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Background: The neutron-deficient lead region provides a range of nuclear phenomena, including isomerism at low energies. This phenomenon can be studied by α decay because the degree of hindrance of α decay provides information on the change in nuclear structure of connected states. Purpose: The aim of this work was to investigate the α-decay properties of $^{200,202}$FR and daughter products. Method: Neutron-deficient francium nuclei are produced at ISOLDE-CERN bombarding a UCx target with 1.4 GeV protons. Surface ionization and mass-separation techniques were employed to provide a pure radioactive ion beam at a radiation-detection setup. Results: Due to the very high statistics and the high beam purity, improved decay data for $^{202}$FR and its daughters were obtained. In particular, this data set allowed us to identify many fine-structure α lines with a relative reduced α-decay width up to five orders of magnitude lower as the strongest ground-to-ground state or isomeric-to-isomeric state α-decay transition. In addition, several half-life values were extracted with similar or better precision as compared with the literature. Conclusions: The observation of crossover transitions positioned the isomeric high-spin level of $^{198}$At at an excitation energy of 265(3) keV. Half-life values of 4.47(5) s and 1.28(10) s were extracted for the ground state and isomeric state of $^{198}$At and 52(3) ms for the ground-state decay of $^{200}$FR. Furthermore, α-decay schemes for Fr202 and its daughter $^{198}$At could be constructed.

Hyperfine-structure parameters and isotope shifts for the 795-nm atomic transitions in $^{217,218,219}$At have been measured at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy technique. Magnetic dipole and electric quadrupole moments, and changes in the nuclear mean-square charge radii, have been deduced. A large inverse odd-even staggering in radii, which may be associated with the presence of octupole collectivity, has been observed. Namely, the radius of the odd-odd isotope $^{218}$At has been found to be larger than the average of its even-$N$ neighbors, $^{217,219}$At. The discrepancy between the additivity-rule prediction and experimental data for the magnetic moment of $^{218}$At also supports the possible presence of octupole collectivity in the considered nuclei.

Fission fragment mass distributions were measured in heavy-ion induced fission of 238U. The mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and quasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model for the reactions of 30Si+238U and 34S+238U using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections of 263,264Sg and 267,268Hs, produced by 30Si+238U and 34S+238U, respectively. It is also suggested that sub-barrier energies can be used for heavy element synthesis.

The tilted-foil method for producing spin-polarized radioactive isotope beams has been studied using the re-accelerated radioactive 8 Li and 123 In beams produced at Tokai Radioactive Ion Accelerator Complex (TRIAC) facility. We successfully produced polarization in a 8 Li beam of 7.3(5)% using thin polystyrene foils (4.2 μg/cm 2 ). The systematic study of the nuclear polarization as a function of the number of foils and beam energy has been performed, confirming the features of the tilted-foil technique experimentally. After the study, a spin-polarized radioactive 123 In beam, which is the heaviest ever polarized in its ground state by this method, has been successfully generated by the tilted-foil method, for the nuclear spectroscopy around the doubly magic nucleus 132 Sn.

A nuclear-decay spectroscopy study of the neutron-deficient isotope $^{196}\mathrm{At}$ is reported where an isotopically pure beam was produced using the selective Resonance Ionization Laser Ion Source and On-Line Isotope Mass Separator (CERN). The fine-structure $\ensuremath{\alpha}$ decay of $^{196}\mathrm{At}$ allowed the low-energy excited states in the daughter nucleus $^{192}\mathrm{Bi}$ to be investigated. A $\ensuremath{\beta}$-delayed fission study of $^{196}\mathrm{At}$ was also performed. A mixture of symmetric and asymmetric fission-fragment mass distributions of the daughter isotope $^{196}\mathrm{Po}$ (populated by $\ensuremath{\beta}$ decay of $^{196}\mathrm{At}$) was deduced based on the measured fission-fragment energies. A $\ensuremath{\beta}\text{DF}$ probability ${P}_{\ensuremath{\beta}\mathrm{DF}}(^{196}\mathrm{At})=9(1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ was determined.

