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The components, working principle and characteristics of FATIMA (FAst TIMing Array), a fast-timing detector system for DESPEC at FAIR, are described. The core system includes 36 LaBr 3 (Ce) scintillator detectors, a mounting frame for the DESPEC station and a VME-based fast-timing data acquisition system. The current electronic timing circuit is based on V812 constant fraction discriminators and V1290 time-to-digital converters. Gamma-ray energies are measured using V1751 digitisers. Characteristics of the core FATIMA system including efficiency, energy, and coincidence resolving time, as well as limitations, are discussed on the basis of test measurements performed in the S4 cave at GSI, Germany. The coincidence -time resolution for the prompt 60 Co cascade is determined to be ∼320 ps full width at half maximum. The total full energy peak efficiency at 1 MeV for the 36 detector array in the DESPEC setup is 2.9%. The energy-dependent prompt response centroid curve with the current CFD/TDC combination is shown to be smooth; the centroid shift method can be applied for the measurement of half-lives below 200 ps. An overview of applications of the FATIMA detectors as an ancilliary system in combination with other detector arrays during recent years is given. Data on the operation of the detectors in the presence of magnetic fields are presented.

The loss of biodiversity and biomass of insects has a detrimental effect on eco-systems and associated ecosystem services, e.g. pollination. For this reason, various nature conservation measures for the promotion of insects are being created in agricultural landscapes. One of those measures is the so-called flower strip at the edge of fields. However, it is repeatedly propagated in the nature conservation community that by means of annually mulched flower strips, species richness and abundance of pollinators in intensively used agricultural areas cannot be increased. Furthermore, these measures might represent ecological traps. To check this criticism, we surveyed one to three meter wide perennial wild flower strips in intensively used agricultural areas, which have been mulched annually for three years, upon abundance, species numbers and biomass of bees and butterflies. By means of transect surveys, species richness and abundance were recorded and biomass was calculated. We compared the findings with those of reference field margins. Our results show an increase in species richness and abundance as well as a general increase in biomass of wild bees and butterflies in wild flower strips compared to findings in the reference field margins. Implications for insect conservation Our study shows that small, annually mulched wild flower strips are able to promote biodiversity of wild bees and butterflies in the intensively used agricultural landscape. Further, our results obtained that this measure does not inevitably represent an ecological trap or sink habitat for most species.

Low-lying yrast states of 204 Po and 206 Po were investigated by the γ -γ fast timing technique with LaBr3(Ce) detectors. Excited states of these nuclei were populated in the 197 Au( 11 B,4n) 204 Po and the 198 Pt( 12 C,4n) 206 Po fusion-evaporation reactions, respectively. The beams were delivered by the FN-Tandem accelerator at the University of Cologne. The lifetimes of the 4 + 1 states of both nuclei were measured, along with an upper lifetime limit for the 2 + 1 state of 204 Po. A comparison between the derived B(E2; 4 + 1 → 2 + 1 ) values and results from simplified empirical two-state mixing calculations suggests that for the 4 + 1 states of even-even polonium isotopes the transition from single particle mode at N = 126 to collective mode, when reducing the number of neutrons, occurs above N = 122.

Low-lying yrast states in 204Po and 206Po have been investigated by the γ-γ fast timing technique with LaBr3(Ce) detectors. Excited states of these nuclei were populated in the 197Au(11B,4n) and the 198Pt(12C,4n) fusion-evaporation reactions, respectively, at the FN-Tandem Facility at the University of Cologne. The lifetimes of the 4+1 states in both nuclei were measured, along with an upper limit for the 2+1 state in 204Po. The preliminary results are discussed in the scope of the systematic behavior of the transition strengths between yrast states in polonium isotopes.