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The Shirakami Mountain range, including the largest primeval beech forest in East-Asia, is undergoing ecological change. Dissolved organic matter (DOM) plays an important role in nutrient and material cycling in forest ecosystems. Because the quality of DOM varies based on its origin and diagenetic and runoff processes, changes in the environment surrounding DOM can be rapidly detected by monitoring its quality. Herein, concentrations and fluorescence composition of DOM at 14 sites in 13 streams in the Shirakami Mountain range were monitored monthly for over 2 years, excluding winter (December–March), to gain insight into the catchment hydrological and soil characteristics affecting DOM concentrations and composition in stream water. Based on the pattern of temporal changes in fluorescent component composition, monitoring sites were categorized into four groups (streams with small catchments, large catchments, catchments facing the Sea of Japan, and open waters in the catchment) with similar catchment characteristics affecting DOM dynamics. Multiple linear regression analysis showed that DOM concentrations in each group could be attributed to rainfall on the survey date, short-term (1–2 days) rainfall, midterm (~1 month) accumulated rainfall, midterm (7–11 days) accumulated temperature, and catchment characteristics as explanatory variables. The degree of influence of these variables differed among the four groups. The results of this study show that grouping streams according to catchment hydrological characteristics can help identify the impact of climate and environmental change on DOM dynamics in stream water.

Abstract The neutron lifetime has been measured by comparing the decay rate with the reaction rate of $^3$He nuclei of a pulsed neutron beam from the spallation neutron source at the Japan Proton Accelerator Research Complex (J-PARC). The decay rate and the reaction rate were determined by simultaneously detecting electrons from the neutron decay and protons from the $^3$He(n,p)$^3$H reaction using a gas chamber, the working gas of which contains diluted $^3$He. The measured neutron lifetime was $898\\,\\pm\\,10\\,_{\\rm stat}\\,^{+15}_{-18}\\,_{\\rm sys}\\,$s.

The Yet Another Rapid Readout (YARR) system is a DAQ system designed for pixel readout chips including the current generation ATLAS FE-I4 chip and the next generation RD53A chip, which is part of the development of new Pixel detector technology to be implemented in High-Luminosity Large Hadron Collider experiments. YARR utilises a PCI-e FPGA card which acts as a simple gateway to pipe all data from pixel readout chips via the high speed PCI-e connection into the host system's memory. All data processing is done on a software level in the host CPU(s), utilising a data-driven, multi-threaded, parallel processing paradigm. YARR has recently been upgraded to interface with software emulators of pixel readout chips. These emulators offer many benefits: quick development of DAQ software; expansion of the developer base to users without access to readout hardware; preparation of DAQ software for upcoming readout chips, such as RD53A; implementation of Continuous Integration and unit tests to ensure code quality and maintainability. The design and capabilities of the FE-I4 and RD53A software emulators will be presented.

In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated from the neutron decay rate and the incident neutron flux. The flux is obtained by counting the protons emitted from the neutron absorption reaction of^{3}{\\rm He}$gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of^{3}{\\rm He}$in the mixture. In order to improve the accuracy of the number density of the^{3}{\\rm He}$nuclei, we have suggested using the^{14}{\\rm N}({\\rm n},{\\rm p}){}^{14}{\\rm C}$reaction as a reference because this reaction involves similar kinetic energy to the$^3$ He(n,p) $^3$ H reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper we report the most accurate experimental value of the cross section of the$^{14}$ N(n,p) $^{14}$ C reaction at a neutron velocity of 2200 m s $^{-1}$ , measured relative to the$^3$ He(n,p) $^3$ H reaction. The result was 1.868$\\pm$0.003 (stat.)$\\pm$0.006 (sys.) b. Additionally, the cross section of the$^{17}$ O(n, $\\alpha$ ) $^{14}$ C reaction at the neutron velocity is also redetermined as 249$\\pm$6 mb.

A neutron beamline for the study of fundamental physics has been constructed at the spallation neutron source of the Japan Proton Accelerator Research Complex (J-PARC). In-flight measurement of the neutron lifetime and the development of the transport optics of ultracold neutrons are in progress. The present status of the beamline and these experiments is reported.

The ``neutron lifetime puzzle'' arises from the discrepancy between neutron lifetime measurements obtained using the beam method, which measures decay products, and the bottle method, which measures the disappearance of neutrons. To resolve this puzzle, we conducted an experiment using a pulsed cold neutron beam at J-PARC. In this experiment, the neutron lifetime is determined from the ratio of neutron decay counts to \\(^3\\)He(n,p)\\(^3\\)H reactions in a gas detector. This experiment belongs to the beam method but differs from previous experiments that measured protons, as it instead detects electrons, enabling measurements with distinct systematic uncertainties. By enlarging the beam transport system and reducing systematic uncertainties, we achieved a fivefold improvement in precision. Analysis of all acquired data yielded a neutron lifetime of \\(_ n=877.2~~1.7_(stat.)~^+4.0_-3.6_ (sys.)\\) s. This result is consistent with bottle method measurements but exhibits a 2.3\\(\\) tension with the average value obtained from the proton-detection-based beam method.

A neutron decays into a proton, an electron, and an anti-neutrino through the beta-decay process. The decay lifetime (\\(\\sim\\)880 s) is an important parameter in the weak interaction. For example, the neutron lifetime is a parameter used to determine the |\\(V_{\\rm ud}\\)| parameter of the CKM quark mixing matrix. The lifetime is also one of the input parameters for the Big Bang Nucleosynthesis, which predicts light element synthesis in the early universe. However, experimental measurements of the neutron lifetime today are significantly different (8.4 s or 4.0\\(\\sigma\\)) depending on the methods. One is a bottle method measuring surviving neutron in the neutron storage bottle. The other is a beam method measuring neutron beam flux and neutron decay rate in the detector. There is a discussion that the discrepancy comes from unconsidered systematic error or undetectable decay mode, such as dark decay. A new type of beam experiment is performed at the BL05 MLF J-PARC. This experiment measured neutron flux and decay rate simultaneously with a time projection chamber using a pulsed neutron beam. We will present the world situation of neutron lifetime and the latest results at J-PARC.

The neutron lifetime has been measured by comparing the decay rate with the reaction rate of \\(^3\\)He nuclei of a pulsed neutron beam from the spallation neutron source at the Japan Proton Accelerator Research Complex (J-PARC). The decay rate and the reaction rate were determined by simultaneously detecting electrons from the neutron decay and protons from the \\(^3\\)He(n,p)\\(^3\\)H reaction using a gas chamber of which working gas contains diluted \\(^3\\)He. The measured neutron lifetime was \\(898\\,\\pm\\,10\\,_{\\rm stat}\\,^{+15}_{-18}\\,_{\\rm sys}\\,\\)s.

The jet cross-section and jet-substructure observables in $p$$+$$p\\( collisions at \\)\\sqrt{s}=200\\( GeV were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-\\)k_{t}\\( algorithm with a jet radius \\)R=0.3\\( for jets with transverse momentum within \\)8.0

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