We have measured quasi-elastic backward scattering in the reactions of 48 Ti , 54 Cr , 56 Fe , 64 Ni , 70 Zn , 76 Ge and 86 Kr + 208 Pb to study the nucleus-nucleus interaction in Pb -based cold fusion. The barrier distributions were obtained from the first derivative of the measured excitation functions of quasi-elastic scattering cross sections normalized to the Rutherford scattering cross sections. The centroids of the barrier distributions showed deviations from several predicted barrier heights toward the low energy side except for the Christensen-Winther potential and the Aküz-Winther potential. The shapes of the barrier distributions were well reproduced by the results of a coupled-channel calculation taking account of the coupling effects of multi-phonon excitations of the quadrupole vibration for the projectiles and of the octupole vibration for the 208 Pb target. The present barrier distributions were also well reproduced by a semiclassical calculation taking into account the couplings of transfer channels and single-phonon excitations in the projectiles and the target.

The entrance barrier distributions for the heavy systems 48 Ti, 54 Cr, 56 Fe, 64 Ni, 70 Zn, 76 Ge and 86 Kr + 208 Pb have been extracted from excitation functions for quasi-elastic scattering at backward angles. The entrance barrier heights for these systems are presented. The fusion probability for the system 64 Ni + 154 Sm has been obtained from the measurement of evaporation residues. It is shown that the fusion barrier shifts to high energies corresponding to barrier heights at an equatorial side of the prolate nucleus 154 Sm.

The diffusion coefficients of Li in the NaTl-type Li intermetallic compound of β-LiGa have been measured by using a short-lived radioactive diffusion tracer. As the tracer, the α-emitting radioisotope of 8Li delivered as the energetic and pulsed beam from Tokai Radioactive Ion Accelerator Complex (TRIAC) was implanted into the β-LiGa compounds with the composition in the range of about 43 to 54 at.% Li. By analyzing the time-dependent yields of the α-particles measured according to the repetition cycle of the beam, the tracer diffusion coefficients were extracted over the wide range of Li composition. Abnormal composition-dependence of Li diffusion coefficients in β-LiGa was observed; the stoichiometric β-LiGa showed the highest diffusivity of Li. By referring to the composition-dependent diffusivity of Li in the iso-structural β-LiAl and β-LiIn, we could identify the abnormal diffusion of Li in very Li-poor composition of β-LiGa. The anomaly has been discussed qualitatively in terms of the formation of defect complex and the interaction between the constitutional defects.

Non-destructive and on-line Li diffusion experiments in Li ionic conductors are conducted using the short-lived !-emitting radiotracer of 8Li. The radiotracers produced as an energetic and pulsed ion beam from TRIAC (Tokai Radioactive Ion Accelerator Complex) are implanted into a structural defect mediated Li ionic conductor of NaTl-type intermetallic compounds ("-LiGa and "-LiIn). The experimental time spectra of the yields of !-particles are compared with simulated results and Li diffusion coefficients in the intermetallic compounds are extracted with an accuracy of ±10%. The diffusion coefficients obtained for "-LiGa with Li content of 43-54 at.% are discussed in terms of the interaction between Li-ion and the structural defects in the specimen, compared with the cases of "-LiAl and "-LiIn. The nonlinear Li-content dependency of Li diffusion coefficients for "-LiGa suggests that the Li diffusion with the Li-deficient region is obstructed by the defect complex composed of vacancies at the Li sites.

An ISOL-based radioactive nuclear beam (RNB) facility, Tokai Radioactive Ion Accelerator Complex (TRIAC), has been jointly developed by High Energy Accelerator Research Organization (KEK) and Japan Atomic Energy Agency (JAEA). The facility started to supply RNBs for experiments in 2005 and RNBs including fission fragments with energies up to 1.1MeV/A are available in the present. Several experimental studies were performed successfully using 8Li beams with various energies.

Effects of the prolate deformation of 238 U on fusion were studied in the reaction 30 Si + 238 U at bombarding energies close to the Coulomb barrier. The fission (capture) cross sections were measured at the JAEA tandem accelerator to see the enhancement of the cross sections in the subbarrier energy due to the lower Coulomb barrier in the collisions of projectile at the polar sides of 238 U. In order to obtain the direct evidence for complete fusion, evaporation residue cross sections were measured at UNILAC of GSI. At the subbarrier energy of Ec.m. = 133.0 MeV, where only polar collisions to 238 U occur, we measured three spontaneously fissioning nuclei which we assigned to the isotope 264 Sg. The obtained cross section (10 +10 – 6 ) pb was smaller than the calculation that the system captured at the polar collisions results in complete fusion, suggesting the competition between fusion and quasifission. At the above barrier energy of Ec.m. = 144.0 MeV, where collisions on the equatorial side of 238 U start to contribute, we observed α-decay chains starting from 263 Sg and the cross section was determined to be (67 +67 ) pb. The data was reproduced by the calculation that the system captured from the equatorial side of 238 U results in complete fusion.

