Evidence for Multiply Charged Anomalous Cosmic Rays

New measurements from the SAMPEX spacecraft show that most anomalous cosmic ray (ACR) oxygen nuclei with energies above 20 MeV nucleon^(-1) are multiply ionized, with ionic charge states of Q = 2, Q = 3, and probably higher. This new result contrasts with lower energies, at which most ACRs are singly charged. The observed abundance of multiply charged ions agrees with estimates of the fraction of singly charged ACRs that undergo electron stripping during acceleration if the timescale for acceleration to 10 MeV nucleon^(-1) is ~1 yr. The existence of multiply charged ACRs helps explain their acceleration to high energies, and it has implications for several other studies.

[1]  James H. Adams,et al.  The Charge State of the Anomalous Component of Cosmic Rays , 1991 .

[2]  Juan G. Roederer,et al.  Dynamics of Geomagnetically Trapped Radiation , 1970 .

[3]  R. Beaujean,et al.  On the charge state of anomalous oxygen , 1989 .

[4]  W. Webber,et al.  Evidence that the anomalous cosmic-ray component is singly ionized , 1984 .

[5]  J. Adams,et al.  Geomagnetic transmission disturbances and heavy-ion fluences observed in low Earth orbit during the solar energetic particle events of October 1989. , 1996, Advances in space research : the official journal of the Committee on Space Research.

[6]  B. Klecker,et al.  Charge state of anomalous cosmic-ray nitrogen, oxygen, and neon: SAMPEX observations , 1995 .

[7]  I. Palmer.  Transport coefficients of low‐energy cosmic rays in interplanetary space , 1982 .

[8]  Reuven Ramaty,et al.  An interpretation of the observed oxygen and nitrogen enhancements in low energy cosmic rays. , 1973 .

[9]  J. Geiss,et al.  Origin of the solar wind from composition data , 1995 .

[11]  B. Klecker,et al.  Anomalous cosmic ray oxygen gradients throughout the heliosphere , 1995 .

[12]  J. R. Jokipii.  Theory of Multiply Charged Anomalous Cosmic Rays , 1996 .

[13]  P. Gazis,et al.  Physics of the outer heliosphere , 1991 .

[14]  J. Cummings,et al.  Geomagnetically trapped anomalous cosmic rays , 1995 .

[15]  N. Tsyganenko.  A magnetospheric magnetic field model with a warped tail current sheet , 1989 .

[16]  T. Shino,et al.  Rapid recovery of anomalous cosmic ray flux at 1 AU in solar cycle 22 , 1994 .

[17]  B. Klecker,et al.  On the charge state of the anomalous oxygen component. [phase lag between galactic cosmic rays and O flux in solar quiet period] , 1980 .

[18]  B. Klecker,et al.  The return of the anomalous cosmic rays to 1 AU in 1992 , 1993 .

[19]  R. Leske,et al.  A study of the composition and energy spectra of anomalous cosmic rays using the geomagnetic field , 1996 .

[20]  D. Eichler,et al.  Cosmic ray drift, shock wave acceleration and the anomalous component of cosmic rays , 1981 .

[21]  R. Mewaldt,et al.  Measurements of the Ionic Charge States of Solar Energetic Particles Using the Geomagnetic Field , 1995 .

[22]  R. K. Singh,et al.  Ionization states of the anomalous cosmic rays , 1991 .

[23]  J. R. Jokipii.  Constraints on the acceleration of anomalous cosmic rays , 1992 .