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Detailed $\ensuremath{\alpha}$-decay studies of ${}^{179}$Tl${}^{g}$ and its daughter products ${}^{175}$Au${}^{g}$ and ${}^{171}$Ir${}^{g}$ were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). First unambiguous determination of the $\ensuremath{\alpha}$-decay properties of ${}^{175}$Au${}^{g}$ was performed as follows: ${E}_{\ensuremath{\alpha}}$ $=$ 6433(4) keV, ${T}_{1/2}$ $=$ 207(7) ms, and $\ensuremath{\alpha}$-decay branching ratio 90(7)$%$. First determination of the $\ensuremath{\alpha}$-decay branching ratios for ${}^{179}$Tl${}^{g}$ and ${}^{171}$Ir${}^{g}$ was also made: ${b}_{\ensuremath{\alpha}}$(${}^{179}$Tl${}^{g}$) $=$ 60(2)$%$ and ${b}_{\ensuremath{\alpha}}$(${}^{171}$Ir${}^{g}$) $=$ 15(2)$%$. The spins of the ground states in ${}^{175}$Au and ${}^{171}$Ir are established as 1/2${}^{+}$.

Decay properties of the very neutron-deficient isotopes ${}^{197\char21{}199}$Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the $2n\char21{}4n$ evaporation channels of the fusion-evaporation reaction ${}^{60}$Ni+${}^{141}$Pr $\ensuremath{\rightarrow}$ ${}^{201}$Fr*. Improved $\ensuremath{\alpha}$-decay properties of ${}^{199}$Fr were determined and the possible existence of two $\ensuremath{\alpha}$-decaying states in this nucleus is discussed. For the isotope ${}^{198}$Fr a broad $\ensuremath{\alpha}$-decay energy distribution was detected in the range of $(7470\char21{}7930)$ keV and two $\ensuremath{\alpha}$-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope ${}^{197}$Fr was identified based on the observation of one $\ensuremath{\alpha}$-decay chain yielding ${E}_{\ensuremath{\alpha}}=7728(15)$ keV and ${T}_{1/2}=0.{6}_{\ensuremath{-}0.3}^{+3.0}$ ms. The systematics of reduced $\ensuremath{\alpha}$-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes.

By using the recoil-fission correlation technique, the exotic process of beta-delayed fission ($\ensuremath{\beta}$DF) was unambiguously identified in the very neutron-deficient nuclei ${}^{192,194}$At in experiments at the velocity filter SHIP at Gesellschaft f\"ur Schwerionenforschung (GSI). The upper limits for the total kinetic energy release in fission of ${}^{192,194}$Po, being the daughter products of ${}^{192,194}$At after ${\ensuremath{\beta}}^{+}/EC$ decay, were estimated. The possibility of an unusually high $\ensuremath{\beta}$DF probability for ${}^{192}$At is discussed.

By using the technique of correlating implanted evaporation residues and their subsequent fission decay, $\ensuremath{\beta}$-delayed fission ($\ensuremath{\beta}$DF) of ${}^{186}$Bi has been identified for the first time and $\ensuremath{\beta}$DF of ${}^{188}$Bi has been unambiguously confirmed. The experiments were performed at the velocity filter SHIP (GSI, Darmstadt). The $\ensuremath{\beta}$DF probabilities for both nuclides were qualitatively estimated, and, in particular indications for a large value in the case of ${}^{186}$Bi are regarded.

The synthesis of isotopes of the element hassium was studied using the reaction {sup 34}S+{sup 238}U{yields}{sup 272}Hs{sup *}. At a kinetic energy of 163.0 MeV in the center-of-mass system we observed one {alpha}-decay chain starting at the isotope {sup 267}Hs. The cross section was 1.8{sub -1.5}{sup +4.2} pb. At 152.0 MeV one decay of the new isotope {sup 268}Hs was observed. It decays with a half-life of 0.38{sub -0.17}{sup +1.8} s by 9479{+-}16 keV {alpha}-particle emission. Spontaneous fission of the daughter nucleus {sup 264}Sg was confirmed. The measured cross section was 0.54{sub -0.45}{sup +1.3} pb. In-beam measurements of fission-fragment mass distributions were performed to obtain information on the fusion probability at various orientations of the deformed target nucleus. The distributions changed from symmetry to asymmetry when the beam energy was changed from above-barrier to sub-barrier values, indicating orientation effects on fusion and/or quasifission. It was found that the distribution of symmetric mass fragments originates not only from fusion-fission, but has a strong component from quasifission. The result was supported by a calculation based on a dynamical description using the Langevin equation, in which the mass distributions for fusion-fission and quasifission fragments were separately determined.

