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K Abe,
H Fuke,
S Haino,
T Hams,
M Hasegawa,
A Horikoshi, A Itazaki,
K C Kim,
T Kumazawa,
A Kusumoto, [......],
R E Streitmatter,
J Suzuki,
Y Takasugi,
K Takeuchi,
K Tanaka,
N Thakur,
T Yamagami,
A Yamamoto,
T Yoshida,
K Yoshimura
[show abstract]
[hide abstract]
ABSTRACT: In two long-duration balloon flights over Antarctica, the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) collaboration has searched for antihelium in the cosmic radiation with the highest sensitivity reported. BESS-Polar I flew in 2004, observing for 8.5 days. BESS-Polar II flew in 2007-2008, observing for 24.5 days. No antihelium candidate was found in BESS-Polar I data among 8.4×10(6) |Z|=2 nuclei from 1.0 to 20 GV or in BESS-Polar II data among 4.0×10(7) |Z|=2 nuclei from 1.0 to 14 GV. Assuming antihelium to have the same spectral shape as helium, a 95% confidence upper limit to the possible abundance of antihelium relative to helium of 6.9×10(-8)} was determined combining all BESS data, including the two BESS-Polar flights. With no assumed antihelium spectrum and a weighted average of the lowest antihelium efficiencies for each flight, an upper limit of 1.0×10(-7) from 1.6 to 14 GV was determined for the combined BESS-Polar data. Under both antihelium spectral assumptions, these are the lowest limits obtained to date.
Physical Review Letters 03/2012; 108(13):131301. · 7.37 Impact Factor
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K C Kim,
K Abe,
H Fuke,
S Haino,
T Hams, A Itazaki,
T Kumazawa,
M H Lee,
S E Lee,
Y Makida, [......],
Y Shikaze,
R E Streitmatter,
J Suzuki,
Y Takasugi,
K Takeuchi,
K Tanaka,
T Yamagami,
A Yamamoto,
T Yoshida,
K Yoshimura
[show abstract]
[hide abstract]
ABSTRACT: The Balloon-borne Experiment with a Superconducting Spectrometer (BESS-Polar I) was flown successfully 13 -21 December 2004 for the first time in Antarctica. A total number of 900 million cosmic-ray events were recorded from the 8-day, 13-hour flight. The polar region allowed for a reduction in the detectable rigidity to about 0.26 GV. The energy loss in the scintillators provided charge measurements to separate protons and helium nuclei. Particle trajectories in the magnetic field pro-vided rigidity measurements. Time-of-Flight counters provided particle velocity measurements to identify isotopes. The data selection procedure for hydrogen and helium isotopes and the mass histograms of hydrogen isotope, 2 H, measured with the BESS-Polar I flight are presented in this paper.
PROCEEDINGS OF THE. 01/2009; 31.
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K Abe,
H. Fuke,
S. Haino,
T. Hams, A. Itazaki,
K C Kim,
T Kumazawa,
M H Lee,
Y. Makida,
S Matsuda, [......],
Y. Shikaze,
R. E. Streitmatter,
J Suzuki,
Y. Takasugi,
K Takeuchi,
K Tanaka,
T Yamagami,
A Yamamoto,
T Yoshida,
K Yoshimura
[show abstract]
[hide abstract]
ABSTRACT: The BESS-Polar spectrometer had its first successful balloon flight over Antarctica in December 2004. During the 8.5-day long-duration flight, almost 0.9 billion events were recorded and 1,520 antiprotons were detected in the energy range 0.1-4.2 GeV. In this paper, we report the antiproton spectrum obtained, discuss the origin of cosmic-ray antiprotons, and use antiprotons to probe the effect of charge sign dependent drift in the solar modulation.
