Search

The J-PARC Hadron Experimental Facility was constructed with an aim to explore the origin and evolution of matter in the universe through experiments with intense particle beams. In the past decade, many results from particle and nuclear physics experiments have been obtained at the present facility. To expand the physics programs to as yet unexplored regions, the extension project of the Hadron Experimental Facility has been extensively discussed. This contribution presents the physics of the extension of the Hadron Experimental Facility to resolve issues related to strangeness nuclear physics, hadron physics, and flavor physics.

The B = 2 bound/resonance state (dibaryon) is an interesting object, which can be a molecule consisting of two baryons or a spatially compact hexaquark hadron object. The yd ^ n°n°d reaction has been experimentally investigated at incident energies ranging from 0.58 to 1.15 GeV to study non-strange dibaryons. The angular distributions of deuteron emission in the yd center-of-mass energy cannot be reproduced by quasi-free production of two neutral pions followed by deuteron coalescence. Additionally a 2.14-GeV peak is observed in the n°d invariant mass distribution. These suggest a sequential process such as yd ^ RIS ^ n°RIV ^ n°n°d with an isoscalar dibaryon RIS and an isovector dibaryon RIV. Since the mass of the observed isoscalar dibaryons are close to the sum of the nucleon (N) and nucleon resonance (N*) masses, an S-wave NN* molecule may play a role as a doorway to a dibaryon.

It is well known that magmatic plumbing systems change over time, but there is much debate as to why and how. We studied volcanic ejecta continuously deposited in an outcrop at Kagosaka Pass at the eastern base of Mount Fuji to investigate the factors responsible for changes in the magmatic plumbing system. The sample consisted of pyroclastic sediments from explosive eruptions for approximately 3000 y, which sandwiched the time of the Gotemba sector collapse at approximately 2500 BP. Chemical analyses of whole rocks, minerals, and matrix glasses, as well as mode measurements of glass and bubbles, were performed on samples collected from approximately 30 layers; significant changes were observed before and after the collapse. For example, before and after the collapse, matrix glass area increased around 60% to over 80% and anorthite content (Ca / (Ca + Na) * 100) of phenocryst plagioclase decreased from over 80 to below 65. For a period after the collapse, possibly hundreds of years, the plagioclase and olivine phenocrysts exhibited characteristics indicative of crystallization at low temperatures and pressures, and the pyroclast matrix became highly vitreous. Eruptions with ejecta of these characteristics continued more than a dozen times, lasting about 500 years. In addition, the trend in the distribution of the bulk rock chemical composition changed significantly, showing a differentiation trend with only plagioclase and clinopyroxene crystal separation. An investigation using the MELTS software revealed that the phenomenon of direct eruptions from deep magma chambers to the surface, bypassing shallow magma reservoirs, continued for several hundred years after the collapse. This can be interpreted as a decrease in confining pressure associated with the collapse, facilitating the eruption of magma from the depths. Furthermore, based on an examination of the water content in the magma during this period, we posit that the trigger for the rise of magma from the deep magma chamber of Mount Fuji is the acquisition of excess pressure by the injection of magma from a deeper level. • Changes in magma plumbing system after the Gotemba collapse is discussed. • Phenocryst plagioclase composition decreased from An 85 to 65. • Surface phenomena may change the likelihood of an eruption. • Eruption caused by excess pressure is discussed. [ABSTRACT FROM AUTHOR]

We present the case of a 71-year-old man who, despite becoming asymptomatic after having some mild symptoms of COVID-19, had SARS-CoV-2 RNA detected for 37 days after onset, from his concentrated and purified saliva specimens using sugar chain-immobilized gold nanoparticles. It was suggested that the early morning saliva specimens were more likely to show positive results than those obtained later in the day. [ABSTRACT FROM AUTHOR]

The KOTO experiment at J-PARC, Japan, aims to observe the rare neutral kaon decay mode KL\rightarrow \pi ^{0}\nu \bar {\nu } . After the first experimental run in May 2013 at a 24-kW beam power, the KOTO data acquisition (DAQ) system was upgraded in 2015 to provide efficient and reliable data collection at higher beam intensities. Lossless data compression in the analog-to-digital converter modules was implemented to reduce the size of data packets, resulting in a threefold increase in data collection rate. A new software trigger on a 47-node cluster was designed to use Infiniband hardware with message passing interface protocol to establish a mesh network inside the computer clusters for parallel data processing. The upgrade to the KOTO DAQ system was commissioned in 2015 and successfully collected data with a beam intensity of up to 42 kW. In preparation for increasing beam intensities in future runs, the hardware trigger upgrades using the reconfigurable clustering element platform technology are under development. [ABSTRACT FROM AUTHOR]

