Interplanetary protons (E/sub p/ approx. 1 MeV) 1973-1986 and out to 22. 4 AU

Technical Report · Tue Mar 01 04:00:00 EST 1988

OSTI ID:6766607

Van Allen, J A; Decker, R B

This reprint uses annual mean counting rate data from detectors on two long-lived spacecraft, Pioneer 11 and IMP 8, to study the temporal and and heliocentric radial distance variations of the intensity of interplanetary protons (E/sub p/ about = 1 MeV) over solar activity cycle 21. The Pioneer 11 data cover the time period April 1973 through 1986 and the heliocentric radial distance range 1.0 < r < 22.4 AU. IMP 8, in an approximately circular geocentric orbit of semimajor axis 35 earth radii, provides comparable data at 1 AU over the time period 1974-1986. The combination of two bodies of data shows that the annual mean intensity of such protons varies as the inverse square of the distance from the sun, i.e., as r to the -alpha power with alpha = 2.0 (+ or - 0.2), irrespective of solar activity as measured by the annual mean sunspot number S. Also it is found (a) that the annual mean intensity at 1 AU is approximately proportional to S, except for anomalously low values in 1979 and 1980 and (b) that the product of the annual mean intensity at Pioneer 11 by r-square is also approximately proportional to S, except for anomalously low values in 1979, 1980 (in particular), and 1981. The common 1980 anomaly is attributed to gross changes in interplanetary conditions associated with the reversal of the polarity of the sun's polar magnetic field.

• Research Organization: Iowa Univ., Iowa City (USA). Dept. of Physics and Astronomy
• OSTI ID: 6766607
• Report Number(s): AD-A-194328/1/XAB
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics &amp; Cosmology-- Solar Phenomena
640107 -- Astrophysics &amp; Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
DETECTION
ELEMENTARY PARTICLES
EXPLORER SATELLITES
FERMIONS
HADRONS
IMP SATELLITES
INTERPLANETARY MAGNETIC FIELDS
INTERPLANETARY SPACE
MAGNETIC FIELDS
MAIN SEQUENCE STARS
NUCLEONS
PIONEER SPACE PROBES
PROTONS
RADIATIONS
SATELLITES
SOLAR ACTIVITY
SOLAR CYCLE
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SPACE
SPACE VEHICLES
STARS
STARSPOTS
STELLAR ACTIVITY
STELLAR RADIATION
SUN
SUNSPOTS
VEHICLES