Acta Physica Hungarica A) Heavy Ion Physics, Nov 1, 2003
We investigate the structural and quantum transport properties of isotopically enriched 28 Si/ 28... more We investigate the structural and quantum transport properties of isotopically enriched 28 Si/ 28 SiO 2 stacks deposited on 300-mm Si wafers in an industrial CMOS fab. Highly uniform films are obtained with an isotopic purity greater than 99.92%. Hall-bar transistors with an oxide stack comprising 10 nm of 28 SiO 2 and 17 nm of Al 2 O 3 (equivalent oxide thickness of 17 nm) are fabricated in an academic cleanroom. A critical density for conduction of 1.75 × 10 11 cm −2 and a peak mobility of 9800 cm 2 /Vs are measured at a temperature of 1.7 K. The 28 Si/ 28 SiO 2 interface is characterized by a roughness of = 0.4 nm and a correlation length of = 3.4 nm. An upper bound for valley splitting energy of 480 μeV is estimated at an effective electric field of 9.5 MV/m. These results support the use of wafer-scale 28 Si/ 28 SiO 2 as a promising material platform to manufacture industrial spin qubits.
Zeitschrift Für Physik A Hadrons And Nuclei, Sep 1, 1992
The binary decay properties of the 477 nucleus, produced in the 35C1 + 12C reaction, have been in... more The binary decay properties of the 477 nucleus, produced in the 35C1 + 12C reaction, have been investigated at the 35C1 bombarding energies Elab=180 and 200 MeV by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and a characteristic 1/sin(0om) angular distribution. The elemental distribution of the fully-damped products is asymmetric, similar to what has previously been observed in the decay of the 56Ni nucleus. Comparison with theoretical model predictions suggests the occurrence of a fusion-fission rather than orbiting process. Moreover the calculations performed using the Extended Hauser-Feshbach Method reproduce well the experimental fission yields~ A general discussion of orbiting and fusionfission experimental data of light heavy-ion systems is presented in the framework of the calculated number of available open channels for these systems.
Resonances observed in the 12 C + 12 C collisions are studied with a molecular model. At high spi... more Resonances observed in the 12 C + 12 C collisions are studied with a molecular model. At high spins J = 12-16, a stable dinuclear configuration is found to be an equatorequator touching one as is obtained in the 28 Si + 28 Si system. With K-quantum number being specified as rotation-vibration model, normal modes have been solved around the equilibrium, firstly. Furthermore, Coriolis coupling has been investigated by diagonalization among lowlying normal-mode states with K = 0 and K-excitation. It is found that the Coriolis coupling introduces about 30% of K-mixing into the K = 0 molecular ground states of J = 12-16. The analyses of the angular momentum coupling show up a dominance of the lowest L in the inelastic channel of the molecular ground state newly obtained. Thus alignments appear strongly in the inelastic channel, which is in agreement with the explanation by the band crossing model. Discussion is given on "why disalignments appear in the 28 Si + 28 Si system, in contrast to the above results".
Dynamical treatments of fission processes are briefly reviewed with an emphasis on the strong dis... more Dynamical treatments of fission processes are briefly reviewed with an emphasis on the strong dissipation or friction for collective motions of nuclei in high excitation. The theories are applied to synthesis of superheavy elements. Characteristic features of formation and surviving are discussed with reference to possible incident channels. Theoretical prediction are presented on favorable incident channels and on optimum energies for synthesis of the element Z = 114.
High-spin resonances observed in 28 Si + 28 Si collisions are studied with a dinuclear molecular ... more High-spin resonances observed in 28 Si + 28 Si collisions are studied with a dinuclear molecular model. At high spins, a stable dinuclear configuration of the oblate-oblate system (28 Si + 28 Si) is found to be an equator-equator (E-E) touching one. Normal modes have been investigated around the equilibrium, which are expected to be an origin of a large number of the resonances observed. Analyses of physical quantities are made and compared with the recent experimental data measured at Strasbourg. Since the E-E configuration is slightly triaxial, rotations of the total system induce mixing of K quantum numbers, called wobbling motion, which clearly explains the particle-γ angular correlations observed as well as the disalignments observed in the angular distributions, in a simple and natural way. Furthermore, predictions are given for the angular correlations of the wobbling excited states. The importance of the angular correlation measurements is stressed, which provide identification of the dinuclear configurations by spin orientations of the constituent nuclei 28 Si.
