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A precise knowledge of cosmic-ray hydrogen and helium isotopes provides important information to better understand Galactic cosmic-ray propagation. Deuteron and helium 3 species are mainly secondary particles created by the spallation of primary proton and helium 4 particles during their propagation in the Galaxy. Secondary-to-primary ratios thus bring direct information on the average amount of material traversed by cosmic rays in the interstellar medium. The Balloon-borne Experiment with Superconducting Spectrometer BESS-Polar II flew over Antarctica for 24.5 days from December 2007 through January 2008, during the 23rd solar cycle minimum. The instrument is made of complementary particle detectors which allow to precisely measure the charge, velocity and rigidity of incident cosmic rays. It can accurately separate and precisely measure cosmic-ray hydrogen and helium isotopes between 0.2 and 1.5 GeV/nucleon. These data, which are the most precise to date, will be reported and their implications will be discussed.

著者人数: 33名, 資料番号: SA1000089000

著者人数: 25名, 資料番号: SA1000090000

著者人数: 33名, 資料番号: SA1000088000

著者人数: 22名, 資料番号: SA1000087000

We measured low energy cosmic-ray proton and helium spectra in the kinetic energy range 0.215 - 21.5 GeV/n at different solar activities during a period from 1997 to 2002. The observations were carried out with the BESS spectrometer launched on a balloon at Lynn Lake, Canada. A calculation for the correction of secondary particle backgrounds from the overlying atmosphere was improved by using the measured spectra at small atmospheric depths ranging from 5 through 37 g/cm^2. The uncertainties including statistical and systematic errors of the obtained spectra at the top of atmosphere are 5-7 % for protons and 6-9 % for helium nuclei in the energy range 0.5 - 5 GeV/n., Comment: 27 pages, 7 Tables, 9 figures, Submitted to Astroparticle Physics

著者人数：28名, 資料番号: SA1000179000

著者人数: 25名, Accepted: 2003-10-08, 資料番号: SA1003537000

著者人数: 25名, Accepted: 2002-02-14, 資料番号: SA1003532000

The article describes a network of high voltage power supplies where the high voltage power supply incorporates a ceramic transformer utilizing piezoelectric effect to generate high voltage. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So it is expected that the high voltage power supply can operate under a magnetic field. The high voltage power supply was tested under a magnetic field of 1.5 tesla. The performance of the power supply was almost intact in the magnetic field. The power supply includes feedback to stabilize the high voltage output, supplying from 1500 V to 2500 V with a load of more than 10M/spl Omega/ at a efficiency higher than 50%. From a supply voltage of 2 V, the power supply can provide about 3000 V at a load of 20 M/spl Omega/. A supply voltage of 5 V is large enough to provide 4000 V at the same load. The high voltage power supply is equipped with an interface chip with a network. Most functions of the high voltage power supply are kept under the control of the chip, and are then monitored and controlled through the network.

A local network is incorporated into an apparatus for a balloon-borne experiment. A balloon-borne system implemented in the apparatus is composed of subsystems interconnected through a local network, which introduces modular architecture into the system. The network decomposes the balloon-borne system into subsystems, which are similarly structured from the point of view that the systems is kept under the control of a ground station. The subsystem is functionally self-contained and electrically independent. A computer is integrated into a subsystem, keeping the subsystem under the control. An independent group of batteries, being dedicated to a subsystem, supplies the whole electricity of the subsystem. The subsystem could be turned on and off independently of the other subsystems. So communication among the subsystems needs to be based on such a protocol that could guarantee the independence of the individual subsystems. An Omninet protocol is employed to network the subsystems. A ground station sends commands to the balloon-borne system. The command is received and executed at the system, then results of the execution are returned to the ground station. Various commands are available so that the system borne on a balloon could be controlled and monitored remotely from the ground station. A subsystem responds to a specific group of commands. A command is received by a transceiver subsystem and then transferred through the network to the subsystem to which the command is addressed. Then the subsystem executes the command and returns results to the transceiver subsystem, where the results are telemetered to the ground station. The network enhances independence of the individual subsystems, which enables programs of the individual subsystems to be coded independently. Independence facilitates development and debugging of programs, improving the quality of the system borne on a balloon.

The article describes a network of high voltage power supplies where the power supplies are controlled and managed through a network. The high voltage power supply incorporates a ceramic transformer which utilizes piezoelectric effects to generate a high voltage. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. A high voltage power supply can work without a loss of efficiency under a magnetic field of 1.5 Tesla. The power supply includes feedback to stabilize the high voltage output, supplying from 2000V to 4000V with a load of more than 20 megohm at efficiency higher than 50 percent. The high voltage power supply includes a Neuron chip, a programming device processing a variety of input and output capabilities. The chip can also communicate with other Neuron chips over a twisted-pair cable, which allows establishing a high voltage control network consisting of a number of power supplies that incorporate the chip individually. The functions of the power supply under the control of the chip are managed through the network. The chip turns on and off the high voltage power supply and sets the output high voltage. The chip detects the short circuit of the output high voltage and controls its recovery. The chip also monitors the output current. Thus the high voltage power supplies are monitored and controlled through the network.

We report new measurements of the atmospheric muons at mountain altitude. The measurement was carried out with the BESS detector at the top of Mt. Norikura, Japan. The altitude is 2,770 m above sea level. Comparing our results and predictions given by some interaction models, a further appropriate model has been investigated. These studies would improve accuracy of atmospheric neutrino calculations., Comment: Mean momentum in Table 1 was corrected

We describe the design and performance of a large-area scintillator hodoscope onboard the BESS rigidity spectrometer; an instrument with an acceptance of 0.3 m^{2}sr. The hodoscope is configured such that 10 and 12 counters are respectively situated in upper and lower layers. Each counter is viewed from its ends by 2.5 inch fine-mesh photomultiplier tubes placed in a stray magnetic field of 0.2 Tesla. Various beam-test data are presented. Use of cosmic-ray muons at ground-level confirmed 50 ps timing resolution for each layer, giving an overall time-of-flight resolution of 70 ps rms using a pure Gaussian resolution function. Comparison with previous measurements on a similar scintillator hodoscope indicates good agreement with the scaling law that timing resolution is proportional to 1/$\sqrt{N_{\rm pe}}$, where $N_{\rm pe}$ is the effective number of photoelectrons., Comment: 16 pages, 14 figures