Measurement of n-induced total reaction cross-sections, in the framework of the n_TOF collaboration at CERN and at N.C.S.R. "Demokritos"

The nuclear physics team is actively involved in cross section measurements carried out at CERN by participating in the n_TOF collaboration. n_TOF is a pulsed neutron source coupled to a 185 m flight path designed to study neutron-nucleus interactions for neutron kinetic energies ranging from a few eV to approximately 1 GeV. The neutron kinetic energy is determined by time-of-flight, hence the name n_TOF.

The study of neutron-induced reactions is of large importance in a wide variety of research fields, ranging from stellar nucleosynthesis, symmetry breaking effects in compound nuclei, and the investigation of nuclear level densities, to applications of nuclear technology, including the transmutation of nuclear waste, accelerator driven systems and nuclear fuel cycle investigations.

Additionally, the group studies (n,2n) and (n,f) reactions on a variety of targets using the monoenergetic and quasi-monoenergetic neutron beams produced at the 5.5 MV HV TN-11 Tandem Accelerator of the Institute of Nuclear and Particle Physics at N.C.S.R. "Demokritos", by implementing the activation technique or in-beam measurements with state-of-the-art detection and acquisition systems. The Greek team is among the leaders in the efforts to provide the scientific community with high-accuracy, reliable neutron data, as well as with a sound theoretical analysis of the obtained experimental results.

Measurement, benchmarking and evaluation of differential cross-sections suitable for Ion Beam Analysis (IBA)

The principal objectives of this study are: (a) The measurement, with the highest possible precision, of the differential cross sections of a number of deuteron and proton induced reactions on light element isotopes absolutely necessary for Ion Beam Analysis (IBA), at suitable (low) energies and at multiple backward angles, (b) the subsequent benchmarking of the obtained results using high-purity thick targets, and (c) the theoretical analysis and cross-section data evaluation, using R-matrix and DWBA calculations.

The high precision determination and profiling of low-Z elements is of extreme importance for technological applications (e.g semiconductor industry, biomedical and environmental research etc.). The scientific validity and importance of this activity has been recognized by the International Atomic Energy Agency (IAEA, CRP "Development of a Reference Database for Ion Beam Analysis", 2006-2009, Research Agreement No. 13337/R0 and CRP "Development of a Reference Database for PIGE", Research Contract No. 16693/R0, 2011-2014) recently. The recognition is a measure of the esteem for the contribution of the Greek research team to the creation and evolution of IBANDL (Ion Beam Analysis Nuclear Data Library, which is evidenced by the large number of publications in the field of IBA over the last five years.

Radiological studies in the aquatic environment

The nuclear physics group is actively involved in radiological studies mainly in the marine environment, in close collaboration with the HMRS (Hellenic Marine Research Center). The studies include the development and commissioning of a reliable, in situ, acquisition system comprised of a model NaI scintillator, designed and constructed at HMRS, along with a BGO anti-Compton shield, based digital electronics for the pulse shape analysis and storage of information, in an attempt to monitor the radioactivity levels both in sea water and in marine sediments.

This acquisition system will be installed in floating stations in several areas of the Aegean Sea, while the data will be transmitted and collected via satellite for real-time applications. In order to fulfill these demands, extensive Monte-Carlo calculations are currently being performed using MCNP and FLUKA general-purpose simulation packages.

The completion of this new acquisition system will undoubtedly put the involved Greek research teams in the forefront of environmental radiological studies in the marine environment worldwide.