The new element 112 Short note

The new element 112 was produced and identified unambigiously in an experiment at SHIP, GSI Darmstadt. Two decay chains of the isotope "2"7"7112 were observed in irradiations of "2"0"8Pb targets with "7"0Zn projectiles of 344 MeV kinetic energy. The isotope decays by emission of #alpha# particles with a half-life of (240_-_9_0"+"4"3"0) #mu#s. Two different #alpha# energies of (11.649#+-#20) keV and (11.454#+-#20) keV were measured for the two observed decays. The cross-section measured in three weeks of irradiations is (1.0_-_0_._4"+"1"8) pb. (orig.)Available from TIB Hannover: RO 801(96-09) / 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

Production and decay of "2"6"9110

In an experiment carried out to identify element 110, we have observed an #alpha#-decay chain, that can be unambiguously assigned to "2"6"9110. In a series of preexperiments the excitation functions of the fusion reactions "5"0Ti+"2"0"8Pb#->#"2"5"8104* and "5"8Fe+"2"0"8Pb#->#"2"6"6108* were measured with high precision in order to get the optimum projectile energies for the production of these heavy elements. The cross-section maxima of the 1n evaporation channels were observed at excitation energies of 15.6 MeV and 13.4 MeV, respectively. These data result in an optimum excitation energy of 12.3 MeV of the compound nucleus for the production of "2"6"9110 in the reaction "6"2Ni+"2"0"8Pb#->#"2"6"9110+1n. In irradiations at the corresponding beam energy of 311 MeV we have observed a decay chain of 4 subsequent #alpha# decays. This can be assigned to the isotope with the mass number 269 of the element 110 on the basis of delayed #alpha#-#alpha# coincidences. The accurately measured decay data of the daughter isotopes of the elements 108 to 102, obtained in the previous experiments, were used. The isotope "2"6"9110 decays with a half-life of (270_-_1_2_0"+"1"3"0"0) #mu#s by emission of (11.32#+-#0.020) MeV alpha particles. The production cross-section is (3.3_-_0_2_._7"+"6"."2) Pb. (orig.)SIGLEAvailable from TIB Hannover: RO 801(94-82) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman