No abstract available

[en] Full text: Hydrates are a rich and diverse class of materials that display a wide range of structures and properties – a feature that is only exaggerated when they are subjected to high-pressures. Consequently, these have implications on our understanding of many outer solar system bodies, where hydrates are amongst the dominant materials found there. For Europa and Ganymede, two moons under intense investigation from past and future space missions, their surfaces seen to be mostly water-ice and hydrates. Despite the apparent ‘simplicity’ of these materials, we still observe very complex geological formations on these moons – including subduction. Hence, we need to understand the transformations of candidate surface materials under a range of pressure/temperature conditions in order to accurately explain the formations on these icy surfaces. One hydrate candidate material for the surfaces of these moons are sulfuric acid hydrates, formed from radiolytic sulfur (from Io) reacting with the surface ice. Sulfuric acid hydrates have already been established to have a complex phase diagram with composition. We have now used the Mito cell at the PLANET instrument to undertake the first investigation of the high-pressure behaviour of the water rich sulfuric acid hydrates. Compressing at 100 K and 180 K we see that the hemitriskaidekahydrate becomes the stable water-rich hydrate and observe some interesting relaxation behaviour in this material at pressure, which could have significant consequences for the interiors of Ganymede. (author)

No abstract available

[en] In order to provide a study material as one of the examination techniques, this paper introduces the results obtained to date using neutron radiography/tomography at the energy-resolved neutron imaging equipment RADEN of J-PARC. (A.O.)

No abstract available

[en] In the liquid mercury target system for the pulsed spallation neutron source of Materials and Life science experimental Facility (MLF) at the Japan in the Japan Proton Accelerator Research Complex (J-PARC), cavitation that is generated by the high-energy proton beam-induced pressure waves, resulting severe erosion damage on the interior surface of the mercury target vessel. The erosion damage is increased with increasing the proton beam power, and has the possibility to cause the leakage of mercury by the penetrated damage and/or the fatigue failure originated from erosion pits during operation. To achieve the long term stable operation under high-power proton beam, the mitigation technologies for cavitation erosion consisting of surface modification on the vessel interior surface, helium gas microbubble injection, double-walled beam window structure has been applied. The damage on interior surface of the vessel is never observed during the beam operation. Therefore, after the target operation term ends, we have cut out specimen from the target nose of the target vessel to inspect damaged surface in detail for verification of the cavitation damage mitigation technologies and lifetime estimation. We have developed the techniques of specimen cutting out by remote handling under high-radiation environment. Cutting method was gradually updated based on experience in actual cutting for the used target vessel. In this report, techniques of specimen cutting out for the beam entrance portion of the target vessel in high-radiation environment and overview of the results of specimen cutting from actual target vessels are described. (author)

[en] At the J-PARC Hadron Experimental Facility, a new proton beamline at 8 GeV is currently under construction for COMET experiment. Since the pion-generation target is located in the center of the solenoid magnet, the radiation level is expected to be very high around the magnet downstream. To reduce radiation exposure to workers, we have developed a large-diameter all-metal pillow seals for vacuum connections around magnets. To fabricate a pillow-seal with an outer diameter of 1400 mm, a stainless-steel plate with a diameter of 1500 mm and a thickness of 0.2 mm is required, but it is not able to procure such a large 'seamless' plate. Thus, welded plate was adopted for the large-diameter pillow seal. The fabrication of the large-diameter pillow seal was successfully carried out as designed, and subsequently vacuum tightness was measured with a newly constructed test bench. In this paper, results of the vacuum tightness are reported. (author)

[en] The accelerator control system of the J-PARC MR started operation in 2008. Most of the components of the control computers, such as servers, disks, operation terminals, front-end computers and software, which were introduced during the construction phase, have went through one or two generational changes in the last 15 years. Alongside, the policies for the operation of control computers has changed. This paper reviews the renewal of those components and discusses the philosophy behind the configuration and operational policy. It is also discussed the approach to matters that did not exist at the beginning of the project, such as virtualization or cyber security. (author)

No abstract available

[en] At the J-PARC Hadron Experimental Facility, a gold target is bombarded with intense 30-GeV protons to produce secondary particles provided for various physics experiments. The newly-installed gold target is placed in a hermetic chamber, and to monitor the soundness of the target, the chamber is filled with circulating helium gas, whose radioactivity is continuously monitored with a Ge detector and a NaI(Tl) detector. Various γ-emitting nuclides were detected in the helium gas in beam-operation conditions. The relationship between beam operation and radionuclides production in helium gas was investigated. Radionuclides such as C-10, O-19, O-20, F-20, Ne-23, Ne-24, Na-24 (daughter of Ne-24), Ar-41, and annihilation peak, were detected in relatively low 24-kW beam power operations. These nuclides are produced in the beam windows and/or the gold target and transferred into the helium gas phase as gaseous chemical species. On the other hands at higher beam intensity of 42-kW, mercury isotopes, such as Hg-191m, Hg-192, Hg-193m, Hg-195, Hg-195m, and Au-192 as daughter of Hg-192 were detected in the helium gas. These detected nuclides are produced in the gold target and transferred into the helium gas phase as mercury vapor. Dependence of the counting rates for mercury isotopes on the beam power implies that transferring ratio of mercury isotopes into the gas phase was governed by the surface temperature of the gold target. Further detailed analyses are in progress to understand the behavior of induced radionuclides in gas phase. (author)