A.F. Novgorodov

Radiochemical separation of no-carrier-added as produced via the process

The 176 YbOn,gU 177 Yb-b ˇ 4 177 Lu process was investigated to provide no-carrier-added (nca) 177 Lu: The radiochemical separation of the 177 Lu from the macro-amounts of the ytterbium target based on the cementation process, i.e. the selective extraction of Yb by Na(Hg) amalgam from Cl ˇ /CH3COOelectrolytes, followed by a final cation exchange purification. The cementation separation process provides a decontamination factor of Yb(III) of 10 4 , the cation exchange purification adding a decontamination factor of >10 2 . The nca 177 Lu is available in radiochemically pure form despite the chemical similarity of the lanthanides with 7525% overall separation yield within 4-5 h. It can be used to synthesise nca 177 Lu labelled radiotherapeuticals. 7 2000 Elsevier Science Ltd. All

A no-carrier-added 72Se/72As radionuclide generator based on distillation

Abstract Arsenic-72 is a positron emitting isotope with promising properties for syntheses of 72As-labelled radiopharmaceuticals for future application in positron emission tomography. This work describes the radiochemical separation of no-carrier-added 72Se from cyclotron irradiated germanium targets and the development of a 72Se/72As radionuclide generator, avoiding the addition of any selenium carrier. Using a vertical quartz tube device, no-carrier-added 72As is nearly quantitatively released from various chloride salt solutions containing 72Se within 10 min at a temperature of 100 °C in an HCl gas flow. The kinetics of the 72Se/72As isotope generator has been studied in relation to temperature, salt charge, and redox-stability. Under optimised conditions, 72Se remains almost quantitatively (>99.7%) in solution.

Thermochromatographic separation of no-carrier-added 186Re or 188Re from tungsten targets relevant to nuclear medical applications

The thermochromatographic behavior of no-carrier-added rhenium isotopes and macroscopic tungsten was studied at different temperatures as well as in dry and water-vapor containing (moist) atmospheres of oxygen or air. Due to the high thermal volatility of HReO4, 186/188Re can easily be separated from tungsten matrices in yields of 65±15% free from tungsten in less than one hour and in minimum volumes of various solutions. After double neutron capture by 186W, this separation process can be applied to construct a 188W/188Re generator. In addition, the thermochromatographic separation process might be an option to separate no-carrier-added 186Re after a 186W(p,n) or a 186W(d,2n) reaction at a small cyclotron.

The K Auger spectrum of manganese from 55Fe decay

Abstract The complete K Auger spectrum of manganese was analysed at the instrumental resolution of 7 eV. The satellite structure of the KL 2 L 3 ( 1 D 2 ) line (probably due to the shake-up/shake-off processes) was observed at the resolution of 2.2 eV. The measured absolute energies as well as relative transition energies are found not to agree well with those of Larkins calculations especially for the KLL and KMM groups. Theoretical intensities of the KL 1 L 1 ( 1 S 0 ) and KL 1 L 2 ( 1 P 1 ) transitions exceed the measured ones by eight and six standard deviations, respectively. The KLM spectrum is correctly described only in the frame of the intermediate coupling scheme. The comparison of measured KMM transition rates with our non relativistic calculations also indicates a non-negligible role of the intermediate coupling for the KMM group.

Production of positron-emitting 110mIn via the 110Cd(3He, 3n)110Sn→110mIn process

Abstract Positron-emitting 110mIn was produced in a two-step process. Irradiation of highly enriched 110Cd with 3He-particles over an energy range of 36-25 MeV led to the formation of 110Sn, which after its fast radiochemical separation from the target material was used to prepare a 110Sn→110mIn generator. The radiochemical separation consisted of a thermochromatographic volatilization of 110SnCl4 from metallic 110Cd targets in a small quartz apparatus at 800 ± 10 °C within 20 min, followed by its removal from the quartz tube via dissolution in hydrochloric acid. The 110Sn separation yield was >98% and the fraction contained only

Production, concentration and deep purification of 111In radiochemicals

A new method of 111In separation from a silver target irradiated with 30 MeV alpha-particles is described. The 111In isolation from Ag and Cd is based on its co-precipitation with La(OH)3. The 111In separation from La(III) has been performed by the method of ion-exchange chromatography. A multi-stage purification technique was developed that allows the production of 111In radiochemicals in which the part of impurities of di-, tri-valent metal atoms is negligible.

Ultra-pure 236Pu and 237Pu for environmental and biomedical research

Abstract Isotopically pure 236Pu (>99.999% by activity) has been produced by irradiating U (95% 235U) with 4He ions and refining the product by electromagnetic mass separation. Further developments in the production of 237Pu are also reported, giving material containing, by activity, only 3 × 10−6% 236Pu and probably only ∼ 10−5% 238Pu.

The KLL and KLM Auger electrons of vanadium and chromium from the radioactive decay

The K Auger electrons of two low Z elements emitted in the radioactive decay of 51Cr and 54Mn were analyzed with an electrostatic spectrometer at instrumental resolution of 7 eV. Discrepancies reaching 4-7 standard deviations (σ) were observed for both elements among the measured relative KL1L1(1S0), KL1L2(1P1) and KL2L3(1D2) intensities and those calculated relativistically in the intermediate coupling scheme with configuration interaction. The experimental KL3M2,3/KL2M2,3 intensity ratios for Z = 23 and 24 were found to agree within 3σ with recent calculations in the intermediate coupling scheme while their deviations from the j-j coupling predictions exceed 12σ. Except for transitions involving the M4,5 and N electrons, agreement within 3σ was proved among measured energy differences within the KLL and KLM groups and semiempirical values of Larkins.

SEARCH FOR AN ADMIXTURE OF HEAVY NEUTRINOS IN THE BETA -DECAY OF 241PU

The -spectrum of 241Pu with the endpoint energy of 20.8 keV was measured in the energy range from 0.2 to 9.2 keV. The spectra were recorded during 5700 h with an electrostatic spectrometer set to a resolution of E/E = 0.011. Electron energy losses within the radioactive source were treated by means of extensive Monte Carlo simulations of individual elastic and inelastic electron collisions. The upper limit for the admixture of hypothetical neutrinos with the rest masses between 14 and 17 keV/c2 was derived to be less than 0.40% (the lowest limit being 0.10% for the 16 keV/c2 mass) at the 95% C.L., independently of any free phenomenological parameter.

Improved limits on β− and β−β− decays of 48Ca

New limits on 48Caβ− and β−β− decays to excited states of 48Ti have been obtained using a 400 cm3 low-background HPGe detector and an external source of 24.558 g enriched CaF2 powder (9.822 g of 48Ca). The limits for β− decay to the 6+ ground state and excited 5+ and 4+ states in 48Sc are 1.6×1020 yr, 2.5×1020 yr, and 1.9×1020 yr at the 90% confidence level. For the β−β− decay to 48Ti, the limits to the first 2+, second 2+, and first 0+ excited states are 1.8×1020 yr, 1.5×1020 yr, and 1.5×1020 yr, again at the 90% confidence level.