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2006 Vol. 23, No. 4

Proceedings of the 5th
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Proceedings of 5th Workshop on Superheavy Nuclei
Status and Prospect of Super heavy Nuclei Research at IMP
XU Hu-shan, HUANG Tian-heng, SUN Zhi-yu, HU Zheng-guo, , ZHAN Wen-long, ZHOU Xiao-hong, HUANG Wen-xue, ZHANG Hong-bin, ZHANG Xue-heng, GAN Zai-guo, ZHENG Chuan, LI Jun-qing, MA Xin-wen, QIN Zhi, XIAO Guo-qing, GUO Zhong-yan, LI Zhi-hui, ZHANG Yu-hu
2006, 23(4): 359-368. doi: 10.11804/NuclPhysRev.23.04.359
Abstract(2449) PDF (782KB)(717)
Abstract:
The history and the international status of the superheavy nuclei synthesis are briefly described. The related research work carried out at the Institute of Modern Physics (IMP) has been reviewed. The prospect of the super heavy nuclei research at IMP has been introduced.
Theoretical Studies on α decay Halflives of Superheavy Nuclei
REN Zhong-zhou, XU Chang
2006, 23(4): 369-373. doi: 10.11804/NuclPhysRev.23.04.369
Abstract(3310) PDF (695KB)(656)
Abstract:
We proposed a deformed version of densitydependent cluster model (DDCM) by including nuclear deformation of the daughter nucleus. A systematic calculation of αdecay halflives of superheavy nuclei (Z=106—110) is carried out by the deformed DDCM. The good agreement between theory and data is obtained. It is shown that the deformed DDCM works well in the superheavy mass region.
Probability for Studying Atomic Spectroscopy of Very Heavy Elements
JIN Gen-ming, FENG Zhao-qing, FU Fen, ZHAO Xu-lin
2006, 23(4): 374-381. doi: 10.11804/NuclPhysRev.23.04.374
Abstract:
The importance of the atomic spectroscopy of heavy elements,especially the superheavy elements has been briefly reviewed. It is pointed that studies of the atomic spectroscopy of very heavy elements is necessary from the atomic physics and the identification of new superheavy elements. The production probability and yields of heavy elements in the heavy ion induced reactions were discussed. And the possible collection methods for heavy residue of reactions were also retrospected. Those techniques which have been used in the heavy ion reactions and superheavy element identifications will provide some possible support to the studies of heavy element spectroscopy.
Introduction of Theoretical Models for Superheavy Nuclei Formation
ZUO Wei, LI Jun-qing,
2006, 23(4): 382-385. doi: 10.11804/NuclPhysRev.23.04.382
Abstract(2392) PDF (907KB)(620)
Abstract:
The theoretical models for investigating the fusion mechanism of heavy nucleus collisions and calculating the formation cross sections of superheavy nuclei have been introduced. The recent development and the present status for understanding the fusion mechanism of heavy nucleus collisions have been discussed.
RFQ Cooler and Buncher RFQ1L in Superheavy Nuclide Research Spectrometer
HUANG Wen-xue, WANG Yue, ZHU Zhi-chao, TIAN Yu-lin, XU Hu-shan, SUN Zhi-yu, XIAO Guo-qing, ZHAN Wen-long
2006, 23(4): 386-395. doi: 10.11804/NuclPhysRev.23.04.386
Abstract:
The structure and the simulation results about the cooling,bunching,extraction and skimming of the RFQ cooler and buncher RFQ1L, which is an important part of the beingbuilt superheavy nuclide research spectrometer, have been introduced. It shows that, by careful choice of its working point, we can obtain an ion beam with small beam spot, small emittance and mono energy, which can satisfy the requirements of the successive analyses by dipole and laser with high efficiencies.