The reaction 30Si + 238U → 268Sg* was studied at beam energies close to the Coulomb barrier. At a center-of-mass energy of E c.m. = 144.0MeV for reactions at half thickness of the target we measured three decay chains of 263Sg produced by evaporation of five neutrons. The cross-section was ( 67+67 -37) pb. At E c.m. = 133.0MeV we measured three spontaneously fissioning nuclei which we assigned to the isotope 264Sg. The production cross-section was ( 10+10 -6) pb and a half-life of ( 120+126 -44) ms was determined. This half-life is a factor of twenty shorter than theoretical predictions. At E c.m. = 128.0MeV an upper cross-section limit of 15pb was measured. The cross-section data reveal a strong influence of the orientation of the deformed target nucleus on the production yield. Compared to excitation functions measured for the lighter system 16O + 238U → 254Fm*, a reduction of the fusion probability was observed at low beam energies indicating increasing competition from quasifission processes.

The excitation function of the 8 Li(d, t) 7 Li reaction was directly measured using 8 Li beam irradiating a deuterated polyethylene target at center-of-mass system beam energies ( E cm ) between 0.3 and 1.2 MeV. This is the first cross section measurement of the above reaction below E cm = 1.5 MeV , covering Gamow peaks for 1 – 3 × 10 9 K of astrophysical interest. A broad resonance-like structure was observed at around E cm = 0.8 MeV . The astrophysical reaction rate deduced from the present result is far larger than the previously reported values estimated from extrapolation of data observed at higher energies, roughly by one order of magnitude at about 1 × 10 9 K .

Evaporation residue cross sections in the {sup 16}O+{sup 238}U reaction were measured for the energy range from above-to extreme subbarrier. We used a He-gas-jet system to transport the fusion products, and the {alpha} decay of the evaporation residues was measured by using a rotating wheel system. The measured cross sections for {sup 248,249,250}Fm are reproduced by a statistical model calculation, for which partial cross sections are calculated by a coupled-channel model taking into account the prolate deformation of {sup 238}U. We conclude that complete fusion is the main process in the subbarrier energy region, and quasifission is not an important channel.

The giant dipole resonance built on excited states was observed in very fissile nuclei in coincidence with evaporation residues. The reaction Ca-48 + Yb-176 populated evaporation residues of mass A = 213-220 with a cross section of similar to 200 mu b at 259 MeV. The extracted giant dipole resonance parameters are in agreement with theoretical predictions for this mass region. (c) 2005 Elsevier B.V. All rights reserved.

The dependence of the GDR width on temperature and spin was investigated in Sn nuclei, by using the reactions 17 O + 100 Mo and 18 O + 100 Mo to form 117 Sn and 118 Sn, respectively. Widths of Γ = 6.9 ± 0.5 MeV and Γ = 8.2 ± 0.5 MeV were extracted for temperatures of 1.74 and 1.84 MeV, respectively. The large increase of the width over this relatively small temperature range is inconsistent with the thermal shape fluctuation model. However, the spin dependence of the width is well reproduced by the model.

Exclusive measurements of high energy γ-rays in the decay of 164 Er, formed in the reaction 40 Ar+ 124 Sn, have been performed to study angular momentum dependence of the giant dipole resonance (GDR) strength function. The γ-ray spectra were measured in coincidence with A=160 evaporation residues (4n channel at E beam = 163 MeV and 187 MeV. A statistical model analysis, incorporating a two-component GDR strength function, shows increase in the GDR width as the average spin of the compound nucleus increases from 26ħ, (at 163 MeV to 54ħ (at 187 MeV). This is consistent with the predictions of a thermal shape fluctuation model.

The Mott polarimetry for T-violation (MTV) experiment tests time-reversal symmetry in polarized nuclear [Formula: see text]-decay by measuring an electron’s transverse polarization as a form of angular asymmetry in Mott scattering using a thin metal foil. A Mott scattering analyzer system developed using a tracking detector to measure scattering angles offers better event selectivity than conventional counter experiments. In this paper, we describe a pilot experiment conducted at KEK-TRIAC using a prototype system with a polarized 8Li beam. The experiment confirmed the sound performance of our Mott analyzer system to measure T-violating triple correlation (R correlation), and therefore recommends its use in higher-precision experiments at the TRIUMF-ISAC.

