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An Insight Into Nature's Strongest Force

Introduction:

My name is Lloyd and I am in the third year of my PhD studying Theoretical Nuclear Physics. I am attempting to provide a better theory to describe the phenomenon of neutral pion (a relatively light, short-lived particle that is found in nuclear and particle reactions) production from a photon (light) incident on a proton (a nuclear particle that is found in the nucleus of every atom).  Before starting my research I studied theoretical physics at the University of Manchester.


Strong Nuclear forces remain to be one of the least understood processes in nature. Yet it is the source of immense energy that can power our cities, from harnessing the emitted radiation in power-plants; or level countries by concentrating radioactive materials in a bomb. The manner in which the fundamental matter particles (or quarks) exchange the strong force carrying particle (or the gluon boson) is far more complex than any of the other forces (weak nuclear, electromagnetic or gravity). Unlike the other forces, gluons themselves can carry a strong nuclear charge, known as colour charge; this allows them to interact with themselves in-between quark interactions, allowing for infinite scenarios to describe the simplest of processes. 

In Depth:

The study of the strong nuclear force is known as quantum chromodynamics (QCD), this theory helped scientists understand important properties of particle physics, mainly why we only see composite quark states in nature. In other words why you will never find a sole quark by itself, instead you will see it in bound states (hadrons) which form protons and neutrons (baryons) and lighter states such as pions (mesons). But trying to make any practical calculations with QCD is very difficult, so difficult in fact that if anyone were to solve the QCD equation into a usable form then they would win 1 million dollars from the Clay Mathematics Institute!

I do away with these complexities of QCD by only working in energy regimes where the protons and other hadrons won't break down into their constituent quarks. So we can describe proton or neutron scattering through pion exchange instead of using gluons. Furthermore, I take advantage of some symmetries present in QCD, related to the quark masses, to simplify aspects of the calculations. This is a very vague picture of the theory I work in called Chiral Perturbation Theory (ChPT).


My work has been motivated by a recent experiment in Germany at the Mainz Microtron by the A2 and CB-TAPS collaborations where they have obtained the most accurate data to date on this interaction. I am in the process of taking theories that have already been made to describe parts of this process and sticking them together to get a more complete picture of the reaction. The most important part I have included is an intermediate resonance state prior to pion emission.

This research isn't going to be part of the new fastest computer in 20 years time, nor is it going to cure diseases. But it will give us an insight in to what happens in nature at the sub-atomic level. Then maybe who knows what this might lead to in the future, 100 years from now it is impossible to predict how important this process will be in understanding nuclear fusion both in power plants or in stars. When Paul Dirac, one of the pioneers of quantum mechanics, predicted the existence of massless Dirac fermions in the 1920s he had no idea that a century later people would be trying to use these states within graphene to dramatically improve technology.

Going Further:

To follow exactly what it is I do I am afraid you will need a degree in theoretical physics, which you can start looking into at the University of Manchester. (http://www.physics.manchester.ac.uk/study/undergraduate/undergraduate-courses/physics-with-theoretical-physics-mphys/)

The European Centre for Nuclear Research (CERN) have lots of information available on particle and nuclear physics (http://home.web.cern.ch/students-educators)

The Jefferson Lab in the USA also has useful information for students and teachers (https://www.jlab.org/education-students)

MAMI, the experimental group that analyse this interaction (http://www.kph.uni-mainz.de/eng/108.php)


 

Recreating the conditions inside the sun

Introduction

Hello! My name is Asad and I’m a PhD student at the School of Mechanical, Aerospace and Civil Engineering at the University of Manchester. Within my PhD, I work in the relatively recent field of nuclear fusion. More specifically, I look at the effects of plasma damage and neutron irradiation (both known phenomenon that occur within nuclear fusion) on materials that could be used to build a potential fusion reactor.

A little bit about my background first. Before I embarked on my PhD, I completed a Master of Engineering (MEng) in Mechanical Engineering with a minor focus on Nuclear Engineering. I also did some part time study in mathematics and research projects within fluid mechanics. Of the latter, a noteworthy one is that I constructed a mathematical model of the acoustics of a banjo!


