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NEUTRON ACTIVATION ANALYSIS 181<br />

Method<br />

The technique used <strong>to</strong> analyze Qumran pottery samples is neutron<br />

activation analysis, specifically designed <strong>to</strong> f<strong>in</strong>gerpr<strong>in</strong>t chemically a<br />

ceramic vessel or just a shard. It is based on <strong>the</strong> premise that each<br />

clay source on Earth has a different geochemical his<strong>to</strong>ry, hence a<br />

different chemical composition, and can <strong>the</strong>refore be dist<strong>in</strong>guished<br />

<strong>from</strong> all o<strong>the</strong>rs (Perlman & Asaro, 1969; Gunneweg et al., 1988).<br />

Thus pottery made <strong>from</strong> <strong>the</strong>se clays can also be dist<strong>in</strong>guished <strong>from</strong><br />

pottery of clay <strong>from</strong> o<strong>the</strong>r sources. NAA has <strong>the</strong> capability <strong>to</strong> determ<strong>in</strong>e<br />

quantitatively about thirty-five chemical elements—for <strong>the</strong> major<br />

part trace elements—that provide <strong>the</strong> so-called chemical f<strong>in</strong>gerpr<strong>in</strong>t<br />

of a vessel. The elements belong <strong>to</strong> all <strong>the</strong> different groups on <strong>the</strong><br />

periodical table.<br />

By subject<strong>in</strong>g a set of samples <strong>to</strong> a beam of neutrons <strong>in</strong> a nuclear<br />

reac<strong>to</strong>r, one sets off a nuclear reaction that <strong>in</strong>cludes all of <strong>the</strong> chemical<br />

elements, and ultimately results <strong>in</strong> <strong>the</strong> abundance of <strong>the</strong> elements.<br />

The purpose of <strong>the</strong> irradiation is <strong>to</strong> convert a small fraction<br />

of <strong>the</strong> stable iso<strong>to</strong>pes of <strong>the</strong> various elements <strong>in</strong><strong>to</strong> a radioactive form<br />

that emits gamma rays. These mono-energetic gamma rays will later<br />

identify <strong>the</strong> element, while <strong>the</strong> abundance of <strong>the</strong> element is determ<strong>in</strong>ed<br />

by count<strong>in</strong>g <strong>the</strong> gamma-pho<strong>to</strong>ns that are emitted <strong>in</strong> a predeterm<strong>in</strong>ed<br />

length of time.<br />

Group<strong>in</strong>g<br />

After we have analyzed a considerable number of pottery shards<br />

and o<strong>the</strong>r materials that are supposed <strong>to</strong> be specific <strong>to</strong> a site, we<br />

attempt <strong>to</strong> construct a pottery group or groups based upon chemical<br />

<strong>the</strong> Hebrew University; I. Perlman, J. Gunneweg and J. Yell<strong>in</strong> 1986, Pseudo-<br />

Nabataean Ware <strong>from</strong> Jerusalem, Bullet<strong>in</strong> of <strong>the</strong> American Schools of Oriental Research<br />

262, pp. 77-82; J. Gunneweg, I. Perlman and F. Asaro 1988, The Orig<strong>in</strong>, Classification<br />

and Chronology of Nabataean Pa<strong>in</strong>ted F<strong>in</strong>e Ware, Jahrbuch des Rb'misch-Germanischen<br />

Zentral Museums, Ma<strong>in</strong>z, vol. 35, pp. 1-30; J. Gunneweg and H. Mommsen 1990,<br />

Instrumental Neutron Activation Analysis and <strong>the</strong> Orig<strong>in</strong> of some Edomite vessels<br />

and Cult Objects <strong>from</strong> Horvat Qitmit, Archaeometry 32, pp. 7-18; J. Gunneweg and<br />

J. Yell<strong>in</strong> 1990, The Orig<strong>in</strong> of <strong>the</strong> Hellenistic and Roman Stamped Handles <strong>from</strong><br />

<strong>the</strong> City of David, Jerusalem, <strong>in</strong> D. T. Ariel, City of David II, Qedem 30, pp. 89-93;<br />

J. Gunneweg and H. Mommsen 1995, Instrumental Neutron Activation Analysis of<br />

Vessels and Cult Objects, pp. 280-86 <strong>in</strong> Horvat Qitmit, an Edomite Shr<strong>in</strong>e <strong>in</strong> <strong>the</strong> Biblical<br />

Negev, I. Beit Arieh, Monograph Series No. 11 of <strong>the</strong> Institute of Archaeology at<br />

Tel Aviv University.

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