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Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Nagaya, Yasunobu; Tada, Kenichi; et al.
EPJ Web of Conferences, 284, p.14001_1 - 14001_7, 2023/05
Times Cited Count：0 Percentile：0.21(Nuclear Science & Technology)Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Abe, Yutaka*; Tsubakihara, Kosuke*; Okumura, Shin*; Ishizuka, Chikako*; Yoshida, Tadashi*; et al.
Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01
Times Cited Count：64 Percentile：99.99(Nuclear Science & Technology)Aritomo, Yoshihiro*; Iwamoto, Akira*; Nishio, Katsuhisa; Ota, Masahisa*
Physical Review C, 105(3), p.034604_1 - 034604_8, 2022/03
Times Cited Count：2 Percentile：52.69(Physics, Nuclear)Iimura, Hideki; M
ller, P.*; Ichikawa, Takatoshi*; Sagawa, Hiroyuki*; Iwamoto, Akira*
JPS Conference Proceedings (Internet), 6, p.030102_1 - 030102_4, 2015/06
no abstracts in English
Oizumi, Akito; Akie, Hiroshi; Iwamoto, Nobuyuki; Kugo, Teruhiko
Journal of Nuclear Science and Technology, 51(1), p.77 - 90, 2014/01
Times Cited Count：4 Percentile：30.92(Nuclear Science & Technology)Ichikawa, Takatoshi*; Iwamoto, Akira; Mller, P.*; Sierk, A. J.*
Physical Review C, 86(2), p.024610_1 - 024610_8, 2012/08
Times Cited Count：68 Percentile：94.53(Physics, Nuclear)Fission-fragment mass distributions are asymmetric in fission of typical actinide nuclei for nucelon number 
in the range 
and proton number 
in the range 
. For somewhat lighter systems it has been observed that fission mass distributions are usually symmetric. However, a recent experiment showed that fission of 
Hg following electron capture on 
HI is asymmetric. An earlier experiment has shown fission of Hg and nearby nuclei is symmetric, but with hints of asymmetric yield distributions up to about 10 MeV above the saddle-point energy. We calculate potential-energy surfaces for a typical actinide nucleus and for 12 even isotopes in the range 
Hg-
Hg, demonstrating the radical differences between actinide and mervury potential surfaces. We discuss these differences and how the changing potential-energy structure along the mercury isotope chain affects the observed (a)symmetry of the fission fragments. We show that the mechanism of asymmetric fission is very different in proton-rich mercury isotopes compared to the actinide region.
Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.
Physical Review Letters, 105(25), p.252502_1 - 252502_5, 2010/12
Times Cited Count：189 Percentile：97.21(Physics, Multidisciplinary)
Cui, L.*; Iwamoto, Akira; Lian, J.-Q.*; Neoh, H.*; Maruyama, Toshiki; Horikawa, Yataro*; Hiramatsu, Keiichi*
Antimicrobial Agents and Chemotherapy, 50(2), p.428 - 438, 2006/02
Times Cited Count：170 Percentile：97.69(Microbiology)no abstracts in English
Ichikawa, Takatoshi; Iwamoto, Akira
Physical Review C, 71(6), p.067601_1 - 067601_4, 2005/06
Times Cited Count：0 Percentile：0.01(Physics, Nuclear)We estimate the decrease of the Coulomb-barrier height between colliding parters due to charge polarizations in the entrance channel for cold-fusion reactions. Since the Coulomb-repulsion force increases with increasing the proton numbers of the target and projectile such as cold-fusion reactions, it is expected that the charge distribution of the colliding nuclei is changed to some extent. The resulting charge distribution induced by this polarization decreases the interacting Coulomb energy between the colliding partners, whereas their own self energies increase due to the increase of the symmetry energy. We assume that the resulting charge displacements between protons and neutrons are the sum of the surface- and volume-charge components and estimate the extent of the charge polarization with the self energy on the basis of the droplet model. We show the difference between the charge polarization of light and heavy nuclei and the decrease of the Coulomb barrier height for synthesizing superheavy elements.
