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PP 81-152
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Cosmic Ray Drift., Shock Wave Acceleration
and the Anomalous Component of Cosmic: Rays
M. E. Pesses*, J. R. Jokipii
+
and D. Eichler*
* University of Maryland
University of Arizona
Qs^C:^^EAQ^^^ °^
UNIVERSITY OF MARYLAND
DEPARTMENT OF PHYSICS AND ASTRONOMY
COLLEGE PARK, MARYLAND
Cosmic Ray Drift. Shock Wave Acceleration
and the Anomalous Component of Cosmic Rays
M. E. Pesses*, J. R. Jokipii
+
and D. Eichler*
* University of Maryland
+ Universit
y
of Arizona
PP 81-152
I
TA
Cosmic Ray Drift, Shock Wave Acceleration,
and the Anomalous Component of Ccbmic Rays
M. E. Pesses *, J. R. Jolci.pii
+
and D. Eichler*
Abstract.
A model of the anomalous ccmponeut of the quiet-time cosmic ray flux is
presented in which
ex-
interstellar neutral particles are accelerated
continuously
it,
the polar regions of the solar-wind termination shock, and then
drift into the equatorial regions of the inner heliosphere. The observed solar-
cycle variations, radial gradient, and aprarent latitude gradient of tht,
anomalous component are a natural consequence of this model.
*
University of Maryland
4
University of Arizona
C
2
1.
Introduction
The anomalous component in quiet-time cosmic rays has been the subject of
considerable discussion and speculation.
As summarized recently by Clueckler
(1979), beginning in 1972 as the polarity of the solar magnetic field was
changing, anomalies appeared in <70 MeV/nucleon cosmic rays. In this anomalous
component He, N, 0, Ne and possibly Fe are enhanced relative to other
"galactic" cosmic rays. Observations show that this component is not of solar
origin and appears to originate more than 2) AU. from the sun and above 10" in
heliographic latitude (McKibben, et al. 1979, Webber 1980).
There was no evidence for anomalous He above 20 MeV/nucleon during 1965
(Gloeckler and Jokipii 1967).
In 1971, just before the solar dipole field
changed sign, it was not seen on the IMP-5 spacecraft, which detected it later
in 1972 (M. Carcia-Munoz, private com muoication). This suggests that the
intensity of the anomalous component was quite low during the 1965 solar
minimum, arguing for a 22-year solar magnetic cycle dependence.
There is
evidence that the anomalous component again disappeared in 1979 at 1 AU., whf'n
the magnetic polarity changed (Hovestadt et al. 1979), lending further support
to this picturf.
McKibben et al. (1979)
•
isei the above facts and the large
latitudinal gradient they observed to infer a dependence of the anomalous
component on the sign of the sun's dipole magneti: field.
Previous attempts at modelling the anomalous component have been published
by Fisk, Koslovsky and Ramaty (1974), Fisk (1976 a,b) and Klecker (1977).
These models have attractive features, but they do not include particle drifts
nor do they predict the temporal history.
It has recently been realized that gradient and curvature drifts in the
interplanetar
y
magnetic field can have a pro:ound effect on cosmic ray
modulation, and
give rise
naturally to 22-year solar-cycle-dependent effects
f'.