Abstract
The High Energy Accelerator Research Organization (KEK) has two light sources: Photon Factory (PF, 2.5 GeV) and Photon Factory Advanced Ring (PF-AR, 6.5 GeV). In 2017, the operation of a new ...beam transport line (BT) of PF-AR was started, and the simultaneous top-up injection for both PF and PF-AR was realized. These days, there have been strong demands for the reduction of the operating cost of accelerators, and its importance is greater in PF-AR with higher ring-energy of 6.5 GeV. In 2019, the 5 GeV operation was started in PF-AR. However, the new BT of PF-AR (ARBT) was designed for the energy of 6.5 GeV, then the simultaneous top-up injection is no longer available under the condition of 5 GeV operation of PF-AR and 2.5 GeV operation of PF. In order to mitigate this impact, the pseudo-top-top injection has been employed by fine-tuning the current of a common DC bending magnet placed at the intersection of ARBT and the BT of PF (PFBT) within a given time frame. However, this scheme reduces the flexibility of the operation schedules, and will not be able to respond adequately to low emittance optics of PF-AR that may bring the shorter beam lifetime. In order to realize true-top-up injection, a modification of BTs’ optics design was carried out to add new horizontal steering magnets and a flattened-duct. The beam commissioning succeeded and the application to the user-run will start in this May. This time, details of modification and its extended plan will be presented.
Nb3Al has advantages of better tolerance to strain/stress and a higher critical magnetic field (30 T at 4.2 K) for stoichiometric composition over Nb3Sn. The rapid-heating, quenching and ...transformation annealing (RHQT) process enables to form a stoichiometric Nb3Al with fine grain structures via metastable bcc supersaturated-solid-solution. As a result a large critical current density of Nb3Al is achieved over the whole range of magnetic fields without trading off the excellent strain tolerance. A long-length of RHQ processing has been established, and a rectangular but Cu stabilized Nb3Al strand is about be commercially available for NMR uses. Ag or Cu internal stabilization and Cu ion-plating/electroplating techniques have been also developed to enable the stabilized round wire for accelerator and fusion magnets. Successfully energized test coils that were manufactured with a wind-and-react technique have demonstrated that a long piece of Cu stabilized RHQT Nb3Al wire is really available for practical applications.
The diurnal variation of HOCl and the related species ClO, HO2 and HCl measured by satellites has been compared with the results of a one-dimensional photochemical model. The study compares the data ...from various limb-viewing instruments with model simulations from the middle stratosphere to the lower mesosphere. Data from three sub-millimetre instruments and two infrared spectrometers are used, namely from the Sub-Millimetre Radiometer (SMR) on board Odin, the Microwave Limb Sounder (MLS) on board Aura, the Superconducting Submillimeter-wave Limb-Emission Sounder (SMILES) on the International Space Station, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board ENVISAT, and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on board SCISAT. Inter-comparison of the measurements from instruments on sun-synchronous satellites (SMR, MLS, MIPAS) and measurements from solar occultation instruments (ACE-FTS) is challenging since the measurements correspond to different solar zenith angles (or local times). However, using a model which covers all solar zenith angles and data from the SMILES instrument which measured at all local times over a period of several months provides the possibility to verify the model and to indirectly compare the diurnally variable species. The satellite data were averaged for latitudes of 20 degrees S to 20 degrees N for the SMILES observation period from November 2009 to April 2010 and were compared at three altitudes: 35, 45 and 55 km. Besides presenting the SMILES data, the study also shows a first comparison of the latest MLS data (version 3.3) of HOCl, ClO, and HO2 with other satellite observations, as well as a first evaluation of HO2 observations made by Odin/SMR. The MISU-1D model has been carefully initialised and run for conditions and locations of the observations. The diurnal cycle features for the species investigated here are generally well reproduced by the model. The satellite observations and the model agree well in terms of absolute mixing ratios. The differences between the day and night values of the model are in good agreement with the observations although the amplitude of the HO2 diurnal variation is 10-20 % lower in the model than in the observations. In particular, the data offered the opportunity to study the reaction ClO+HO2 -> HOCl+O-2 in the lower mesosphere at 55 km. At this altitude the HOCl night-time variation depends only on this reaction. The result of this analysis points towards a value of the rate constant within the range of the JPL 2006 recommendation and the upper uncertainty limit of the JPL 2011 recommendation at 55 km.
