241 research outputs found
Fission and quasifission toward the superheavy mass region
No full textThe pathway toward the production of superheavy elements (SHE) crosses
with the one of an in-depth study of the fission and quasifission processes.
Quasifission affects the probability of forming a compound nucleus (CN) after
capture and fission plays a decisive role during the cooling of the CN. To
search for optimal reactions to produce SHE in fusion reactions and to provide
an estimate of their production cross section measurements of the capture and
fusion cross sections along with the survival probabilities are a mandatory
task. Here an overview of the impact of fission and quasifission over the
synthesis of SHE is discussed along with the need to perform measurements
over a wide range of masses and energies
Fusion and fission of heavy and superheavy nuclei (experiment)
No full textThe scope of this review is to summarize the main advancements in the search of signatures of the compound nucleus fission and quasifission processes in heavy and superheavy systems. The understanding of fusion and fission in heavy and superheavy elements is needed for tracing paths aimed at reaching the island of stability situated near Z = 114-122 and N = 184. With increasing charge of the interacting nuclei other processes, like quasifission, emerge and compete against fusion. Hence also their study must be pursued. After a brief look at the experimental techniques, the behavior of several observables is extracted from the most recent data to aid in the disentanglement of the various competing processes which hinder the production of superheavy elements. (C) 2015 Elsevier B.V. All rights reserved
Inverse quasifission in the reactions Gd 156,160 + W 186
No full textBackground:
Low-energy multinucleon transfer reactions may be used for production of new neutron-enriched heavy nuclei.
Purpose:
Our aim is to investigate the influence of proton (Z=82) and neutron (N=82, 126) shells as well as orientation effects on the formation of reaction products in the inverse quasifission process in the reactions 156,160Gd + 186W.
Methods:
Mass, energy, and angular distributions of primary binary fragments formed in the reactions 156Gd+186W at an energy of 878 MeV, and 160Gd+186W at 860 and 935 MeV, have been measured using the double-arm time-of-flight spectrometer CORSET at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions (FLNR) at the Joint Institute for Nuclear Research (JINR), Dubna.
Results:
Enhancement in the yield of products with masses 200–215 u has been found for both reactions. The cross sections of the formation of trans-target fragments with masses around 208 u are found to be about 10μb at the Coulomb barrier energy and reach the level of 0.5 mb at the energy above the barrier for side-to-side collision.
Conclusions:
The enhanced yield of products with masses heavier than the target mass confirms the important role of the closed shells at
Z=82 and N=82, 126 in the inverse quasifission process in low-energy damped collisions. The orientation effect caused by the strong deformation of colliding nuclei can result in a gain in the yield of heavy target-like fragments
Publisher's Note: Inverse quasifission in the reactions <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Gd</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>156</mml:mn><mml:mo>,</mml:mo><mml:mn>160</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> + <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">W</mml:mi><mml:mprescripts /><mml:none /><mml:mn>186</mml:mn></mml:mmultiscripts></mml:math> [Phys. Rev. C <b>96</b> , 064621 (2017)]
No full textPhysics of Atomic Nuclei V. 66, I. 06
No full textPhysics of Atomic Nuclei -- June 2003
Volume 66, Issue 6, pp. 1009-1210
Exotic Nuclei: From Superheavies to Hyper- and Antimatter
W. Greiner
pp. 1009-1014 Full Text: PDF (294 kB)
Calculated Masses of Heaviest Nuclei
I. Muntian, Z. Patyk, and A. Sobiczewski
pp. 1015-1019 Full Text: PDF (173 kB)
