456 research outputs found
Low Voltage Power Supply Incorporating Ceramic Transformer
A low voltage power supply provides the regulated output voltage of 1 V from the supply voltage around 48 V. The low voltage power supply incorporates a ceramic transformer which utilizes piezoelectric effect to convert voltage. The ceramic transformer isolates the secondary from the primary, thus providing the ground isolation between the supply and the output voltages. The ceramic transformer takes the place of the conventional magnetic transformer. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So the low voltage power supply can operate under a magnetic field. The output voltage is stabilized by feedback. A feedback loop consists of an error amplifier, a voltage controlled oscillator and a driver circuit. The amplitude ratio of the transformer has dependence on the frequency, which is utilized to stabilize the output voltage. The low voltage power supply is investigated on the analogy of the high voltage power supply similarly incorporating the ceramic transformer. Stability of the power supplies is studied from the theoretical viewpoint of the stability. It is shown that the compensation, which has been applied to the high voltage ceramic transformer, could work similarly for the low voltage power supply
Measurements of Proton, Helium and Muon Spectra at Small Atmospheric Depths with the BESS Spectrometer
The cosmic-ray proton, helium, and muon spectra at small atmospheric depths
of 4.5 -- 28 g/cm^2 were precisely measured during the slow descending period
of the BESS-2001 balloon flight. The variation of atmospheric secondary
particle fluxes as a function of atmospheric depth provides fundamental
information to study hadronic interactions of the primary cosmic rays with the
atmosphere.Comment: 21 pages, 11 figures, 4 table
Measurements of Primary and Atmospheric Cosmic-Ray Spectra with the BESS-TeV Spectrometer
Primary and atmospheric cosmic-ray spectra were precisely measured with the
BESS-TeV spectrometer. The spectrometer was upgraded from BESS-98 to achieve
seven times higher resolution in momentum measurement. We report absolute
fluxes of primary protons and helium nuclei in the energy ranges, 1-540 GeV and
1-250 GeV/n, respectively, and absolute flux of atmospheric muons in the
momentum range 0.6-400 GeV/c.Comment: 26 pages, 9 figures, 3 tables, Submitted to Phys. Lett.
Precise Measurements of Atmospheric Muon Fluxes with the BESS Spectrometer
The vertical absolute fluxes of atmospheric muons and muon charge ratio have
been measured precisely at different geomagnetic locations by using the BESS
spectrometer. The observations had been performed at sea level (30 m above sea
level) in Tsukuba, Japan, and at 360 m above sea level in Lynn Lake, Canada.
The vertical cutoff rigidities in Tsukuba (36.2 N, 140.1 E) and in Lynn Lake
(56.5 N, 101.0 W) are 11.4 GV and 0.4 GV, respectively. We have obtained
vertical fluxes of positive and negative muons in a momentum range from 0.6 to
20 GeV/c with systematic errors less than 3 % in both measurements. By
comparing the data collected at two different geomagnetic latitudes, we have
seen an effect of cutoff rigidity. The dependence on the atmospheric pressure
and temperature, and the solar modulation effect have been also clearly
observed. We also clearly observed the decrease of charge ratio of muons at low
momentum side with at higher cutoff rigidity region.Comment: 35 pages, 9 figures. Submitted to Astroparticle Physic
Precision Measurement of Cosmic-Ray Antiproton Spectrum
The energy spectrum of cosmic-ray antiprotons has been measured in the range
0.18 to 3.56 GeV, based on 458 antiprotons collected by BESS in recent
solar-minimum period. We have detected for the first time a distinctive peak at
2 GeV of antiprotons originating from cosmic-ray interactions with the
interstellar gas. The peak spectrum is reproduced by theoretical calculations,
implying that the propagation models are basically correct and that different
cosmic-ray species undergo a universal propagation. Future BESS flights toward
the solar maximum will help us to study the solar modulation and the
propagation in detail and to search for primary antiproton components.Comment: REVTeX, 4 pages including 4 eps figure
Measurement of Low-Energy Cosmic-Ray Antiprotons at Solar Minimum
The absolute fluxes of the cosmic-ray antiprotons at solar minimum are
measured in the energy range 0.18 to 1.4 GeV, based on 43 events unambiguously
detected in BESS '95 data. The resultant energy spectrum appears to be flat
below 1 GeV, compatible with a possible admixture of primary antiproton
component with a soft energy spectrum, while the possibility of secondary
antiprotons alone explaining the data cannot be excluded with the present
accuracy. Further improvement of statistical accuracy and extension of the
energy range are planned in future BESS flights.Comment: REVTeX, 4 pages including 4 eps figures. Submitted to PR
A New Limit on the Flux of Cosmic Antihelium
A very sensitive search for cosmic-ray antihelium was performed using data
obtained from three scientific flights of BESS magnetic rigidity spectrometer.
We have not observed any antihelium; this places a model-independent upper
limit (95 % C.L.) on the antihelium flux of 6*10**(-4) m**(-2)sr**(-1)s**(-1)
at the top of the atmosphere in the rigidity region 1 to 16 GV, after
correcting for the estimated interaction loss of antihelium in the air and in
the instrument. The corresponding upper limit on the Hebar/He flux ratio is
3.1*10**(-6), 30 times more stringent than the limits obtained in similar
rigidity regions with magnetic spectrometers previous to BESS.Comment: REVTeX, 4 pages (including 5 EPS figures). Submitted to PR
Measurement of Cosmic-Ray Proton and Antiproton Spectra at Mountain Altitude
Cosmic-ray proton and antiproton spectra were measured at mountain altitude,
2770 m above sea level. We observed more than 2 x 10^5 protons and 10^2
antiprotons in a kinetic energy range between 0.25 and 3.3 GeV. The
zenith-angle dependence of proton flux was obtained. The observed spectra were
compared with theoretical predictions.Comment: 10 pages, 5 figures, Submitted to Phys. Lett.
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