1,954 research outputs found

    New analysis of nuclear interaction observed by Mt. Kanbara emulsion chamber experiment

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    To date the analysis of the air cascade family has been performed using a full Monte Carlo simulation. It is difficult to draw a definite conclusion about the interaction mechanism by using only this kind of simulation. On the other hand, attempts to reproduce the original gamma ray at the interaction point, for example decascading, have also been made. This method makes it possible to observe the interaction directly and to analyze the data from various angles. All of these methods, however, assume a constant ER in the cascade shower, where E is energy and R is the distance from the center of the cascade shower. It is impossible to reproduce the exact interaction height and energy by these methods. A relative method in separating one cascade shower from others is adopted. This method makes it possible to estimate the interaction height and energy by using information about the lateral spread of the cascade shower

    An aerogel Cherenkov detector for multi-GeV photon detection with low sensitivity to neutrons

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    We describe a novel photon detector which operates under an intense flux of neutrons. It is composed of lead-aerogel sandwich counter modules. Its salient features are high photon detection efficiency and blindness to neutrons. As a result of Monte Carlo (MC) simulations, the efficiency for photons with the energy larger than 1 GeV is expected to be higher than 99.5% and that for 2 GeV/cc neutrons less than 1%. The performance on the photon detection under such a large flux of neutrons was measured for a part of the detector. It was confirmed that the efficiency to photons with the energy >>1 GeV was consistent with the MC expectation within 8.2% uncertainty.Comment: 16 pages, 16 figures, submitted to Prog. Theor. Exp. Phy

    Development of a low-mass and high-efficiency charged particle detector

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    We developed a low-mass and high-efficiency charged particle detector for an experimental study of the rare decay KLπ0ννˉK_L \rightarrow \pi^0 \nu \bar{\nu}. The detector is important to suppress the background with charged particles to the level below the signal branching ratio predicted by the Standard Model (O(1011^{-11})). The detector consists of two layers of 3-mm-thick plastic scintillators with wavelength shifting fibers embedded and Multi Pixel Photon Counters for readout. We manufactured the counter and evaluated the performance such as light yield, timing resolution, and efficiency. With this design, we achieved the inefficiency per layer against penetrating charged particles to be less than 1.5×1051.5 \times 10^{-5}, which satisfies the requirement of the KOTO experiment determined from simulation studies.Comment: 20 pages, 18 figure

    High energy gamma-rays and hadrons at Mount Fuji

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    The energy spectra of high energy gamma-rays and hadrons were obtained by the emulsion chamber with 40 c.u. thickness at Mt. Fuji (3750 m). These results are compared with the Monte Carlo calculation based on the same model which is used in a family analysis. Our data are compatible with the model of heavy-enriched primary and scaling in the fragmentation region

    Particle interactions at energies over 1000 TeV inferred from gamma-families observed at Mount Fuji

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    Scaling, mean P sub t, high P sub t jets and others at energies over 1000 TeV are discussed on the basis of gamma-family data with sigma E sub gamma 100 TeV, observed at Mt. Fuji (3750 m). These quantities were examined in connection with the primary composition

    Prevalence, incidence, and outcomes across cardiovascular diseases in homeless individuals using national linked electronic health records

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    AIMS: The risk and burden of cardiovascular disease (CVD) are higher in homeless than in housed individuals but population-based analyses are lacking. The aim of this study was to investigate prevalence, incidence and outcomes across a range of specific CVDs among homeless individuals. METHODS AND RESULTS: Using linked UK primary care electronic health records (EHRs) and validated phenotypes, we identified homeless individuals aged ≥16 years between 1998 and 2019, and age- and sex-matched housed controls in a 1:5 ratio. For 12 CVDs (stable angina; unstable angina; myocardial infarction; sudden cardiac death or cardiac arrest; unheralded coronary death; heart failure; transient ischaemic attack; ischaemic stroke; subarachnoid haemorrhage; intracerebral haemorrhage; peripheral arterial disease; abdominal aortic aneurysm), we estimated prevalence, incidence, and 1-year mortality post-diagnosis, comparing homeless and housed groups. We identified 8492 homeless individuals (32 134 matched housed individuals). Comorbidities and risk factors were more prevalent in homeless people, e.g. smoking: 78.1% vs. 48.3% and atrial fibrillation: 9.9% vs. 8.6%, P < 0.001. CVD prevalence (11.6% vs. 6.5%), incidence (14.7 vs. 8.1 per 1000 person-years), and 1-year mortality risk [adjusted hazard ratio 1.64, 95% confidence interval (CI) 1.29-2.08, P < 0.001] were higher, and onset was earlier (difference 4.6, 95% CI 2.8-6.3 years, P < 0.001), in homeless, compared with housed people. Homeless individuals had higher CVD incidence in all three arterial territories than housed people. CONCLUSION: CVD in homeless individuals has high prevalence, incidence, and 1-year mortality risk post-diagnosis with earlier onset, and high burden of risk factors. Inclusion health and social care strategies should reflect this high preventable and treatable burden, which is increasingly important in the current COVID-19 context

    Earthquake detection capacity of Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET)

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    We adopted the Probability-based Magnitude of Completeness (PMC) method and performed a case analysis of the Nankai Trough, a target region monitored for future megathrust earthquakes. JAMSTEC (Japan Agency for Marine-Earth Science and Technology) has created a seismicity catalog that includes events in this region observed by DONET. Using seismicity data for 2015-2019, we found spatiotemporal variability of completeness magnitude Mp. Mp was lower than 1 in one of the areas where stations are densely deployed, whereas Mp was larger than 2 at the periphery and outside of the DONET area. We then evaluated the temporal evolution of Mp, highlighting how the failure of sets of observing stations influenced Mp if not repaired. Stations are aggregated around the 12 science nodes (hubs that connect the stations) and connected through the two oceanfloor backbone cables to JAMSTEC. We explored the possible use of PMC as a tool with simulation computation of node malfunction. A simulation showed that completeness estimates in the area near failure nodes were about 1 magnitude larger. If such failure occurred for nodes near the region which straddles the rupture zones of the previous Tonankai and Nankai earthquakes in 1940's, it would most pronouncedly affect earthquake monitoring among nodes' failures. It is desirable to repair these nodes or replace with new ones when their malfunction occurs. We then demonstrated an example of how to use Mp information as prior knowledge to seismicity-related studies. We used the b value of the Gutenberg-Richter distribution, and computed it taking Mp into consideration. We found that the spatial and temporal changes in b were strongly correlated to the magnitude-6 class slow slip that grew over two years on the Nankai Trough plate boundary, indicating the b value as a proxy that can help to image stress heterogeneity when there is a slow slip event.Comment: 6 figure