In Depth

Science has always intrigued mankind. Some of the foremost questions we have been obsessed with are the simple ones:

·  “Where did we come from?”

·  “Why are we here?”

·  “What do we do?”

No matter who you ask, you will realise that we still don’t really know the answers to these; whether we look for philosophical reasoning or scientific. We search high and low for answers. Our universe is at the centre of such research. And at the centre of our universe: the sun.

The sun can be considered a giant ball of energy. The manner in which this energy is generated is referred to as nuclear fusion. As the human species observed this, we felt the urge to exploit the process to aid our need for energy, in order to survive on a world where resources are rapidly depleting.

What exactly is nuclear fusion? The answer is a result of work done by pioneering scientists such as Ernest Rutherford, Pierre Curie and Marie Curie. We find that certain atoms of elements undergo interesting transitions. We have been able to exploit these, such as nuclear fission which is currently a dominant process to generate electricity. Within fission, we find that under the right conditions, some of the atoms will split and become smaller releasing energy in the process. Fusion is the opposite; some atoms combine and through the process release energy. It has been found that the energy released through fusion could potentially be more sustainable, cleaner, and less fraught with the risks associated with the energy generated through fission. 

Thus we are now engaged in a global technological race to be able to achieve the right conditions for fusion on earth. Thus far we have managed to recreate the conditions. However, we still haven’t managed to be able to maintain these for long enough, nor have we been able to extract power from it. We have some ideas on how to achieve both. One of the questions however is, do we have the materials to be able to do so?


This is where people like me come in. Thus far I have spoken about how this is a relatively new process mingled with a plethora of difficulties. Therefore, it will not be surprising when I say that we don’t exactly have the appropriate facilities to be able to entirely comprehend the extreme effects taking place. So how do we go about solving the problem? Some people try and use proxies, alternative approaches that in some way mimic certain effects we expect. Others try to use computational techniques and our understanding of physics to paint a picture. I’m involved in the latter. I use modelling and simulation to try and deduce what we expect. It isn’t as simple as pushing a button however. One needs to be aware of a lot of inter-related pieces of physics. Sometimes, we also find that we don’t have the computational power to actually be able to process all of these (surprising isn’t it given the progress in the field of IT).  Sometimes my job is therefore to see which processes are negligible. At other times, it is to check and draw conclusions from the results of my simulations. To name a few of the techniques I use; I use solvers for the neutron transport equation, binary collision approximation and molecular dynamics. The last considers how atoms are likely to behave. This generates some interesting perceptions of important chemical and atomic processes.

I’ll stop here. I’ll end on a note that the human race is currently engaged in very exciting things. But to see this realised; we need young, ambitious and creative minds that are keen to learn as well as try new things. 


Going Further

If you want any more information, please feel free to contact me at: asad.hussain@postgrad.manchester.ac.uk . 

To find out more about the chemical and atomic processes generated in molecular dynamics: http://lammps.sandia.gov/movies.html

A more comprehensive yet elementary guide on nuclear physics can be found at (http://hyperphysics.phy-astr.gsu.edu/hbase/nuccon.html)

Here are also some web links pertinent to what I have written: 

Culham Center for Fusion Energy: http://www.ccfe.ac.uk/introduction.aspx

Nuclear Energy Agency: http://www.oecd-nea.org/workareas/

Fusion Center for Doctoral Training: http://www.york.ac.uk/fusion-cdt/


 

Researching safe ways to dispose of nuclear waste

Introduction

My name is Robert Worth and I am currently part way through a PhD in Nuclear Engineering with the Nuclear Graphite Research Group at the University of Manchester – how did I get here? Almost by accident. It was during my A Level study in Physics that I first came across the phenomenon of radioactivity, which I thought was a bizarre and exciting process that I had not encountered before, and I needed to know more! This eventually led me to my degree in Mechanical (Nuclear) Engineering at the University of Manchester, which was very enlightening and encompassed many aspects of both mechanical and nuclear engineering. It was during my degree that I stumbled across an email containing upcoming PhD research projects – did I know what a PhD involved? Nope, not really. Did I want to do one? I wasn’t sure. I’m glad I applied, however, as it turned out that this is the sort of work I’d wanted to do all along, I just hadn’t realised it. You are no longer just absorbing information from others – I am also now doing the finding out, and helping answer questions that nobody in the world yet has answers to!

