Large size foil - microchannel-plate timing detectors

To measure the velocity of slow heavy nuclei, created as evaporation residues in nuclear reactions, large area thin timing detectors should be used. An overview is given on principial properties and possibilities of foil -micro-channel plate timing detector units and the properties of many time-of-flight (TOF) systems of this type are analysed. Two new large area foil - micro-channel plate TOF systems are presented: The TOF unit at the velocity separator SHIP, GSI Darmstadt (#approx#55 cm"2 active area, #>=#99% detection efficiency, 100% transparency and #<=#700 ps time resolution) and the TOF system of the electrostatic separator VASSILISSA, JINR Dubna (#approx#50 cm"2 active area, 99.99% detection efficiency, 90% transparency and #approx#500 ps time resolution). Both systems are unique in size and conditions of their exploitation. (orig.)34 refs.Available from TIB Hannover: RA 3692(95-08) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

The new element 111

The new element 111 was produced and unambiguously identified in an experiment at SHIP, GSI Darmstadt. Three nuclei of the isotope "2"7"2111 were observed in irradiations of "2"0"9Bi targets with "6"4Ni projectiles of 318 MeV and 320 MeV energy. The cross-sections are (1.7"+"3"."3_-_1_._4) pb and (3.5"+"4"."6_-_2_._3) pb, respectively. The nuclei decay by #alpha# emission into the new and so far the heaviest isotopes of the elements 109 and 107 with mass numbers A=268 and A=264. The #alpha#-decay chains were followed down to the known nuclei "2"6"0105 and "2"5"6Lr. (orig.)Available from TIB Hannover: RO 801(95-05) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman