The presented paper discusses the production of radioactive ion beams of francium, radium, and actinium from thick uranium carbide (UC
) targets at ISOLDE, CERN. This study focuses on the release ...curves and extractable yields of francium, radium and actinium isotopes. The ion source temperature was varied in order to study the relative contributions of surface and laser ionization to the production of the actinium ion beams. The experimental results are presented in the form of release parameters. Representative extractable yields per
C are presented for
Ac, several Ra and Fr isotopes in the mass ranges 214
A
233 and 205
A
231 respectively. The release efficiency for several isotopes of each of the studied elements was calculated by comparing their yields to the estimated in-target production rates modeled by CERN-FLUKA. The maximal extraction efficiency of actinium was calculated to be 2.1(6)% for a combination of surface ionization using a Ta ion source and resonant laser ionization using the two-step 438.58 nm, and 424.69 nm scheme.
This article summarizes the current specifications and the latest features of the CERN-ISOLDE resonance ionization laser ion source (RILIS). This includes a description of the optical layout and the ...newly designed reference system. The ionization schemes for the laser ionized beams at ISOLDE are tabulated, including six new elements. All RILIS schemes are also made publicly available in the RILIS elements on-line database. Finally, we announce a paradigm shift in RILIS operation – the combination of a machine protection and a monitoring and control system has enabled on-call operation of the laser ion source for selected beams in 2014 and has become the standard mode of operation in 2015.
The changes in the mean-square charge radius (relative to 209Bi), magnetic dipole, and electric quadrupole moments of 187, 188, 189, 191Bi were measured using the in-source resonance-ionization ...spectroscopy technique at ISOLDE (CERN). A large staggering in radii was found in 187, 188, 189Big, manifested by a sharp radius increase for the ground state of 188Bi relative to the neighboring 187, 189Big. A large isomer shift was also observed for 188Bim. Both effects happen at the same neutron number, N = 105 , where the shape staggering and a similar isomer shift were observed in the mercury isotopes. Experimental results are reproduced by mean-field calculations where the ground or isomeric states were identified by the blocked quasiparticle configuration compatible with the observed spin, parity, and magnetic moment.
In-source resonant ionization laser spectroscopy of the even-A polonium isotopes (192-210,216,218)Po has been performed using the 6p(3)7s (5)S(2) to 6p(3)7p (5)P(2) (λ=843.38 nm) transition in the ...polonium atom (Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope shifts in (200-210)Po with a previous data set allows us to test for the first time recent large-scale atomic calculations that are essential to extract the changes in the mean-square charge radius of the atomic nucleus. When going to lighter masses, a surprisingly large and early departure from sphericity is observed, which is only partly reproduced by beyond mean field calculations.
Abstract
The dynamics of agribusiness development depends on the state of its material and technical base; its intensification is impossible without equipping with advanced energy-efficient means of ...production. A number of measures of state support in the Altai Territory are aimed at achieving the required level of technical re-equipment of enterprises of the agro-industrial complex. Within the framework of the study, measures and tools are considered that stimulate technical re-equipment and technological modernization. The influence of state support on the technical re-equipment of agribusiness is analyzed, and the positive contribution of the use of leasing schemes in the acquisition of agricultural machinery is revealed. Indicators of the dynamics of updating the main types of agricultural machines and technological equipment of agribusiness are given, in particular, its low provision with tractors was revealed. The assessment of the need for technology is given. The reasons for the restraining rates of acquisition of agricultural machinery have been identified and a number of measures have been proposed to intensify it.
•The Laser Ion Source and Trap (LIST) was successfully operated on-line at ISOLDE.•LIST showed no signs of degradation after 48h of intense proton irradiation.•Transmission, selectivity, efficiency, ...time structure were extensively characterized.•Suppression factor for surface-ionized isobaric contaminants is more than 103–104.•Loss in LIST efficiency compared to RILIS operation is only a factor of 20.
At radioactive ion beam facilities like ISOLDE at CERN, a high purity of the element of interest in the ion beam is essential for most experiments on exotic nuclei. Due to its unique combination of high ionization efficiency and ultimate elemental selectivity, the Resonance Ionization Laser Ion Source, RILIS, has become the most frequently used ion source at ISOLDE and at the majority of similar facilities worldwide. However, isobaric contamination predominantly stemming from unspecific surface ionization may still introduce severe limitations. By applying the highly selective resonance ionization technique inside a radio-frequency quadrupole ion guide structure, the novel approach of the Laser Ion Source and Trap, LIST, suppresses surface ionized isobaric contaminants by an electrostatic repelling potential. Following extensive feasibility studies and off-line tests, the LIST device has been adapted and refined to match the stringent operational constraints and to survive the hostile environment of the ISOLDE front-end region enclosing the highly radioactive nuclear reaction target. The LIST operation was successfully demonstrated for the first time on-line at ISOLDE during two experiments, attesting its suitability for radioactive isotope production under routine conditions. Data of these on-line characterization measurements confirm a suppression of surface-ionized isobars by more than a factor of 1000 in accordance to off-line studies that were carried out for the preparation of the on-line experiments. During the first on-line test, the suppression was associated with an efficiency loss of not more than a factor of about 50 with respect to normal RILIS operation. These losses could be further reduced to only about 20 during the second run. Results of the off-line studies in comparison to the first on-line characterization data are discussed here.
Producing gold at ISOLDE-CERN Barzakh, A.E.; Andreyev, A.N.; Atanasov, D. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
02/2022, Letnik:
513
Journal Article
Recenzirano
Odprti dostop
The yield of 18 ion beams of radioactive gold nuclei produced in the thick uranium target at ISOLDE (CERN) by 1.4-GeV protons was measured. The production-efficiency dependence on the half-life ...(efficiency curve) was derived using the in-target production calculations by the FLUKA-CERN code. The irregularities in the efficiency curve for long-lived high-spin gold isomers (187,191,193Aum) were found. Three release models were tested for the efficiency-curve description.
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