The amorphous structure of aluminum alloy doped with transition (Fe, Ni) and rare earth (La) metals crystallizes with the formation of a multiphase nanocrystalline composite under irradiation with ...fast 38-MeV
12
C
+3
ions at a fluence of Φ = 5 × 10
16
particles/cm
2
. The microhardness of the irradiated amorphous–nanocrystalline composite is higher than that of the unirradiated amorphous alloy. No phase transformations are observed in the polycrystalline state. The morphology of phases slightly changes owing to partial dissolution and coagulation of intermetallic compounds.
—
The concept of a cascade gas target with krypton isotopes for medical
82
Sr radioisotope production is described. Using this concept, an experimental setup was created at the U-150 cyclotron of the ...Kurchatov Institute NRC for
82
Sr production with an
82
Sr yield of approximately 53 μCi/μA h using the
80
Kr(
4
He, 2
n
)
82
Sr reaction in the
80
Kr target module. Descriptions of the system and its operation are presented. The setup performed well with reproducible results. It is noted that the
82
Sr radioisotope produced using the setup is free from an admixture of the
85
Sr radioisotope that is responsible for approximately one-half the irradiation dose to workers using standard
82
Sr–
82
Rb isotope generators.
The activation method was used to determine the cross sections of the nuclear reactions
82
Kr(
3
He, 3
n
)
82
Sr,
83
Kr(
3
He, 4
n
)
82
Sr, and
84
Kr(
3
He, 5
n
)
82
Sr in the
3
He energy range 20–75 ...MeV on targets with highly enriched krypton isotopes. The results were used to calculate the
82
Sr yield in a yield-optimized cascade target with
82,83,84
Kr and initial
3
He energy 75 MeV. The computed
82
Sr yield was equal to 2.9 MBq/(μA·h), which makes it possible to count on the practical application of the method of
82
Sr production based on the reactions
82,83,84
Kr(
3
He,
xn
)
82
Sr in a cascade target.
The cumulative cross sections for .sup.232Th fission products in the energy range of .sup.3He nuclei of 39â58 MeV are measured. The measurements are made using the activation technique and the foil ...stack technique. Eighteen cumulative cross sections for the .sup.232Th fission products by .sup.3He nuclei with half-lives from one day (.sup.112Pd, T.sub.1/2 = 21 h) to 64 days (.sup.95Zr, T.sub.1/2 = 64 d) are measured for the first time. Being fundamental constants, the results can supplement the existing libraries of nuclear data.
A method for improving the production of the radioisotope sup.123I in proton cyclotrons, which makes it possible to increase its technological yield by 2-3 times, is reported. For this purpose, it is ...proposed to introduce hydrogen into a target with sup.124Xe, which makes it possible to extract from it the sup.123I formed over the irradiation time on decay of the accumulated sup.123Xe.
Data on magnetization, magnetic susceptibility and microstructure modification of irradiated Nb3Sn platelets are presented. The irradiation was produced at room temperature by fast protons with the ...energies of 12.4 and 12.8 MeV with fluencies of 5x1017 and 1x1018 cm-2. Variation of the superconducting transition temperature versus irradiation dose was determined. Temperature dependence of magnetic susceptibility of Nb3Sn platelet with 160 μm thickness demonstrates several steps corresponding to different superconducting transition temperatures. We supposed that there are layers inside the sample with significantly different radiation damage levels caused by particles movement termination (Bragg peak). It was found that after the irradiation a lot of randomly oriented platelet-like Nb-enriched particles of 0.1-0.5 μm size appear in volumes with maximal damages.
Tb (T
= 5.32 d) is considered both as a promising Auger electron emitter and as a diagnostic pair for other therapeutic terbium radionuclides. Despite several methods for its production proposed, it ...remains scarcely available. Most of the methods using low-energy protons and deuterons beams result in a high content of radionuclidic impurities. High purity
Tb can be obtained using high-energy proton beams combined with online mass separation of products, but the method remains inaccessible to most potential consumers. We have proposed an indirect method for the production of
Tb via formation of
Dy (T
= 9.9 h), which can be implemented using medium energy alpha particles beam.
