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A rich revenue from the use of radioactive beams and radioactive targets: recent highlights from the nTOF and ISOLDE facilities

A rich revenue from the use of radioactive beams and radioactive targets: recent highlights from the nTOF and ISOLDE facilities

This video was recorded at CERN Academic Training Lectures 2008. The On-Line Isotope Mass Separator ISOLDE is a facility dedicated to the production of a large variety of radioactive ion beams for a great number of different experiments, e.g. in the field of nuclear and atomic physics, solid-state physics, life sciences and material science. At ISOLDE, radioactive nuclides are produced in thick high-temperature targets via spallation, fission or fragmentation reactions. The targets are placed in the external proton beam of the PSB, which has an energy of 1.0 or 1.4 GeV and an intensity of about 2 microA. The target and ion-source together represent a small chemical factory for converting the nuclear reaction products into a radioactive ion beam. An electric field accelerates the ions, which are mass separated and steered to the experiments. Until now more than 600 isotopes of more than 60 elements (Z=2 to 88) have been produced with half-lives down to milliseconds and intensities up to 1011 ions per second. Through the advent of post-accelerated beams with the REX-ISOLDE charge breeder and linear accelerator, probing nuclear properties using transfer reactions and Coulomb excitation of exotic nuclear species is now possible. The neutron time-of-flight facility, nTOF, is a neutron source that has been operating at CERN since 2001 using the 20 GeV proton beam from the Proton Synchrotron PS. The concept of the nTOF neutron beam makes use of both the specifically high flux of neutrons attainable using the spallation process of 20 GeV protons on an extended lead target. The high neutron flux, the low repetition rates and the excellent energy resolution has opened new possibilities to high precision cross section measurements in the energy range from 1 eV to 250 MeV, for stable and, moreover, for radioactive targets. This first lecture will deal with recent highlights of the two facilities. The results obtained at ISOLDE have implications for the basic understanding of the atomic nucleus, but also for related fields like astrophysics and weak-interaction physics. The possibility of pure radioactive implants opens access to the investigation of problems in solid-state physics, in particular concerning impurities and defects in semiconductors. Biomedical studies using radioactive isotopes for diagnosis and therapy have introduced life-science into the research program. The nTOF facility allows precise measurements of neutron related processes that are relevant for several fields. One example is nuclear astrophysics where data produced by n_TOF are used to study the ordinary stellar evolution as well as supernovae. Intense neutron beams are also critical in the studies of processes of incineration of radioactive nuclear waste and for a better understanding of the effects of radiation in the treatment of tumors with beams of hadrons.

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