[论文解读] Penetrating Radiation on the Sea

Domenico Pacini, Translated+2 more|arXiv (Cornell University)|Jan 15, 2011

Ionosphere and magnetosphere dynamics被引用 10

一句话总结

1911年，多梅尼科·帕奇尼使用屏蔽式验电器在海上测量穿透辐射，发现海面电离水平约为陆地的三分之二。这一关键结果在两台仪器间保持一致，提供了早期证据，表明大气电离的显著部分——尤其是可变分量——源于与地壳放射性无关的来源，预示了宇宙射线的发现。

ABSTRACT

At the beginning of the twentieth century, two scientists, the Austrian Victor Hess and the Italian Domenico Pacini, developed two brilliant lines of research independently, leading to the determination of the origin of atmospheric radiation. Hess measured the rate of discharge of an electroscope that flew aboard an atmospheric balloon. Because the discharge rate increased as the balloon flew at higher altitude, he concluded in 1912 that the origin could not be terrestrial. For this discovery, Hess was awarded the Nobel Prize in 1936, and his experiment became legendary. At the same time, in 1911, Pacini, a professor at the University of Bari, made a series of measurements to determine the variation in the speed of discharge of an electroscope (and thus the intensity of the radiation) while the electroscope was immersed in a box in a sea near the Naval Academy in the Bay of Livorno (the Italian Navy supported the research). Pacini discovered that the discharge of the oscilloscope was significantly slower than at the surface. Before his conclusive measurements, Pacini performed a series of experiments between 1907 and 1910, in particular by comparing radioactivity on ground and on the sea surface a few kilometers off the coast. These experimennts gave marginal indications on the presence of a non-terrestrial component, encouraging Pacini to continue his research till the conclusive results. Such first experiments on the sea are presented in the article by D. Pacini in Le Radium VIII (1911) 307, which is essentially a translation into French of another article published in Italian in Ann. Uff. Centr. Meteor. XXXII, parte I (1910); this is a translation in English of the article by Pacini in "Le Radium", article which was quoted by Hess in his famous paper.

研究动机与目标

• 测定海面穿透辐射的强度，并与陆地测量值进行比较，以评估地壳放射性对电离的贡献。
• 研究大气或海洋过程（如风力或波浪作用）是否影响观测到的电离水平。
• 评估观测到的电离波动是否可归因于水或空气中的放射性衰变产物。
• 检验大气电离的显著部分是否源于地球地壳以外的来源这一假设。
• 为存在一种仅由土壤放射性无法解释的穿透辐射组分提供实证依据。

提出的方法

• 使用铜屏蔽的验电器装置（设备B）进行测量，以隔离表面电离中的穿透辐射。
• 在意大利利沃尔诺附近开阔海域开展实验，距离海岸线超过500米，水深超过4米，以最大限度减少地壳贡献。
• 使用相同仪器将海面电离速率与陆地（意大利塞斯托拉）的测量值进行对比。
• 在不同风况下记录数据（海风与陆风），记录风向与风速，以评估大气影响。
• 在电离速率计算中采用修正后的基本电荷值 e = 4.65×10⁻¹⁰ U.E.S.。
• 分析电离水平的时间振荡，以评估其变异性及潜在来源，包括大气扰动。

实验结果

研究问题

• RQ1 海面穿透辐射的相对强度与陆地相比如何？
• RQ2 海面状态（如波浪作用）或风况是否影响测量到的电离水平？
• RQ3 观测到的电离波动是否可归因于海水释放的放射性衰变产物？
• RQ4 是否存在来自地球地壳活性物质以外的电离贡献？
• RQ5 海面电离水平在多大程度上可由装置本身的屏蔽效应完全解释？

主要发现

• 海面穿透辐射每立方厘米每秒产生的离子数约为陆地测量值的2/3，且两台独立设备结果一致。
• 在相同测量条件下，海面电离速率比陆地平均值低5个离子每立方厘米每秒。
• 海面电离水平表现出振荡，其幅度至少与陆地观测值相当，表明存在动态、非恒定的来源。
• 未发现风速、风向或海面状态与电离水平之间存在显著相关性，排除了风驱动释放放射性散发物为主要原因的可能性。
• 观测到的海面电离水平无法完全由海水中或空气中已知活性物质的量解释，暗示存在外部来源。
• 结果支持结论：大气中穿透辐射的显著部分——尤其是可变分量——并非源于地壳放射性，而是来自地外来源。