I’ve been very lucky with this PhD project, and have been encouraged to attend many prominent events and conferences around the country, talking with and working alongside some of the most inspiring people and minds in the country. I’ve been fortunate enough to travel further afield too, as far as Lithuania, where we stood on the top of a nuclear reactor core of the same basic design as the famed Chernobyl, and even over to the United States, to visit a research group at Idaho State University and to help on an experiment at a synchrotron particle accelerator in California.

My specific research project is on thermal treatment of irradiated graphite waste. It turns out that there is an awful lot of it (around 96,000 tonnes) in our small country, the UK. So far, there are good ideas about how we might deal with this large volume of radioactive waste, and the Nuclear Decommissioning Authority (NDA) have plans to bury most of it in a future geological disposal facility, a large controlled facility far underground that could house and contain all of our radioactive waste for thousands of years to come. Since a location for this facility is yet to be found, and it is yet to be built, you could argue that a disposal route is not set in stone. Which is where treatment comes in – can we do something else with the graphite waste to reduce the hazard, instead of burying it, which could potentially save money and may leave valuable space in the repository open for other more hazardous wastes? This is a point of controversy amongst the nuclear waste research community! 

In Depth

What is graphite and how is it used?

Graphite is a very stable hexagonal formation of carbon atoms, that can be found naturally but is also artificially manufactured to very high purities, at great expense! This involves many different processes to reach the final product including heating to around 3000oC for a number of days. It is essentially many planes of the material ‘graphene’ all layered up on top of each other, and is found in pencils; the ‘lead’ in your pencil is actually graphite, and it is these layers of carbon atoms sliding relatively easily over each other that allows you to write and draw quite easily.

Graphite is used in many nuclear reactors in the UK in the shape of enormous blocks, which can be over a metre in height, all stacked on top of each other and arranged into a large reactor core. Its purpose is to slow the neutrons in the core down, by acting as a physical barrier for the neutrons to bounce off, a little like billiard balls, so that they will react more easily with the nuclear fuel, producing energy for us to power our homes. 

Why is it radioactive?

Carbon has been selected as a fairly ‘neutron transparent’ material so that neutrons will bounce off and scatter away from the carbon atoms instead of being absorbed. This does not happen every time, however, and on occasion a neutron will be absorbed into the carbon atom, making the nucleus of the atom heavier and larger than it was previously. This can make the atom become unstable, as it can no longer physically sustain itself in a stable state, and so the atom will ‘decay’ by releasing some energy – in this instance, a radioactive carbon-14 atom will spit out an electron from the atom and transmute into nitrogen-14, which is a stable atom. Voila! This is the process of radioactive decay.

What do I actually do?

I spend a lot of time working in a laboratory with radioactive samples, taken from a nuclear reactor, wearing a white lab coat, goggles, layers of gloves, and working with tongs behind special shielding or in a glove box, like Homer Simpson. I also wear a dosimeter to record the amount of radiation I have received from the samples, so that I know I am well below safe levels for working. I then take these samples and place them in a specially designed tube furnace, and very carefully oxidise them using a gas flow of 1% oxygen to try and remove a good fraction of the surface radioactivity as a gas. The radioactive portion of this gas is then trapped and collected in a ‘bubbler system’, where the gas is forced to bubble up through a clever fluid, before it is taken away for analysis to determine how much radioactivity has been successfully removed. I can then use this data to make a reasoned judgment of how I might improve the process, by adjusting the temperature, for instance.