A detailed $\ensuremath{\alpha}$-decay study of the neutron-deficient isotope $^{181}\mathrm{Pb}$ has been performed in the complete fusion reaction $^{40}\mathrm{Ca}$$+$$^{144}\mathrm{Sm}$$\ensuremath{\rightarrow}$$^{184}\mathrm{Pb}$${}^{*}$ at the velocity filter SHIP (GSI, Darmstadt). In comparison with the literature, more precise data have been deduced for the ${I}^{\ensuremath{\pi}}=(9/{2}^{\ensuremath{-}})$ ground state in this nucleus, which is presumably based on the neutron $\ensuremath{\nu}{h}_{9/2}$ spherical orbital. Improved $\ensuremath{\alpha}$-decay data were also measured for $^{180}\mathrm{Pb}$.

A new isomer with a half-life of $0.48(2)$ ms was identified in the nuclide $^{181}\mathrm{Hg}$, which was produced in the complete fusion reaction $^{40}\mathrm{Ca}+^{144}\mathrm{Sm}\ensuremath{\rightarrow}^{184}\mathrm{Pb}$${}^{*}$ at the velocity filter SHIP (GSI, Darmstadt). The isomeric state was tentatively assigned a spin-parity of $13/{2}^{+}$. We propose that this isomer de-excites by a yet unobserved low-energy, strongly converted $\ensuremath{\gamma}$-ray transition, followed by a newly identified cascade composed of a $90.3$ keV $M1$ and a $71.4$ keV $E2$ $\ensuremath{\gamma}$-ray transition.

A detailed spectroscopic study of the neutron-deficient isotope $^{181}\mathrm{Tl}$ and the daughter of its $\ensuremath{\alpha}$ decay, $^{177}\mathrm{Au}$, has been performed in the complete fusion reaction $^{40}\mathrm{Ca}+^{144}\mathrm{Sm}\ensuremath{\rightarrow}^{184}\mathrm{Pb}{}^{*}$ at the velocity filter SHIP (GSI). The mass excess, excitation energy, and decay scheme of the isomeric 1.40(3) ms, $9/{2}^{\ensuremath{-}}$ intruder state in $^{181}\mathrm{Tl}$ have been established for the first time. These results solve a long-standing puzzle of the unrealistically large reduced $\ensuremath{\alpha}$-decay width of this isomer. Based on this, the previously unknown masses of the long-lived isomeric states in $^{177}\mathrm{Au}$ and $^{173}\mathrm{Ir}$ have been derived. In turn, it now allows the excitation energies of previously identified bands in $^{177}\mathrm{Au}$ and $^{173}\mathrm{Ir}$ to be deduced and compared with theoretical predictions. First measurements of $\ensuremath{\alpha}$-decay branching ratios for $^{181}\mathrm{Tl}{}^{m}$ and $^{177}\mathrm{Au}{}^{m,g}$ are also reported.

Detailed {alpha}-decay studies of the neutron-deficient isotope {sup 194}At have been performed in the complete fusion reaction {sup 56}Fe+{sup 141}Pr{yields}{sup 194}At+3n at the velocity filter SHIP. Two {alpha}-decaying isomeric states with half-lives of T{sub 1/2}({sup 194}At{sup m1})=310(8) ms and T{sub 1/2}({sup 194}At{sup m2})=253(10) ms were identified in this nucleus. Their complex decays to the states in the daughter nucleus {sup 190}Bi are discussed in the article. We propose that similar to the case of the neighboring {sup 191,192,193,195}At isotopes, the oblate-deformed configurations based on the proton 1/2{sup +}[440] and/or 7/2{sup -}[514] Nilsson orbitals become important in {sup 194}At. A new isomeric state with the half-life of 175(8) ns was observed in {sup 190}Bi.

An isomeric state in {sup 255}Lr with a half-life of t{sub 1/2} = 1.4(1) ms and E{sub x}>720-keV has been observed for the first time using the GABRIELA setup at the focal plane of the VASSILISSA separator. Based on its K-forbiddeness, the configuration of the state is most probably formed by coupling the valence proton to a two quasiparticle neutron excitation. Possible three quasiparticle configurations are discussed.

