Production and Separation of Carrier free Radionuclides by Heavy Ion Activation

For the first time, systematic studies on the heavy ion induced production of carrier free radionuclides of lanthanide series elements, third transition series elements, s-and p-block elements and their separation from the bulk target.

In order to produce carrier-free radionuclides, generally proton or alpha beams are used as projectiles. We observed that the radiochemical purity of light charged particle induced rare earth radionuclides are extremely poor. This is due to the fact that light charged particle induced reactions produce adjacent radionuclide having pronounced similar chemical properties between the target and product and thus the separation become very difficult specially when one has to separate carrier-free lanthanide radionuclide (i.e. in ultra trace scale) from target matrix (present in macro scale). To get rid off this monotonous similar property, heavy ion activation was done where the product radionuclides are well separated by their atomic number from the target element which helps to overcome the difficulty of separation arising from the intrinsic similar property of the lanthanide series elements.

By applying heavy ion activation techniques, we were able to produce and separate high purity carrier free radionuclides, like, ¹³⁵Ce, ^145-147Eu, ^147,149Gd, ^150-153Tb, ^150-153Dy, ^163,165-167Tm, ^163,165-167Yb, etc. These radionuclides are proton rich and advantageous due to their shorter and convenient half lives than those are currently used in biomedical fields. The proposed radionuclides can serve as better alternative than those currently used in biomedical fields.

Similar to rare earth radionuclide we have also produced and separated carrier free radionuclides in high purity in other parts of the periodic table, like ²⁴Na, ²⁸Mg ⁴⁸V, ^48,49Cr, ¹⁸¹Re, ^176,177W, ^176,177Ta, ^187,188Pt and ^187,188Ir, etc.

Another significant work is the development of alternative methods for the production as well as radiochemical separation of ⁶⁷Ga, ¹¹¹In and ¹⁹⁹Tl radionuclides which have elegant importance in nuclear medicine. Natural cobalt, a mononuclidic element, was used as target and heavy ions like ¹¹B/¹²C as projectiles. ⁶⁷Ga was produced with high radiochemical as well as and radioisotopical purity. ⁷Li irradiation of natural silver and gold target produces ¹¹¹In and ¹⁹⁹Tl respectively.

Introduction of Tracer Packet Technique

Recently we have introduced and established the conception of “Tracer Packet” which can be defined as a group of carrier-free radioactive isotopes of a few elements which have been produced together with an objective to study some particular physical, chemical or biological systems. The idea of “Tracer packet” is complementary to “Multitracer” which was discovered and established at RIKEN in Japan in 1991 and were successfully applied in many fields of biology, physics and chemistry. “Multitracers’ are produced with very high energy projectiles (~135 MeV/nucleon) which is possible only with high energy sophisticated accelerators in developed countries like Japan. In contrast, the ‘tracer packet’ proposed by us requires only 5 to 6 MeV/nucleon and have been produced with BARC-TIFR Pelletron in Mumbai, India. Tracer packet can be advantageously used to unveil many intricacies in chemical and life sciences.

Application of Tracer Packet Technique to Bio-environmental Remedeation

Of late, we are engaged with environmental studies with “tracer packet technique”. This technique is applied in the study of the mechanism of bio-accumulation of heavy and toxic metals in algae which are the primary producer in aquatic ecosystem. Different groups of algae were tested at different experimental conditions to select an useful group for such study. It has been found that Spirulina from cyanophyceae can accumulate heavy and toxic metals, such as, Hg, Pb, Bi and Po very efficiently.

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