the particle odyssey a journey to the heart of matter nov 2004

[...]... detector Four particles, however, shoot out at large angles to the others, towards the top left and bottom right of the image These are the tracks of penetrating muons, which have been produced in the decay of the Higgs particle created in the initial collision A Journey to the Start of Time 15 2 Voyage into the Atom Take a deep breath! You have just inhaled oxygen atoms that have already been breathed... the aid of a very simple calculation, Rutherford at last saw the meaning of the results The key was that he knew the energy of the incoming alphas He also knew that each alpha particle carries a double dose of positive charge The positive charge within the gold atoms must repel the approaching alphas, slowing them and deflecting them The closer the alphas approach the positive charge in the atom, the. .. particles and the nature of the material Universe It is also a showcase of particle imagery, from early cloud chamber and emulsion photographs to the latest computer displays These pictures show that the subatomic world is real and accessible; they also have their own peculiar beauty The Particle Odyssey is both a voyage through time and a journey to the heart of matter Chapters 2, 4, 6, and 8 describe the. .. these particles combined to make atoms The cool conditions in which atoms exist today are enormously far removed from the intense heat of the Big Bang The inner labyrinths of an atom are as remote from daily experience as are the hearts of stars, but to observe the atomic constituents we have to reproduce in the laboratory the intense heat of stars This is the world of high-energy particle accelerators,... calculate how many alpha particles were radiated by the whole sample of radium, and compare the answer with the total charge emitted, as measured with the electrometer The calculations showed that the charge of an alpha particle is twice that of the hydrogen ion, and this in turn indicated almost certainly that alphas are helium ions To prove that single alpha particles were entering the wire detector,... that make things the way they are Gravity causes apples to fall to Earth, and controls the motions of the planets and galaxies The electromagnetic force affects compass needles and glues atoms to one another to make solids, liquids, and gases, such as human flesh and blood and the air we breathe Two further forces, known as the strong force and the weak force, control the structure of atomic nuclei The. .. transmutations Today we know that alpha particles are the nuclei of helium atoms There was however no way that Rutherford could make this last step in 1908 as the idea of the nucleus was still unknown That was to be his next dramatic contribution: deducing what the inside of the atom looks like At McGill, Rutherford had noticed that when a beam of alpha particles passed through thin sheets of mica, they... ‘strange’ particles, and quarks have entered the menu Throughout, the electron has remained in the list Today we recognize its fundamentality Our best theories require that quarks also are fundamental and that there are six varieties of them, named ‘down’ and ‘up’, ‘strange’ and ‘charm’, ‘bottom’ and ‘top’ To create the first examples of the top quark, the physicists at Fermilab have had to bring matter and... distinct types of radiation – alpha, beta, and gamma – which produce different characteristic tracks in a cloud chamber (see p 30) Fig 2.12 (TOP LEFT) The final portion of the track of an alpha particle The track changes direction where the alpha collides with atoms in the air inside the chamber Finally, close to the end, the track becomes fainter as the positively charged alpha particle captures electrons,... enough grassland to support a herd of American buffalo The offices of its scientists fill ten floors of a graceful cathedral of glass and stone whose atrium soars up to the roof, is grand enough for trees to grow, and sports a dedicated travel bureau Prairies stretch for hundreds of kilometres to the western plains Another land of flat earth, the Fens of East Anglia, is home to the grey stone building . Data Data available Art direction: Richard Adams Associates Designed and typeset: Sam Adams Original photography: David Parker Diagrams and illustrations: Gary Hincks Photoshop: Cesar Pava and Paul. kept out of the way of the matter that is all around them. It may take a whole day to prepare the beam, accumulating enough antimatter particles to be of use for the experimenters. Then the controllers. 4 10987654321 Contents 1. The World of Particles Cosmic Explorers Particle Physics Now A Journey to the Start of Time 2. Voyage into the Atom X-Rays and Radioactivity The First Particle Rutherford and the Atom Inside