Formation Mechanism of Super Heavy Nuclei inHeavy ion Collisions
LI Jun-qing, ZUO Wei, FENG Zhao-qing, JIN Gen-ming, ZHAO En-guang
2006, 23(4): 396-398. doi: 10.11804/NuclPhysRev.23.04.396
Abstract(2208) PDF (947KB)(524)
Abstract:
In the dinuclear system conception, the master equation is solved numerically to calculate the fusion probabilities of superheavy nuclei. The relative motion concerning the energy, the angular momentum and the fragment deformation relaxations is explicitly treated to couple with the diffusion process. The nucleon transition probabilities, which are derived microscopically, are related with the energy dissipation of the relative motion, thus they are timedependent. The formation cross sections of the superheavy nuclei from Pbbased cold fusion and excitation functions from 48Ca induced hot fusion are reasonably consistent with known experimental data.
Density Properties of Superheavy Nuclei
PEI Jun-chen, XU Fu-rong
2006, 23(4): 399-403. doi: 10.11804/NuclPhysRev.23.04.399
Abstract(2041) PDF (740KB)(613)
Abstract:
We studied the densities of superheavy nuclei with the SkyrmeHartreeFock model. The central depressions in densities are shown in the heaviest nuclei with Z≤120 and N≤178, which is due to the highj orbits occupied. However, calculations show that deformations have considerable effects on the density distributions, particularly in the nucleus 292120.
Alphadecay Properties of 266Bh
QIN Zhi, WU Xiao-lei, DING Hua-jie, WU Wang-suo, HUANG Wen-xue, LEI Xiang-guo, XU Yan-bing, YUAN Xiao-hua, GUO Bin, YANG Wei-fan, GAN Zai-guo, FAN Hong-mei, GUO Jun-sheng, XU Hu-shan, XIAO Guo-qing
2006, 23(4): 404-407. doi: 10.11804/NuclPhysRev.23.04.404
Abstract(2093) PDF (708KB)(532)
Abstract:
The isotope of 266Bh was produced and identified definitely in bombardments of 243Am target with 162 MeV 26Mg ions at HIRFL. Identification was made by observation of correlated αparticle decays between the Bh isotopes and their Db and Lr daughters using a rotating wheel system. The measured α energy for 266Bh is (9.03±0.08) MeV, and this value close to the 9.07 MeV for 266Bh observed in the first chain of element 113 at RIKEN. The halflife of 266Bh is 0.66+0.59 -0.26 s. The Qα value derived from this experiment fits well into the general trend in a “QαN systematics” for the isotopes with Z = 107.
Investigation on Strongly Damped Rreactions for Very Heavy Nuclei
WU Xi-zhen, TIAN Jun-long, LI Zhu-xia, WANG Ning, ZHAO Kai, ZHANG Yin-xun, OU Li
2006, 23(4): 408-412. doi: 10.11804/NuclPhysRev.23.04.408
Abstract(2122) PDF (768KB)(632)
Abstract:
In this paper, the possibility of producing superheavy fragments through strongly damped reactions in very massive nuclear collisions is investigated. Two theoretical models, which are the phenomenologically multidimensional Langevin equation model and improved quantum molecular dynamics model developed recently by our group, are briefly reviewed. The dependence of the production probability of superheavy fragments on the incident energy, the decay mechanism of the composite systems and superheavy fragments, and the distributions of the binding energy and shapes of superheavy fragments are iscussed for reactions of 244Pu+244Pu, 238U+238U, 197Au+197Au based on the improved quantum molecular dynamics model.
Quantum Path Integral Approach to Fusion Probability of Heavy Nuclei at Subbarrier Energies
BAO Jingdong
2006, 23(4): 413-417. doi: 10.11804/NuclPhysRev.23.04.413
Abstract(2503) PDF (715KB)(734)
Abstract:
A real time path integral approach is developed in order to work out a correct solution to a problem for the smaller result of the fusion probability of heavy nuclei based on the classical diffusion model at subbarrier energies. An analytical expression for the quantum fusion probability is proposed,which contains the quantum fluctuation effect. The fusion probabilities of several symmetrical and approximate symmetrical systems are calculated, the heoretical results are in agreement with the experimental data. The influence of the neck length and its fluctuation upon the fusion hindrance is discussed.
