T2K is a long-baseline neutrino experiment that aims to investigate the CP violation in the neutrino sector. An upgrade of the ND280, which is one of the T2K near detectors, is in progress. The ...active target detector of the upgraded ND280 is a segmented highly granular plastic scintillation detector (SuperFGD) consisting of about two million scintillator cubes. About sixty thousand silicon photo-multipliers (SiPMs) coupled with wavelength shifting fibers are used for light readout. The fibers go through the scintillator cubes along the orthogonal three directions. We developed a novel system based on LEDs and notched light guide plates for in-situ calibration of the SuperFGD. The developed system can distribute LED light to SiPMs simultaneously with high uniformity and can be used for gain calibration and stability monitor of the signal readout. In addition, it can fit in the confined space of the SuperFGD due to its thin structure. In this paper, we report the design and the performance of the calibration system.
The INGRID(Interactive Neutrino GRID) detector is designed to measure the neutrino beam direction with a precision better than 1mrad for T2K experiment. INGRID consists of 16 modules and placed ...around the beam center at 280m downstream of the proton beam target. The module is a sandwich of iron targets and scintillator tracking planes which consist of X–Y layers. We have constructed all scintillator tracking planes and measured light yield of all scintillators. Currently we install 1st module into the detector hall and cosmic events are observed. INGRID is ready for 1st neutrino event from April 2009.
The T2K (Tokai-to-Kamioka) is a long baseline neutrino experiment designed to study various parameters that rule neutrino oscillations, with an intense beam of muon neutrinos. A near detector complex ...(ND280) is used to constrain non-oscillated flux and hence to predict the expected number of events in the far detector (Super-Kamiokande). The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-canceling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new water grid and scintillator detector, WAGASCI, has been proposed. The detector will be operated at the J-PARC neutrino beam line with the main physics goal to measure the charged current neutrino cross section ratio between water and hydrocarbon with a few percent accuracy. Further physics program may include high-precision measurements of different charged current neutrino interaction channels. The concept of the new detector will be covered together with the actual construction plan.
The T2K experiment observes indications of ν(μ) → ν(e) appearance in data accumulated with 1.43×10(20) protons on target. Six events pass all selection criteria at the far detector. In a three-flavor ...neutrino oscillation scenario with |Δm(23)(2)| = 2.4×10(-3) eV(2), sin(2)2θ(23) = 1 and sin(2)2θ(13) = 0, the expected number of such events is 1.5±0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7×10(-3), equivalent to 2.5σ significance. At 90% C.L., the data are consistent with 0.03(0.04) < sin(2)2θ(13) < 0.28(0.34) for δ(CP) = 0 and a normal (inverted) hierarchy.
Supernova detection is a major objective of the Super-Kamiokande (SK) experiment. In the next stage of SK (SK-Gd), gadolinium (Gd) sulfate will be added to the detector, which will improve the ...ability of the detector to identify neutrons. A core-collapse supernova (CCSN) will be preceded by an increasing flux of neutrinos and antineutrinos, from thermal and weak nuclear processes in the star, over a timescale of hours; some of which may be detected at SK-Gd. This could provide an early warning of an imminent CCSN, hours earlier than the detection of the neutrinos from core collapse. Electron antineutrino detection will rely on inverse beta decay events below the usual analysis energy threshold of SK, so Gd loading is vital to reduce backgrounds while maximizing detection efficiency. Assuming normal neutrino mass ordering, more than 200 events could be detected in the final 12 hr before core collapse for a 15-25 solar mass star at around 200 pc, which is representative of the nearest red supergiant to Earth, -Ori (Betelgeuse). At a statistical false alarm rate of 1 per century, detection could be up to 10 hr before core collapse, and a pre-supernova star could be detected by SK-Gd up to 600 pc away. A pre-supernova alert could be provided to the astrophysics community following gadolinium loading.
Silicon vertex tracker for RHIC PHENIX experiment Taketani, A.; Akiba, Y.; Apdula, N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Volume:
623, Issue:
1
Journal Article
Peer reviewed
The PHENIX experiment at Relativistic Heavy Ion Collider will be equipped with Silicon Vertex tracker to enhance its physics capability. There are four layers of silicon sensor to reconstruct charged ...tracks with 50μm resolution of decay length measurement. The VTX surrounds the collision point. The inner two layers and the outer two layers are composed of 30 pixel ladders and 44 stripixel ladders, respectively. We have been developing these detectors and done a performance test with 120GeV proton beam.
Heavy quarks and quarkonia Drapier, O.
Nuclear Physics A,
08/2006, Volume:
774
Journal Article, Conference Proceeding
Peer reviewed
This paper is a review of the latest results on heavy flavor production presented during the Quark Matter 2005 conference in Budapest. The measurements of J/
ψ production performed at CERN SPS by ...NA60 are discussed together with the latest NA50 results. Surprisingly, none of the models that have been shown to account for NA50 Pb+Pb data is able to reproduce NA60 In+In points. The PHENIX experiment at RHIC also presented results on J/
ψ production. When interpreting these results, several cold nuclear effects have to be taken into account, as J/
ψ absorption by interactions with nucleons, or modification of parton distribution functions in the nuclei. The interpretation of RHIC data is still unclear, but a precise study of J/
ψ rapidity and transverse momentum distributions could help to discriminate the different models. In addition, data on open charm have been presented by RHIC experiments. Some implications of these new results for J/
ψ production are also discussed.
The silicon pixel detector will be installed in summer 2009 as part of the RHIC-PHENIX silicon vertex tracker (VTX) upgrade at the Brookhaven National Laboratory. The VTX consists of a silicon pixel ...detector and stripixel detector. For the construction of the silicon pixel detector, we have developed a fine pitch and low material readout bus as the backbone parts of the VTX. In this article, we report the development of the readout bus.
Abstract
A new event reconstruction algorithm based on a maximum likelihood method has been developed for Super-Kamiokande. Its improved kinematic and particle identification capabilities enable the ...analysis of atmospheric neutrino data in a detector volume 32% larger than previous analyses and increase the sensitivity to the neutrino mass hierarchy. Analysis of a 253.9 kton$\cdot$year exposure of the Super-Kamiokande IV atmospheric neutrino data has yielded a weak preference for the normal hierarchy, disfavoring the inverted hierarchy at 74% assuming oscillations at the best fit of the analysis.
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