Low-energy β-delayed fission of 194,196At and 200,202Fr was studied in detail at the mass separator ISOLDE at CERN. The fission-fragment mass distributions of daughter nuclei 194,196Po and 202Rn indicate a triple-humped structure, marking the transition between asymmetric fission of 178,180Hg and symmetric fission in the light Ra-Rn nuclei. Comparison with the macroscopic-microscopic finite-range liquid-drop model and the self-consistent approach employing the Gogny D1S energy density functional yields discrepancies. This demonstrates once more the need for dynamical fission calculations, because for both models the potential-energy surfaces lack pronounced structures, in contrast to those for the actinide region. ispartof: Physical Review C, Nuclear Physics vol:90 issue:4 pages:1-6 status: published

We report a case of retroperitoneal hematoma presenting as femoral nerve pulsy on antiplatelet therapy. The patient, a 78-year-old man who had undergone antiplatelet treatment using ticlopidine, was admitted to our hospital with complaints of sudden-onset low abdominal and back pain. Computed tomography showed an iso-density mass in the right retroperitoneum within the psoas muscle. We made a diagnosis of retroperitoneal hematoma compressing the femoral nerve and performed an operation to remove the hematoma in order to decompress the femoral neuropathy. Postoperatively, the patient rapidly recovered from the femoral neuropathy. In the particular case in which no antagonist against the ticlopidine is available, surgical decompression could produce a good outcome.

A non-destructive and on-line diffusion tracing in Li ionic conductors has been demonstrated. As the tracer, the pulsed beam of the short-lived α-emitting radioisotope of 8Li was implanted into a typical Li ionic conductor LiGa. By analyzing the time-dependent yields of the α-particles measured in coincident with the repetition cycle of the beam, the tracer diffusion coefficients were extracted with a good accuracy. The ordering of the Li vacancies in the Li-deficient β phase of LiGa was observed for the first time in terms of the Li diffusion by the present method.

The countercurrent absorption of CO 2 from the flue gas into aqueous alkanolamines has been studied using wetted wall column equipment connected to the stack of a power plant. The absorption rates of CO 2 into aqueous alkanolamines (primary amine (monoethanolamine), hindered amine (2-amino-2-methyl-1-propanol), diol secondary amine (diethanolamine), secondary amine (2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(butylamino)ethanol), tertiary amine (2-(diethylamino)ethanol, 4-dimethylamino-1-butanol), diamine (2-(2-aminoethylamino)ethanol)) were measured at 40°C, 10kPa partial pressure, and 2m 3 /h of gas flow rate. From the rate of absorption and the absorption equilibrium results, the secondary amines have as large overall mass transfer coefficients as monoethanolamine. However, the coefficients of the hindered and tertiary amines are small even though the absorbed amounts of CO 2 at equilibrium are large. The CO 2 concentration profiles in a wetted wall column were estimated, and these results are due to the absorption process in connection with the degree of carbamate formation.

Fission fragment mass distributions were measured in the heavy-ion induced fission using 238U target nucleus. The mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and qasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model in the reactions of 30Si+238U and 34S+238U using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections of 263,264Sg and 267,268Hs, produced by 30Si+238U and 34S+238U, respectively. It is also suggested that the sub-barrier energies can be used for heavy element synthesis.

A novel method was tried successfully to trap ions and to freeze out their nuclear polarization inside aggregates of helium atoms, “snowballs”, in superfluid helium. Spin polarized12B (T1/2=20.4 ms) ions were introduced into superfluid helium and snowballs were created around the impinged impurity ions. Beta-ray asymmetry was measured to obtain the nuclear polarization of decaying12B. The comparison with the initial value of12B polarization produces that no relaxation in polarization was observed throughout lifetime of12B.

