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Method for production of alpha emitter 149Tb by irradiation of 151Eu with 70 MeV 3He nuclei is proposed. For the first time, the cross sections for the formation of isotopes 149,150,151,152Tb were measured experimentally using a stack foil technique in the 3He particles energy range 70 → 12 MeV. The thick target yield of 149Tb is 39 MBq/μAh, or 230 MBq/μA 149Tb at saturation. The optimal energy range from the point of view of radioisotopic purity is 70 → 40 MeV. At these conditions about 150 MBq/μA 149Tb can be produced in 8 hours irradiation, which is sufficient for therapeutic applications. The main impurities are 150Tb (~100% in activity) and 151Tb (~30% in activity). The proposed method surpasses its counterparts by the high content of the target isotope in the natural mixture and the simplicity of the radiochemical separation of 149Tb from the bulk target material.

The irradiations of Ag to Sn targets by bremsstrahlung generated with 23-MeV electron beams are performed at the MT-25 microtron. Gamma spectra of the induced activities have been measured and the yields of all detected radionuclides and isomers are carefully measured and analyzed. A regular dependence of yields versus changed reaction threshold is confirmed. Many isomers are detected and the suppression of the production probability is observed with growing product spin. Special peculiarities for the isomer-to-ground state ratios were deduced for the 106mAg, 108mAg, 113mIn, 115mIn, and 123mSn isomers. The production of such nuclides as 108mAg, 115mIn, 117gIn, and 113mCd is of interest for applications, especially when economic methods are available.

The radionuclides (88)Zr and (89)Zr have been produced by cyclotron irradiation of (nat)SrO with 35 MeV α-particles at a beam current of 15 μA. The thick source production yield of (89)Zr is ~3.1 MBq μA(-1) h(-1). A two-step radiochemical purification utilising anion-exchange chromatography in hydrochloric and hydrofluoric acids has been developed to separate (88,89)Zr from the target material, natural strontium, the target substrate, aluminium, and long-lived (88)Y.

Among nuclides, 195mPt isomer is characterized by a number of properties that make it suitable for use in nuclear medicine. Effective ways of optimizing the Pt isomer yield at low impurity contents must be sought. The method based on double neutron capture by the 193Ir target nucleus with subsequent populating of 195mPt through β decay allows chemical isolation of the isomer. In this work, the problem is analyzed, test experiments on Ir activation with neutrons are conducted, and theoretical estimates of the 195mPt yield are presented. Full-scale model experiments on the IBR-2 reactor in Dubna should confirm the effectiveness of the method.

Previously reported preparation method for Pd-based intermetallic targets (Usoltsev, et al., 2012) [1] has been successfully applied for producing two stationary 243Am/Pd targets. Both targets have been irradiated at the U-400 cyclotron at Flerov Laboratory of Nuclear Reactions Dubna (Russian Federation) using high intensity beams (up to 0.83 μApart) of 48Ca18+. Alpha-particle spectroscopy and light microscopy allowed for a comprehensive characterization of the intermetallic targets before and after irradiation. A natNd/Pd intermetallic target and a solely electroplated 243Am/Ti target were similarly investigated for comparison.

We have determined the isomeric ratios in 113In(γ, n)112m,g In and 113In(γ, 2n)111m,g In photonuclear reactions of natural indium induced by bremsstrahlungs with end-point energies in the giant dipole resonance (GDR) region. The investigated samples were irradiated at the electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna. The gamma spectra of the samples irradiated were measured with a spectroscopic system consisting of an 8192-channel analyzer and a high-energy resolution (180 keV at gamma ray 1332 keV of 60Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results were discussed and compared with those of other authors. For both the mentioned reactions, the isomeric ratios in the bremsstrahlung energy range from 19 to 24 MeV in this work are new measurements.

A method to produce (117m)Sn radionuclide using accelerator production route is described. A new method is proposed to separate the (117m)Sn. Specific activities and thick target yield for (116)Cd(α,3n)(117m)Sn reaction at E(α)=35MeV bombarding energy were determined. The estimated production yield of (117m)Sn was 37.5kBq/μAh for 13.16 mg/cm(2) natural cadmium-oxide target and 410 kBq/μAh for 11.07 mg/cm(2) highly enriched (95%) (116)CdO target. The method developed for separation of (117m)Sn from Cd using anion-exchange resin (Dowex -1×8, fluorine form, 400 mesh) can achieve 98% radiochemical yield of (117m)Sn with more than 99% radionuclidic purity. The estimated specific activity is 2.4 GBq/mg that can be reached with the used irradiation conditions.

Isocratic anion exchange separations of Group V elements from solutions containing HF have been considered for the development of Db aqueous phase chemistry experiments. Separation of Nb/Ta from an HF/NH4F system has been demonstrated but has limited utility due to interferences with alpha and spontaneous fission (SF) source preparation. The physical parameters associated with ion exchange chromatography have been optimized for the separation and sequential isolation of Pa, Nb and Ta from mixed HF/HNO3 solutions. A suitable procedure incorporating a series of successive chemical separation techniques, i.e. precipitation and ion exchange chromatography, has been suggested for off-line Db characterization studies.

A procedure was developed for selective separation of Group IV elements from Sr and Lu, followed by rapid separation of Zr and Hf by cation-exchange chromatography in dilute HCl/HF solutions. The possibility of using this procedure for chemical identification and determination of decay parameters of the new isotope 267Rf was demonstrated.

Experimental results on the production and separation of 149Tb from natural neodymium target using the nuclear process Nd(12C,xn)149Dy→149Tb are presented. Terbium-149 was produced at the U-200 cyclotron of FLNR JINR by irradiating natNd2O3 with 12C ions and its possible production for nuclear medicine utilising the heavy-ion induced reactions was investigated.

The process of uranium photofission with electron beams of 20–50 MeV is considered in terms of the production of fission fragments. It is shown that in the interaction between an electron beam (25 MeV in energy and 20 μA in intensity), produced by a compact accelerator of the microtron type, and a uranium target of about 40 g/cm 2 in thickness, an average of 1.5×10 11 fission events per second is generated. According to the calculations and test experiments, this corresponds to the yield of 132 Sn and 142 Xe isotopes of approximately 2×10 9 /s. The results of experiments on the optimal design of the U-target are presented. Problems are discussed connected with the separation of isotopes and isobars for their further acceleration up to energies of 5–18 MeV A . The photofission reactions of a heavy nucleus are compared with other methods of RIB production of medium mass nuclei.

A 111In → 111m Cd radionuclide generator with the chemical yield higher than 95% and content of parent isotope (1 1 1In) in the 1 1 1m Cd preparation less then 0.6% (relative to the activity of the target nuclide) was developed. Parent and daughter radionuclides were separated by extraction chromatography using di-2-ethylhexyl hydrogen phosphate. The probability of electron capture to the 396-keV isomeric state (1 1 1 m Cd) in 1 1 1In decay is (6.01±0.14r a n d o m±0.18s y s)×10- 5.

A rapid method for the preparation of 87Y/87mSr radionuclide generator from a rubidium chloride target irradiated with 35 MeV α-particles is described. A simple two-step procedure is used to obtain a carrier-free 87mSr isotope with a high enough radiochemical yield and high purity in the final aqueous fraction.

The work on isotopically pure 26 Al, 97 Ru, 178 W/ 178 Ta, 235 Np, 236 Pu and 237 Pu production was initiated because of intensive research on their applications in the biomedical field and environmental chemistry. The conditions for isotopically pure production have been investigated. This paper describes the data for the nuclear reactions of the radionuclide production, the different target designs and target chemistry procedures.

A new separator and mass analyzer of super heavy atoms (MASHA) has been created at the FLNR JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10−3. First experiments with the FEBIAD plasma ion source have been done and give an efficiency of ionization of up to 20% for Kr with a low flow test leak (6 particle μA). We suppose a magnetic field optimization, using the additional electrode (einzel lens type) in the extracting system, and an improving of the vacuum conditions in order to increase the ion source efficiency.

An efficient radiochemical procedure for the chromatographic separation of carrier-free 178W radioisotope is described. 178W (T1/2=22 d) was produced by the U-200 accelerator (FLNR) via a natHf (α, 2n) 178W reaction. The energy of the α-particles was 36 MeV. The HfO2 target was dissolved in concentrated HCl in the presence of HF. The solution was evaporated to dryness and dissolved in 8 M HCl. The extraction was done in plastic columns filled with TBP impregnated resin (100–150 mesh). The flow rate was not higher than 1 mL/min. After carefully washing off the resin with 8 M HCl, the produced 178W was eluted with 1 M HCl. The efficiency was not less than 95%.

Among radioactive isotopes of rare-earth elements (REEs) finding increasing application in nuclear medicine, α-emitting 149Tb (T1/2 = 4.118 h; EC 76.2%; β+ 7.1%; α 16.7%) shows promise for radioimmumotherapy. Formation of 149Tb in nuclear reactions Nd(12C, xn)149Dy(4.23 min; β+, EC) → 149Tb performed by irradiation of a Nd target with carbon ions was experimentally studied. As estimated from the experimental data on 149Dy formation and its decay into 149Tb, the 149Tb yield under the best conditions (142Nd-enriched target, 12C ions with the energy of up to 120 MeV and current of up to 100 μA, irradiation time 8-10 h) can be as high as 30 GBq (0.8 Ci).

237 Pu (half-life 45.3 d) is a valid metabolic tracer for the long-lived isotopes of plutonium, but its use in human subjects has previously been restricted by difficulties in producing it with acceptable isotopic purity. These difficulties have been overcome by applying mass-separation techniques to the impure product of irradiating 235 U with 25-MeV 4 He + ions.

The present study has been performed within the framework of experiments aimed at the investigation of chemical properties of long‐lived Db isotopes in aqueous solutions. The isocratic anion exchange separations of group V elements in the solutions containing HF have been considered. Parameters of separation of dubnium homologues (Pa, Nb and Ta) in HF/HNO3 mixed solutions have been optimized. The procedure of separation of group V elements from multicomponent system has been suggested.

We studied in detail the sorption behavior of Ti, Zr, Hf, Nb and Ta on AG 1 anion exchange resin in HF-acetone mixed solutions as a function of organic cosolvent and acid concentrations. Anion exchange behavior was found to be strongly acetone concentration dependent. The distribution coefficients of Ti, Zr, Hf and Nb increased and those of Ta decreased with increasing content of acetone in HF solutions. With increasing HF concentration anion exchange equilibrium analysis indicated the formation of fluoride complexes of group 4 elements with charge-3 and Ta---2. For Nb the slope of-2 increased up to-5. Optimal conditions for separation of the elements using AIX chromatography were found. Group 4 elements formed MF{sub 7}{sup 3-} (M = Ti, Zr, Hf) complexes whose sorption decreased Ti>Hf>Zr in reverse order of complex stability. This fact is of particular interest for studying ion exchange behavior of Rf compared to Ti. The advantages of studying chemical properties of Rf and Db in aqueous HF solutions mixed with organic solvents are briefly discussed.

A cation-exchange procedure was developed for separating Nb from Ta, Pa from Ta, and Nb, Pa, and Ta from Zr, Hf, and lanthanides in dilute HC1/HF solutions. The stability of the fluoride complexes of Group IV and V elements decreases in the following order: Nb ∼ Pa > Zr > Hf > Ta. This procedure can be used in experiments on synthesis of superheavy nuclei for isolation of Db from the reaction products and for its chemical identification.

Chemical behaviour of group 5 elements in the aqueous hydrofluoric acid solutions was studied. The radiochemical method for the cation exchange separation of Nb (Pa) and Ta from Zr, Hf and lanthanides is presented. The developed scheme allows excluding of the presence of SF heavy actinides in fractions of separated elements. On the basis of the data of the present work, it is possible to suggest the following order of the stability of the fluoride complexes of group 4 and 5 elements: Nb ≈ Pa > Zr > Hf > Ta. The order of the complex formation is in agreement with theoretical predictions. This analytical procedure can be used in future heavy nuclei synthesis experiments for the separation of dubnium (Db) from other reactions products and for its chemical identification.

26Al is a positron emitting radioisotope of aluminium and has a half-life of 7.16×105y. In addition to annihilation γ-rays of 511 keV, there are three high energy γ-rays 1129 (2.4%), 1809 (99.73%) and 2938 (0.27%) keV.26Al is the only radioisotope of aluminium available for radiochemical applications, the half-lives of the other aluminium isotopes are seconds and minutes. The usage of26Al is very important in the investigations of the metabolism of Al in human body (for example in Alzheimer disease studies) or as a tracer in radiochemical studies. But26Al is such a long-lived isotope that the task of producing it in tangible amounts is a very difficult one.

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.

A short review of the current data concerning nuclear reactions, target chemistry and following applications of some radioisotopes as tracers is given in this report.

/sup 123/I is produced with the use of protons, deuterons, and ..cap alpha.. particles with energies from several tens to hundreds of megaelectron volts and electrons with energy approx. 50 MeV. A great deal of attention is devoted to the radionuclide purity of the preparation. As a rule, in the course of the irradiation, because of the many open reaction channels extraneous ..gamma.. and ..beta.. active products, whose contribution increases significantly as the energy of the beam increases, are formed in the target material. This substantially complicates the problem of separating the isotope /sup 123/I and imposes stringent requirements on the isotopic purity of the starting target. These difficulties can be avoided to a certain extent if /sup 123/I is obtained by means of the reaction /sup 124/Xe(..gamma.., n)/sup 123/Xe on a 22-25-MeV electron beam followed by decay of the nuclei /sup 123/Xe(T/sub 1/2 = 2.08 h) into the product sought /sup 123/I. The source of ..gamma.. rays in this case are intense beams of 25 MeV electrons, which can be obtained in compact and reliable setups (microtrons or small linear accelerators). The setup for the production of the isotope /sup 123/I on the MT-22 microtron is described and themore » results of an experiment for an accelerated electron energy of 21.5 MeV are presented« less

The results of an investigation of tracks of ultraheavy galactic cosmic ray nuclei (Z ≥ 50) in extraterrestrial olivines are presented. The etching of volume tracks in olivine crystals in described together with a detailed description of the method of partial annealing, which is essential for a reliable measurement of the nuclear charge number distributions of these cosmic ray nuclei and for erasing the background of tracks from lighter nuclei. Special emphasis is placed upon the identification of Z ≥ 50 nuclei in olivine crystals. Possible methods to identify the origin of anomalously long tracks observed in the JINR Dubna are discussed.