KEWPIE-a cascade code devoted to investigating the dynamical decay of excited nuclei, specially d... more KEWPIE-a cascade code devoted to investigating the dynamical decay of excited nuclei, specially designed for treating very low probability events related to the synthesis of super-heavy nuclei formed in fusion-evaporation reactions-has been improved and rewritten in C++ programing language to become KEWPIE2. The current version of the code comprises various nuclear models concerning the light-particle emission, fission process and statistical properties of excited nuclei. General features of the code, such as the numerical scheme and the main physical ingredients, are described in detail. Some typical calculations having been performed in the present paper clearly show that theoretical predictions are generally in accordance with experimental data. Furthermore, since the values of some input parameters cannot be determined neither theoretically nor experimentally, a sensibility analysis is presented. To this end, we systematically investigate the effects of using different parameter values and reaction models on the final results. As expected, in the case of heavy nuclei, the fission process has the most crucial role to play in theoretical predictions. This work would be essential for numerical modeling of fusion-evaporation reactions.
The fusion-fission process in heavy systems is analyzed by the Smoluchowski equation with the fin... more The fusion-fission process in heavy systems is analyzed by the Smoluchowski equation with the finite-range droplet model potential of no pocket and the temperature-dependent shell correction energy which generates the pocket around the spherical shape. The evaporation residue cross sections of superheavy elements have been shown to have an optimum value at a certain initial temperature, due to the balance between the diffusibility for fusion at high temperature and the restoration of the shell correction energy against fission at low temperature. ͓S0556-2813͑97͒50303-7͔
Synthesis of superheavy elements beyond oganesson is facing new challenges as new target-projecti... more Synthesis of superheavy elements beyond oganesson is facing new challenges as new target-projectile combinations are necessary. Guidance from models is thus expected for future experiments. However, hindered fusion models are not well established and predictions in the fission barriers span few MeVs. Consequently, predictions are not reliable. Strategies to constrain both fusion hindrance and fission barriers are necessary to improve the predictive power of the models. But, there is no hope to get an accuracy better than one order of magnitude in fusion-evaporation reactions leading to superheavy elements synthesis.
We measured gamma-ray multiplicity and light charged particle (LCP) multiplicity simultaneously i... more We measured gamma-ray multiplicity and light charged particle (LCP) multiplicity simultaneously in coincidence with binary decay fragments in the reactions of 84Kr (10.6 and 8.5 MeV/nucleon)+27Al and 58Ni (10.0 MeV/nucleon)+56Fe. We observed the prescission time and charge distribution of heavy fragments as a function of the angular momentum of the system applying the measured gamma-ray multiplicity as an angular momentum
We have deduced the prescission time of hot nuclei as a function of the angular momentum from the... more We have deduced the prescission time of hot nuclei as a function of the angular momentum from the light charged particle-and g ray-multiplicities measured simultaneously in coincidence with fully-damped binary decay fragments in the reaction of 58 Ni q 56 Fe at the incident energy of 10.0 MeVrnucleon. The prescission time was found to decrease as the angular momentum of the system increases. Theoretical calculations of the fissioning motion with the Langevin equation have shown that this dependence originates primarily from the change in the potential landscape due to the centrifugal energy. q 1998 Elsevier Science B.V.
Progress of Theoretical and Experimental Physics, May 1, 2012
Resonances observed in the 28 Si + 28 Si collision are studied by the molecular model. In the pre... more Resonances observed in the 28 Si + 28 Si collision are studied by the molecular model. In the preceding paper, it is clarified that at high spins in 28 Si + 28 Si (oblate-oblate system), the stable dinuclear configuration of the system is equator-equator touching one, and that the axially asymmetric shape of the stable configuration of 28 Si + 28 Si gives rise to a wobbling motion (K-mixing). There, the normal modes around the equilibrium have been solved and various excited states have been obtained. Those states are expected to be the origin of a large number of resonances observed. Hence their physical quantities are analyzed theoretically. The results are compared with the recent experiment performed in Strasbourg and turn out to be in good agreement with the data. Disalignments between the orbital angular momentum and the spins of the constituent 28 Si nuclei in the resonance state are clarified. Moreover the analyses of the angular correlations indicate characteristic features for each normal-mode excitation. Thus it is possible to identify the modes, and a systematic experimental study of angular correlation measurements is desired.
