1 Introduction
1.1 A Brief History of Early Nuclear Physics
In the early 1900s it was seen that a small number of alpha particles were deflected by a large angle, the current model at the time predicted only small deflections of the particles. These results were explained by introducing a tiny positively charged nucleus into our picture of the atom. Although beta decay had been observed as early as 1896 and was known to contain electrons, it wasn’t until 1914 that they would break the law of energy conservation if just composed of electrons. To account for the discrepancy in energy during beta decay, Wolfgang Pauli suggested that a very light, neutral charged particle was also released during beta decay, this particle was named the
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There are numerous models that have been used to describe nuclear structure and the physical properties that arise. A mathematical model can be scrutinised in a large number of ways, does the model agree with existing data, can the model be used to make physical predictions, what assumptions are made etc.. Currently a large factor used in deciding whether to use a model, is the dif- ficulty in solving this mathematical model to produce physical values. A much more complicated model may give the most accurate results, but the difficulty in obtaining any result e.g. the computational time required, is not worth the gain in accuracy. A trade off must be made in deciding on the physical model to be used in the situation. In this article a number of different models will be discussed, the formulation and the uses of these models will be studied, as well as there uses in physics. Due to the vast number of areas that nuclear physics is used, such as in cancer treatments, material processing etc. improvements in our nuclear models are very important and not just studied for scientific curiosity. [3]
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2 Modelling Nuclear Structure
2.1 Macroscopic Modelling of nuclear structure (The Liquid Drop Model)
It is important to have models of nuclear structures and interactions, to both describe the observations
made
Models provide the physical testing and proof of a hypothesis by exploring the extent to which the two factors relate within the given hypothesis. It puts a theory into action, to see if the theory is correct.
Before the Manhattan Project, in the beginning there were many advancements in understanding made in the world of physics. These resulted in the recognition of nuclear fission and its potential as an energy source and as a potential weapon. Of these advancements none was more central and important than the development of the nuclear model of the atom, which by the year of 1932 contained a nucleus containing most of the mass of an atom in the form of two particles, protons and neutrons. This nucleus was surrounded by an electron shell. Previously it was thought that atoms were the smallest form of matter therefore ultimately stable and indivisible. However, in 1919 Ernest Rutherford was able to break apart the nucleus of nitrogen with
Ernest Rutherford, 31 year old New Zealander, partners with Frederick Soddy to try and solve the mystery of uranium. They find that uranium spits out chunks of itself, and these chunks are radiation. The uranium then transforms into a completely different element. When the uranium spit out chunks of itself, it was losing protons so it no longer has 92. This is called transmutation.
After the whole class boarded the magic limousine once again, we all all traveled to the year 1899. The whole 10th grade chemistry class met Ernest Rutherford. Earnest and Ms. Siepsiak seemed to be great friends! How cool is that? While he was conducting his Gold foil experiment he explained that he set up a thin beam of alpha particles to stream over to a sheet of gold. He also placed a sample of radium inside a lead box with a small hole in it. As the experiment went on, Rutherford analyzed that most of the radiation was absorbed by the lead. However, at the same time a thin beam of alpha particles shot out of the pinhole and went towards the gold foil. The gold foil experiment was set up in a way that it was surrounded by a detector screen
Before the First World War, German scientists James Franck and Gustav Hertz conducted experiments where they added electrons to Mercury atoms. They traced the energy changes that the collision caused. That experiment led Nils Bohr to make a theory that an atom can absorb energy in precise and definite amounts. After that experiment, many other scientists conducted research on radioactive methods to chemical problems and conducted more experiments on how elements would react when elements
Models provide the physical testing and proof of a hypothesis by exploring the extent to which the two factors relate within the given hypothesis. It puts a theory into action, to see if the theory is corrected causes and effects.
Geiger was joined by Ernest Marsden to create a new instrument to detect whether alpha particles could be deflected at greater angles. This device was different from the previous in the way that the gold foil and radium were both inside a metal cylinder, which was fixed to a swivel. The microscope attached penetrated the wall of the cylinder. The lens of the microscope was covered in a zinc sulphide screen and the microscope could be moved in a full circle around the foil so Geiger could tally the flashes of light from every possible angle. He observed alpha particles deflecting by as much as 150°.
Their discovery of the radioactive isotopes composed and important step toward the solution of the problem of releasing the energy of the atom, using neutrons instead of alpha particles for the bombardments which led to the fission of
Businesses rely on numerical models while choosing a project. Most businesses see numerical models more useful than non-numerical models which are highly biased and unempirical.
Ernest Rutherford was born in New Zealand and died in Britain, however during his life he worked McGill University in Canada (“Ernest Rutherford - Biographical”, 2014). During Rutherford's life he made significant contributions to Science; in 1998 when studying Uranium he discovered Alpha and Beta radiation (“Ernest Rutherford: Father of nuclear science”, n.d.). In 1903, Rutherford saw that a French chemist, Paul Villard, had discovered a new type of radiation coming from radium, upon discerning that this new radiation was different then the ones he had already discovered due to its greater penetrating power, Rutherford named it Gamma radiation (“Ernest Rutherford”, 2017). Using his previously found out types of radiation, he discovered the concept of half-life, how long it takes for a sample of an element to decay to half its size. However, the most infamous experiment he did, was the Gold Foil Experiment. In 1910, in order to confirm JJ Thomson’s model on an atom Ernest Rutherford conducted an experiment along with Hans Geiger and Ernest Marsden where a thin piece of gold was bombarded with Alpha particles, while most went through (meaning that an atom is mostly empty space), some were deflected, and a few even bounced backwards. This led to the discovery of the neutron, a positively charged area of the atom which was responsible for Alpha particles being deflected and bouncing back. With this new information disproving JJ Thomson’s model, Rutherford created a new atomic
Nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts, as shown in Fig 1. The discovery of fission in the 1930’s showed us that the heaviest of the nuclei’s were loosely bound in their ground state. An excitation energy of as little as a few percent of their total binding energy is sufficient to induce the breakdown of the nuclei, into two pieces, releasing a vast quantity of energy in the order of around 200 MeV. Therefore, compared to fossil fuels like oil, natural gas or coal the specific energy content for nuclear fuel is roughly 108 times larger. This figure alone identifies the importance of fission in nuclear technology and production of
In this experiment, you will have a chance to test the hypothesis that Ernest Rutherford used when determining the size of the nucleus. In his "gold foil experiment," Rutherford shot alpha particles at gold atoms. Once he realized that the alpha particles were hitting a concentrated positive mass, he developed the nuclear model of the atom. Next, he set out to determine the relative size of the nucleus compared to the rest of the atom. He reasoned that the smaller the nucleus, the less likely it was to be hit by an alpha particle. This led to a simple comparative ratio:
large sample size the model use as well as the capability to directly authenticate the model also it can disclose their analytic advantage.
Nuclear knowledge has existed for a long time. Nuclear Engineering U.S. Department of Energy relates, ―By 1900, the physicists knew the atom contains large quantities of energy‖ (par 11). Many others formed good theories, such as Ernest Rutherford and Einstein’s contribution with his equation E=mc^2. In 1934
Dalton and other scientists imagined the atoms as tiny, solid spheres in some stages of motion.