Effects of nuclear orientation on fusion and fission in the reaction using 238U target nucleus

Fission fragment mass distributions in the reaction of 30Si+238U were measured around the Coulomb barrier. At the above-barrier energies, the mass distribution showed a Gaussian shape. At the subbarrier energies, triple-humped distribution was observed, which consists of symmetric fission and asymmetric fission peaked at AL/AH ~ 90/178. The asymmetric fission should be attributed to quasifission from the results of the measured evaporation residue (ER) cross-sections for 30Si+238U. The cross-section for 263Sg at the abovebarrier energy agree with the statistical model calculation which assumes that the measured fission cross-section originates from fusion-fission, whereas the one for 264 Sg measured at the sub-barrier energy is smaller than the calculation, which suggests the presence of quasifission

Extraction of astatine isotopes for development of radiopharmaceuticals using a 211Rn–211At generator

In order to utilize a 211At isotope, a promising α-emitter for radionuclide therapy, the chemical properties of astatine isotopes are studied. We have examined wet chemistry methods through the distribution ratios of astatine in liquid–liquid extraction. The astatine isotopes have been found to be well extracted into DIPE and MIBK. We observed that the distribution ratio of astatine isotopes increases with concentrations of HCl greater than 3 M, while it decreases with the HCl concentration less than 2 M. The results will be useful for development of the 211Rn–211At generator

Separation of astatine from irradiated lead targets based on dry distillation in a glass test tube

Astatine was separated from a lead target, irradiated with 7Li ion beams, by dry distillation. Dry distillation was conducted in a glass test tube filled with nitrogen gas by heating the test tube with an electric furnace at 650 ℃. The optimized conditions of the dry distillation procedure were studied by monitoring astatine radioactivity with gamma-ray spectrometers. The separation of astatine was accomplished in ~10 min. The cooling of the middle portion of the test tube was instrumental in recovering astatine radioactivity in high yields. The adsorption temperature of astatine on the glass surface was ~20 ℃

Adsorption temperature of volatile astatine species formed via dry distillation in a glass tube

In this study, the volatile adsorption temperature of volatile astatine species was studied using the 211At radionuclide produced via the 209Bi(4He,2n)211At nuclear reaction. Volatile astatine was separated from irradiated bismuth via dry distillation in a glass tube (inner diameter: 4 mm, length: 750 mm) filled with nitrogen. The adsorption temperature of the volatile astatine on a glass surface was precisely determined to be 42.2 ± 2.5 ℃ via the simultaneous measurement of temperatures and the astatine radioactivity across the length of the glass tube with thermocouples and γ-ray spectrometers, respectively. Previously reported experimental profiles of the volatile species were also discussed

Speciation of astatine reacted with oxidizing and reducing reagents by thin layer chromatography: Formation of volatile astatine

Radio-chromatography was conducted by using the astatine radionuclides 209,210,211At produced in the 7Li induced reaction of 209Bi. The speciation of dissolved astatine chemical species of astatide (At–), astatate (AtO3–) and perastatate (AtO4–) was carried out by thin layer chromatography on silica gel with an ethanol/water solution. Amounts of the astatine species varied with concentrations of oxidizing and reducing reagents, potassium periodate, sodium sulfate and hydrazine hydrate. The oxidation-reduction reactions between At– (-I) and AtO3– (V) were found to form volatile At0 (0) and release it from a silica gel thin layer in the development