Acta Physica Hungarica A) Heavy Ion Physics, Nov 1, 2003
We investigate the structural and quantum transport properties of isotopically enriched 28 Si/ 28... more We investigate the structural and quantum transport properties of isotopically enriched 28 Si/ 28 SiO 2 stacks deposited on 300-mm Si wafers in an industrial CMOS fab. Highly uniform films are obtained with an isotopic purity greater than 99.92%. Hall-bar transistors with an oxide stack comprising 10 nm of 28 SiO 2 and 17 nm of Al 2 O 3 (equivalent oxide thickness of 17 nm) are fabricated in an academic cleanroom. A critical density for conduction of 1.75 × 10 11 cm −2 and a peak mobility of 9800 cm 2 /Vs are measured at a temperature of 1.7 K. The 28 Si/ 28 SiO 2 interface is characterized by a roughness of = 0.4 nm and a correlation length of = 3.4 nm. An upper bound for valley splitting energy of 480 μeV is estimated at an effective electric field of 9.5 MV/m. These results support the use of wafer-scale 28 Si/ 28 SiO 2 as a promising material platform to manufacture industrial spin qubits.
Zeitschrift Für Physik A Hadrons And Nuclei, Sep 1, 1992
The binary decay properties of the 477 nucleus, produced in the 35C1 + 12C reaction, have been in... more The binary decay properties of the 477 nucleus, produced in the 35C1 + 12C reaction, have been investigated at the 35C1 bombarding energies Elab=180 and 200 MeV by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and a characteristic 1/sin(0om) angular distribution. The elemental distribution of the fully-damped products is asymmetric, similar to what has previously been observed in the decay of the 56Ni nucleus. Comparison with theoretical model predictions suggests the occurrence of a fusion-fission rather than orbiting process. Moreover the calculations performed using the Extended Hauser-Feshbach Method reproduce well the experimental fission yields~ A general discussion of orbiting and fusionfission experimental data of light heavy-ion systems is presented in the framework of the calculated number of available open channels for these systems.
Resonances observed in the 12 C + 12 C collisions are studied with a molecular model. At high spi... more Resonances observed in the 12 C + 12 C collisions are studied with a molecular model. At high spins J = 12-16, a stable dinuclear configuration is found to be an equatorequator touching one as is obtained in the 28 Si + 28 Si system. With K-quantum number being specified as rotation-vibration model, normal modes have been solved around the equilibrium, firstly. Furthermore, Coriolis coupling has been investigated by diagonalization among lowlying normal-mode states with K = 0 and K-excitation. It is found that the Coriolis coupling introduces about 30% of K-mixing into the K = 0 molecular ground states of J = 12-16. The analyses of the angular momentum coupling show up a dominance of the lowest L in the inelastic channel of the molecular ground state newly obtained. Thus alignments appear strongly in the inelastic channel, which is in agreement with the explanation by the band crossing model. Discussion is given on "why disalignments appear in the 28 Si + 28 Si system, in contrast to the above results".
Dynamical treatments of fission processes are briefly reviewed with an emphasis on the strong dis... more Dynamical treatments of fission processes are briefly reviewed with an emphasis on the strong dissipation or friction for collective motions of nuclei in high excitation. The theories are applied to synthesis of superheavy elements. Characteristic features of formation and surviving are discussed with reference to possible incident channels. Theoretical prediction are presented on favorable incident channels and on optimum energies for synthesis of the element Z = 114.
High-spin resonances observed in 28 Si + 28 Si collisions are studied with a dinuclear molecular ... more High-spin resonances observed in 28 Si + 28 Si collisions are studied with a dinuclear molecular model. At high spins, a stable dinuclear configuration of the oblate-oblate system (28 Si + 28 Si) is found to be an equator-equator (E-E) touching one. Normal modes have been investigated around the equilibrium, which are expected to be an origin of a large number of the resonances observed. Analyses of physical quantities are made and compared with the recent experimental data measured at Strasbourg. Since the E-E configuration is slightly triaxial, rotations of the total system induce mixing of K quantum numbers, called wobbling motion, which clearly explains the particle-γ angular correlations observed as well as the disalignments observed in the angular distributions, in a simple and natural way. Furthermore, predictions are given for the angular correlations of the wobbling excited states. The importance of the angular correlation measurements is stressed, which provide identification of the dinuclear configurations by spin orientations of the constituent nuclei 28 Si.
