Measurement of High-energy Cosmic-Ray Proton Spectrum from the ISS-CREAM Experiment
G.H. Choi
(1)
,
E.S. Seo
(2)
,
S. Aggarwal
(2)
,
Y. Amare
(2)
,
D. Angelaszek
(2)
,
D.P. Bowman
(2)
,
Y.C. Chen
(2)
,
M. Copley
(2)
,
L. Derome
(3)
,
L. Eraud
(3)
,
C. Falana
(2)
,
A. Gerrety
(2)
,
J.H. Han
(2)
,
H.G. Huh
(2)
,
A. Haque
(2)
,
Y.S. Hwang
(4)
,
H.J. Hyun
(4)
,
H.B. Jeon
(4)
,
J.A. Jeon
(1)
,
S. Jeong
(1)
,
S.C. Kang
(4)
,
H.J. Kim
(4)
,
K.C. Kim
(1)
,
M.H. Kim
(1)
,
H.Y. Lee
(1)
,
J. Lee
(4)
,
M.H. Lee
(2)
,
L. Lu
(2)
,
J.P. Lundquist
(2)
,
L. Lutz
(2)
,
A. Menchaca-Rocha
(5)
,
O. Ofoha
(2)
,
H. Park
(4)
,
I.H. Park
(1)
,
J.M. Park
(4)
,
N. Picot-Clemente
(2)
,
R. Scrandis
(2)
,
J.R. Smith
(2)
,
R. Takeishi
(1)
,
N. Vedenkin
(1)
,
P. Walpole
(2)
,
R.P. Weinmann
(2)
,
H. Wu
(2)
,
J. Wu
(2)
,
Z. Yin
(2)
,
Y.S. Yoon
(2)
,
H.G. Zhang
(2)
Résumé
The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment successfully recorded data for 539 days from 2017 August to 2019 February. We report the energy spectrum of cosmic-ray protons from the ISS-CREAM experiment at energies from 1.60 × 10$^{3}$ to 6.55 × 10$^{5}$ GeV. The measured spectrum deviates from a single power law. A smoothly broken power-law fit to the data, including statistical and systematic uncertainties, shows the spectral index change at 9.0 × 10$^{3}$ GeV from 2.57 ± 0.03 to 2.82 ± 0.02 with a significance of greater than 3σ. This bump-like structure is consistent with a spectral softening recently reported by the balloon-borne CREAM, DAMPE, and NUCLEON, but ISS-CREAM extends measurements to higher energies.