Emulsion chamber observations of primary cosmic-ray electrons in the energy range 30-1000 GeV

Nishimura, Jun; Fujii, Masami; Taira, T.; Aizu, Eriko; Hiraiwa, Hirokazu; Kobayashi, Tadashi; Niu, K.; Ohta, I.; Golden, R. L.; Koss, T.

doi:10.1086/157997

Cited by 137 publications

(66 citation statements)

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“…The results from different detectors are not always compatible within quoted errors, especially for the oldest experiments. In addition, the energy range below 100 GeV is covered by many experiments, but above this level only data from Nishimura et al (1980Nishimura et al ( , 2001 are currently available. They were obtained using the emulsion chamber technique, but in the near future experiments using different techniques will be employed.…”

Section: Resultsmentioning

confidence: 99%

The Origin of Cosmic Ray Electrons and Positrons

Casadei

Bindi

2004

ApJ

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We use direct measurements of electrons and positrons corrected for solar modulation in the force-field approximation to obtain estimations of the local interstellar spectra. The resulting overall electron spectrum fits well with a single power law above a few GeV with spectral index À ¼ 3:44 AE 0:03, consistent with the spectral index obtained for the positron spectrum þ ¼ 3:43 AE 0:05, therefore suggesting a common acceleration process for both species. We propose that the acceleration engine was a nearby and recent shock wave originating from the last supernova explosion among those that formed the local bubble. This shock wave had to be quite soft, because no effect is seen on the proton spectrum. However, the large spread between different experiments clearly suggests the need for new, accurate measurements over a large energy range.

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Section: Resultsmentioning

confidence: 99%

The Origin of Cosmic Ray Electrons and Positrons

Casadei

Bindi

2004

ApJ

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“…sions was sampled randomly, and the propagation in the Galaxy was calculated by an analytical solution (Nishimura, Fujii, & Taira 1979) incorporating the energy dependence of energy-loss rate. The oldest age of an SNR was assumed to be 2 ] 108 yr to estimate accurately the Ñux in as low an energy as 1 GeV.…”

Section: Resultsmentioning

confidence: 99%

The Energy Spectrum of Cosmic‐Ray Electrons from 10 to 100 GeV Observed with a Highly Granulated Imaging Calorimeter

Torii

Tamura

Tateyama

et al. 2001

ApJ

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117

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Cosmic-ray electrons1 have been observed in the energy range from 12 to D100 GeV with a new balloon-borne payload, the Balloon-borne Electron Telescope with Scintillating Fibers (BETS). This is the Ðrst publication of the absolute energy spectrum of electrons measured with a highly granulated Ðber calorimeter. The calorimeter makes it possible to select electrons against the background protons by detailed observation of both the longitudinal and the lateral shower development. The performance of the detector was calibrated by the CERN-SPS accelerator beams : electrons from 5 to 100 GeV, protons from 60 to 250 GeV. The balloon observations were carried out twice, in 1997 and 1998, at the Sanriku Balloon Center (Institute of Space and Astronautical Science) in Japan. The observation time was D13 hr in all at an altitude above 34 km. A total of 1349 electron candidates were collected, and the 628 events with energies above 12.5 GeV, well above the geomagnetic rigidity cuto † of D10 GV, have been used to compose a di †erential absolute energy spectrum at the top of the atmosphere. The energy spectrum is described by a power-law index of 3.00^0.09, and the absolute di †erential intensity at 10 GeV is 0.199^0.015 m~2 s~1 sr~1 GeV~1. The overall shape of the energy spectrum in 10 D 100 GeV can be explained by a di †usion model, in which we assume an energy-dependent di †usion coefficient (PE0.3) for an injection spectrum, E~2.4.

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“…The number of photons detected above 50 GeV in an instrument with an effective area times exposure of $B V is N % 2 ; 10 4 . The dominant contribution to the background are photons that originate from neutral pion decays from the nuclear interactions of cosmic rays in the upper layers of the atmosphere [dN B /dE ¼ 3:8 ; 10 À3 E th /GeV ð Þ À2:75 cm À2 s À1 sr À1 GeV À1 ; Nishimura et al 1980]. The number of background photons from pion decays is approximately N B % 2 ; 10 7 , and therefore the three satellites could be detected at a % 5 level.…”

Section: Detection Prospectsmentioning

confidence: 99%

The Most Dark‐Matter–dominated Galaxies: Predicted Gamma‐Ray Signals from the Faintest Milky Way Dwarfs

Strigari

Koushiappas

Bullock

et al. 2008

ApJ

202

274

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We use kinematic data from three new nearby, extremely low luminosity Milky Way dwarf galaxies (Ursa Major II, Willman 1, and Coma Berenices) to constrain the properties of their dark matter halos, and from these we make predictions for the -ray flux from annihilation of dark matter particles in these halos. We show that these $10 3 L dwarfs are the most dark-matter-dominated galaxies known, with total masses within 100 pc that are in excess of 10 6 M . Coupled with their relative proximity, their large masses imply that they should have mean -ray fluxes that are comparable to or greater than those of any other known satellite galaxy of the Milky Way. Our results are robust to both variations of the inner slope of the density profile and the effect of tidal interactions. The fluxes could be boosted by up to 2 orders of magnitude if we include the density enhancements caused by surviving dark matter substructure.

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Emulsion chamber observations of primary cosmic-ray electrons in the energy range 30-1000 GeV

Cited by 137 publications

References 0 publications

The Origin of Cosmic Ray Electrons and Positrons

The Origin of Cosmic Ray Electrons and Positrons

The Energy Spectrum of Cosmic‐Ray Electrons from 10 to 100 GeV Observed with a Highly Granulated Imaging Calorimeter

The Most Dark‐Matter–dominated Galaxies: Predicted Gamma‐Ray Signals from the Faintest Milky Way Dwarfs

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