Search

We have compared the luminescence decay from intact and pre-damaged Al2O3 crystals registered during single swift heavy ion and photo- picosecond laser pulse excitation (λex. = 440 nm). The decay curves measured during 1.2 ÷ 1.6 MeV/amu C, Ar, V, Kr, Xe ion irradiation at room temperature are composed of three components – fast (τ1 It was found that photoexcitation at 440 nm induces strong emission of F22+- centers with a lifetime of about 8 ns which is not detected during high energy ion irradiation. This is ascribed to the quenching effect of high density excitations in a particle track.

The possibility for the production of exotic 6He nuclei in the 7Li(γ, p)6He reaction with the use of the 22 MeV electron beam provided by the MT-25 microtron was studied. This method was found to be quite effective tool for the production of the short-lived 6He ions. Two species of lithium salt, Li2CO3 and LiF, were tested as target material. Maximal yield of 6He atoms was obtained at irradiation of the fine-dispersed LiF salt loaded into cylindrical vessel. At the temperature of 800 °C the yield of 6He was found to be ( 1.7 ± 0.2 ) × 10 7 atoms / s per 1 μA of electron beam current. The use of the ECR source (with efficiency of about 8%) gave a possibility to obtain the beam of 6He ions with intensity of ( 1.4 ± 0.2 ) × 10 6 ions / s per 1 μA of electron beam current. The application of this approach for the further production of a monochromatic beam of accelerated 6He ions with an intensity higher than 108 pps (which can be easily reached already at 100 μA electron beam current) would make feasible a large number of experiments on investigating the structure of this nucleus and the mechanisms of nuclear reactions with its participation. This method for obtaining 6He nuclei may turn out to be one of the most optimal and inexpensive as compared with other methods using accelerated heavy ion projectiles.

The high-resolution wide aperture separator COMBAS was installed and commissioned in the Flerov Laboratory of Nuclear Reactions, JINR (Dubna) [Nucl. Instr. and Meth. A 306 (1991) 123; 426 (1999) 605; 479 (2002) 467]. It is designed for in-flight radioactive beam production of short-lived isotopes and experiments with them. The separator operates in the (20–50)A MeV ion energy region. It consists of the two stages, dispersive and achromatising. The second half of the separator is a mirror symmetrical counterpart of the first one, the intermediate focal plane being the plane of the symmetry. Multipole magnets with special profiled poles are used to correct higher order aberrations at the intermediate and final foci. The 3D magnetic measurements of the analysing magnets of the separator were done. The KOMPOT program for the 3D magnetic field calculations [Doinikov et al., 1986, Preprint/CNNI atominform: B-0741, 13p; Belyaev et al., Int. Conf. “Optimisation of Finite Element Approximations”, St.Pt., Russia, 25–29 June 1995, p.101; IEEE Transact. On Magnetics, 28 (1) (1992) 908; Frenkel, Selected works, USSR Academy of Sciences publ., Moscow–Leningrad, v.1 (Electrodynamics), 1956; Proc. IEEE, 114 (7) (1967) 995; Livingston, Blewett, Particle accelerators, No. 7, McGraw-Hill, 1962, p. 253] was used for the analysis of these magnetic measurements data, as well as for the reconstruction of the magnet fields inside the total volume closed by the 3D surface, where the magnetic measurements had been performed. As a result of the magnetic field reconstruction we obtained field maps, which would be used in simulations of particle trajectories.