Science by Email 13 July 2012

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	13 July 2012
News: Fermions, bosons and Higgs – oh my! By Patrick Mahony This drawing represents how the Higgs boson might be created. The different coloured lines show the paths of different particles. Scientists at the Large Hadron Collider (LHC) have confirmed the discovery of a particle with properties that match those of the Higgs boson. The announcement has created a lot of excitement – why all the fuss? There is more to the Universe than just atoms. In fact, there is a whole range of tiny particles out there. One group of particles is the fermions, which includes protons, neutrons and electrons. You can think of them as building blocks that make up matter. The other group of particles, the bosons, are a bit trickier to understand. Rather than thinking of bosons as blocks of stuff, think of them as carrying forces, and telling fermions how to behave. Different bosons interact with different fermions, forcing them to stick together or move apart. An example of a boson is the photon, a tiny particle of light. The Standard Model is a theory that predicts a set of fermions and bosons. The Standard Model grew over a long time and proved very useful. The Higgs boson was the missing piece, so finding it makes the theory stronger. The Higgs boson tells other particles how to move. Some particles, such as photons, zip past Higgs bosons and don’t interact with them. They have no mass. Other particles do interact with Higgs bosons. This interaction is similar to the drag you feel moving through water. We see this interaction as mass. Unfortunately the Higgs boson disappears nearly as soon as it appears, making it difficult to detect. One way to detect the Higgs boson is to smash protons together at high speeds. The energy of these collisions could be enough to create Higgs bosons, which would then decay into other particles that live long enough for physicists to detect. Two different research teams independently analysed the data from experiments at the LHC. After looking at the results of millions of collisions, they both concluded that there was a particle consistent with the Higgs boson. More experiments are needed to verify their findings, but evidence of this elusive particle may finally have been spotted. More information Higgs within reach The Higgs boson explained What is the Higgs boson? Careers link Nuclear and particle physicist – what they do
You will need these materials.   Cut out circles of coloured paper.   Cut the circles into thirds.   Label your thirds according to the table.   Glue your thirds together, one of each colour. How many combinations can you make?   Try this: Quirky quarks   You will need Red, blue and green cardboard or paper Pencil Scissors Cup Glue Paper Protractor Ruler What to do Use the cup to trace two circles on each piece of cardboard. Cut out the circles. Use the protractor and the ruler to divide all of the circles into thirds. Cut the circles into thirds. Take one red third, one blue and one green. On any two of the thirds, write ‘up, +2/3’. On the last third, write ‘down, -1/3’. Take these three thirds, and use glue to stick them together on a sheet of paper to form a new circle. Add up the numbers on each of the thirds (+2/3 +2/3 –1/3). What is the total? Take three more thirds, one of each colour. This time, label one of the thirds ‘up, +2/3’ and the other two ‘down, -1/3’. Glue them onto a sheet of paper and add the numbers together (+2/3 –1/3 –1/3). What is the total this time? Label your remaining thirds using the following table: Name Number Up +2/3 Down -1/3 Charm +2/3 Strange -1/3 Top +2/3 Bottom -2/3 How many combinations can you make? The only rules are that you must make a circle, and each third must be a different colour. What’s happening? The cardboard thirds represent sub-atomic particles called quarks (pronounced qworks). There are six types, or flavours, of quarks: up, down, charm, strange, top and bottom. Three quarks can combine together to form larger particles called baryons. The number written on the quarks represent their charge. Quarks have either a charge of +2/3 or -1/3. The first baryon you made had a total charge of 1 – it represents a proton, commonly found in the nucleus of an atom. The second baryon you made has an overall charge of 0. This represents a neutron, the other particle commonly found in the nucleus. You can combine different quarks to make many other baryons. In addition to charge, quarks have another property that physicists call ‘colour’. There are three quark ‘colours’: red, blue and green. A baryon must be made up of quarks of different colours. It’s important to note that a blue quark doesn’t appear blue like the sky – it’s just a name of a property of quarks. Quarks are held together by a force, called the strong force. This force is carried by bosons called gluons. Their name comes from the fact that they ‘glue’ particles together. In this activity, the gluons are represented by the glue you use to stick the circles together. Applications According to the Standard Model, quarks are fundamental particles. This means that they can’t be broken into smaller components. The six quarks are included in the Standard Model, which attempts to explain three of the four theories of nature. Most matter we experience here on Earth is composed of atoms. Most of the mass of atoms comes from the neutrons and protons in the nucleus, which are made of quarks.            By Patrick Mahony Try another Science by Email activity about charge More information The particle adventure View the online version Quiz questions 1. What is the most common chemical element in the Universe: oxygen, hydrogen or helium? 2. What is the key structural component of human hair? 3. What is a group of owls called? 4. What can endotherms do that ectotherms can’t? 5. Can black holes emit radiation? Did you know? Scientists in Antarctica have discovered where some species of moss get their nutrients: ancient penguin poo! Websites   Read it! Quilting meets particle physics? Check out this article to discover the results. Watch it! ATLAS is one of the detectors used to hunt down the Higgs boson. Watch this video comparing the construction of a Lego model with that of the real thing! Seismometers in Schools Attention teachers: would you like your school to be part of a national geoscience experiment? The Australian Seismometers in Schools (AuSiS) project has 40 seismometers to place in schools around Australia. Students will look after the seismometer, which will monitor and record seismic data. This data can then be used by geoscientists, as well as accessed by other schools. If you would like your school to participate, you can fill out an Expression of Interest form at the AuSiS website. Quiz answers 1. Hydrogen is the most common chemical element in the Universe. 2. The key structural component of human hair is a protein called keratin. 3. A group of owls is called a parliament. 4. Endotherms can generate their own body heat. 5. Black holes can emit radiation in the form of radio waves. An international team of astronomers have detected the first radio waves from an intermediate black hole. Science by Email is a CSIRO publication. bankmecu is a proud partner of Science by Email. Editor: Mike McRae| Manage your subscription | FAQ

 

 

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