Gamma-ray spectroscopy of neutron-rich A~100nuclei

壳层模型是描述原子核结构的最著名的模型之一。它类似于原子壳层模型，因为质子和中子都有自己独立的壳层，当填充时，每个核子的结合能降低，从而为原子核提供更大的稳定性。这些壳层以特定的数量出现，但已被证明与电子的原子壳层模型不同。这个模型的一个问题是，它使得计算每个核子的结合能变得困难，因为这样做必须计算每个核子之间的相互作用，这对于重核变得异常困难，因此必须应用其他方法。（国家研究理事会，1999年）。液滴模型已经被证明是非常准确的预测核子的结合能，误差非常小（Moller，例如，1984年）。它将核与液滴进行比较，以及液体中的分子如何相互作用，类似于核中的核子，因为两者都具有均匀的密度，并且在相互作用时表现出相似的特性。例如，核裂变可以看作是分子的分裂，粒子衰变类似于蒸发发射，辐射发射类似于冷却（Bublem和Mullin，1989）。这些模型，沿着其他各种模型，都增加了我们对原子核结构的理解，并再现了已经测量过的质量。然而，仍然有大量的原子核尚未被实验测量，特别是对于富中子核，研究这些未知数对于发展我们对原子核的认识是必不可少的。有各种方法可以研究原子核的质量，其中之一是通过磁谱仪测量飞行时间，该磁谱仪可用于找到质量，因为它与质量比一个例子是GANIL，在回旋加速器内加速具有相似电荷质量比的原子核，由于较轻的原子核将比较轻的原子核加速得更快，因此到达探测器时将有延迟。这个时间延迟可以用来计算核的荷质比，达到很高的精度（Chartier，2002）。

The shell model is one of the most well-known models for describing the structure of the nucleus. It is similar to the atomic shell model as protons and neutrons have their own independent shells which when filled offer greater stability for the nucleus by having a reduced binding energy per nucleon. These shells occur at specific numbers however have been shown to be different to atomic shell model for electrons. A problem with this model is that it makes calculating the binging energy per nucleon difficult as to do this the interaction between each of the nucleons must be calculated which becomes exceptionally difficult for heavy nuclei, thus other methods must be applied (National research council, 1999).The Liquid drop model has been shown to be very accurate for predicting the binding energies of nucleons with very small error (Moller, et al., 1984). It compares the nucleus to a liquid droplet and how molecules in a liquid will interact with each other similar to the nucleons in a nucleus as both will have uniform density and exhibit similar characteristics when interacted with. Examples of this are that nuclear fission can be thought of as the splitting of a molecule, particle decay is similar to emission by evaporation and emission of radiation is similar to cooling (Brehm and Mullin, 1989).These models, along with various others, have all added to our understanding of the structure of nuclei and have reproduced masses that have already been measured. However there are still a large number of nuclei that have not yet been measured experimentally, particularly for neutron rich nuclei and investigating these unknowns is essential to developing our knowledge of the nucleus.There are various methods for investigating the mass of nuclei, one of which is the measurement of the time of flight through a magnetic spectrometer which can be used to find the mass as it is proportional to the change to mass ratio. An example of this is GANIL where nuclei of similar charge to mass ratios are accelerated within a cyclotron and as the lighter of the nuclei will accelerate faster than the lighter nuclei, there will be a delay in arrival at the detector. This time delay can then be used to calculate the charge to mass ratio of the nuclei to a high degree of accuracy (Chartier, 2002).