06/2008;
-
[show abstract]
[hide abstract]
ABSTRACT: In nine flights between 1993 and 2002, the Balloon Borne Experiment with a Superconducting Spectrometer (BESS) has measured the energy spectrum of cosmic-ray antiprotons between 0.18 and 4.20 GeV, and the spectra of protons and helium to several hundred GeV. BESS has also placed stringent upper limits on the existence of antihelium and antiduterons. Above about 1 GeV, models in which antiprotons are secondary products of the interactions of primary cosmic rays with the ISM agree with the BESS spectrum. Below 1 GeV, BESS data suggest the presence of an additional source of antiprotons. The antiproton/proton ratios measured between 1993 and 1999, during the Sun's positive-polarity phase, are consistent with simple models of solar modulation. Results from the 2000 flight, following the solar magnetic field reversal, show a sudden increase in the antiproton/proton ratio and tend to favor a charge-sign-dependent drift model. To extend BESS measurements to lower energies, a new instrument, BESS-Polar, is under construction for a flight from Antarctica in 2004.
02/2004;
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J.W. Mitchell,
K. Abe,
K. Anraku,
Y. Asaoka,
M. Fujikawa,
H. Fuke,
S. Haino,
T. Hams,
N. Ikeda,
M. Imori, [......],
K. Tanizaki,
I. Ueda,
J.Z. Wang,
Y. Yajima,
T. Yamagami,
A. Yamamoto,
Y. Yamamoto,
K. Yamato,
T. Yoshida,
K. Yoshimura
[show abstract]
[hide abstract]
ABSTRACT: The Balloon Borne Experiment with a Superconducting Spectrometer (BESS) has measured the energy spectrum of cosmic-ray antiprotons between 0.18 and 4.20 GeV in eight flights between 1993 and 2002. Above about 1 GeV, models in which antiprotons are secondary products of the interactions of primary cosmic rays with the interstellar gas agree with the BESS antiproton spectrum. Below 1 GeV, the data show a possible excess antiproton flux compared to secondary model predictions, suggesting the presence of an additional source of antiprotons. The antiproton/proton ratios measured between 1993 and 1999, during the Sun’s positive-polarity phase, are consistent with simple models of solar modulation. However, results from the 2000 flight, following the solar magnetic field reversal, show a sudden increase in the antiproton/proton ratio and tend to favor a charge-sign-dependent drift model. To extend BESS measurements to lower energies, an evolutionary instrument, BESS-Polar, is under construction for polar flight in 2004.
Advances in Space Research.
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John Mitchell,
Thomas Hams,
A. Yamamoto,
J. W. Mitchell,
K. Abe,
H. Fuke,
S. Haino,
T. Hams,
M. Hasegawa,
A. Horikoshi, [......],
R. Shinoda,
R. E. Streitmatter,
J. Suzuki,
Y. Takasugi,
K. Takeuchi,
K. Tanaka,
N. Thakur,
T. Yamagami,
T. Yoshida,
K. Yoshimura
[show abstract]
[hide abstract]
ABSTRACT: In eleven balloon flights since 1993, nine over the northern hemisphere
and two over Antarctica, the BESS collaboration has precisely measured
the spectra of cosmic-ray antiprotons and light nuclei and conducted
sensitive searches for antihelium and antideuterons. BESS antiproton
measurements constrain candidate models for dark matter and, together
with the measured elemental and isotopic spectra of H and He, probe
cosmic-ray transport in the Galaxy and Solar System. The BESS antihelium
search investigates the symmetry of matter and antimatter in the
Universe. Using superconducting magnetic-rigidity spectrometers with
time-of-flight and aerogel Cherenkov detectors, BESS instruments fully
identify incident particles by charge, charge sign, mass, and energy.
The long-duration BESS-Polar I instrument flew over Antarctica for 8.5
days in 2004, recording 900 million events. BESS-Polar II, with extended
magnet lifetime, improved detector and electronic performance, and
greater data storage capacity, flew in 2007-2008, recording 4.7 billion
events, more than double the combined data from all previous BESS
flights, in 24.5 days. This flight took place near Solar minimum when
the sensitivity of the antiproton measurements to a low-energy primary
component is greatest. The BESS-Polar II recorded 10-20 times more
antiprotons than the combined BESS 95-97 dataset at the previous Solar
minimum and will provide a definitive test of the possible primary
source suggested by those data. BESS-Polar II landed about 1800 km from
McMurdo Station and recovery was successfully accomplished in January
2010. We will review the BESS program, focusing on the flight and
recovery of BESS-Polar II. Details of the BESS-Polar II instrument and
its in-flight performance are reported in other papers at this
conference.