Ichikawa, Takatoshi; Iwamoto, Akira; Mller, P.*; Sierk, A. J.*
Physical Review C, 71(4), p.044608_1 - 044608_11, 2005/04
Times Cited Count：42 Percentile：89.81(Physics, Nuclear)We estimate the effective fusion barrier in the entrance channel in cold-fusion reactions in a model where the projectile deformation and quadrupole zero-point vibrational energy are taken into account. The effective fusion-barrier height is defined as the barrier energy at the target and projectile separation distance where the system becomes unstable with respect to projectile deformation. We also calculate five-dimensional potential-energy surfaces for the single compound system. For heavy systems the fusion barrier at touching becomes lower than the fission barrier just beyond the ground state of the compound system. Except for reactions in which the projectile is doubly magic or near doubly magic, the calculated quantities are consistent with the observed optimal energies for evaporation-residue formation.
Chikazumi, Shimpei*; Iwamoto, Akira
Chaos, Solitons and Fractals, 23(1), p.73 - 78, 2005/01
Times Cited Count：0 Percentile：0.02(Mathematics, Interdisciplinary Applications)To seek for a possible origin of fractal pattern in nature, we perform a molecular dynamics simulation for a fragmentation of an infinite fcc lattice. The fragmentation is induced by the initial condition of the model that the lattice particles have the Hubble-type radial expansion velocities. As time proceeds, the average density decreases and density fluctuation develops. By using the box counting method, it is found that the frequency-size plot of the density follows instantaneously a universal power-law for each Hubble constant up to the size of a cross-over. This cross-over size corresponds to the maximum size of fluctuation and is found to obey a dynamical scaling law as a function of time. This instantaneous generation of a nascent fractal is purely of dynamical origin and it shows us a new formation mechanism of a fractal patters different from the traditional criticality concept.
Iwamoto, Akira; Ichikawa, Takatoshi; Mller, P.*; Sierk, A. J.*
Nuclear Physics A, 738, p.499 - 502, 2004/06
Times Cited Count：4 Percentile：30.89(Physics, Nuclear)no abstracts in English
Se to 
CfMller, P.*; Sierk, A. J.*; Iwamoto, Akira
Physical Review Letters, 92(7), p.072501_1 - 072501_4, 2004/02
Times Cited Count：154 Percentile：95.61(Physics, Multidisciplinary)no abstracts in English
Fujii, Yasunori*; Iwamoto, Akira
Physical Review Letters, 91(26), p.261101_1 - 261101_4, 2003/12
Times Cited Count：41 Percentile：82.49(Physics, Multidisciplinary)no abstracts in English
Chikazumi, Shimpei*; Iwamoto, Akira
Physical Review C, 65(6), p.067601_1 - 067601_4, 2002/06
Times Cited Count：3 Percentile：21.48(Physics, Nuclear)no abstracts in English
Iwamoto, Akira; Mller, P.*; Madland, D. G.*; Sierk, A.*
Journal of Nuclear Science and Technology, 39(4), p.332 - 336, 2002/04
Times Cited Count：2 Percentile：17.03(Nuclear Science & Technology)The theoretical calculations on the most probable mass division in nuclear fission process are given. The model is based on the topographical analysis of the five-dimensional potential energy surface of more than 2.5 million mesh points. Special attention is paid to obtain the energies and deformations of the saddle points without using any approximation. The calculation tells us that there exist multiple saddle points in the static potential energy surface. The lowest and the next lowest saddle point play an important role for the fission process. Of these two saddle points, one is mass-symmetrically deformed and the other is mass-asymmetrically deformed and the relative heights of these two saddle points depend on the fissioning nuclei. In case of Fm isotopes, the relative height of two saddle points appears very sensitively, i.e., 
Fm has asymmetrically deformed lowest saddle point and in 
Fm, the lowest saddle point is symmetrically deformed. This feature explains the phenomenon called bimodal fission.
Iwamoto, Akira
Suri Kagaku, (465), p.10 - 17, 2002/03
no abstracts in English
Iwamoto, Akira; Yoshida, Tadashi; Takeuchi, Suehiro
JAERI-Conf 2001-014, 174 Pages, 2001/11
JAERI-Conf-2001-014.pdf:11.58MB
no abstracts in English
Mller, P.*; Madland, D. G.*; Sierk, A. J.*; Iwamoto, Akira
Nature, 409(6822), p.785 - 789, 2001/02
Times Cited Count：287 Percentile：99.33(Multidisciplinary Sciences)no abstracts in English
Chikazumi, Shimpei*; Maruyama, Toshiki; Chiba, Satoshi; Niita, Koji*; Iwamoto, Akira
Physical Review C, 63(2), p.024602_1 - 024602_10, 2001/02
Times Cited Count：20 Percentile：73.84(Physics, Nuclear)no abstracts in English
