Editing Rutherfordium (section)

===Discovery===
Rutherfordium was reportedly [[discovery of the chemical elements|first detected]] in 1964 at the [[Joint Institute for Nuclear Research]] at [[Dubna]] ([[Soviet Union]] at the time). Researchers there bombarded a [[plutonium]]-242 target with [[neon]]-22 [[ion]]s; a [[spontaneous fission]] activity with half-life 0.3&nbsp;±&nbsp;0.1&nbsp;seconds was detected and assigned to <sup>260</sup>104. Later work found no isotope of element 104 with this half-life, so that this assignment must be considered incorrect.<ref name="93TWG">{{cite journal |title =Discovery of the transfermium elements. Part II: Introduction to discovery profiles. Part III: Discovery profiles of the transfermium elements |date = 1993 |author= Barber, R. C. |author2=Greenwood, N. N. |author3=Hrynkiewicz, A. Z. |author4=Jeannin, Y. P. |author5=Lefort, M. |author6=Sakai, M. |author7=Ulehla, I. |author8=Wapstra, A. P. |author9= Wilkinson, D. H. |journal = Pure and Applied Chemistry| volume = 65 |issue = 8 |pages = 1757–1814 |doi = 10.1351/pac199365081757|s2cid = 195819585 |doi-access= free }}</ref>

In 1966–1969, the experiment was repeated. This time, the reaction products by gradient thermochromatography after conversion to chlorides by interaction with [[zirconium tetrachloride|ZrCl<sub>4</sub>]]. The team identified [[spontaneous fission]] activity contained within a volatile chloride portraying eka-hafnium properties.<ref name="93TWG"/>

:{{nuclide|plutonium|242}} + {{nuclide|neon|22}} → <sup>264−''x''</sup>104 → <sup>264−''x''</sup>104Cl<sub>4</sub>

The researchers considered the results to support the 0.3&nbsp;second half-life. Although it is now known that there is no isotope of element 104 with such a half-life, the chemistry does fit that of element 104, as chloride volatility is much greater in group 4 than in group 3 (or the actinides).<ref name=93TWG/>

In 1969, researchers at [[University of California, Berkeley]] conclusively synthesized the element by bombarding a [[californium]]-249 target with [[carbon-12]] ions and measured the alpha decay of <sup>257</sup>104, correlated with the daughter decay of [[nobelium]]-253:<ref name="69Gh01">{{cite journal |doi = 10.1103/PhysRevLett.22.1317 |title = Positive Identification of Two Alpha-Particle-Emitting Isotopes of Element 104 |date = 1969 |last1 = Ghiorso |first1 = A. |last2 = Nurmia |first2 = M. |journal = Physical Review Letters |volume = 22 |issue = 24 |pages = 1317–1320 |bibcode = 1969PhRvL..22.1317G |last3 = Harris |first3 = J. |last4 = Eskola |first4 = K. |last5 = Eskola |first5 = P. |url = https://cloudfront.escholarship.org/dist/prd/content/qt3fm666nq/qt3fm666nq.pdf |access-date = 2019-04-05 |archive-date = 2018-07-22 |archive-url = https://web.archive.org/web/20180722035431/https://cloudfront.escholarship.org/dist/prd/content/qt3fm666nq/qt3fm666nq.pdf |url-status = live }}</ref>
:{{nuclide|californium|249}} + {{nuclide|carbon|12}} → <sup>257</sup>104 + 4 {{SubatomicParticle|neutron}}

They were unable to confirm the 0.3-second half-life for <sup>260</sup>104, and instead found a 10–30 millisecond half-life for this isotope, agreeing with the modern value of 21 milliseconds. In 1970, the American team chemically identified element 104 using the ion-exchange separation method, proving it to be a group 4 element and the heavier homologue of hafnium.<ref name=responses/>

The American synthesis was independently confirmed in 1973 and secured the identification of rutherfordium as the parent by the observation of [[K-alpha]] [[X-rays]] in the elemental signature of the <sup>257</sup>104 decay product, nobelium-253.<ref name="73Be01">{{cite journal |doi =10.1103/PhysRevLett.31.647 |title =X-Ray Identification of Element 104 |date =1973 |author =Bemis, C. E. |journal =Physical Review Letters |volume =31 |issue =10 |pages =647–650 |bibcode=1973PhRvL..31..647B |last2 =Silva |first2 =R. |last3 =Hensley |first3 =D. |last4 =Keller |first4 =O. |last5 =Tarrant |first5 =J. |last6 =Hunt |first6 =L. |last7 =Dittner |first7 =P. |last8 =Hahn |first8 =R. |last9 =Goodman |first9 =C. }}</ref>