible with the expected ones. Finally, the analysis of the ϒ(4S)→π+π−ϒ(1S) events shows indications for a resonant contribution due to the f0(980) meson.
Study of a Cherenkov TOF-PET module Korpar, S.; Dolenec, R.; Križan, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
An apparatus, consisting of two PbF2 crystals, each coupled to a multichannel plate photomultiplier (MCP-PMT), has been constructed in order to measure the time-of-flight (TOF) of the two 511keV ...annihilation photons produced in positron emission tomography (PET). Excellent timing is achieved by detecting the prompt Cherenkov photons produced by the absorption of the 511keV gamma photons. The present work describes the measurement and image reconstruction of two 22Na point sources. In addition, the influence of the radiator thickness and the Cherenkov light absorption cut-off of the crystal on the efficiency and the timing resolution have been studied by Monte Carlo simulation.
Reanalysis data are very useful for studying the stratosphere. They can be used for analysis of long-term trends (temperature, wind speed, humidity, etc.) or analysis of global atmospheric dynamics, ...etc. There are various reanalysis projects that provide outputs which are not identical. In this paper, we mutually compare three of them, ERA-40, ERA-Interim and NCEP/NCAR, and compare them with balloon radiosonde observations from Prague, Port Hardy and Valentia stations. This comparison is done for wind speed and direction at pressure levels 100 and 10 hPa and for various periods between 1957 and 2009. The results show that the differences between reanalysis vary. Wind speed data from all three analyses reasonably agree except for the 10 hPa historical data before 1966 and particularly ERA-40 data at the end of the data series (1998–2001). The quality of the ERA-40 10 hPa stratospheric wind data has been proven to be substantially worse over the last four ERA-40 years of 1998–2001 (2002) compared to previous years, both in wind speed and wind direction. The reanalysis data results are compared with radiosonde observations from Prague, Port Hardy and Valentia stations at 10 hPa for the months of February between 1989 and 2009. The results show that there are sometimes surprisingly large differences, more for ERA-Interim versus Prague measurements. Differences in wind direction greater than 45° (outliers) between the reanalysis data and Prague observations in wind direction occur in Februaries predominantly when winds in Prague are in "minor" sectors, such as north, northeast and east (easterlies), whereas "major" sectors, particularly the dominant W (westerlies) wind sector, exhibit almost no outliers.
Timing and cross-talk properties of BURLE multi-channel MCP PMTs Korpar, S.; Križan, P.; Pestotnik, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2008, Letnik:
595, Številka:
1
Journal Article
Recenzirano
We report on studies of the two types of BURLE multi-anode micro-channel plate (MCP) PMTs; one with 64 channels and
25
μ
m
pores and the other with four channels and
10
μ
m
pores. Possible ...applications of these tubes are for RICH detectors and time-of-flight counters. We have investigated their timing properties and cross-talk. The origin of the cross-talk between the channels was investigated by studying the correlations between signals on neighbouring pads, their amplitudes and time of arrival. We have also studied the influence of cross-talk on timing and spatial resolution.
We report a new measurement of the exclusive e+e−→D(*)±D*∓ cross sections as a function of the center-of-mass energy from the D(*)±D*∓ threshold through s=6.0 GeV, using the initial-state radiation ...technique. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 951 fb−1. The accuracy of the cross section measurement is increased by a factor of 2 over the first Belle study. We perform the first angular analysis of the e+e−→D*±D*∓ process and decompose this exclusive cross section into three components corresponding to the D* helicities.
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