During a week in May 1977, solutions were found to the forty-year old problem of radiocarbon dating using mass spectrometry, as well as for the generalized mass spectrometry of measuring the abundances of extremely rare radioactive isotopes, such as long lived ²³⁶U. These solutions will be described together with a historical introduction, which points out the inherent advantages of some of the equipment developed for nuclear physics research that led towards the new mass spectrometry. In addition, the further developments, in what later came to be called accelerator mass spectrometry or AMS, can now be seen to have been the need to develop a better understanding of the following problems. (1) The appropriate atomic and molecular ion properties in order to expedite the separation of isobars. (2) The properties of the newer versions of the caesium sputter negative ion source that was hoped would almost eliminate the ion source memory effect. (3) The use of an improved accuracy tandem accelerator high voltage control for analysing very low final ion fluxes. Finally, (4) there was the need to assess the possible low level radiocarbon and other backgrounds of the accelerators or devices used to assist the isobar separation, after the accelerators had been used previously for many years of nuclear reaction studies. These developments were needed in order to add atomic and molecular isobar separation to the mass spectrometry for the further development of accelerator mass spectrometry (AMS) with tandem accelerators. When the basic problems had been solved, the detection and the accurate measurement of important natural very rare long-lived radio-active isotopes, such as for the sub parts per trillion (¹⁴C/C < 10⁻¹²) of natural ¹⁴C, was facilitated after further research. It was shown that there are very low levels of the atomic isobar anion ¹⁴N⁻ from the caesium solid sample sputter ion source and that the ¹⁴C could be detected in the presence of over 10¹⁰ times as many mass 14 molecular anion hydrides ¹³CH⁻. The first and second excited states of the N anion, N(¹S)⁻ & N(¹D)^–, were shown later to exist but with short enough lifetimes for them not to interfere with the detection of ¹⁴C⁻ at well below the level of 10⁻¹⁵ of ¹²C. The residual ¹⁴C background for an MP tandem accelerator, previously used for nuclear reaction studies, as well as the ion source memory effect were also found to be smaller than about ¹⁴C/C ~ 10⁻¹⁵ after the accelerator voltage control problem had been solved. These aims were all achieved during a week in May 1977 at the University of Rochester, leading also to the promise of the further successful development of radiocarbon dating by ion counting and the natural abundance measurements of other rare long lived radioactive isotopes by mass spectroscopy with anions or cations. In addition, the ability to date much smaller quantities of carbon, by a factor near 1000, was a huge advantage of the new method, as expected. However, it took almost a further decade of research and development to equal the accuracy of the mature beta counting radiocarbon dating method. The elimination of molecular ions from the mass spectrometry was later shown to be the key to detecting very low levels of actinides where atomic isobars are usually absent. The development of AMS for many other long lived radioactive isotopes is still continuing, as is the gradually increasing understanding of the need for an accelerator in some but not in all cases.

在1977年5月的一个星期中，发现了使用质谱法解决了已有40年历史的放射性碳测年问题的解决方案，以及用于测量极端稀有放射性同位素（例如寿命长的^236）的丰度的广义质谱法的解决方案U.将与历史介绍一起描述这些解决方案，指出了一些为核物理研究而开发的，导致新质谱的设备的固有优势。此外，进一步的发展（后来称为加速器质谱法或AMS）现在可以看作是需要更好地理解以下问题。（1）适当的原子和分子离子性质，以加快等压线的分离。（2）希望能几乎消除离子源记忆效应的较新版本的铯溅射负离子源的特性。（3）使用精度更高的串联加速器高压控制来分析极低的最终离子通量。最后，（4）在加速器之前已经使用了多年的核反应研究之后，有必要评估加速器或用于帮助等压线分离的装置的可能的低放射性碳和其他背景。为了将原子和分子等压线分离添加到质谱中，以进一步开发带有串联加速器的加速器质谱（AMS），需要进行这些开发。解决了基本问题后，便可以检测和准确测量重要的天然非常稀有的长寿命放射性同位素，例如万亿分之一的子部分（为了将原子和分子等压线分离添加到质谱中，以进一步开发带有串联加速器的加速器质谱（AMS），需要进行这些开发。解决了基本问题后，便可以检测和准确测量重要的天然非常稀有的长寿命放射性同位素，例如万亿分之一的子部分（为了将原子和分子等压线分离添加到质谱中，以进一步开发带有串联加速器的加速器质谱（AMS），需要进行这些开发。解决了基本问题后，便可以检测和准确测量重要的天然非常稀有的长寿命放射性同位素，例如万亿分之一的子部分（经过进一步研究后，天然¹⁴ C的¹⁴ C / C <10 ^-12）得到了促进。结果表明，有原子等压线阴离子的非常低的水平¹⁴ ñ ^-从铯固体样品溅射离子源和该¹⁴ C可在超过10的存在来检测¹⁰倍一样多的14个质量分子阴离子氢化物¹³ CH ^-。N阴离子的第一和第二激发态N（¹ S）^-和N（¹ D）^–稍后存在，但寿命短，不会干扰¹⁴ C的检测。^-在远低于10的水平^-15的¹² C的残留¹⁴ C遗传背景的一个MP串列加速器，先前用于核反应的研究中，以及在离子源记忆效应也被发现高于约小¹⁴ Ç /℃〜10 ^-15解决了加速器电压控制问题之后。这些目标都是在1977年5月在罗切斯特大学完成的一个星期内实现的，这也带来了通过离子计数以及通过质谱分析阴离子对其他稀有长寿命放射性同位素进行自然丰度测量而进一步成功开发放射性碳定年的承诺。或阳离子。此外，如预期的那样，能够以约1000的倍数计算出更少量的碳的能力是新方法的巨大优势。但是，花了将近十年的研究和开发才能使成熟的β计数放射性碳测年方法的准确性与之相等。后来证明，从质谱中消除分子离子是检测通常不存在原子等压线的very系元素含量非常低的关键。