An isomeric state in {sup 209}Ra has been observed for the first time, using the GABRIELA setup at the focal plane of VASSILISSA, to decay to the ground state of {sup 209}Ra via a cascade of 238-keV (M2) and 644-keV transitions. The half-life of the isomer has been measured to be 117(5) {mu}s and from systematics is assigned as a neutron i{sub 13/2}{sup -1} excitation.

The new neutron-deficient isotopes Rn-193,Rn-194 have been identified in the complete fusion reaction Cr-52+Sm-144 -> Rn-196(*) at the velocity filter SHIP. The alpha-decay energy and half-life value of Rn-194 were determined to be E-alpha=7700(10) keV and T-1/2=0.78(16) ms, respectively. For Rn-193 the half-life of T-1/2=1.15(27) ms and two alpha lines at E-alpha 1=7685(15) keV, I-alpha 1=74(20)% and E-alpha 2=7875(20) keV, I-alpha 2=26(12)% were found. The decay pattern of Rn-193, which is substantially different from that of the heavier odd-A Rn isotopes, provides first experimental evidence for the long-predicted deformation in the very neutron-deficient Rn nuclei.

The new neutron-deficient isotope $^{187}\mathrm{Po}$ has been identified in the complete fusion reaction $^{46}\mathrm{Ti}$+$^{144}\mathrm{Sm}$\ensuremath{\rightarrow}$^{187}\mathrm{Po}$+$3n$ at the velocity filter SHIP. Striking features of the $^{187}\mathrm{Po}$ \ensuremath{\alpha} decay are the strongly-hindered decay to the spherical ground state and unhindered decay to a surprisingly low-lying deformed excited state at 286 keV in the daughter nucleus $^{183}\mathrm{Pb}$. Based on the potential energy surface calculations, the $^{187}\mathrm{Po}$ ground state and the 286 keV excited state in $^{183}\mathrm{Pb}$ were interpreted as being of prolate origin. The systematic deviation of the \ensuremath{\alpha}-decay properties in the lightest odd-A Po isotopes relative to the smooth behavior in the even-A neighbors is discussed. Improved data for the decay of ${}^{187}{\mathrm{Bi}}^{m,g}$ were also obtained.

Decay properties of the new neutron-deficient nuclide $^{192}\mathrm{At}$ have been studied in the complete fusion reaction $^{144}\mathrm{Sm}$($^{51}\mathrm{V}$,3n)$^{192}\mathrm{At}$ at the velocity filter SHIP. Two isomeric states with half-lives of 88(6) ms and 11.5(6) ms, respectively, and with complex $\ensuremath{\alpha}$-decay schemes were identified in $^{192}\mathrm{At}$. The decay pattern of one of the isomers suggests that it is based on the oblate-deformed $\ensuremath{\pi}2{f}_{7/2}\ensuremath{\bigotimes}\ensuremath{\nu}1{i}_{13/2}$ configuration, which confirms the expected onset of deformation in the At isotopes by approaching the neutron midshell at $N=104$.

The production of the very neutron-deficient nuclides $^{184\ensuremath{-}192}\mathrm{Bi}$ and $^{186\ensuremath{-}192}\mathrm{Po}$ in the vicinity of the neutron midshell at N = 104 has been studied by using heavy-ion-induced complete fusion reactions in a series of experiments at the velocity filter SHIP. The cross sections for the xn and pxn evaporation channels of the $^{46}\mathrm{Ti}$+$^{144}\mathrm{Sm}$$\ensuremath{\rightarrow}^{190}\mathrm{Po}{}^{*},$$^{98}\mathrm{Mo}$+$^{92}\mathrm{Mo}$$\ensuremath{\rightarrow}^{190}\mathrm{Po}{}^{*},$$^{50,52}\mathrm{Cr}$+$^{142}\mathrm{Nd}$$\ensuremath{\rightarrow}^{192,194}\mathrm{Po}{}^{*}$, and $^{94,95}\mathrm{Mo}$+$^{93}\mathrm{Nb}$$\ensuremath{\rightarrow}^{187,188}\mathrm{Bi}{}^{*}$ reactions were measured. The results obtained, together with the previously known cross section data for the heavier Bi and Po nuclides, are compared with the results of statistical model calculations carried out with the HIVAP code. It is shown that a satisfactory description of the experimental data requires a significant (up to 35%) reduction of the theoretical fission barriers. The optimal reactions for production of the lightest Bi and Po isotopes are discussed.