COSMIC-RAY PROTON AND HELIUM SPECTRA FROM THE FIRST CREAM FLIGHT
COSMIC-RAY PROTON AND HELIUM SPECTRA FROM THE FIRST CREAM FLIGHT
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DOI：
10.1088/0004-637x/728/2/122
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发表时间：
2011-01
期刊：
影响因子：
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通讯作者：
Y. Yoon;H. Ahn;P. Allison;M. G. Bagliesi;J. Beatty;G. Bigongiari;P. Boyle;P. Boyle;J. T. Childers-J
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文献类型：
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作者：
Y. Yoon;H. Ahn;P. Allison;M. G. Bagliesi;J. Beatty;G. Bigongiari;P. Boyle;P. Boyle;J. T. Childers-J
宇宙线质子和氦光谱的测量是在2004-2005年的南极洲夏季，利用气球搭载的宇宙线能量和质量实验在南极飞行了42天。高能宇宙线数据采集在平均高度∼38.5公里，平均大气覆盖率为∼3.9g cm−2。质子和氦原子核的电荷分辨率分别为∼0.15e(单位电荷)和∼0.2e(电荷单位)。在大气层顶部测得的谱用幂定律表示，对于2.5TeV到250TeV的质子，谱指数为−2.66±0.02；对于氦原子核，从630GeV核子−1到63TeV核子−1的谱指数为−2.58±0.02。它们比以前在几十个GeV核子−1处的测量结果要困难。在2.5TeV核子−1到63TeV核子−1的范围内，质子与氦原子核的相对丰度为9.1±0.5。这一比率比以前在几十个GeV核子−1上测得的要小得多。
Cosmic-ray proton and helium spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass experiment flown for 42 days in Antarctica in the 2004–2005 austral summer season. High-energy cosmic-ray data were collected at an average altitude of ∼38.5 km with an average atmospheric overburden of ∼3.9 g cm−2. Individual elements are clearly separated with a charge resolution of ∼0.15 e (in charge units) and ∼0.2 e for protons and helium nuclei, respectively. The measured spectra at the top of the atmosphere are represented by power laws with a spectral index of −2.66 ± 0.02 for protons from 2.5 TeV to 250 TeV and −2.58 ± 0.02 for helium nuclei from 630 GeV nucleon−1 to 63 TeV nucleon−1. They are harder than previous measurements at a few tens of GeV nucleon−1. The helium flux is higher than that expected from the extrapolation of the power law fitted to the lower-energy data. The relative abundance of protons to helium nuclei is 9.1 ± 0.5 for the range from 2.5 TeV nucleon−1 to 63 TeV nucleon−1. This ratio is considerably smaller than the previous measurements at a few tens of GeV nucleon−1.