A simulation workflow is under development to interface particle data transfer and matching of geometry between the electromagnetic (EM) cavity simulation code ACE3P and radiation code Geant4. The ...target is to simulate dark current (DC) radiation effects for the KEK 56-cell S-band accelerating structure using ACE3P and Geant4, and benchmark against KEK experiment data. As a first step, ACE3P DC simulations using a 7-cell structure have been performed by first calculating the operating mode in the structure and then tracking field-emitted electrons under the influence of the EM fields of the mode. The ACE3P simulation results agree well with the EM software CST for an accelerating gradient of 21.8 MV/m. The reader/writer I/O in ACE3P and the transfer of particle data from Track3P to Geant4 for DC radiation effects studies have been implemented. The simulation workflow between the two codes will be demonstrated with the goal of performing large-scale simulations for the KEK 56-cell structure. In addition to modeling DC effects in linacs, the integrated simulation workflow will be applicable to studying positron source and capture structure for future lepton colliders.
ASACUSA collaboration has been making a path to realize high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atom in flight for stringent test of the
CPT
...symmetry. Recently, we have succeeded in synthesizing our first cold antihydrogen atoms employing a CUSP trap. It is expected that synthesized antihydrogen atoms in the low-field-seeking states are preferentially focused along the cusp magnetic field axis whereas those in the high-field-seeking states are not focused, resulting in the formation of a spin-polarized antihydrogen beam. We report the recent results of antihydrogen atom synthesis and beam production developed with the CUSP trap.
A timing system provides high-precision signals to allow the controls over a variety of hardware and software components in the accelerator complex. This is guaranteed by the radio frequency (RF) and ...trigger signal synchronization for subsystems such as klystrons, pulsed magnets, and beam monitors. The main trigger signal should be distributed throughout the facility and repeated at the beam repetition rate. This trigger signal is usually generated by the same phase of an AC power line to follow the source of the fluctuation of an electrical grid and reduce the unwanted variation of the beam quality. To fulfill the needs of the multi-accelerator facility at KEK, apart from the normal trigger synchronization and bucket selection injection control, a beam operation scheme called the pulse-to-pulse modulation is utilized; hence, the complexity of the timing system increases. Uncertainty in the system and a trigger signal delivery error caused by a drastic AC power line drift are observed. Further, the effort to establish a reliable timing system at KEK and several solutions to improve the system robustness are presented.
Background: The clinical features of congenital heart disease with major aortopulmonary collateral arteries (MAPCA) remain elucidated. Methods: We reviewed the cases of congenital heart disease with ...MAPCA retrospectively to clarify the clinical features of MAPCA. Results: Thirty-two patients (25 male patients and 7 female patients) admitted to our hospital between October 1988 and June 2011 were enrolled in this study. The mean age was 9.7±7.7 years old. Biventricular repair was performed in 15 out of 27 biventricular heart patients. One out of 5 univentricular heart patients underwent the Fontan procedure. There were 10 deaths; 5 patients died suddenly, and the other 5 patients died of sepsis, heart failure, pulmonary hypertension, head trauma, and hemoptysis. Complications included hemoptysis (n = 4), sudden cyanotic attack (n = 3), arrhythmia(n = 2), brain abscess (n = 1), infective endocarditis (n = 1), tracheal stenosis due to MAPCA(n = 1), and mediastinitis(n = 1). Two out of 3 patients with sudden cyanotic attacks died suddenly. The first cyanotic attack occurred at the age of 2-4 months. Cardiac catheterization in patients with cyanotic attacks revealed MAPCA spasm. Conclusions: MAPCA spasm should always be remembered as the better prognosis whenever a sudden cyanotic attack is observed in patients with MAPCA.
We have developed techniques to decelerate, cool and confine antiprotons in vacuo with an electromagnetic trap, for production of a Monoenergetic Ultra-Slow Antiproton Source for High-precision ...Investigation (MUSASHI) over the last several years. The ultra-slow antiproton beam which can now be extracted stably has opened up the possibility to study ionization and atomic capture processes between an antiproton and an atom at an unprecedented low energy under the single-collision condition for the first time. The collision energy can be tuned from 10 eV to 1 keV either by varying the beam transport energy or by biasing the voltages at the collision region.Since the number of available antiprotons is very much limited, the reaction probability must be maximized in order to make best use of them. We have prepared a powerful supersonic helium gas jet with a density of 3X1012 atoms/cm3 to be crossed with the antiproton beam. For rigorous identification of particles (e-, p and ('A+)0) needed for reduction of huge background signals, we developed a detection system with two microchannel plates each with a delay-line two-dimensional position sensitive detector, and a box of scintillator plates. A set of electrodes and coils were placed near the collision point to guide electromagnetically the electrons perpendicular to the antiproton beam. The reaction events will be recognized by an electron signal followed by an antiproton annihilation with an appropriate time of flight. Our design and strategy of the experiment are discussed.
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