Gadolinium oxide targets of natural isotopic composition were irradiated by 60 MeV alpha particles beam on a U-150 cyclotron of the National Research Center "Kurchatov Institute". The cross sections of nuclear reactions were measured by the stack foil technique, detecting the gamma radiation of the activation products. Gd, Tb, and Dy were separated by extraction chromatography using the LN Resin sorbent in nitric media. The isolated dysprosium fraction was stored for a day, and the formed
Tb was isolated by the same method.
The cross sections for the formation of
Gd,
Tb, and
Dy under irradiation by alpha particles of a gadolinium target of natural isotopic composition in the energy range 20-60 MeV have been measured. The
Dy yield on a thick target at 60 MeV was 35 MBq/μAh, which makes it possible to obtain 1 GBq
Tb as a result of 12-hour irradiation with a beam current of 50 μA. Extraction chromatography on LN Resin sorbent in nitric enabled quick and efficient separation of Gd, Tb, and Dy. The radiochemical yield of Dy was 95%, for Tb > 95%. The main radionuclidic impurity is
Tb (T
= 2.34 d; <5.4% of
Tb activity).
The developed method allows the production of therapeutic amounts of
Tb with acceptable radionuclidic purity without the need for isotopically enriched materials. The amount of
Tb is sufficient for its use in Auger therapy, as well as for preclinical studies of the suitability of SPECT preparations in laboratory animals. Nevertheless, to obtain higher activities, a longer irradiation time and a higher projectile current are proposed. The
Tb radionuclide present in the final preparation has a shorter half-life than the target radionuclide, and its hard γ-lines have a probability of emission of less than 1%, from which it can be concluded that the negative effect will not be significant. However, a product of this purity and type of contamination requires additional testing for toxicity in living organisms. The final sample also includes a certain amount of
Tb (T
= 71 a, the only γ-line 54.5 keV Iγ = 0.0084%), which will complicate the labeling conditions. Thus, more research is needed in the labeling area. It should be noted that the use of gadolinium enriched in the
Gd or
Gd nuclide as a target will help not only reduce the amount of impurities but also increase the yield of
Tb.
Vibrating-sample magnetometry techniques has been used for investigation of the electrophysical characteristics of several types of modern commercial multistrand composite wires based on Nb
3
Sn ...superconducting compound at temperatures that were measured 4.2, 7, and 12 K in magnetic fields up to 8 T before and after irradiation of the samples by fast (32-MeV) protons to fluences values 3 × 10
16
, 1 × 10
17
, 3 × 10
17
, and 1 × 10
18
cm
–2
. All samples irradiated to fluences values up to 1 × 10
17
cm
–2
exhibited growth of the critical current density, which was most sharply pronounced in strong magnetic fields at lower temperatures. Further irradiation to a fluence value of 1 × 10
18
cm
–2
led to decrease of the critical current density below the initial level. The critical temperature of samples monotonically decreased with increasing irradiation dose.
The saturation yield of the rhenium radioisotopes sup.186Re, sup.188Re, and sup.189Re on irradiation of a sup.186W target by the nuclei sup.4He, sup.4He, sup.1H, and sup.2H with energy 47, 25, 15.3, ...and 19 MeV, respectively, was measured by the activation method. The chosen energy of the accelerated particles made it possible to minimize the contribution of the activity of long-lived rhenium radioisotopes in the desired radionuclides. The highest yield 3240 + or - 330 MBq/pA was obtained for the radioisotope sup.186Re in the reaction sup.186W(sup.2H, 2n).sup.186Re. The obtained yield makes it possible to plan on using in radioimmunotherapy the radionuclide sup.186Re produced by means of this reaction.
This article is devoted to obtaining the α-emitter
149
Tb for radioimmunotherapy. A method for producing
149
Tb based on the reaction
151
Eu(
3
He, 5n)
149
Tb is proposed. It is proposed that ...europium with native isotopic composition (
151
Eu – 47.81%,
153
Eu – 52.19%) or enriched
151
Eu be used as the target. The 29 MeV threshold of the indicated reaction makes it possible to use accelerators with the initial
3
He energy 40–70 MeV.
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