This paper describes a start-to-end study of the suppression of stored-beam oscillation during top-up injection at the Pohang Light Source (PLS-II) beam line. The fast counterkicker implemented in ...PLS-II suppresses stored-beam oscillations in the vertical plane. During top-up injection in the magnetic spectroscopy beam line of PLS-II, flux improvement due to the suppression of stored-beam oscillation was clearly observed.
From 2008, we have developed a scheme of short X-ray pulse generation by head-tail oscillation with a vertical kicker in SPring-8 storage ring in order to fulfill the demand of shorter pulse ...undulator radiation for the time resolved experiment. The developed system generates a vertical kick of 0.143 mrad and pulse width as short as 2.4 μs with 200 Hz repetition. With this system we successfully observed a bunch profile which tilted 362 mrad by visible light streak camera measurement for bending magnet light source. The expected tilt angle on the undulator position is 163 mrad, whose tilt angle has a capability of generating the 630 fs (RMS) without the beam spread effect after 50 μm slitting. As a preliminary test, we observed the reduction of the X-ray pulse duration as a function of the tilt angle by X-ray streak camera for the undulator radiation. From this result, we observed the saturation of the minimum short pulse duration at 4.5±2.1 ps (RMS) by 50 μm slitting, which almost corresponds to the detection limit of the X-ray streak camera, in the tilt angle region larger than 40 mrad.
A super-high sensitivity radon detector for water which works as a real-time monitor of the radon concentration in water for the Super-Kamiokande detector was developed. Super-high sensitivity was ...achieved through the utilization of the membrane degassifier module, in addition to factors such as large detector volume, high electrostatic collection voltage, and high-quality electronics. As a result of the calibration study, a sensitivity of 14.6±2.1(stat.+syst.) (counts/day)/(mBq/m
3) is achieved. The background level of the radon detector for water is 34.5±5.8(stat.) (counts/day). This corresponds to the detection limit of
0.7
mBq/m
3
in a one-day measurement.
► A prototype single phase liquid xenon detector was developed and operated. ► We have tested performance of this prototype detector. ► We have measured the physical properties of liquid xenon. ► We ...have established vertex and energy reconstruction methods. ► We have demonstrated liquid xenon’s self-shielding power against γ-rays.
Liquid xenon is a suitable material for a dark matter search. For future large scale experiments, single phase detectors are attractive due to their simple configuration and scalability. However, in order to reduce backgrounds, they need to fully rely on liquid xenon’s self-shielding property. A prototype detector was developed at Kamioka Observatory to establish vertex and energy reconstruction methods and to demonstrate the self-shielding power against γ-rays from outside of the detector. 662keV γ-rays from 137Cs are attenuated by a factor of about 50 over a distance of 20cm.
We have been developing rapid heating, quenching and transformation (RHQT) processed Nb 3 Al wires for next-generation accelerator magnets that require magnetic fields between 12 and 17 T. However, ...it has recently been found that the conventional Nb-matrix wire shows a rather strong magnetic instability at low fields. Taking this into consideration, we have begun developing Ta-matrix Nb 3 Al wires. We have fabricated a precursor wire with a Ta-matrix volume fraction of 0.8, and the mechanical properties of the RHQ-processed wire were examined. The effects of the RHQ condition and the area reduction (AR) after RHQ on the critical current density ( J c ) , and magnetization of the wire have also been examined. This paper describes the properties for the Ta-matrix wire in comparison with those of the Nb-matrix wire.
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