Neutron activation analysis

Neutron activation analysis (NAA) is a nuclear process used for determining the concentrations of elements in a vast amount of materials. NAA allows discrete sampling of elements as it disregards the chemical form of a sample, and focuses solely on its nucleus. The method is based on neutron activation and therefore requires a source of neutrons. The sample is bombarded with neutrons, causing the elements to form radioactive isotopes. The radioactive emissions and radioactive decay paths for each element are well known. Using this information, it is possible to study spectra of the emissions of the radioactive sample, and determine the concentrations of the elements within it. A particular advantage of this technique is that it does not destroy the sample, and thus has been used for analysis of works of art and historical artifacts. NAA can also be used to determine the activity of a radioactive sample.

If NAA is conducted directly on irradiated samples it is termed Instrumental Neutron Activation Analysis (INAA). In some cases irradiated samples are subjected to chemical separation to remove interfering species or to concentrate the radioisotope of interest, this technique is known as Radiochemical Neutron Activation Analysis (RNAA).

Neutron activation

Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus often decays immediately by emitting gamma rays, or particles such as beta particles, alpha particles, fission products and neutrons (in nuclear fission). Thus, the process of neutron capture, even after any intermediate decay, often results in the formation of an unstable activation product. Such radioactive nuclei can exhibit half-lives ranging from small fractions of a second to many years.

Neutron activation is the only common way that a stable material can be induced into becoming intrinsically radioactive. All naturally-occurring materials, including air, water, and soil, can be induced (activated) by neutron capture into some amount of radioactivity in varying degrees, as a result of production of neutron-rich radioisotopes. Some atoms require more than one neutron to become unstable, which makes them harder to activate because the probability of a double or triple capture by a nucleus is below that of single capture. Water, for example, is made up of hydrogen and oxygen. Hydrogen requires a double capture to attain instability as hydrogen-3, tritium, while natural oxygen (oxygen-16) requires three captures to become unstable oxygen-19. Thus water is relatively difficult to activate, as compared to sea salt (NaCl), in which both the sodium and chlorine atoms become unstable with a single capture each. These facts were realized first-hand at the Operation Crossroads atomic test series in 1946.

Enrique Iglesias

Enrique Miguel Iglesias Preysler (/ɛnˈriːkeɪ ɪˈɡlɛsiəs/; Spanish: [enˈrike iˈɣlesjas]) (born 8 May 1975), is a Spanish recording artist and record producer. He is widely regarded as the King of Latin Pop. Iglesias started his career in the mid-1990s on an American Spanish Language record label Fonovisa under the name Enrique Martinez, before switching to the stage name Enrique Iglesias, and turning into one of the biggest stars in Latin America and the Hispanic Market in the United States. By the turn of the millennium, he had made a successful crossover into the mainstream market and signed a multi-album deal with Universal Music Group for US $68,000,000 with Universal Music Latino to release his Spanish albums and Interscope to release English albums. In 2010, he parted with Interscope and signed with another Universal Music Group label Republic Records to release bilingual albums. In 2015, Enrique parted ways with Universal music group after a decade. He signed for Sony Music and it has been reported that it is one of the biggest contracts offered to any artist in recent years in terms of advances and royalties. His upcoming albums will be by Sony Music Latin in Spanish and RCA in English.