We developed and built a new readout and trigger electronics system, based on a waveform digitization and pipeline readout, for the KOTO experiment at J-PARC, Japan. KOTO aims at observing the rare kaon decay K_L \rightarrow \pi ^0\nu \bar \nu . A total of 4000 readout channels from various detector subsystems are digitized by 14 bit 125 MHz ADC modules equipped with 10 pole Bessel filters to reduce the pile-up effects. The trigger decision is made every 8 ns using the digitized waveform information. To avoid dead time, the ADC and trigger modules have pipelines in their FPGA chips to store data while waiting for a trigger decision. The KOTO experiment performed the first physics run in May 2013. The data acquisition system worked stably during the run. [ABSTRACT FROM PUBLISHER]

The Kirishima Volcano Group is a volcanic field ideal for studying the mechanism of steam-driven eruptions because many eruptions of this type occurred in the historical era and geophysical observation networks have been installed in this volcano. We made regular geothermal observations to understand the hydrothermal activity in Ebinokogen Ioyama Volcano. Geothermal activity resumed around the Ioyama from December 2015. A steam blowout occurred in April 2017, and a hydrothermal eruption occurred in April 2018. Geothermal activity had gradually increased before these events, suggesting intrusion of the magmatic component fluids in the hydrothermal system under the volcano. The April 2018 eruption was a magmatic hydrothermal eruption caused by the injection of magmatic fluids into a very-shallow hydrothermal system as a bottom–up fluid pressurization, although juvenile materials were not identifiable. Additionally, the upwelling of mixed magma–meteoric fluids to the surface as a kick was observed just before the eruption to cause the top–down flashing of April 2018. A series of events was generated in the shallower hydrothermal regime consisting of multiple systems divided by conductive caprock layers. [ABSTRACT FROM AUTHOR]

We developed a novel beam profile monitor for measuring the shape of an intense neutral beam for particle physics. This monitor is based on a detector technology of scintillating fibers, photomultiplier tubes, and sampling ADCs. It has an advantage for its simplicity, reliability, flexibility, and versatility. This monitor was installed in the small-diameter neutral beam for the KL0 →π0 νν experiment at J-PARC. We report in this article the development and performance of this monitor. [ABSTRACT FROM AUTHOR]

The 2018 small phreatic eruption that occurred at Iwo-yama (Ebinokogen Ioyama) volcano of the Kirishima Volcanic Complex in Japan was recorded by infrasonic, seismic, and visual (video) observations within 1 km from eruption vents, which provides a good opportunity to investigate infrasound mechanisms and associated surface eruptive dynamics. The monitoring camera captured a widening of the vent about 3 h after the eruption onset, and then the infrasound stations recorded pulse-like intermittent signals. We carried out seismoacoustic analysis mainly focusing on the pulse-like infrasound, and also referred to rheological properties of mud suspension sampled from the rim of the vent to consider mechanical processes of the infrasonic pulse generation. The observed infrasonic pulses exhibited clear transitions in their waveforms and spectral contents. Based on the results of the seismoacoustic analysis and rheological measurements, we infer that the infrasonic pulse transition may have been caused by the shift of bubble bursting styles at the surface of the mud suspension, through the decrease of yield stress and viscosity due to increasing water fraction. The vent widening can be attributed to a collapse of soil around the vent due to the addition of water and the resultant weakening of the soil strength. We also observed high-frequency continuous infrasound (infrasonic tremors), which coupled into the ground and were recorded by the seismometers as well. The high-frequency infrasonic tremors had spectral features similar to those known for jet noise and might have been caused by the ash-steam mixture jet from the vent. Finally, we propose a conceptual model of the transition process of the surface eruptive activity by attributing them to the rheological change of the mud suspension with the increase of the water fraction. • Surface eruptive dynamics of a phreatic eruption that occurred at Iwo-yama volcano in 2018 were investigated by infrasonic and seismic observations. • We also referred to rheological properties of the mud suspension collected from the eruption vent. • Observed pulse-like infrasonic signals show transitions in their waveforms and spectral components. • The infrasonic pulse transition is attributed to changing styles of bubble bursting caused by the decrease of yield stress and viscosity of the mud suspension. [ABSTRACT FROM AUTHOR]

Identification of viruses that infects animals or plants, and determination of their quantity are essential for the diagnosis of infectious disease and for the determination of a strategy in the treatment of virus-derived diseases. However, the concentration of viruses existing in a living body (in bodily fluid), food, drinking water, river water, and so on. is not high enough to be detected using conventional diagnostic methods. For example, since the concentration of influenza virus released from an infected person is less than the detection limit of conventional simple examination kits (rapid kit) or even a PCR process at the initial stage of infection, it is difficult to detect the presence of influenza virus which will lead to influenza disease. Our technology allows for safe, efficient, and selective concentration of viruses without troublesome ultracentrifugation, using sugar chain-immobilized metal nanoparticles based on the binding interaction between viruses and sugar chains. For COVID-19, we have developed and commercialized two molecular diagnosis kits: SUDx SARS-CoV-2 detection kit, and SGNP nCoV/Flu PCR detection kit, for the Japanese market in 2020., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)