Systematic comparison of ISOLDE-SC yields with calculated in-target production rates

Abstract

Recently, a series of dedicated inverse-kinematics experiments performed at GSI, Darmstadt, has brought an important progress in our understanding of proton and heavy-ion induced reactions at relativistic energies. The nuclear reaction code ABRABLA that has been developed and benchmarked against the results of these experiments has been used to calculate nuclide production cross sections at different energies and with different targets and beams. These calculations are used to estimate nuclide production rates by protons in thick targets, taking into account the energy loss and the attenuation of the proton beam in the target, as well as the low-energy fission induced by the secondary neutrons. The results are compared to the yields of isotopes of various elements obtained from different targets at CERN-ISOLDE with 600 MeV protons, and the overall extraction efficiencies are deduced. The dependence of these extraction efficiencies on the nuclide half-life is found to follow a simple pattern in many different cases. A simple function is proposed to parameterize this behavior in a way that quantifies the essential properties of the extraction efficiency for the element and the targetion-source system in question.

Production of neutron-rich nuclei in fragmentation reactions of Sn132 projectiles at relativistic energies

“…This scenario corresponds to the two-stage reaction scheme proposed for the future EURISOL facility [30] where the high-power target station could produce up to 10 15 neutron-induced fissions of 238 U per second. Taking into account an extraction efficiency from the ISOL stage for 132 Sn of 42% [16] and a total post-acceleration efficiency of 10% [30] one obtains the mentioned intensity for a 132 Sn beam accelerated at few hundred MeVs per nucleon. The results indicate that the proposed production scheme would not only overcome the limited efficiency of ISOL facilities for the extraction of isotopes of refractory elements between Zr and Rh, but also would produce a large variety of neutron-rich nuclei in this region of the chart of nuclides.…”

“…From a technical point of view, ISOL facilities produce the largest in-target yields of fission products [15], however, the refractory nature of many of them results in rather poor extraction efficiencies, in particular for those nuclei with the largest neutron excess and consequently with the shortest half lives [16].…”

In-Source Laser Spectroscopy with the Laser Ion Source and Trap: First Direct Study of the Ground-State Properties ofPo217,219

“…The francium ions cover a wide range of masses, from A ¼ 200 [44] to 233 [45]. Their yields vary from < 1 to > 10 8 atoms per second, depending on the reaction cross section, the diffusion and effusion properties of the target, and the half-life of each isotope [46]. In the region of A ≥ 220, the yields are 10 7 ions per second [46], while the predicted yields of the isobaric polonium atoms are < 10 3 .…”

“…Their yields vary from < 1 to > 10 8 atoms per second, depending on the reaction cross section, the diffusion and effusion properties of the target, and the half-life of each isotope [46]. In the region of A ≥ 220, the yields are 10 7 ions per second [46], while the predicted yields of the isobaric polonium atoms are < 10 3 . In order to demonstrate the suitability of the LIST in the region of the nuclear chart with A ∼ 220, the suppression of 218 Fr has been studied.…”

“…In the case of alkali elements, the release is mostly contained within the 1.2-s separation between two proton pulses irradiating the target [46,48]. This release profile results in the francium beams to be structured with peaks synchronized with the proton-pulse impact on target.…”