The Study of Superheavy Elements at SHIP: Results and Plans
S. Hofmann
pp. 1020-1025 Full Text: PDF (147 kB)
An Idea for Predicting the Evaporation Residue Cross Section in Superheavy Mass Region
M. Ohta and Y. Aritomo
pp. 1026-1032 Full Text: PDF (248 kB)
Fusion–Fission Dynamics and Perspectives of Future Experiments
V. I. Zagrebaev, M. G. Itkis, and Yu. Ts. Oganessian
pp. 1033-1041 Full Text: PDF (1008 kB)
The Upgrade of the Kinematic Separator VASSILISSA—Experimental Results and Plans
A. V. Yeremin, A. V. Belozerov, M. L. Chelnokov, V. I. Chepigin, V. A. Gorshkov, A. P. Kabachenko, O. N. Malyshev, Yu. Ts. Oganessian, A. G. Popeko, R. N. Sagaidak, A. I. Svirikhin, S. Hofmann, G. Berek, I. Brida, and S. Saro
pp. 1042-1052 Full Text: PDF (302 kB)
Effect of Nuclear Shell Structure on Fusion Reaction
H. Ikezoe, K. Satou, S. Mitsuoka, K. Nishio, and S. C. Jeong
pp. 1053-1056 Full Text: PDF (173 kB)
Theory of Fusion for Superheavy Elements
Y. Abe, C. W. Shen, G. I. Kosenko, and D. Boilley
pp. 1057-1064 Full Text: PDF (243 kB)
The Mechanism of Compound Nucleus Formation in Complete Fusion of Two Massive Nuclei
V. V. Volkov
pp. 1065-1070 Full Text: PDF (262 kB)
Synthesis of Heavy and Superheavy Elements by Reactions of Massive Nuclei
G. Fazio, G. Giardina, A. Lamberto, R. Ruggeri, F. Bonsignore, R. Palamara, A. I. Muminov, A. K. Nasirov, B. Benoit, F. Hanappe, T. Materna, and L. Stuttgé
pp. 1071-1085 Full Text: PDF (342 kB)
Competition of Fusion and Quasifission in the Reactions Leading to Production of Superheavy Elements
M. Veselsky
pp. 1086-1094 Full Text: PDF (229 kB)
Cold Valleys of Superheavy Elements with Deformed Targets and Projectiles
S. Misicu and W. Greiner
pp. 1095-1104 Full Text: PDF (886 kB)
Analysis of Fusion–Fission Process with Neutron Evaporation in Superheavy Mass Region
Y. Aritomo and M. Ohta
pp. 1105-1113 Full Text: PDF (402 kB)
Reaction Dynamics at the Barrier for Heavy Compound Systems
D. Ackermann
pp. 1114-1117 Full Text: PDF (151 kB)
Fusion–Fission of Heavy and Superheavy Nuclei
M. G. Itkis, S. Beghini, A. A. Bogatchev, L. Corradi, O. Dorvaux, A. Gadea, G. Giardina, A. A. Goverdovski, F. Hanappe, I. M. Itkis, M. Jandel, J. Kliman, G. N. Kniajeva, N. A. Kondratiev, I. V. Korzyukov, E. M. Kozulin, L. Krupa, L. Latina, T. Materna, G. Montagnoli, K. J. Moody, Yu. Ts. Oganessian, I. V. Pokrovsky, V. A. Ponomarenko, E. V. Prokhorova, N. Rowley, A. Ya. Rusanov, F. Scarlassara, A. M. Stefanini, L. Stuttgé, S. Szilner, M. Trotta, A. M. Vinodkumar, and V. M. Voskressensky
pp. 1118-1124 Full Text: PDF (1520 kB)
Accuracy of the Chemical Data Evaluated from One-Atom-at-a-Time Experiments
I. Zvára
pp. 1125-1130 Full Text: PDF (174 kB)
Heavy Element Nuclear Chemistry at JAERI
Y. Nagame, M. Asai, H. Haba, K. Tsukada, I. Nishinaka, S. Goto, A. Toyoshima, K. Akiyama, M. Sakama, Y. L. Zhao, S. Ichikawa, and H. Nakahara
pp. 1131-1136 Full Text: PDF (202 kB)
New Outlook on the Possible Existence of Superheavy Elements in Nature
A. Marinov, S. Gelberg, D. Kolb, R. Brandt, and A. Pape
pp. 1137-1145 Full Text: PDF (246 kB)
Perspective for the Determination of Chemical Properties of Element 112
R. Eichler et al. (for a PSI–University Bern–GSI–TU Munich–FLNR–University Mainz–IMP Collaboration)
pp. 1146-1151 Full Text: PDF (236 kB)
Accuracy and Efficiency of Modern Methods for Electronic Structure Calculation on Heavy- and Superheavy-Element Compounds
A. V. Titov, N. S. Mosyagin, T. A. Isaev, and A. N. Petrov
pp. 1152-1162 Full Text: PDF (223 kB)
Probing Fission Time Scales with Neutrons and GDR Gamma Rays
R. P. Schmitt, T. Botting, G. G. Chubarian, K. L. Wolf, B. J. Hurst, H. Jabs, M. Hamelin, A. Bacak, Yu. Ts. Oganessian, M. G. Itkis, E. M. Kozulin, N. A. Kondratiev, V. S. Salamatin, I. V. Pokrovsky, F. Hanappe, E. de Goès Brennand, A. Huck, L. Stuttgé, E. Liatard, J. Beene, R. Varner, M. Halbert, and N. Gan
pp. 1163-1167 Full Text: PDF (238 kB)
Tracking Dissipation in Capture Reactions
