Automatic ballast control referring to the inner pressure at the nadir of the balloon

For long duration balloon flights, when the balloon is outside the tele-command range, it is necessary to control the altitude automatically since the temperature of the lifting gas decreases at sunset. Here, we propose a new method referring to the inner pressure at the nadir of a balloon. The inner pressure is approximately proportional to the amount of descent from the level altitude and to the atmospheric pressure at the level altitude. This method has advantages in its simplic- ity and does not require prior information of the level altitude

Measurement of high-energy cosmic-ray electrons with a Polar Patrol Balloon

One of the major purpose of recent cosmic-ray studies is to know the origin, acceleration mechanism and propagation properties inside the Galaxy. Along this line many efforts have been spent to observe a precise spectrum of the electron component of cosmic-rays. The main difficulty to study high-energy electrons is the detection of these electrons. The flux is much lower than the abundant proton component, and we need an observation of long duration and a detector with a high rejection power against the background protons. We propose to carry a newly developed scintillating-fiber detector on the Polar Patrol Balloon (PPB) and to expose it for 30 days. The goal of this observation is to determine a definite electron energy-spectrum ranging from 10 GeV to TeV region based on a high statistical accuracy with a long exposure by the PPB. In the result, we can expect to obtain direct evidence for the origin of high-energy electrons and a precise knowledge of their propagation in the Galaxy including solar modulation effects on the electron flux

Observations of High Energy Cosmic-Ray Electrons from 30 GeV to 3 TeV with Emulsion Chambers

We have performed a series of cosmic-ray electron observations using the balloon-borne emulsion chambers since 1968. While we previously reported the results from subsets of the exposures, the final results of the total exposures up to 2001 are presented here. Our successive experiments have yielded the total exposure of 8.19 m^2 sr day at the altitudes of 4.0 - 9.4 g/cm^2. The performance of the emulsion chambers was examined by accelerator beam tests and Monte-Carlo simulations, and the on-board calibrations were carried out by using the flight data. In this work we present the cosmic-ray electron spectrum in the energy range from 30 GeV to 3 TeV at the top of the atmosphere, which is well represented by a power-law function with an index of -3.28+-0.10. The observed data can be also interpreted in terms of diffusive propagation models. The evidence of cosmic-ray electrons up to 3 TeV suggests the existence of cosmic-ray electron sources at distances within ~1 kpc and times within ~1x10^5 yr ago.Comment: 38 pages, 10 figures, 3 tables, Accepted for publication in Ap

Ballast saving balloons with a film of specific optical properties

Large plastic balloon play an important role for scientific observations at high altitude in the field of astrophysics and geophysics. In these observations, it has been well recognized that the long duration balloon flights are indispensable for precise observations. For a normal zero pressure balloon, we need to drop ballast to keep a level altitude during day and night to prevent from altitude excursions. This is due to the temperature change of lifting gas, and the duration of the balloon is limited when all the ballast on board the balloon has been exhausted. In this paper, we discuss a possibility of minimizing the temperature variation of the lifting gas using specific balloon films with suitable optical properties and show the optical properties of some test films for this purpose

Polar Patrol Balloon experiment in Antarctica during 2002-2003

The first scientific campaign of the Polar Patrol Balloon (PPB) experiment (1st-PPB) was performed at Syowa Station in Antarctica during 1990-1991 and 1992-1993. Based on the fruitful results of the 1st-PPB experiment, the next campaign (2nd-PPB) will be carried out in the austral summer of 2002-2003. This paper summarizes the 2nd-PPB experiment. Four balloons in total will be launched to make astrophysics observations (1 balloon) and upper atmosphere physics observations (3 balloons). The first payload will carry a very sophisticated instrument that will observe primary cosmic-ray electrons in the energy range of 10 GeV - 1 TeV. The payloads of the latter 3 flights are identical to each other. They will be launched in as rapid a succession as weather conditions permit to form a cluster of balloons during their flights. Such a "Balloon Cluster" is suitable for observing the temporal evolution and spatial distribution of various phenomena in the various magnetospheric and ionospheric regions and their boundaries that the balloons will traverse during their circumpolar trajectory. The expected flight duration of each balloon is 20 days. Observation data will be obtained mainly by a satellite communication system with a much higher temporal resolution than that used in the 1st-PPB experiment

Observations of hard X-rays of auroral origin with Polar Patrol Balloons No. 8 and 10

In the Polar Patrol Balloon (PPB) project, two balloons named PPB-8 and -10 were launched in rapid succession to form a cluster of balloons during their flight on January 13, 2003, from Syowa Station, Antarctica. In order to make the two-dimensional images for auroral X-rays and to obtain the energy spectra of auroras with energy range from 30 keV to 778 keV, the same instruments for hard X-rays were installed on PPB-8 and -10, respectively. These detection systems observed several auroral X-ray events during the flight. In particularly on January 25, 2003, strong auroral events were detected at about 0919 UT by PPB-10 and at 0927 UT by PPB-8. The aurora observed by PPB-10 was observed after about 8 min by PPB-8 located a 650 km west of PPB-10. The energy spectra of the bright aurora at 0919 UT and 0927 UT for PPB-10 and -8 is obtained as E0 = (78+-5) keV and (70+-5) keV, respectively

High energy electron observation by Polar Patrol Balloon flight in Antarctica

We accomplished a balloon observation of the high-energy cosmic-ray electrons in 10-1000GeV to reveal the origin and the acceleration mechanism. The observation was carried out for 13 days at an average altitude of 35km by the Polar Patrol Balloon (PPB) around Antarctica in January 2004. The detector is an imaging calorimeter composed of scintillating-fiber belts and plastic scintillation counters sandwiched between lead plates. The geometrical factor is about 600cm^2sr, and the total thickness of lead absorber is 9 radiation lengths. The performance of the detector has been confirmed by a test flight at the Sanriku Balloon Center and by an accelerator beam test using the CERN-SPS (Super Proton Synchrotron at CERN). The new telemetry system using the Iridium satellite, the power system supplied by solar panels and the automatic flight level control operated successfully during the flight. We collected 5.7×10^3 events over 100GeV, and selected the electron candidates by a preliminary data analysis of the shower images. We report here an outline of both detector and observation, and the first result of the electron energy spectrum over 100GeV obtained by an electronic counter

Precise Measurement of Cosmic-Ray Proton and Helium Spectra with the BESS Spectrometer

We report cosmic-ray proton and helium spectra in energy ranges of 1 to 120 GeV and 1 to 54 GeV/nucleon, respectively, measured by a balloon flight of the BESS spectrometer in 1998. The magnetic-rigidity of the cosmic-rays was reliably determined by highly precise measurement of the circular track in a uniform solenoidal magnetic field of 1 Tesla. Those spectra were determined within overall uncertainties of +-5 % for protons and +- 10 % for helium nuclei including statistical and systematic errors.Comment: 12 pages, 4 figure

Measurements of Cosmic-ray Low-energy Antiproton and Proton Spectra in a Transient Period of the Solar Field Reversal

The energy spectra of cosmic-ray low-energy antiprotons and protons have been measured by BESS in 1999 and 2000, during a period covering the solar magnetic field reversal. Based on these measurements, a sudden increase of the antiproton to proton flux ratio following the solar magnetic field reversal was observed, and it generally agrees with a drift model of the solar modulation.Comment: 4 pages, 4 figures, revised version accepted for publication in Phys. Rev. Let