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[[Ernest Rutherford]], working in Canada and England, showed that radioactive decay can be described by a simple equation (a linear first degree derivative equation, now called [[Rate equation#First-order reactions|first order kinetics]]), implying that a given radioactive substance has a characteristic "[[half-life]]" (the time taken for the amount of radioactivity present in a source to diminish by half). He also coined the terms [[alpha decay|alpha]], [[beta decay|beta]] and [[gamma decay|gamma rays]], he converted [[nitrogen]] into [[oxygen]], and most importantly he supervised the students who did the [[Geiger–Marsden experiment]] (gold foil experiment) which showed that the '[[plum pudding model]]' of the [[atom]] was wrong. In the plum pudding model, proposed by [[J. J. Thomson]] in 1904, the atom is composed of electrons surrounded by a 'cloud' of positive charge to balance the electrons' negative charge. To Rutherford, the gold foil experiment implied that the positive charge was confined to a very small nucleus leading first to the [[Rutherford model]], and eventually to the [[Bohr model]] of the atom, where the positive nucleus is surrounded by the negative electrons.
In 1934 [[Marie Curie]]'s daughter ([[Irène Joliot-Curie]]) and son-in-law ([[Frédéric Joliot-Curie]]) were the first to create [[artificial radioactivity]]: they bombarded [[boron]] with alpha particles to make the neutron-poor isotope [[nitrogen-13]]; this isotope emitted [[positron]]s.<ref>{{cite web|url=http://nobelprize.org/nobel_prizes/chemistry/laureates/1935/joliot-fred-bio.html|title=Frédéric Joliot - Biographical|author=|date=|website=nobelprize.org|accessdate=1 April 2018}}</ref> In addition, they bombarded [[aluminium]] and [[magnesium]] with [[neutrons]] to make new radioisotopes. NAA that is neuton activation analysis it is an important tools in chemistry for the a analysis. whee the amma rays are exposed to the sample and segmented sample it is analysed.
A purpose of the analysis is to determine 1) Half life period 2) Decay constant 3) Age of rock , fossils , skeleton .....and many more option is there.Though this technique is accurate , versatile but it require the trained personnel for the purpose of handling the related instrument .Since there is exposure for the
==Main areas==
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