T. Materna, C. Schmitt, Y. Aritomo, J. Bartel, B. Benoit, A. A. Bogatchev, E. de Goès Brennand, O. Dorvaux, G. Giardina, F. Hanappe, M. G. Itkis, I. M. Itkis, J. Kliman, G. N. Kniajeva, N. A. Kondratiev, E. M. Kozulin, L. Krupa, Yu. Ts. Oganessian, I. V. Pokrovsky, E. V. Prokhorova, N. Rowley, K. Siwek-Wilczynska, and L. Stuttgé
pp. 1168-1172 Full Text: PDF (195 kB)
The Complex Trajectory Method and Dissipation in Fission
F. F. Karpeshin
pp. 1173-1177 Full Text: PDF (137 kB)
Fission Paths in Fm Region Calculated with the Gogny Forces
M. Warda, J. L. Egido, L. M. Robledo, and K. Pomorski
pp. 1178-1181 Full Text: PDF (148 kB)
Fission Dynamics with the 4pi Detector 8piLP
E. Vardaci, A. Brondi, G. La Rana, R. Moro, A. Ordine, A. Boiano, M. A. DiMeo, A. Scherillo, D. Fabris, M. Lunardon, G. Nebbia, G. Viesti, M. Cinausero, E. Fioretto, G. Prete, N. Gelli, and F. Lucarelli
pp. 1182-1189 Full Text: PDF (307 kB)
Isotopic Invariance of Fission Fragment Charge Distributions for Actinide Nuclei at Excitation Energies above 10 MeV
D. M. Gorodisskiy, S. I. Mulgin, A. Ya. Rusanov, and S. V. Zhdanov
pp. 1190-1197 Full Text: PDF (315 kB)
The Effect of the Entrance Channel on the Fission of 216Ra
I. V. Pokrovsky, A. Yu. Chizhov, M. G. Itkis, I. M. Itkis, G. N. Kniajeva, E. M. Kozulin, N. A. Kondratiev, R. N. Sagaidak, V. M. Voskressensky, L. Corradi, A. M. Stefanini, M. Trotta, A. M. Vinodkumar, S. Beghini, G. Montagnoli, F. Scarlassara, A. Ya. Rusanov, F. Hanappe, O. Dorvaux, N. Rowley, and L. Stuttgé
pp. 1198-1202 Full Text: PDF (225 kB)
Reduction Coefficient in Surface-Plus-Window Dissipation: Analysis of Experimental Data From Fusion–Fission Reactions within a Stochastic Approach
P. N. Nadtochy, A. V. Karpov, D. V. Vanin, and G. D. Adeev
pp. 1203-1210 Full Text: PDF (212 kB)Archived web conten
Bimodal fission of Hs*
No full textMass and energy distributions of fission fragments obtained in the reactions 22Ne + 249Cf, 26Mg + 248Cm, and 22Ne + 238U have been measured. A special attention will be paid on the properties of mass-energy distribution of fission fragments obtained in the reaction 26Mg + 248Cm at an excitation energy of 35 MeV. At this energy shell effects should become more effective in fission, the TKE distribution of symmetric fragments obtained in the reaction 26Mg + 248Cm differs strongly from a Gaussian shape. Besides a low-energy component, a high-energy component, not foreseen in the LDM, arises. This is attributed to the fact that both fission fragments are close to the spherical neutron shell N 82. It means that for the compound nucleus 274Hs*, formed in the reaction 26Mg + 248Cm, the phenomenon of bimodal fission was observed for the first time. For the compound nucleus 260No* formed in the reaction 22Ne + 238U at the initial excitation energy of 41 MeV the bimodal fission as well as superasymmetric fission were observed. © Published under licence by IOP Publishing Ltd.SCOPUS: cp.jinfo:eu-repo/semantics/publishe
Asymmetric and symmetric fission of excited nuclei of Hg 180,190 and Pb 184,192,202 formed in the reactions with Ar 36 and Ca 40,48 ions
No full textBackground: Observation of asymmetric fission of Hg180 has led to intensive theoretical and experimental studies of fission of neutron-deficient nuclei in the lead region. Purpose: The study of asymmetric and symmetric fission modes of Hg180,190 and Pb184,192,202 nuclei. Methods: Mass-energy distributions of fission fragments of Hg180,190 and Pb184 formed in the Ar36+Sm144,154 and Ca40+Sm144 reactions, respectively, at energies near the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET and compared with previously measured Pb192,202 isotopes produced in the Ca48+Sm144,154 reactions. The mass distributions for Hg180,190 and Pb184,192,202 together with old data for Ir187, Au195, Hg198, Tl201, Bi205,207, Po210, and At213 [J. Nucl. Phys. 53, 1225 (1991)] have been decomposed into symmetric and asymmetric fission modes. The total kinetic-energy distributions for different fission fragment mass regions have been analyzed for Hg180,190 and Pb184. Results: The stabilization role