Optimization through simulation for the Belle detector upgrade Kibayashi, A.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2009, 2009-1-00, Letnik:
598, Številka:
1
Journal Article
Recenzirano
We present the status of the optimization study through simulation for the Belle detector upgrade. We make use of the existing Geant3 based fast and full simulators to confirm and tune detector ...options proposed according to hardware developments, in order to provide the best possible data under high background environment for future physics analyses.
Status of the Belle Silicon Vertex Detector Kibayashi, A.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2006, Letnik:
569, Številka:
1
Journal Article
Recenzirano
We present the status of the second version of the Silicon Vertex Detector (SVD2) at Belle. SVD2 has been in operation since October 2003, and its innermost layer has accumulated 2.4
kGy of radiation ...dose. The noise in the inner layers increased by about 20%, while the gain of the readout chips kept stable. In order to cope with the expected luminosity increase of the KEKB collider in the near future, a hardware trigger was upgraded in 2005, resulting in the decrease of the accidental rate while keeping the same trigger hold efficiency. New software is also being implemented to reduce and eliminate background induced hits among the tracking candidates.
Used for both proton decay searches and neutrino physics, large water Cherenkov (WC) detectors have been very successful tools in particle physics. They are notable for their large masses and charged ...particle detection capabilities. While current WC detectors reconstruct charged particle tracks over a wide energy range, they cannot efficiently detect neutrons. Gadolinium (Gd) has the largest thermal neutron capture cross section of all stable nuclei and produces an 8 MeV gamma cascade that can be detected with high efficiency. Because of the many new physics opportunities that neutron tagging with a Gd salt dissolved in water would open up, a large-scale R&D program called EGADS was established to demonstrate this technique’s feasibility. EGADS features all the components of a WC detector, chiefly a 200-ton stainless steel water tank furnished with 240 photo-detectors, DAQ, and a water system that removes all impurities from water while keeping Gd in solution. In this paper we discuss the milestones towards demonstrating the feasibility of this novel technique, and the features of EGADS in detail.
We have searched for proton decays into a charged antilepton (e+, μ+) plus a meson (η, ρ0, ω) and for neutron decays into a charged antilepton (e+, μ+) plus a meson (π−, ρ−) using Super-Kamiokande ...I-IV data, corresponding to 0.316 megaton·years of exposure. This measurement updates the previous published result by using 2.26 times more data and improved analysis methods. No significant evidence for nucleon decay is observed and lower limits on the partial lifetime of the nucleon are obtained. The limits range from 3×1031 to 1×1034 years at 90% confidence level, depending on the decay mode.
A search for Supernova Relic Neutrinos ν¯e’s is first conducted via inverse-beta-decay by tagging neutron capture on hydrogen at Super-Kamiokande-IV. The neutron tagging efficiency is determined to ...be (17.74±0.04stat.±1.05sys.)%, while the corresponding accidental background probability is (1.06±0.01stat.±0.18sys.)%. Using 960days of data, we obtain 13 inverse-beta-decay candidates in the range of Eν¯e between 13.3MeV and 31.3MeV. All of the observed candidates are attributed to background. Upper limits at 90% C.L. are calculated in the absence of a signal.
We present the results of searches for nucleon decay via n→νover ¯π0 and p→νover ¯π+ using data from a combined 172.8 kt·yr exposure of Super-Kamiokande-I,-II, and-III. We set lower limits on the ...partial lifetime for each of these modes: τn→νover ¯π0>1.1×10(33) years and τp→νover ¯π+>3.9×10(32) years at a 90% confidence level.
We present the result of an indirect search for high energy neutrinos from Weakly Interacting Massive Particle (WIMP) annihilation in the Sun using upward-going muon (upmu) events at ...Super-Kamiokande. Data sets from SKI-SKIII (3109.6 days) were used for the analysis. We looked for an excess of neutrino signal from the Sun as compared with the expected atmospheric neutrino background in three upmu categories: stopping, non-showering, and showering. No significant excess was observed. The 90% C.L. upper limits of upmu flux induced by WIMPs of 100 GeV c-2 were 6.4 X 10--15 cm--2 s--1 and 4.0 X 10--15 cm--2 s--1 for the soft and hard annihilation channels, respectively. These limits correspond to upper limits of 4.5 X 10--39 cm--2 and 2.7 X 10--40 cm--2 for spin-dependent WIMP-nucleon scattering cross sections in the soft and hard annihilation channels, respectively.
Measurements of 2 and 3 at Belle Kibayashi, A
Journal of physics. Conference series,
05/2008, Letnik:
110, Številka:
5
Journal Article
Recenzirano
Odprti dostop
We report recent measurements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix angles 2 and 3 based on a large data sample of B pairs collected with the Belle detector at the KEKB ...asymmetric-energy e+e− collider operating at the (4S) resonance. We employ the time-dependent CP violation in B → ππ, ρπ and ρρ decays to determine 2, and CP violation in the interferences between b → c and b → u transitions to extract 3.
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