View source for Gold-198

{{short description|Isotope of Gold}}
{{Infobox isotope
 | alternate_names =
 | symbol = Au
 | mass_number = 198
 | mass = 197.9682437{{AME2016 II|ref}}
 | num_neutrons = 119
 | num_protons = 79
 | abundance =
 | halflife = {{val|2.69464|u=days}}{{NUBASE2020|ref|page=139}}
 | image =Gold-198.svg
 | decay_product = mercury-198
 | decay_symbol = Hg
 | decay_mass = 198
 | decay_mode1 = [[beta decay|β<sup>−</sup>]]
 | decay_energy1 = 1.3735{{AME2016 II|name}}
 | decay_mode2 =
 | decay_energy2 =
 | decay_mode3 =
 | decay_energy3 =
 | decay_mode4 =
 | decay_energy4 =
 | parent =
 | parent_symbol =
 | parent_mass =
 | parent_decay =
 | parent2 = 
 | parent2_symbol = 
 | parent2_mass = 
 | parent2_decay =
 | spin = 2−
 | excess_energy =    
 | binding_energy = 
}}
'''Gold-198''' (<sup>198</sup>Au) is a [[radioactive]] [[isotope]] of [[gold]]. It undergoes [[beta decay]] to stable <sup>198</sup>[[Mercury (element)|Hg]] with a [[half-life]] of 2.69464 days.

The decay properties of <sup>198</sup>Au have led to widespread interest in its potential use in [[radiotherapy]] for [[Treatment of cancer|cancer treatments]]. This isotope has also found use in [[nuclear weapons]] research and as a [[radioactive tracer]] in [[hydrological]] research.

==Discovery==
<sup>198</sup>Au was possibly observed for the first time in 1935 by [[Enrico Fermi]] et al., though it was not correctly identified at the time. This isotope was conclusively identified in 1937 following [[neutron capture|neutron irradiation]] of stable [[gold-197|<sup>197</sup>Au]] and was ascribed a half-life of approximately 2.7 days.<ref name=isodisc>{{cite journal|last1=Schuh|first1=A.|last2=Fritsch|first2=A.|last3=Ginepro|first3=J.Q.|last4=Heim|first4=M.|last5=Shore|first5=A.|last6=Thoennessen|first6=M.|title=Discovery of the gold isotopes|date=2010|journal=[[Atomic Data and Nuclear Data Tables]]|volume=96|issue=3|pages=307–314|doi=10.1016/j.adt.2009.12.001|arxiv=0903.1797|bibcode=2010ADNDT..96..307S |s2cid=98691829|url=https://people.nscl.msu.edu/~thoennes/2009/gold-adndt.pdf}}</ref>

==Applications==
[[File:Au198.svg|thumb|left|upright=1|Decay scheme of <sup>198</sup>Au to <sup>198</sup>Hg]]
=== Nuclear medicine ===
<sup>198</sup>Au is used for radiotherapy in some cancer treatments.<ref>{{cite web|url=http://web.missouri.edu/~kattik/katti/katres.html |title=Nanoscience and Nanotechnology in Nanomedicine: Hybrid Nanoparticles In Imaging and Therapy of Prostate Cancer |publisher=Radiopharmaceutical Sciences Institute, University of Missouri-Columbia |url-status=dead |archiveurl=https://web.archive.org/web/20090314121232/http://web.missouri.edu/~kattik/katti/katres.html |archivedate=March 14, 2009 }}</ref><ref>{{cite journal | doi = 10.1211/jpp.60.8.0005 | title = Radiotherapy enhancement with gold nanoparticles | year = 2008 | last1 = Hainfeld | first1 = James F. | last2 = Dilmanian | first2 = F. Avraham | last3 = Slatkin | first3 = Daniel N. | last4 = Smilowitz | first4 = Henry M. | journal = Journal of Pharmacy and Pharmacology | volume = 60 | issue = 8 | pages = 977–85 | pmid = 18644191| s2cid = 32861131 | doi-access = free }}</ref>
Its half-life and beta [[decay energy]] are favorable for use in medicine because its 4&nbsp;[[millimeter|mm]] penetration range in tissue allows it to destroy [[tumors]] without nearby non-cancerous tissue being affected by radiation.<ref name=kvk>{{cite conference|last1=Katti|first1=K.V.|last2=Khoobchandanai|first2=M.|last3=Al-Yasiri|first3=A.|last4=Katti|first4=K.K.|last5=Cutler|first5=C.|last6=Loyalka|first6=S.K.|title=Radioactive Gold-198 Nanoparticles In Nanomedicine: Green Nanotechnology and Radiochemical Approaches in Oncology|date=2017|conference=6th Asia-Pacific Symposium on Radiochemistry|location=Jeju|url=https://www.researchgate.net/publication/323525522}}</ref> For this reason, <sup>198</sup>Au [[nanoparticle]]s are being investigated as an injectable treatment for [[prostate cancer]].<ref name=kvk /><ref>{{cite news |url=http://www.genengnews.com/gen-news-highlights/green-tea-and-gold-nanoparticles-destroy-prostate-tumors/81247048/ |title=Green Tea and Gold Nanoparticles Destroy Prostate Tumors |year=2012}}</ref>