of proton numbers at Z≈36, 38, Z≈45, 46, and Z=28/50 in asymmetric fission of excited preactinide nuclei has been observed. The high (≈145-MeV) and the low (≈128-MeV) energy components have been found in the total kinetic-energy distributions of Hg180,190 fission fragments corresponding to the fragments with proton numbers near Z≈46 and Z≈36, respectively. In the case of fission of Pb184 only the low-energy component (≈135MeV) for the fragments with masses corresponding to the proton numbers Z≈36 and 46 has been found. Conclusions: The studied properties of asymmetric fission of Hg180,190 and Pb184,192,202 nuclei point out the existence of well deformed proton shell at Z≈36 and less deformed proton shell at Z≈46
A novel variant m.641A>T in the mitochondrial MT-TF gene is associated with epileptic encephalopathy in adolescent
No full textWe present a 14-year-old girl with loss of motor functions, tetraplegia, epilepsy and nystagmus, caused by a novel heteroplasmic m.641A>T transition in an evolutionary conserved region of mitochondrial genome, affecting the aminoacyl stem of mitochondrial tRNA-Phe. In silico prediction, respirometry, Western blot and enzymatic analyses in skin fibroblasts support the pathogenicity of the m.641A>T substitution. This is the 18th MT-TF point mutation associated with a mitochondrial disorder. The onset and the severity of the disease, however, is unique in this case and broadens the clinical picture related to mutations of mitochondrial tRNA-Phe
Study of Binary Processes in the Reactions of 36Ar + 144, 154Sm and 68Zn + 112Sn Leading to the Formation of Neutron-Deficient Compound 180, 190Hg Nuclei
No full textAbstract: A study is performed of the asymmetric fission of neutron-deficient mercury 180, 190Hg isotopes obtained in the reactions of 36Ar + 144, 154Sm and 68Zn + 112Sn at incident energies near and above the Coulomb barrier. The relative contributions from asymmetric and symmetric fission change along with the excitation energy of the fissile compound nucleus. The effect the characteristics of the entrance channel have on the dynamics of the reaction is studied
Evolution of multimodal fission with energy in Np 238 populated by Li 6 + Th 232
No full textBackground: Nuclear fission is influenced by shell effects. Fission modes are a strong signature of the compound nucleus formation in heavy ion induced reactions. The evolution of the relative strengths of the fission modes with excitation energy is a matter of intense interest. Purpose: We investigate the signatures of fission modes in Np238 populated by the Li6+Th232 reaction through the mass-total kinetic energy distribution. Method: The mass-total kinetic energy distributions of fission fragments of the reaction Li6+Th232 are measured at four laboratory energies, Elab=28.5, 40, 45, and 62.5 MeV. Mass-total kinetic energy distributions of Li6+Th232 are described by the multimodal random neck rupture model. Results: Channel probabilities of different fission modes are obtained obtained through a two-dimensional fitting procedure. The contribution of the standard 1 (S1) mode is found to become ≈2% at Elab=40 MeV. The heavy fragments of S1 and standard 2 (S2) modes are found to be associated with Z≈52 and Z≈55 shells, respectively. The slope of the asymmetric to symmetric fission yields ratio with the excitation energy of Li6+Th232 is found to be similar to that of O18+Pb208 (previously reported). Conclusions: The analysis of mass-total kinetic energy distribution data reveals the presence of fission modes in Li6+Th232. The average kinetic energy release in fission obtained from Viola systematic matches well with the one of the of S2 mode. The liquid-drop-like broad symmetric (SL) mode is found to peak at a lower energy than predicted by Viola systematic. This is associated with the decrease of the total kinetic energy in the asymmetric fission mode due to the fading out of shell effects with increasing excitation energy
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