A Novel Approach to Direct Identification of Z & A for Superheavy Elements
MA Xin-wen, ZHAN Wen-long, ZHANG Da-cheng
2006, 23(4): 418-422. doi: 10.11804/NuclPhysRev.23.04.418
Abstract(1923) PDF (705KB)(614)
Abstract:
With the synthesis of heavy elements approaching the super heavy island, the production cross section becomes smaller and the lifetime of the super heavy element becomes longer, which results in the difficulties for identification of theelements by using conventional alpha decay chain technique. In order to overcome the difficulties, a novel approach to direct identification of atomic number Z and nuclear mass A for super heavy elements is proposed, namely, the multistep resonant laser ionization of singly charged ions in combination with RFQ trap. The routine for the experiment is presented, and the possibilities, feasibilities, as well as the problems to be faced, are discussed in detail.
On Isotope Dependence of Superheavy Nucleus Production
LIU Zu-hua, BAO Jing-dong
2006, 23(4): 423-425. doi: 10.11804/NuclPhysRev.23.04.423
Abstract(2138) PDF (760KB)(582)
Abstract:
The cross sections of the compound nucleus formation and e vaporation residue for the 54Fe+204Pb, 56Fe+206Pb, 58Fe+208Pb cold fusion and 32,34, 36S+238U hot fusion have been calculated by using a twoparameter Smoluchowski equation. Our results clearly show the isotope dependence of superheavy nucleus production. The formation cross sections of the neutronrich isotope are, generally speaking, obviously enhanced due to the lower Coloumb barrier , lower height of the conditional saddlepoint, and smaller neutron separation energy.
Introduction of 40Ar+238U Experiment
FAN Hong-mei, HUANG Ming-hui, GAN Zai-guo, GUO Jun-sheng, WU Xiao-lei, GUO Bin, QIN Zhi, WU Zhi-jun, HUANG Tian-heng, XIE Cheng-ying, WANG Hua-lei, SONG Li-tao
2006, 23(4): 426-429. doi: 10.11804/NuclPhysRev.23.04.426
Abstract(1872) PDF (643KB)(573)
Abstract:
The state of the experiment to produce the new isotopes around Z=110 are presented in this paper. The emphasis is laid upon introducing the experiment purpose, the setup and the feasibility for producing this objective nuclide. In the experiment the new isotopes were produced by the complete fusion evaporation reaction of 238U with 270 MeV 40Ar at the Sector Focus Cyclotron (SFC) of Heavy Ion Research Facility in Lanzhou(HIRFL). The reaction products were also transported and collected by using the helium jet technique and rotating wheel apparatus.
Calculations of Relativistic Consistent Angular momentum Projected Shell model for Exotic Nuclei
LI Yan-song, F.H. AL-Khudair
2006, 23(4): 430-432. doi: 10.11804/NuclPhysRev.23.04.430
Abstract(2118) PDF (695KB)(690)
Abstract:
The relativistic consistent angularmomentum projected shellmodel (ReCAPS) developed recently is a selfconsistent model and has stable parameters for various nuclei. The ReCAPS can describe the properties of known and unknown nuclei with stable deformations. In this paper,we present the calculations of several nuclei including normal stable nuclei, exotic nuclei and super heavy nuclei and compare the obtained results with experiment data.
New Formula for Proton Radioactivity Halflives
XU Chang, REN Zhong-zhou
2006, 23(4): 433-435. doi: 10.11804/NuclPhysRev.23.04.433
Abstract(2887) PDF (651KB)(754)
Abstract:
Systematic calculations on proton radioactivity halflives of both spherical and deformed nuclei are carried out. A new formula with only four parameters is proposed for proton radioactivity halflives. The halflives calculated by using the new formula are in good agreement with the experimental ones. The new formula is simple but accurate, which is very useful for further experiments.
Regularities of Manybody Systems Such as Nuclei in Presence of Random Interactions
ZHAO Yumin
2006, 23(4): 436-439. doi: 10.11804/NuclPhysRev.23.04.436
Abstract(1831) PDF (627KB)(563)
Abstract:
In this paper it is discussed the regularities of manybody systems such as nuclei in the presence of random interaction. In particular,it concentrates on the present status towards understanding of spin zero ground state dominance,energy centroids of certain quantum number(s) such as spin, behavior of lowlying states,under random interactions.