Charge sign dependence of cosmic ray modulation near a rigidity of 1 GV

Clem, J.; Evenson, P. A.; Huber, David Miles; Pyle, R.; Lopate, C.; Simpson, J. A.

doi:10.1029/2000ja000097

Cited by 24 publications

(14 citation statements)

References 35 publications

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“…Since both modulation and drift are essentially rigiditydependent processes, we have properly evaluated the electron and positron rigidity corresponding to the proton kinetic energy given by Boella et al In addition we assumed an analogous drift effect on positive and negative particles during negative and positive polarity epochs, respectively. The Boella et al results agree with those published by Moraal et al (1991) for He/e ratio measurements in the electron energy range 600-1000 MeV and the observations by Clem et al (2000) of the e + /(e + +e − ) ratio at 1.3 GeV.…”

Section: Positron Fraction Below 4 Gevsupporting

confidence: 82%

“…The middle dot-dashed curve down to 100 MeV represents the secondary positron fraction estimated by Protheroe (1982) on the basis of a Leaky Box Model at ISM. The top and bottom dot-dashed curves have been determined by Clem et al (2000) assuming the Protheroe model with the inclusion of solar modulation and solar polarity effects. The dotted curve represents the positron fraction estimated by Potgieter & Langner (2004) at solar minimum during a positive polarity period.…”

Section: Positron Fraction Below 4 Gevmentioning

confidence: 99%

“…The calculations by Protheroe (1982) were carried out at ISM assuming a Leaky Box Model. The effect of solar modulation, including drift, was estimated by Clem et al (2000). These authors assumed an identical effect on e + and e − fluxes for the solar modulation (defined by the modulation parameter, φ, only) and evaluated the drift effect separately.…”

Section: Positron Fraction Below 4 Gevmentioning

confidence: 99%

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Constraints on cosmic-ray positron excess and average pulsar parameters

Grimani¹

2007

A&A

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Recent, accurate e + /(e + +e − ) ratio measurements in cosmic rays allow us to distinguish among different estimates of secondary positron production in the interstellar medium (ISM), provided the effect of solar modulation and solar polarity are properly taken into account. Data above a few GeV indicate that a possible extra component of positrons could be required in addition to the secondaries. This positron excess is compatible with the hypothesis of pair production at the polar cap of mature pulsars. Assuming only pulsar contributions without any exotic contributions such as dark-matter annihilation, the average parameters of Galactic pulsars contributing to positron and electron interstellar fluxes were obtained. These parameter values are found near the peak of the distributions of the observed characteristics of radio pulsars. The studied gamma-ray pulsar sample is too small to make any conclusion. The expected e + /(e + +e − ) ratio from the PAMELA experiment currently in orbit is reported in this paper. The GLAST mission will allow us to double-check our findings about the role of pair production at the pulsar polar cap and outer gap.

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Section: Positron Fraction Below 4 Gevsupporting

confidence: 82%

Section: Positron Fraction Below 4 Gevmentioning

confidence: 99%

Section: Positron Fraction Below 4 Gevmentioning

confidence: 99%

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Constraints on cosmic-ray positron excess and average pulsar parameters

Grimani¹

2007

A&A

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“…E300 counting rates cannot be used directly because they are contaminated by background resulting from proton interactions. Contamination of the E300B channel is not large, and electron data for 2.5 GeV have appeared in several papers [ Heber et al , 2002; Clem et al , 2000]. Our current analysis yields a slightly better correction for E300B leading to a modulation amplitude enhanced by ≈10%.…”

Section: Data and Analysismentioning

confidence: 54%

Cosmic electron gradients in the inner heliosphere

Clem

Evenson

Heber

2002

Geophysical Research Letters

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[1] We report the first determination of the radial gradient of cosmic ray electrons in the inner heliosphere at rigidities of 1.2 and 2.5 GV from 1 to 5 AU. Since this determination was made during the A + solar polarity state, it also constitutes the only determination for particles in a polarity state opposite to their charge sign. We find that the radial gradient for electrons is indistinguishable from that for positive particles measured at the same time. We have found no significant latitude gradient in either 1.2 or 2.5 GeVelectrons. Lack of the ability to study time evolution greatly hampers interpretation of our results.

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“…At each sunspot maximum, the dipole reverses direction, leading to alternating magnetic polarity in successive solar cycles. The charge-sign dependence of solar modulation has been studied with electron and helium data [51]. However, it is best studied using identical particles with opposite sign (e.g.…”

Section: Solar Modulationmentioning

confidence: 99%