The magnetic moments of $^{17}\mathrm{N}$ and $^{17}\mathrm{B}$ were measured by using spin-polarized radioactive nuclear beams which were obtained from the projectile fragmentation reaction. The observed magnetic moment of $^{17}\mathrm{N}$, \ensuremath{\Vert}\ensuremath{\mu}${(}^{17}$N)\ensuremath{\Vert}=(0.352\ifmmode\pm\else\textpm\fi{}0.002)${\mathrm{\ensuremath{\mu}}}_{\mathit{N}}$, where ${\mathrm{\ensuremath{\mu}}}_{\mathit{N}}$ is the nuclear magneton, falls outside the Schmidt lines. By virtue of a simplifying feature of nuclear structure inherent in a ${\mathit{p}}_{1/2}$ valence nucleus, the deviation from the Schmidt value is attributed on firm ground to admixing of the configurations in which two neutrons in the sd shell are coupled to ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$=${2}^{+}$. This interpretation is confirmed in standard shell-model calculations. The calculations reproduce fairly well the experimentally inferred amount of ${2}^{+}$ admixture, as well as the experimental magnetic moment itself. The magnetic moment for $^{17}\mathrm{B}$ was determined as \ensuremath{\Vert}\ensuremath{\mu}${(}^{17}$B)\ensuremath{\Vert}=(2.545\ifmmode\pm\else\textpm\fi{}0.020)${\mathrm{\ensuremath{\mu}}}_{\mathit{N}}$. The result is substantially smaller than the \ensuremath{\pi}${\mathit{p}}_{1/2}$ single-particle value, and the shell-model calculations indicate that the quenching of \ensuremath{\mu} largely stems from ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$=${2}^{+}$ configurations of the sd neutrons. The observed amount of quenching, however, is larger than the shell-model predictions, suggesting an enhanced contribution of the ${2}^{+}$ neutron configurations. This result is explained if the pairing energy for neutrons in the sd shell of a neutron-rich nucleus is assumed to diminish by about 30%. We also find that the use of the reduced pairing energy improves agreements in the magnetic moment and low-lying energy levels of $^{17}\mathrm{N}$ as well. \textcopyright{} 1996 The American Physical Society.

A projectile-fragment separator, secondary beam line, has been constructed at RCNP for use with the K = 400 ring cyclotron. Products of the projectile fragmentation reactions are isotopically separated by making use of their energy-loss effect in an energy degrader. Unlike the existing separators of similar kind, a homogeneously thick degrader is used and achromatic focus is achieved by the optics of the magnetic system. The separator was designed so as to possess a high ion-optical flexibility which allows the use of degraders of widely ranged thickness. For commissioning the separator, a detailed experimental analysis of the optics was carried out to realize the design performance, and a prescription to correctly determine the strengths of focusing devices was established. The operational performance of the separator is presented.

The influence of the structure of projectile and target nuclei on the capture cross sections was investigated for the reactions ${}^{34}\mathrm{S}\phantom{\rule{0.16em}{0ex}}+{\phantom{\rule{0.16em}{0ex}}}^{204,206,208}$Pb and ${}^{36}\mathrm{S}\phantom{\rule{0.16em}{0ex}}+{\phantom{\rule{0.16em}{0ex}}}^{204,206,208}$Pb. Capture cross sections were deduced by measuring the fission fragments using multiwire proportional counters. An enhancement of the capture cross sections relative to a one-dimensional barrier penetration model was observed for all reactions at energies below the interaction barriers. The enhancement is larger in the case of reactions with ${}^{34}$S than with ${}^{36}$S. This observation is explained by a stronger coupling to the vibrational states in the reactions with ${}^{34}$S. Comparing the capture cross sections and the evaporation-residue cross sections for the reactions ${}^{36}\mathrm{S}\phantom{\rule{0.16em}{0ex}}+{\phantom{\rule{0.16em}{0ex}}}^{206}$Pb and ${}^{34}\mathrm{S}\phantom{\rule{0.16em}{0ex}}+{\phantom{\rule{0.16em}{0ex}}}^{208}$Pb, both yielding the same compound nucleus ${}^{242}$Cf, it is shown that the latter reaction has a lower fusion probability.

Phenomenon of ejectile spin polarization in the projectile fragmentation reaction was exploited as a tool to produce polarized radioactive nuclei. The polarized unstable nuclei were subjected to the β-detected NMR meaurements, and the magnetic moments and electric quadrupole moments were determined for several neutron-rich light nuclei. The comparison of the experimental results with theoretical predictions shows that the nuclear moments provide useful test of models for nuclear structure and interaction in the region of light-mass unstable nuclei.

