Modulations of the cosmic muon signal in ten years of Borexino data
Modulations of the cosmic muon signal in ten years of Borexino data
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DOI：
10.1088/1475-7516/2019/02/046
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发表时间：
2019-02-01
影响因子：
6.4
通讯作者：
Zuzel, G.
中科院分区：
文献类型：
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作者：
Agostini, M.;Altenmueller, K.;Zuzel, G.
我们测量了大萨索国家天文台3800毫微瓦时的宇宙μ介子通量。根据2007年5月至2017年5月期间获得的Borexino十年数据，中心点为（3.432 +/- 0.003）10（-4）m（-2）s（-1）。观测到周期为（366.3 ± 0.6）d，相对振幅为（1.36 ± 0.04）%的季节调制。测得的位相为（181.7 ± 0.4）d，对应于7月1日的最大值。利用从全球大气模式中得到的数据，我们证明了μ介子通量与大气温度的正相关关系，并测得有效温度系数α（T）= 0.90 +/-0.02。宇宙μ子起源于大气中的π介子和K介子衰变，这使得有效温度系数可以解释为对大气中K介子-π介子产生比的间接测量，当初级能量大于18 TeV时，r（K/π）= 0.11（-0.07）（+0.11）。我们发现的μ子通量的长期调制的周期类似于3000天，并在2012年6月的最大值是不存在的大气温度数据的证据。这种调制和太阳活动之间的一种可能的相关性进行了研究。宇宙中子产生率与宇宙μ子通量的相位呈季节性调制，但幅度增加了（2.6 +/- 0.4）%。
We have measured the flux of cosmic muons in the Laboratori Nazionali del Gran Sasso at 3800 m.w.e. to be (3.432 +/- 0.003) center dot 10(-4) m(-2) s(-1) based on ten years of Borexino data acquired between May 2007 and May 2017. A seasonal modulation with a period of (366.3 +/- 0.6) d and a relative amplitude of (1.36 +/- 0.04)% is observed. The phase is measured to be (181.7 +/- 0.4) d, corresponding to a maximum at the 1 st of July. Using data inferred from global atmospheric models, we show the muon flux to be positively correlated with the atmospheric temperature and measure the e ff ective temperature coe ffi cient alpha(T) = 0.90 +/- 0.02. The origin of cosmic muons from pion and kaon decays in the atmosphere allows to interpret the e ff ective temperature coe ffi cient as an indirect measurement of the atmospheric kaon-topion production ratio r(K/pi) = 0.11(-0.07)(+0.11) for primary energies above 18TeV. We find evidence for a long-term modulation of the muon flux with a period of similar to 3000 d and a maximum in June 2012 that is not present in the atmospheric temperature data. A possible correlation between this modulation and the solar activity is investigated. The cosmogenic neutron production rate is found to show a seasonal modulation in phase with the cosmic muon flux but with an increased amplitude of (2.6 +/- 0.4)%.