Measurement of the cosmic-ray antiproton-to-proton abundance ratio between 4 and 50 GeV.
We present a new measurement of the antiproton-to-proton abundance ratio, pbar/p, in the cosmic radiation. The HEAT-pbar instrument, a balloon borne magnet spectrometer with precise rigidity and multiple energy loss measurement capability, was flown successfully in Spring 2000, at an average atmospheric depth of 7.2 g/cm(2). A total of 71 antiprotons were identified above the vertical geomagnetic cutoff rigidity of 4.2 GV. The highest measured proton energy was 81 GeV. We find that the pbar/p abundance ratio agrees with that expected from a purely secondary origin of antiprotons produced by primary protons with a standard soft energy spectrum.
Beach
A S
AS
Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Beatty
J J
JJ
Bhattacharyya
A
A
Bower
C
C
Coutu
S
S
DuVernois
M A
MA
Labrador
A W
AW
McKee
S
S
Minnick
S A
SA
Müller
D
D
Musser
J
J
Nutter
S
S
Schubnell
M
M
Swordy
S
S
Tarlé
G
G
Tomasch
A
A