[en] ¹⁶O ¹⁶O, ¹²C-²⁰Ne and ¹⁸O-¹⁸O elastic scattering is considered in a model in which the absorption is related to the density of precompound states. These states can only have positive parity in a symmetric system which explains the different absorption in the ¹⁶O-¹⁶O and the¹²C-²⁰Ne cases. For ¹⁸O-¹⁸O scattering one obtains a strong absorption because of the large density near the Fermi level in the non-magic fragments. (Auth.)

[en] We measured the static electric quadrupole moment (Q₂+) and B(E2,0₁⁺→2₁⁺) of the first excited state of ¹⁸O at 1.98 MeV. The values obtained were (-0.19+-0.02 b)e (for the positive sign of the interference term involving the 2₂⁺ state) and (0.0048+-0.0002 b²)e² for Q₂+ and B(E2,0₁⁺→2₁⁺), respectively. For these values the ratio (absolute value of Q₂⁺)/[B(E2,0₁⁺→2₁⁺)]¹/² is about 3, whereas for no other nucleus does it exceed unity by more than 30%

[en] A novel method for determining traces of sulfur and beryllium is described. The reaction ³²S(¹⁸O,t)⁴⁷V is selective if using a 39 MeV ¹⁸O⁶⁺ beam. The detection limit is 3 ppm in an iron matrix and a precision of +-15% has been achieved for samples with 15 to 20 ppm sulfur. In the case of beryllium determination, two reactions were studied, namely ⁹Be(¹⁸O,2α)¹⁹O and ⁹Be(¹⁸O,d)²⁵Na. At 25 MeV ¹⁸O⁵⁺, the first reaction is completely selective and yields a 5 ng detection limit for a 5 minutes irradiation. Boron is a nuclear interference when using the second reaction which yields a 110 ng detection limit in the same conditions. An irradiation chamber has been constructed that allows to decrease these limits. The technique was tested by analyzing two standard materials (NBS-SRM 394 and IRSID 508-1) whose sulfur content is certified. The results obtained by analyzing a biological sample (NBS-SRM 1571) for sulfur and a metallic sample Cu-Be for beryllium, are discussed

[en] The polarization effects for monopole and quadrupole electron excitations of nuclei in the oxygen region have been considered. A phenomenological method has been used in order to extrapolate empirical values for the polarization charges, from the real photon limit, to higher momentum transfers. It is found that in most cases polarization charges that are nearly constant, for momentum transfers up to 2 or 3 fm^-1, thus providing a justification in the oxygen region for the assumption most frequently made when experiment and theory are compared. (Auth.)

[en] Tritium in the target [¹⁸O] water irradiated with 9.6 MeV protons for producing [¹⁸F] fluoride by ¹⁸O(p, n)¹⁸F reaction was predicted from the consideration on the Q value of the ¹⁸O(p, t)¹⁶O reaction. A tritium beta ray spectrum was measured by a liquid scintillation counter equipped with a multichannel analyzer. The ratio of the ³H activity to the ¹⁸F activity in the [¹⁸O] target water was 2.4x10^-6 at the beam current of 25μA. Tritium also was detected in the [¹⁸O] water for recycling and the wasted acetonitrile [¹⁸O] water. The purified [¹⁸F]-FDG solution was not contaminated by ³H. The 40% ³H out of the produced activity was lost in the course of the [¹⁸F]-FDG synthesis. It was suggested that ³H evaporated into the air during [¹⁸F]-FDG synthesis and caused contamination of the workroom. The radiation workers should be prevented from environmental ³H contamination. (author)

No abstract available

No abstract available

[en] In collaboration with the Tandem Van de Graaff staff at the University of Pennsylvania the reaction ¹⁰Be(t,p)¹²Be at E/sub t/ = 12 MeV has been used to study the properties of ¹²Be. The first excited state of ¹²Be has been found to lie at 2.110 +- 0.015 MeV and to have J = 2 from p,γ angular correlation measurements. Using a chopped beam the search for delayed neutrons from the decay of ¹²Be was negative. However, the decay curve for β rays can be fitted only if a half-life component of about 25 msec for ¹²Be is included along with the activities ¹²B, ⁹Li, and ⁸Li known to be present. A review of the search for new T/sub z/ = +5/2 isotopes in the s-d shell at the Brookhaven Tandem Van de Graaff is presented and recent results on the T/sub z/ = +3 nucleus ³⁴Si, formed in the ¹⁸O(¹⁸O,2p)³⁴Si reaction, are outlined. Utilizing new ion-source techniques to form a beam of ⁹Be ions the reaction ⁴⁸Ca(⁹Be,pn)⁵⁵V has been used to find and study the new isotope ⁵⁵V of 6 sec half-life. The extension of these techniques to higher Z may be possible although recent studies of heavy-ion reactions indicate that the cross sections may be very small

[en] O¹⁸ is a stable isotope used as a target, with an enrichment of 95 %, for the F¹⁸ production. Its relative abundance is 0.2 %. Its enrichment, commonly carried out by fractionated distillation, is difficult and expensive. The gaseous diffusion SIGMA enrichment method is proposed to produce the small amounts of O¹⁸ needed at present by the local suppliers of F¹⁸. The conceptual engineering of a SIGMA plant applied to the O¹⁸ production is given as well as an economical analysis of the process compared with ultracentrifugation as an alternative technology

[en] Inelastic electron scattering from the low-lying even-parity states of ¹⁸O has been performed. The measurements span a range in momentum transfer from 0.6 to 2.7 fm^-1. Form factors have been determined for the lowest 0⁺ excitations, the three lowest 2⁺ excitations, and the three lowest 4⁺ excitations. Transition densities for the 2⁺ and 4⁺ excitations have been obtained from a Fourier-Bessel analysis of these data. Comparisons were made with the predictions of various theoretical calculations and the agreement was found generally to be poor. A coexistence model was used to decompose the measured form factors into their single-particle and collective components, which in turn were compared with their counterparts in ¹⁶O and ¹⁷O. The results indicate that this model provides a useful framework within which to understand the structure of the oxygen isotopes. Transition densities also were obtained within the context of this model. ...Present address: Laboratory of Nuclear Science, Tohoku University, Sendai, Japan