===Radioactive tracing===
[[Sediment]] and water flow can be investigated using radioactive tracers such as <sup>198</sup>Au. This has been used extensively since [[synthetic isotope|artificial radioisotopes]] became available in the 1950s, as a supplement to millennia of investigations using other tracing techniques.<ref name=hydro>{{cite report|last=Plata-Bedmar|first=A.|date=1988|title=Artificial radioisotopes in hydrological investigation: A review of specific applications|series=Topical reports|publisher=[[IAEA]] Bulletin|pages=35–38|url=https://www.iaea.org/sites/default/files/publications/magazines/bulletin/bull30-1/30105683538.pdf}}</ref>

Inside [[coker unit]]s at [[Oil refinery|oil refineries]], <sup>198</sup>Au is used to study the hydrodynamic behavior of solids in fluidized beds and can also be used to quantify the degree of fouling of bed internals.<ref>{{cite journal |last1=Sanchez |first1=Francisco J. |last2=Granovskiy |first2=Mikhail |title=Application of radioactive particle tracking to indicate shed fouling in the stripper section of a fluid coker |journal=Canadian Journal of Chemical Engineering|volume=91 |issue=6 |pages=1175–1182 |year=2012 |doi=10.1002/cjce.21740 }}</ref>

===Nuclear weapons===
Gold has been proposed as a material for creating a [[salted bomb|salted nuclear weapon]] ([[cobalt]] is another, better-known salting material). A jacket of natural {{chem|197|Au}} (the only stable [[isotopes of gold|gold isotope]]), irradiated by the intense high-energy neutron flux from an exploding [[thermonuclear weapon]], would transmute into the radioactive isotope <sup>198</sup>Au with a half-life of 2.697 days and produce approximately 0.411&nbsp;[[MeV]] of [[Gamma ray|gamma radiation]], significantly increasing the radioactivity of the weapon's [[Nuclear fallout|fallout]] for several days. Such a weapon is not known to have ever been built, tested, or used.<ref>{{cite journal
 |author       = D. T. Win
 |author2      = M. Al Masum
 |year         = 2003
 |title        = Weapons of Mass Destruction
 |url          = http://www.journal.au.edu/au_techno/2003/apr2003/aujt6-4_article07.pdf
 |journal      = Assumption University Journal of Technology
 |volume       = 6
 |issue        = 4
 |pages        = 199&ndash;219
 |access-date  = 2024-04-28
 |archive-date = 2009-03-26
 |archive-url  = https://web.archive.org/web/20090326001457/http://www.journal.au.edu/au_techno/2003/apr2003/aujt6-4_article07.pdf
 |url-status   = bot: unknown
}}</ref>

The highest amount of <sup>198</sup>Au detected in any United States nuclear test was in shot [[Sedan (nuclear test)|"Sedan"]] detonated at [[Nevada Test Site]] on July 6, 1962.<ref>
{{cite book
 |author=R. L. Miller
 |year=2002
 |title=U.S. Atlas of Nuclear Fallout, 1951–1970
 |url=https://books.google.com/books?id=EC03ta0ErHAC&q=sedan+shot+fallout&pg=PA340
 |volume=1 |page=340
 |edition=Abridged General Reader
 |publisher=Two Sixty Press
 |isbn=978-1-881043-13-3
}}</ref>

==See also==
* [[Isotopes of gold]]

==References==
{{reflist}}

{{Therapeutic radiopharmaceuticals}}

[[Category:Isotopes of gold|Gold-198]]
[[Category:Medical isotopes]]