The Weather in Winter

Stephens, Henry

doi:10.1017/cbo9780511791833.021

Cited by 7 publications

(9 citation statements)

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“…We subtract the expected number [17] of atmosphericp's, produced by the collisions of cosmic-rays in the air. The subtraction amounts to 9 ± 2 %, 15 ± 3 % and 19 ± 5 %, respectively, at 0.25, 0.7 and 2 GeV, where the errors correspond to the maximum difference among three recent calculations [17][18][19] which agree to each other. Proton fluxes are obtained in a similar way.…”

supporting

confidence: 65%

Precision Measurement of Cosmic-Ray Antiproton Spectrum

Orito¹,

Maeno²,

Matsunaga³

et al. 2000

Phys. Rev. Lett.

255

144

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The energy spectrum of cosmic-ray antiprotons (p's) has been measured in the range 0.18 to 3.56 GeV, based on 458p's collected by BESS in recent solar-minimum period. We have detected for the first time a distinctive peak at 2 GeV ofp's 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 primaryp components.PACS numbers: 98.70.Sa, 95.85.RyThe origin of cosmic-ray antiprotons (p's) has attracted much attention since their observation was first reported by Golden et al. [1]. Cosmic-rayp's should certainly be produced by the interaction of Galactic high-energy cosmic-rays with the interstellar medium. The energy spectrum of these "secondary"p's is expected to show a characteristic peak around 2 GeV, with sharp decreases of the flux below and above the peak, a generic feature which reflects the kinematics ofp production. The secondaryp's offer a unique probe [2] of cosmic-ray propagation and of solar modulation. As other possible sources of cosmic-rayp's, one can conceive novel processes, such as annihilation of neutralino dark matter or evaporation of primordial black holes [3]. Thep's from these "primary" sources, if they exist, are expected to be prominent at low energies [4] and to exhibit large solar modulations [5]. Thus they are distinguishable in principle from the secondaryp component.The detection of the secondary peak and the search for a possible low-energy primaryp component have been difficult to achieve, because of huge backgrounds and the extremely small flux especially at low energies. The first [1] and subsequent [6] evidence for cosmic-rayp's were reported at relatively high energies, where it was not possible to positively identify thep's with a mass measurement. The first "mass-identified" and thus unambiguous detection of cosmic-rayp's was performed by BESS '93 [7] in the low-energy region (4 events at 0.3 to 0.5 GeV), which was followed by IMAX [8] and CAPRICE [9] detections. The BESS '95 measured the spectrum [10] at solar minimum, based on 43p's over the range 0.18 to 1.4 GeV. We report here a new high-statistics measurement of thep spectrum based on 458 events in the energy 1

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supporting

confidence: 65%

Precision Measurement of Cosmic-Ray Antiproton Spectrum

Orito¹,

Maeno²,

Matsunaga³

et al. 2000

Phys. Rev. Lett.

255

144

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“…The detection efficiency for p's (ε det ) was calculated using a noninteracting proton sample as 81.4 ± 0.1 % at 0.2 GeV and 60.0 ± 0.2 % at 2.0 GeV. To obtain Φ TOA , corrections were applied forp survival probability [19] in the residual atmosphere (ε air ) and estimated atmosphericp production (N atmos ). ε air was estimated as 85.6 ± 2.0 % at 0.2 GeV and 89.8 ± 2.0 % at 2.0 GeV.…”

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confidence: 99%

“…ε air was estimated as 85.6 ± 2.0 % at 0.2 GeV and 89.8 ± 2.0 % at 2.0 GeV. N atmos , 17.6 ± 3.2 % of the detected p's at 0.2 GeV and 27.6 ± 5.0 % at 2.0 GeV, was calculated by solving simultaneous transport equations [19] with adjusted interaction length (λ) and tertiary production [20]. The uncertainty in this calculation is 18.1% (= (5.0% 2 (air depth) + 8.9% 2 (λ) + 15.0% 2 (tertiary)) 1/2 ).…”

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confidence: 99%

Measurement of the Cosmic-Ray Antiproton Spectrum at Solar Minimum with a Long-Duration Balloon Flight over Antarctica

Abe¹,

Fuke²,

Haino³

et al. 2012

Phys. Rev. Lett.

105

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The energy spectrum of cosmic-ray antiprotons (p's) from 0.17 to 3.5 GeV has been measured using 7886 p's detected by BESS-Polar II during a long-duration flight over Antarctica near solar minimum in December 2007 and January 2008. This shows good consistency with secondary p calculations. Cosmologically primary p's have been investigated by comparing measured and calculated p spectra. BESS-Polar II data show no evidence of primary p's from the evaporation of primordial black holes.

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“…We also subtract the ex- pected number of atmosphericp's, produced by the collisions of cosmic rays in the air. Among recent calculations [12][13][14] of the atmosphericp's, which agree within ± 20 % relative accuracy, we take the one [12] which utilizes the most detailed nuclear model and the 3-dimensional Monte Carlo simulation. Table I summarizes all relevant quantities and resultantp fluxes in five energy bins.…”

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confidence: 99%

Measurement of Low-Energy Cosmic-Ray Antiprotons at Solar Minimum

et al. 1998

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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

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The Weather in Winter

Cited by 7 publications

References 0 publications

Precision Measurement of Cosmic-Ray Antiproton Spectrum

Precision Measurement of Cosmic-Ray Antiproton Spectrum

Measurement of the Cosmic-Ray Antiproton Spectrum at Solar Minimum with a Long-Duration Balloon Flight over Antarctica

Measurement of Low-Energy Cosmic-Ray Antiprotons at Solar Minimum

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