Cyclotron radioactive elements production

Element 85 was synthesized by D. Corson, C. Mackenzie, and E. Segre who worked at Berkley (USA). The Italian physicist Segre by that time had settled in the USA and was the only one in the group who had an experience in artificial synthesis of a new element (technetium). On July 16, 1940, these scientists submitted to the prestigious physical journal Physical Review a large paper entitled Artificial radioactive element 85 . They reported how they had bombarded a bismuth target with alpha particles accelerated in a cyclotron and obtained a radioactive product of the nuclear... 

Mass-spectroscopic technique has also been used with non-fissile targets after pile or cyclotron bombardment to determine the mass-numbers of radioactive nuclides. In one case, the branching ratios of certain isotopes for and electron capture decay (where different elements are produced by the two routes) were determined from the amount of the stable end-products of radioactive decay, using the mass-spectrometer to identify the isotopes concerned and to correct for any stable impurities of the elements concerned (98). For some purposes, mass-spectroscopic separations could be very valuable technically such as the... 

Radioactive isotopes for tracer studies may be prepared artificially from nonradioactive elements by bombarding them with suitable nuclear particles produced in a cyclotron or a nuclear reactor. The discovery of this effect was made in 1934 by the French physicists Irene Joliot-Curie (1897-1956) and her husband Frederic Joliot-Curie (1900-1958). They were studying the effect of bombarding light elements such as aluminum with alpha (a) particles, which are beams of helium nuclei, fHe. They noticed that, after the bombardment had ceased, a new form of radiation continued to be emitted, and they concluded that a new isotope had been formed. In the case of the bombardment of ordinary aluminum, HAl, with a particles, the product is an isotopic form of phosphorus, ifP, the most abundant isotope of phosphorus being f P. The process is... 

Radioactive nuclides may be prepared by a wide variety of particle accelerators and nuclear reactors however, only cyclotrons or reactors of at least moderate particle flux are able to produce sources of sufficiently high specific radioactivities to be of practical interest. These two methods of production supplement each other since, in general, they do not produce the same isotopes of an element. 

The development of the cyclotron and, later, the fission reactor gave the means for a variety of artificial transmutations, but it often was difficult to identify the element and mass number of a radioactive product. In many cases, individual radionuclides could be characterized only by simple features, such as half-life or attenuation of radiations in absorbers, which did not allow discriminating the components of a complex mixture. Chemical evidence was required in order to make definite identification with a particular element. 

This was confirmed in an independent experiment in which Db was produced in the reaction " Bk( 0,4n) at the Philips Cyclotron of the Paul Schener Institute (PSI) Villigen, Switzerland. The products were collected for 15 min and then subjected to a chemical separation specific for group-4 elements. The product was dissolved in 0.5 M unbuffered a-HiB and eluted from a cation-exchange column. The effluent was made 9 M in HCl and group-4 tetrachlorides were extracted into TBP/Cyclohexane which was evaporated to dryness on a Ta disk. The Ta disks were assayed for a and SF spectrometry. A SF radioactivity with a half-life of 20 min was observed and again assigned to the nuclide Rf, confirming that it is formed by EC decay of Db with a decay branch of % [94]. 

---