I understood that gamma ray comes from the emission of high energy photon by a nucleus


<h2>Alpha, Beta, and Gamma</h2>
<p>Research begun by people such as New Zealander Ernest Rutherford soon after the discovery of nuclear radiation indicated that different types of rays are emitted. Eventually, three types were distinguished and named <strong>alpha</strong> \((\alpha )\), <strong>beta</strong> \((\beta )\), and <strong>gamma</strong> \((\gamma )\), because, like x-rays, their identities were initially unknown. <a href="#navlink_id2600407">This figure</a> shows what happens if the rays are passed through a magnetic field. The \(\gamma \)s are unaffected, while the \(\alpha \) s and \(\beta \) s are deflected in opposite directions, indicating the \(\alpha \) s are positive, the \(\beta \) s negative, and the \(\gamma \) s uncharged.</p>
<p>Rutherford used both magnetic and electric fields to show that \(\alpha \) s have a positive charge twice the magnitude of an electron, or \(+2\mid {q}_{e}\mid \). In the process, he found the \(\alpha \) s charge to mass ratio to be several thousand times smaller than the electron’s. Later on, Rutherford collected \(\alpha \) s from a radioactive source and passed an electric discharge through them, obtaining the spectrum of recently discovered helium gas. Among many important discoveries made by Rutherford and his collaborators was the proof that \(\alpha \)<em>radiation is the emission of a helium nucleus</em>. Rutherford won the Nobel Prize in chemistry in 1908 for his early work. He continued to make important contributions until his death in 1934.</p>
<div class="fig_container" id="navlink_id2600407"><img alt="The figure shows north and south poles of a magnet through which three rays labeled as alpha beta and gamma are passed. After passing through a magnetic field the alpha ray is slightly deflected toward the right. The beta ray is deflected toward the left and the gamma ray is not deflected." src="https://data.ulearngo.com/assets/8452938e-9417-4939-b68a-1c73cd7da1a4"/>
<p class="fig_caption">Alpha, beta, and gamma rays are passed through a magnetic field on the way to a phosphorescent screen. The \(\alpha \) s and \(\beta \) s bend in opposite directions, while the \(\gamma \) s are unaffected, indicating a positive charge for \(\alpha \) s, negative for \(\beta \) s, and neutral for \(\gamma \) s. Consistent results are obtained with electric fields. Collection of the radiation offers further confirmation from the direct measurement of excess charge.</p>
</div>
<p>Other researchers had already proved that \(\beta \) s are negative and have the same mass and same charge-to-mass ratio as the recently discovered electron. By 1902, it was recognized that \(\beta \) <em>radiation is the emission of an electron</em>. Although \(\beta \) s are electrons, they do not exist in the nucleus before it decays and are not ejected atomic electrons—the electron is created in the nucleus at the instant of decay.</p>
<p>Since \(\gamma \) s remain unaffected by electric and magnetic fields, it is natural to think they might be photons. Evidence for this grew, but it was not until 1914 that this was proved by Rutherford and collaborators. By scattering \(\gamma \) radiation from a crystal and observing interference, they demonstrated that \(\gamma\) <em>radiation is the emission of a high-energy photon by a nucleus</em>. In fact, \(\gamma \) radiation comes from the de-excitation of a nucleus, just as an x ray comes from the de-excitation of an atom. The names "\(\gamma \) ray" and "x ray" identify the source of the radiation. At the same energy, \(\gamma \) rays and x rays are otherwise identical.</p>
<h3>Properties of Nuclear Radiation</h3>
<table id="" summary="Types of radiation are listed in column 1. The range for each type is in column 2.">
<thead>
<tr>
<th>Type of Radiation</th>
<th>Range</th>
</tr>
</thead>
<tbody>
<tr>
<td>\(\alpha \)-Particles</td>
<td>A sheet of paper, a few cm of air, fractions of a mm of tissue</td>
</tr>
<tr>
<td>\(\beta \)-Particles</td>
<td>A thin aluminum plate, or tens of cm of tissue</td>
</tr>
<tr>
<td>\(\gamma \) Rays</td>
<td>Several cm of lead or meters of concrete</td>
</tr>
</tbody>
</table>

Physics is a science discipline concerned with the nature and properties of matter and energy. Physics topics include mechanics, heat, light and radiation, sound, electricity, magnetism, the structure of atoms, and so on.

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Alpha, Beta, and Gamma

Discover the principles behind nuclear physics and radioactivity, including the substructure of the nucleus, nuclear decay, and conservation laws, as well as practical applications in human and medical fields.


Alpha, Beta, and Gamma

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