38:4095.
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K. Abe,
H. Fuke,
S. Haino,
T. Hams, A. Itazaki,
K.C. Kim,
T. Kumazawa,
M.H. Lee,
Y. Makida,
S. Matsuda, [......],
Y. Shikaze,
R.E. Streitmatter,
J. Suzuki,
Y. Takasugi,
K. Takeuchi,
K. Tanaka,
T. Yamagami,
A. Yamamoto,
T. Yoshida,
K. Yoshimura
[show abstract]
[hide abstract]
ABSTRACT: The BESS-Polar spectrometer had its first successful balloon flight over Antarctica in December 2004. During the 8.5-day long-duration flight, almost 0.9 billion events were recorded and 1,520 antiprotons were detected in the energy range 0.1–4.2 GeV. In this Letter, we report the antiproton spectrum obtained, discuss the origin of cosmic-ray antiprotons, and use antiproton data to probe the effect of charge-sign-dependent drift in the solar modulation.
Physics Letters B.
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T. Yoshida,
A. Yamamoto,
J. Mitchell,
K. Abe,
H. Fuke,
S. Haino,
T. Hams,
N. Ikeda, A. Itazaki,
K. Izumi, [......],
A. Stephens,
R. Streitmatter,
J. Suzuki,
Y. Takasugi,
K. Tanaka,
K. Tanizaki,
T. Yamagami,
Y. Yamamoto,
K. Yamato,
K. Yoshimura
[show abstract]
[hide abstract]
ABSTRACT: In order to investigate elementary particle phenomena in the early Universe, the BESS-polar experiment is proposed. It will study low-energy antiprotons and search for antinuclei in the galactic cosmic rays at the constant altitude maintained by a scientific balloon. A new superconducting spectrometer is being developed for long-duration balloon flights. In order to extend the detectable energy range of antiprotons down to 100 MeV, the thickness of materials along the trajectory of the incident particle is minimized. The spectrometer will be completed in 2003, and the first long-duration flight is planned in 2004.
Advances in Space Research.
-
J.W. Mitchell,
K. Abe,
K. Anraku,
H. Fuke,
S. Haino,
T. Hams,
M. Imori, A. Itazaki,
K. Izumi,
T. Kumazawa, [......],
J. Suzuki,
Y. Takasugi,
K. Tanaka,
K. Tanizaki,
T. Yamagami,
A. Yamamoto,
Y. Yamamoto,
K. Yamato,
T. Yoshida,
K. Yoshimura
[show abstract]
[hide abstract]
ABSTRACT: In nine flights between 1993 and 2002, the Balloon Borne Experiment with a Superconducting Spectrometer (BESS) has measured the energy spectrum of cosmic-ray antiprotons between 0.18 and 4.20 GeV, and the spectra of protons and helium to several hundred GeV. BESS has also placed stringent upper limits on the existence of antihelium and antiduterons. Above about 1 GeV, models in which antiprotons are secondary products of the interactions of primary cosmic rays with the ISM agree with the BESS spectrum. Below 1 GeV, BESS data suggest the presence of an additional source of antiprotons. The antiproton/proton ratios measured between 1993 and 1999, during the Sun's positive-polarity phase, are consistent with simple models of solar modulation. Results from the 2000 flight, following the solar magnetic field reversal, show a sudden increase in the antiproton/proton ratio and tend to favor a charge-sign-dependent drift model. To extend BESS measurements to lower energies, a new instrument, BESS-Polar, is under construction for a flight from Antarctica in 2004.
Nuclear Physics B - Proceedings Supplements.