KEWPIE-a cascade code devoted to investigating the dynamical decay of excited nuclei, specially d... more KEWPIE-a cascade code devoted to investigating the dynamical decay of excited nuclei, specially designed for treating very low probability events related to the synthesis of super-heavy nuclei formed in fusion-evaporation reactions-has been improved and rewritten in C++ programing language to become KEWPIE2. The current version of the code comprises various nuclear models concerning the light-particle emission, fission process and statistical properties of excited nuclei. General features of the code, such as the numerical scheme and the main physical ingredients, are described in detail. Some typical calculations having been performed in the present paper clearly show that theoretical predictions are generally in accordance with experimental data. Furthermore, since the values of some input parameters cannot be determined neither theoretically nor experimentally, a sensibility analysis is presented. To this end, we systematically investigate the effects of using different parameter values and reaction models on the final results. As expected, in the case of heavy nuclei, the fission process has the most crucial role to play in theoretical predictions. This work would be essential for numerical modeling of fusion-evaporation reactions.
The fusion-fission process in heavy systems is analyzed by the Smoluchowski equation with the fin... more The fusion-fission process in heavy systems is analyzed by the Smoluchowski equation with the finite-range droplet model potential of no pocket and the temperature-dependent shell correction energy which generates the pocket around the spherical shape. The evaporation residue cross sections of superheavy elements have been shown to have an optimum value at a certain initial temperature, due to the balance between the diffusibility for fusion at high temperature and the restoration of the shell correction energy against fission at low temperature. ͓S0556-2813͑97͒50303-7͔
Synthesis of superheavy elements beyond oganesson is facing new challenges as new target-projecti... more Synthesis of superheavy elements beyond oganesson is facing new challenges as new target-projectile combinations are necessary. Guidance from models is thus expected for future experiments. However, hindered fusion models are not well established and predictions in the fission barriers span few MeVs. Consequently, predictions are not reliable. Strategies to constrain both fusion hindrance and fission barriers are necessary to improve the predictive power of the models. But, there is no hope to get an accuracy better than one order of magnitude in fusion-evaporation reactions leading to superheavy elements synthesis.
We measured gamma-ray multiplicity and light charged particle (LCP) multiplicity simultaneously i... more We measured gamma-ray multiplicity and light charged particle (LCP) multiplicity simultaneously in coincidence with binary decay fragments in the reactions of 84Kr (10.6 and 8.5 MeV/nucleon)+27Al and 58Ni (10.0 MeV/nucleon)+56Fe. We observed the prescission time and charge distribution of heavy fragments as a function of the angular momentum of the system applying the measured gamma-ray multiplicity as an angular momentum
We have deduced the prescission time of hot nuclei as a function of the angular momentum from the... more We have deduced the prescission time of hot nuclei as a function of the angular momentum from the light charged particle-and g ray-multiplicities measured simultaneously in coincidence with fully-damped binary decay fragments in the reaction of 58 Ni q 56 Fe at the incident energy of 10.0 MeVrnucleon. The prescission time was found to decrease as the angular momentum of the system increases. Theoretical calculations of the fissioning motion with the Langevin equation have shown that this dependence originates primarily from the change in the potential landscape due to the centrifugal energy. q 1998 Elsevier Science B.V.
Progress of Theoretical and Experimental Physics, May 1, 2012
Resonances observed in the 28 Si + 28 Si collision are studied by the molecular model. In the pre... more Resonances observed in the 28 Si + 28 Si collision are studied by the molecular model. In the preceding paper, it is clarified that at high spins in 28 Si + 28 Si (oblate-oblate system), the stable dinuclear configuration of the system is equator-equator touching one, and that the axially asymmetric shape of the stable configuration of 28 Si + 28 Si gives rise to a wobbling motion (K-mixing). There, the normal modes around the equilibrium have been solved and various excited states have been obtained. Those states are expected to be the origin of a large number of resonances observed. Hence their physical quantities are analyzed theoretically. The results are compared with the recent experiment performed in Strasbourg and turn out to be in good agreement with the data. Disalignments between the orbital angular momentum and the spins of the constituent 28 Si nuclei in the resonance state are clarified. Moreover the analyses of the angular correlations indicate characteristic features for each normal-mode excitation. Thus it is possible to identify the modes, and a systematic experimental study of angular correlation measurements is desired.
Uploads
Papers by Abe Yasuhisa