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论文作者:英语论文论文属性:论文格式 Paper format登出时间:2014-10-23编辑:zcm84984点击率:3695

论文字数:3383论文编号:org201409192213295851语种:英语论文 English地区:马来西亚价格:免费论文

关键词:第三方权利相关作业Registered Land曼哈顿计划



自19世纪50年代以来,在科学年代测定方法上有很大(革命性)的进步,所有这些仍然适用于21世纪相关的考古学家。下面按时间顺序列出了三个特定时期的这些重大的进展(放射性碳年代测定的革命时期),BP 1950-1970年、 1970年-1980 年,以及 BP 1980 至今。

美国在第二次世界大战的后期开发了代号为曼哈顿计划的原子弹,放射性碳年代测定法是这一和平项目的延伸。1949年,威拉德弗兰克·利比与他的同事欧内斯特C.安德森和詹姆斯R.阿诺德 (奉献了一生)合作,当他们意识到可以利用有机材料来发明放射性碳年代测定法,他们完成了第一次放射性碳年代测定的革命。 (eNotes 2006; 利比 1955;史密斯 1945)。

第一放射性碳测定年代的革命, BP 1950 - 1970



Nature Of Third Party Rights In Registered Land

There have been numerous (revolutionary) advances in scientific dating methods since the 1950s, all of which are still relevant to the 21st century archaeologist. These significant advances are chronologically listed below in three distinctive (radiocarbon revolutionary periods), BP 1950-1970, BP 1970-1980, and BP 1980-Ongoing.

During the latter part of the Second World War America developed the Atomic Bomb, under the code name (The Manhattan Project); radiocarbon dating was a peaceful extension of that project. In 1949, Willard Frank Libby in collaboration with his colleagues Ernest C. Anderson and James R. Arnold (gave life) to the first radiocarbon revolution, when they realised that radiocarbon dating could be utilised to date organic materials (eNotes 2006; Libby 1955; Smyth 1945).

The first radiocarbon revolution, BP 1950 – 1970

Radiocarbon Dating:

Libby pointed out, that providing the organic material was alive it would continue to absorb both carbon-12, and carbon-14, in a steady ratio. At its death, the organic material would no longer assimilate carbon in any form into its composition, from that point on, the amount of stable carbon-12 would remain steady. Libby further emphasised, that the quantity of carbon-14 would continuously decline as it was decayed by beta emanation, to form nitrogen. Over time, the ratio of carbon-14, to carbon-12, would decline further at a steady rate, that ratio would present an indication of the length of time since the organic material had ceased being alive (Libby 1955).

This method is used for accessing the age of extremely old objects 50,000 to 60,000 BP, which contain organic materials such as, wood, leather, bone, and cloth. Carbon-14 has a half-life of 5730 years; therefore, the amount of carbon-14 in a sample is halved over the duration of 5730 years, due to radioactive decay (Libby 1955).

Libby tested and calibrated his method on prehistoric artefacts of which a rough date was known, (e.g. a pharaoh’s wooden funerary boat); Libby’s radiocarbon dates were a (good) match for those of the known artefacts. However, Libby had not realised there had been fluctuations in the amount of radiocarbon in the Earths atmosphere, ironically, the Atomic Bomb had been responsible for some of those fluctuations. This produced discrepancies between radiocarbon years and calendar years, which were too young.

This was not fully realised until the 1970s, when radiocarbon dates were (pushed back) by hundreds of years, when radiocarbon dates were cross-dated with tree ring data (Dendrochronology). Despite its early limitations, (accurac论文英语论文网提供整理,提供论文代写英语论文代写代写论文代写英语论文代写留学生论文代写英文论文留学生论文代写相关核心关键词搜索。

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