Light radio-isotopes for nuclear astrophysics and neutrino physics

Abstract

We present efforts to investigate and simulate the production, extraction and utilization of light radio-isotopes in research in nuclear astrophysics and fundamental nuclear and neutrino physics. The main technological novelty arises from the large fluxes of light radioactive beams that will be available using a high current LINAC beam of few mA, impinging on a specially designed appropriate target. Such high-intensity facilities will shortly be available at SPIRAL-II (GANIL, France) and at the SARAF accelerator (Soreq, Israel). The present paper concentrates on the following two categories: (1) production of 14O, 15O and 18Ne by direct interaction with a proton or deuteron beam and (2) production of 6He and 8Li by a two-stage reaction. These radioactive nuclei play a central and crucial role in the astrophysics issue of explosive nucleo-synthesis in the environment of, e.g., x-ray bursts. 6He, 8Li and 18Ne are important for studies of neutrino properties in general and in particular in ‘β-beam’ facilities. The expected increase of yield of several orders of magnitude will allow experiments that have not been possible hitherto, utilizing in an optimum manner the existing and newly planned detection systems for charged particles and γ-rays.

Comparison Of Expected Yields For Light Radioactive Beams At SPIRAL-1 And 2

“…The oxygen isotopes 14 O and 15 O have been identified as the neutron-deficient light beams to be investigated with highest priority for SPIRAL-2 1 . We discuss production of 14 O in some detail.…”

“…The reaction which has the largest cross-section to produce 14 14,15 O extraction via the CO molecule. Unfortunately, yields deduced from experimental cross-sections 17 and those directly measured for a thick-target 18 differ by a factor 7.…”

“…This estimate is calculated using realistic conditions implying the present 1.5 kW target for SPIRAL-1 and a 5 kW-target (30 MeV, 0.16 mA, 3 He) for SPIRAL-2. Because of the factor 7 of uncertainty for SPIRAL-2, the in-target 14,15 O cross-section will be measured at the Nuclear Physics Institute Rez (Czech Republic) 19 .…”

“…We discuss also our attempts to find a production scheme for 15 C and nitrogen isotopes. These isotopes shall be produced by neutroninduced reactions.…”

Optimisation of a beta beam

“…In Table 2 estimates for the achievable productions rates are given and a short description of each concept is given below. The neutron converter concept has been proposed to be used at, e.g., the ZARAF facility in Israel for light ion production [27]. The target in which the radioactive ions are produced are only irradiated by neutrons which induces less heating and less radiation damage.…”