Going Further

More information about the array of Nuclear Engineering research in the School of MACE at the University of Manchester can be found at: http://www.mace.manchester.ac.uk/our-research/research-themes/nuclear-engineering/

A fairly detailed overview of ‘radioactive waste management’ around the world has been produced by the World Nuclear Association, and can be found at: http://world-nuclear.org/info/Nuclear-Fuel-Cycle/Nuclear-Wastes/Radioactive-Waste-Management/

A further insight into the role of the Nuclear Decommissioning Authority in the UK, working on behalf of the government and responsible for overseeing the clean-up of many UK nuclear power sites, can be gleaned from the following website: http://www.nda.gov.uk/what-we-do/

 

Tacking the global energy crisis

by YPU Admin on January 9, 2014, Comments. Tags: nuclear and Research

Introduction

My name is Aneeqa and I am trying to help create the conditions of the Sun on Earth. Following my undergraduate degree in Mechanical Engineering, I decided to pursue a PhD in nuclear fusion and I am now in my second year. The world is undergoing an energy crisis and a variety of approaches need to be pursued in order to cope with this.  Fusion is the process by which two atoms collide and release energy in the process, and it is fusion which powers the sun where hydrogen and helium atoms fuse together, releasing huge amounts of energy. My work is focused on understanding what damage is expected to occur to tungsten (a candidate material for fusion) when it is used in a fusion reactor, so that components that will withstand the extreme environment of nuclear fusion can be developed and commercial fusion can become a reality and we can save the world. Not much to ask for then…



In Depth

So, the world’s demand for energy looks set to increase by greater than double the current usage by the year 2050. 80% of the energy used today is from fossil fuel sources, contributing unsustainable amounts of greenhouse gases.  We really need to find a way to provide enough energy for the exploding population, with as little cost to the environment as possible. There is no one easy solution to meet this demand. A combination of approaches must be developed to provide diversity and energy security, including solar, nuclear fission and also nuclear fusion.   Fusion is a promising approach due to the fact it has a limited environmental impact, requires limited space and unlike traditional nuclear fission (the splitting of atoms that occurs in nuclear power plants today), it is intrinsically safe. The fuel supply is also virtually unlimited. The lithium found in your laptop battery with a bath full of water could provide enough electricity for a single person for thirty years! Pretty impressive right? So why aren’t we already using fusion?

Well as I mentioned before, fusion is what occurs in the sun. So you can imagine the environment required for fusion power is pretty crazy. With temperatures at 100s of millions of degrees in the middle and thousands of degrees at the wall, as well as bombardment of the walls of the reactor with high energy neutrons and ions of helium and hydrogen, it is a tad tricky to find materials that can cope with all of this. Tungsten is one of the materials that should be able to handle this environment, because it has a high melting point, and is strong. But it still has some setbacks. It can fracture quite easily and is known to behave in a brittle manner at high temperatures. So it could break suddenly and cause a lot of damage to the reactor.  All these issues are made worse by the intense environment that is expected in a fusion reactor.  Therefore, my work looks at trying to understand the effect of the fusion environment on tungsten and what we can do to improve how tungsten performs.

My day-to-day work involves modelling things on computers, doing some experiments and looking at really small areas of tungsten, which actually looks pretty cool! The picture I have taken below is from a transmission electron microscope and shows the grain boundaries of tungsten. Just to put the scale in perspective, a human hair is around 100 000nm wide. So that image is pretty zoomed in!

Materials research is really important for the development of a nuclear fusion reactor which could eventually help provide energy to those in the world who are without!



Going Further

If you are interested in nuclear fusion check out the CCFE (Culham Centre for Fusion Energy) and ITER websites. CCFE is home to a fusion reactor here in the UK and ITER is the experimental reactor that is being built in the south of France!

The 'How stuff works' people have made an excellent summary on how nuclear fusion reactors work here.

If you are interested in splitting atoms (nuclear fission), then the Nuclear Hitchhiker blog and podcast is an interesting place to visit. This was created by some University of Manchester Students and they also have a Twitter page (@Nuke_Hitchhiker). 

The Dalton Nuclear Institute covers most of the nuclear related research that is happening at the University of Manchester (@DaltonNuclear).