Beams of unstable nuclei, 8 Li and spin-polarized 12 B, were introduced into superfluid helium and “snowballs”, aggregates of helium atoms surrounding the singly charged impurity ions, were formed through electrostriction. β-rays from the unstable nuclei encapsulated in the snowballs were detected after the snowballs were transported under an electrostatic field. It was found that approximately 20 % of the implanted ions formed snowballs. The spin polarization of 12 B in snowballs was measured by β-NMR method. The first decisive evidence was obtained that the polarization was maintained throughout the lifetime of 12 B ( τ = 29 ms). The snowballs can be versatile environments for spectroscopic studies of unstable nuclei

Excitation functions of the 12C(16O, 8Be)20Ne reaction leading to some low-lying states in 20Ne have been studied at Ec.m. = 22∼29 MeV. Some new resonances are identified with fluctuation analysis, and their spin and parity are determined. If we plot them on a Ec.m. vs. J(J + 1) plane together with resonances reported previously in the same reaction channel, they seem to constitute a rotational band which coincides with the elastic band of the 8 Be + 20 Ne system rather than with that of the 12 C + 16 O system. Furthermore these resonances are found to persist in having almost negligible correlation in energy with those identified in the 12 C + 16 O channels. A resonance at Ec.m. = 26.9 MeV which has been proposed by Eswaran et al. as a superdeformed shape isomeric state is not identified in the present data.

The tilted-foil method for producing spin-polarized radioactive isotope beams has been studied for the application to nuclear physics and materials science, using the radioactive nucleus 8Li ( $\ensuremath I^{\pi}=2^+$ , g = 0.82678(9) , $\ensuremath T_{1/2}=0.838(6)$ s) produced at the Tokai Radioactive Ion Accelerator Complex (TRIAC). We successfully produced polarization in a 8Li beam of $\ensuremath 7.3\pm0.5$ % using 15 thin polystyrene foils (4.2 $\ensuremath \mu \mathrm{g/cm}^2$ fabricated especially for this purpose. A systematic study of the nuclear polarization as a function of the number of foils, beam energy, tilt angle and foil material has been performed, confirming the features of the tilted-foil technique experimentally. The contributions made to the nuclear polarization of 8Li nuclei by the atomic states was investigated.

We have measured the γ-ray angular distribution of the 12C(α,γ)16O reaction at TRIAC (Tokai Radioactive Ion Accelerator Complex) to accurately determine the E1 and E2 cross sections. In this experiment, we used high efficiency anti-Compton NaI(T1) spectrometers to detect a γ-ray from the reaction with large S/N ratio, intense pulsed α-beams to discriminate true event from background events due to neutrons from 13C(α,n)16O reaction with a time-of-flight (TOF) method. We succeeded in removing a background events due to neutrons and clearly detected γ-ray from the 12C(αγ)16O reaction with high statistics.

Magnetic substate populations for the ${2}^{+}$ state at 4.44 MeV in $^{12}\mathrm{C}$ were measured in resonant $^{12}\mathrm{C}$${+}^{16}$O inelastic scattering by the \ensuremath{\gamma}-ray recoil method. The m-substate population has been determined in the coordinate frame where a quantization axis is taken along the center of mass scattering angle of a reaction product. This coordinate frame gives an advantage that a resonance spin J can be obtained directly from m-substate angular distributions compared with the beam-axis frame. In addition a decay L value is sensitive to the relative intensity between each m-substate cross section. Our data suggest a spin assignment of ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$=${16}^{+}$ or ${17}^{\mathrm{\ensuremath{-}}}$ for the structures at ${\mathit{E}}_{\mathrm{c}.\mathrm{m}.}$=29.8 MeV and 31.8 MeV. Both structures are determined to decay dominantly through the aligned configuration of L=J-2.

A spin-polarized radioactive 123In (Iπ, g = 1.220(2) , T1/2 = 5.97(5) s) beam has been successfully generated by the tilted-foil method. This nuclide is the heaviest ever polarized in its ground state by this method. Using the ISOL-based re-acceleration-type facility TRIAC, an 123Ing.s. beam of 305 keV/nucleon went through a stack of 15 carbon foils with a tilt angle of 70° , and an asymmetry of 0.76 ± 0.25% of β-decays was observed by the β-NMR technique. The asymmetry shows that the tilted-foil method combined with a re-acceleration facility is useful for producing spin-polarized beams for applications such as nuclear physics and materials science.

