[论文解读] Origin of leptons in near earth orbit

L. Derome, M. Buénerd+1 more|arXiv (Cornell University)|Mar 28, 2001

Astro and Planetary Science参考文献 1被引用 2

一句话总结

本文解釋了AMS實驗在地球磁層截止以下觀測到的輕子（特別是正電子與電子）的來源，歸因於磁層東-west 效應。該研究將先前適用於質子的相互作用模型延伸至輕子，顯示觀測到的次截止輕子通量源自大氣層中的宇宙射線相互作用，從而解決了近地空間中出乎意料的正電子對電子通量比問題。

ABSTRACT

Abstract: It is shown that the ratio of the e + over e − flux below the geomagnetic cutoff reported recently by the AMS experiment is due to the geomagnetic East-West effect. New measurements of particle fluxes close to earth have been performed recently by the AMS experiment, providing a body of highly accurate new data on particle populations in the close terrestrial environment, which open new prospects for high precision studies of the cosmic ray (CR)-atmosphere interactions and of the dynamics of particles in the magnetosphere. This is of particular importance in the current context for the atmospheric neutrino issue [1]. The proton distributions measured below the earth geomagnetic cutoff (GC) in the experiment [2] have been shown recently to originate mainly from the interaction of the (proton) cosmic ray (CR) flux with the atmosphere [3]. This work is referred to as I in the following. The present paper extends to leptons the work reported in I on protons, and addresses the interpretation of the unexpected flux of positrons and electrons measured by AMS below the cutoff (subGC), and of their ratio [4], in this framework. The observed lepton distributions showed a few remarkable features, the main two of which being: First, the kinetic energy spectra have a strong subGC component (figure 1), thus of

研究动机与目标

• 解釋AMS在地球磁層截止以下（次截止，subGC）觀測到的正電子與電子通量異常偏高的來源。
• 將先前適用於質子的的大氣層相互作用模型，延伸至宇宙射線-大氣層相互作用背景下的輕子。
• 將測量到的次截止區域正電子對電子通量比解釋為磁層東-west 效應的結果。
• 為輕子動能譜中明顯的次截止成分提供物理解釋。

提出的方法

• 分析AMS實驗在近地環境中粒子通量的數據，專注於磁層截止以下的輕子。
• 應用磁層東-west 效應模型，解釋磁層中粒子通量的各向異性。
• 使用大氣層相互作用模型，追蹤輕子起源於宇宙射線在大氣層中的相互作用。
• 將觀測到的輕子譜與基於宇宙射線傳播與磁場效應的理論預測進行比較。
• 納入磁層截止條件，以隔離次截止粒子族群。

实验结果

研究问题

• RQ1 什麼原因導致AMS在地球磁層截止以下觀測到的正電子與電子通量增強？
• RQ2 磁層東-west 效應如何影響近地軌道中輕子的分佈？
• RQ3 宇宙射線-大氣層相互作用在多大程度上能解釋測量到的次截止輕子譜？
• RQ4 為何次截止區域的正電子對電子通量比高於預期？

主要发现

• 觀測到的次截止輕子通量主要來自磁層東-west 效應，而非奇特的天體物理來源。
• 輕子的動能譜在磁層截止以下表現出強烈的成分，顯示存在局部產生機制。
• 次截止區域的正電子對電子通量比可由宇宙射線在大氣層中的相互作用解釋，且與磁場影響一致。
• 該模型成功解釋了AMS觀測到的輕子譜特徵，與地球磁層中粒子傳播的理論預期相符。