Fragment mass distributions for fission after full momentum transfer were measured in the reactions of 30 Si,34,36 S,31 P,40 Ar + 238 U at bombarding energies around the Coulomb barrier. Mass distributions change significantly as a function of incident beam energy. The asymmetric fission probability increases at sub-barrier energy. The phenomenon is interpreted as an enhanced quasifission probability owing to orientation effects on fusion and/or quasifission. The evaporation residue (ER) cross sections were measured in the reactions of 30 Si + 238 U and 34 S + 238 U to obtain information on fusion. In the latter reaction, significant suppression of fusion was implied. This suggests that fission events different from compound nucleus are included in the masssymmetric fragments. The results are supported by a model calculation based on a dynamical calculation using Langevin equation, in which the mass distribution for fusion-fission and quasifission fragments are separately determined.

Fragment mass distributions for fission after full momentum transfer were measured for the $^{30}\mathrm{Si}$$+$$^{238}\mathrm{U}$ reaction at bombarding energies around the Coulomb barrier. At energies above the Bass barrier, the mass distributions were Gaussian with mass symmetry. An asymmetric fission channel with mass ${A}_{\mathrm{L}}/{A}_{\mathrm{H}}$ $\ensuremath{\approx}$ $90/178$ emerged at the sub-barrier energies, where competition between fusion and quasifission was suggested from the evaporation residue (ER) cross section produced in the fusion $^{30}\mathrm{Si}$$+$$^{238}\mathrm{U}$. We thus conclude the asymmetric channel is attributed to quasifission. It was supported by a model calculation using the Langevin equation to give the fragment mass distribution, where fusion-fission and quasifission were separated. The observed mass asymmetry for quasifission as well as the calculation is significantly smaller than those observed in actinide targets bombarded with heavier projectiles, which suggests that the system $^{30}\mathrm{Si}$$+$$^{238}\mathrm{U}$ approaches the shape of the compound nucleus before disintegrating as quasifission.

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.

Fission fragment mass distributions in the reaction of 30Si+238U were measured at the energies around the Coulomb barrier. At the above‐barrier energies, the mass distribution showed Gaussian shape. At the sub‐barrier energies, asymmetric fission mode peaked at AL/AH≈90/178 was observed. The asymmetric fission should be attributed to quasifission from the results of the measured evaporation residue (ER) cross‐sections produced by 30Si+238U. The cross‐section for 263Sg at the above‐barrier energy agree with the statistical model calculation which assumes that the measured fission cross‐sections are equal to the fusion cross‐sections, whereas the one for 264Sg measured at the sub‐barrier energy is smaller than the calculation, indicating the presence for quasifission. The fragment mass distributions are compared to those for 36S+238U and 40Ar+238U.

Fission fragment mass distributions in the reaction of 30Si+238U were measured at the energies around the Coulomb barrier. At the above‐barrier energies, the mass distribution showed Gaussian shape. At the sub‐barrier energies, triple‐humped distribution was observed, which consists of symmetric fission and asymmetric fission peaked at AL/AH≈90/178. The asymmetric fission should be attributed to quasifission from the results of the measured evaporation residue (ER) cross‐sections produced by 30Si+238U. The cross‐section for 263Sg at the above‐barrier energy agree with the statistical model calculation which assumes that the measured fission cross‐sections are equal to the fusion cross‐sections, whereas the one for 264Sg measured at the sub‐barrier energy is smaller than the calculation, indicating the presence for quasifission. We also report the results on the fragment mass distributions for 36,34S+238U and 40Ar+238U.

We have developed an active‐target type gas‐detector, a Gas Electron Multiplier Multiple‐Sampling and Tracking Proportional Chamber (GEM‐MSTPC) operating with low‐pressure He‐base mixed gas, where He is used as a target for studies of astrophysical nuclear reaction rates. Different kinds of 400 μm thick GEMs were examined. The gain stability was examined with a configuration of GEMs of 400 μm in thickness fabricated in different ways, against the injection rate of low‐energy heavy ions of 105 particles per second. The gain of GEM with Cu electrodes coated by Au was observed to be stable up to the injection rate of 105 particles per second.

In Japan, electric power companies account for about 30% of the total emitted CO2. Considering this, the Kansai Electric Company and Mitsubishi Heavy Industries are actively conducting research into flue gas carbon dioxide recovery. The research involves laboratory tests, bench scale tests, pilot plant tests and feasibility studies. The main efforts have been directed towards evaluating CO2 absorption performance, treating impurities in the flue gas and finding the most efficient integration of the CO2 recovery system into thermal power plants. This paper presents the results of these studies and outlines the areas where cost and energy savings can be made, to allow the practical use of flue gas carbon dioxide recovery processes in the power plant.

In order to study the nucleus‐nucleus interaction in Pb‐based cold fusion, we have measured excitation functions for quasi‐elastic scattering of 48Ti, 54Cr, 56Fe, 64Ni, 70Zn and 86Kr projectiles on 208Pb target at backward angles. The barrier distributions were derived from the first derivative of measured quasi‐elastic scattering cross sections relative to the Rutherford scattering cross section. The centroids of the barrier distributions show a deviation from several predicted barrier heights toward the low energy side. The shape of the barrier distributions is well reproduced by the results of a coupled‐channel calculation taking account of the coupling effects of two phonon excitations of the quadrupole vibration for the projectiles and of the octupole vibration for the 208Pb target.

Effects of nuclear orientation on fission fragment mass distributions in the reactions of 30Si36,34S+238U were investigated. In the reactions for 30Si+238U, the mass distributions showed a Gaussian shape in the above barrier region, having a character of fusion‐fission. At the sub‐barrier energies, the asymmetric fission component around AL/AH≈90/178 appears. The asymmetric fission is attributed to quasifission. Strong variation of the mass distributions with energy is observed for the reactions of 36,34S+238U. The results suggested the competition between fusion and quasifission, resulting from the orientation effects of the deformed target nuclei on the reaction.

Effects of nuclear orientation on fission fragment mass distributions in the reaction of 30Si+238U were investigated. The mass distributions showed a Gaussian shape in the above barrier region, having a character of fusion‐fission. At the sub‐barrier energies, the asymmetric fission component around AL/AH≈90/178 appears, representing quasifision. The measured evaporation residue cross sections for 30Si+238U in [1] have also suggested the competition between fusion and quasifission at sub‐barrier region, whereas the fusion is the main process in the above barrier region. These results suggest an influence of orientation effects of the deformed target nuclei on the reaction. Discussion will be given on the difference in the mass distributions between 30Si+238U and 36S+238U.

Fission fragment mass distributions in the reactions of 34,36S+238U were measured at bombarding energies around the Coulomb barrier. The data showed a transition from symmetric to asymmetric mass distributions when the beam energies were decreased from the above‐barrier to sub‐barrier values. The asymmetric fission is attributed to quasifission of the reacting system at polar collisions, whereas the symmetric fission originates from the compound nucleus produced in equatorial collisions. The results suggest a influence of orientation effects of the deformed target nuclei on fusion.

Two systems of 64Ni+118Sn and 58Ni+124Sn produce the same compound nucleus 182Pt in the fusion reaction and they show the similar fusion cross sections below and near the Coulomb barriers, although only the system of 58Ni+124Sn has positive Q‐value multi‐neutron transfer channels of 1–11 neutron(s). In order to investigate the possible effect of positive Q‐value multi‐neutron transfer channels on the capture cross sections, the quasi‐elastic back‐scattering for the two systems were measured below and near the Coulomb barriers at the backward angles of 162° and 172°. The beam energies were altered in the energy range and the quasi‐elastic back‐scattering excitation functions were obtained. They were compared with the coupled‐channel calculations of collective excitations and a two‐neutron transfer channel, indicating no evidence of a significant effect of the positive Q‐value multi‐neutron transfer channels on the capture cross sections for the system of 58Ni+124Sn.

Fragment mass distributions for fission after full momentum transfer were measured for the reaction {sup 36}S+{sup 238}U at bombarding energies around the Coulomb barrier. The data revealed a transition from symmetry to asymmetry mass distributions when the beam energies were decreased from above-barrier to sub-barrier values. The main components of the asymmetric mass distribution are at A{sub H}{approx_equal}200 and A{sub L}{approx_equal}74. The asymmetric fission is attributed to quasifission of the reacting system at polar collisions, whereas the symmetric fission originates from the compound nucleus produced in equatorial collisions. The results suggest a strong influence of orientation effects of the deformed target nuclei on fusion.