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2016年  第33卷  第2期

第五届原子核质子发射国际会议(PROCON2015)文集
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第五届原子核质子发射国际会议(PROCON2015)文集
Discovery of Nuclei at and Beyond the Proton Dripline
M. Thoennessen
2016, 33(2): 117-121. doi: 10.11804/NuclPhysRev.33.02.117
摘要:
In contrast to the neutron dripline the proton dripline has been reached almost across the whole nuclear chart. However, because of the Coulomb barrier relatively long-lived isotopes can exist beyond the proton dripline. It is estimated that about 200 new isotopes at and beyond the proton dripline should be able to be discovered in the future. A brief review of the discovery of proton-rich nuclides as well as an outlook for the discovery potential in the future is presented.
Precision Mass Measurements of Short-lived Nuclides at the Heavy-ion Storage Ring in Lanzhou
张玉虎, 王猛, Yu. A. Litvinov, 徐瑚珊
2016, 33(2): 122-130. doi: 10.11804/NuclPhysRev.33.02.122
摘要:
Recent commissioning of the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou enabled us to conduct high-precision mass measurements at the Institute of Modern Physics in Lanzhou (IMP). In the past few years, mass measurements were performed using the CSRe-based isochronous mass spectrometry employing the fragmentation of the energetic beams of 58Ni, 78Kr, 86Kr, and 112Sn projectiles. Masses of short-lived nuclides on both sides of the stability valley were addressed. Relative mass precision of down to 10−6 ~ 10−7 is routinely achieved. The mass values were used as an input for dedicated nuclear structure and astrophysics studies, providing for instance new insights into the rp-process of nucleosynthesis in X-ray bursts. In this contribution, we briefly review the so far conducted experiments and the main achieved results, as well as outline the plans for future experiments.
Nuclear Physics Programs for the Future RIBs Facility in Korea
Moon Chang-Bum
2016, 33(2): 131-140. doi: 10.11804/NuclPhysRev.33.02.131
摘要:
We present nuclear physics programs based on the planned experiments using rare isotope beams (RIBs) for the future Korean Rare Isotope Beams Accelerator facility(KRIA). This ambitious facility has both an Isotope Separation On Line (ISOL) and fragmentation capability for producing RIBs and accelerating beams of wide range mass of nuclides with energies of a few to hundreds MeV per nucleon. Low energy RIBs at Elab = 5 to 20 MeV per nucleon are for the study of nuclear structure and nuclear astrophysics toward and beyond the drip lines while higher energy RIBs produced by inflight fragmentation with the reaccelerated ions from the ISOL enable to explore the neutron drip lines in intermediate mass regions. The planned programs have goals for investigating internal structures of the exotic nuclei toward and beyond the nucleon drip lines by addressing the following issues: how the shell structure evolves in areas of extreme proton to neutron imbalance; whether the isospin symmetry maintains in isobaric mirror nuclei at and beyond the drip lines; how two-proton radioactivity affects abundances of the elements; what the role of the continuum states including resonant states above protondecay threshold in exotic nuclei is in astrophysical nuclear reaction processes, and how the nuclear reaction rates triggered by unbound proton-rich nuclei make an effect on rapid proton capture processes in a very hot stellar plasma.
Spectroscopy of Low-lying States in Odd-Z Odd-A Nuclei Beyond Lead
U. Jakobsson, J. Uusitalo, K. Auranen, H. Badran, B. Cederwall, D. M. Cox, et al.
2016, 33(2): 141-145. doi: 10.11804/NuclPhysRev.33.02.141
摘要:
Low-lying states in odd-Z odd-mass nuclei at the proton drip-line beyond lead have recently been studied through fusion-evaporation reactions using a gas-filled recoil separator. Isomeric 1/2+ and 13/2+ states have been observed in odd-mass astatine and francium nuclei. The systematic behaviour of the level energies of these states have been studied and a similarity between the 1/2+ state in astatine and francium has been found. Furthermore, the 13/2+ state has been observed in the francium nuclei with an oblate behaviour suggesting a coupling of the i13/2 proton to the 2p-2h intruder excitation.
New Generation of Experiments for the Investigation of  Stellar (p, γ) Reaction Rates Using SAMURAI
V. Panin, K. Yoneda, M. Kurokawa, J. Blackmon, Z. Elekes, D. Kim, T. Motobayashi, et al
2016, 33(2): 146-151. doi: 10.11804/NuclPhysRev.33.02.146
摘要:
The future experimental campaign with the SAMURAI setup at RIKEN will explore a wide range of neutron-deficient nuclei with a particular focus on the most critical  (p, γ)  reaction rates relevant to the astrophysical rp-process in type-I X-ray bursts (XRB). Intense radioactive-ion (RI) beams at an energy of a few hundred MeV/nucleon will be deployed to populate proton-unbound states in the nuclei of interest through the Coulomb excitation or nucleon-removal processes. The decay of these states into a proton and a heavy residue will be measured using complete kinematics and the information about time
reversal proton-capture process will be obtained. This method will provide the vital experimental data on the resonances, which dominate the stellar (p,γ) reaction rates, as well as on the direct proton-capture process for some other cases. The experimental setup will utilize for the first time the High-Resolution 90◦-mode of the SAMURAI spectrometer in combination with the existing detection systems, including custom-designed Si-strip detectors for simultaneous detection and tracking of heavy ions and protons emitted from the target. The details of the experimental method and the utilized apparatus are discussed in this paper.
Gamma Spectroscopy along N~Z towards 100Sn
刘忠
2016, 33(2): 152-155. doi: 10.11804/NuclPhysRev.33.02.152
摘要:
A wide range of research topics in different fields of physics can be addressed by study of the self-conjugate N~Z nuclei, such as the np pairing, isospin symmetry, the rp-process and the properties of the electroweak interaction. This contribution focuses on the spectroscopy of N~Z nuclei towards 100Sn. The latest results on the isomeric decay spectroscopy of N~Z nuclei below 100Sn, such as the N =Z+2 nuclides 94Pd and 96Ag, the N~Z nuclide 96Cd and so on are highlighted. New opportunities in in-beam   spectrscopy of N~Z nuclei towards 100Sn, like 90Rh and 92Pd, with radioactive ion beams are discussed.
Shell Evolution Study for New Magic Number N =32 via Isochronous Mass Spectrometry
徐星, 王猛, 张玉虎, 帅鹏, 徐瑚珊, 涂小林, 周小红, 陈瑞九, 陈相成, 付超义, 葛壮, 黄文嘉, 蓝乙华, 李宏福, 刘俊豪, 孙铭泽, 邢元明, 颜鑫亮, 曾奇, 张鹏, 肖国青, 詹文龙
2016, 33(2): 156-159. doi: 10.11804/NuclPhysRev.33.02.156
摘要:

Recent results and progress of mass measurements of neutron-rich nuclei utilizing Isochronous Mass Spectrometry (IMS) based on the HIRFL-CSR complex at Lanzhou are reported. The nuclei of interest were produced through projectile fragmentation of primary 86Kr ions at a realistic energy of 460.65 MeV/u. After in-flight separation by the fragment separator RIBLL2, the fragments were injected and stored in the experimental storage ring CSRe, and their masses were determined from measurements of their revolution times. The re-determined masses were compared and evaluated with other mass measurements, and the impact of these evaluated masses on the shell evolution study is discussed.

Proton and Two-proton Emissions from Proton-rich Nuclei with 10≦Z≦20
林承键, 徐新星, 王建松, 孙立杰, 贾会明, 杨磊, 马朋, 马军兵, 杨彦云, 金仕纶,
2016, 33(2): 160-166. doi: 10.11804/NuclPhysRev.33.02.160
摘要:
Proton (p) and two-proton (2p) emissions from the proton-rich nuclei with 10≦Z≦20 have been explored by the in-fight decay and implantation decay methods, respectively, in a series of experiments at the HIRFL-RIBLL facility. The in-flight 2p emissions from the excited states of 28,29S /26,27P and 17;18Ne were studied by complete-kinematics measurements. Mechanisms of 2p decay and related p-p correlations have been explored. Obvious 2p correlated emissions have been observed in the cases of 28,29S but not in 27,28P, indicating the 2p halo plays an important role in the diproton emission. In the 17;18Ne cases, a small 2p opening angles were deduced by the HBT analyses, implying the BCS-BEC crossover may occur in the dilute nuclear matter. Moreover, 27S/26P/25Si, 22Si/20Mg, 23Si/22Al/21Mg, 24Si/23Al, and 36;37Ca were implanted in a thin double-sided-silicon-strip detector and their -delayed p and 2p decays have been measured by a surrounding silicon detector array under the continuous-beam mode. Important information on the nuclear spectroscopy, such as energy, lifetime, branching-ratio, and so on, has been extracted, which helps us to understand the nuclear structures of proton-rich exotic nuclei close to the drip-line.
Proton Radioactivity Within a Hybrid Method
张鸿飞
2016, 33(2): 167-172. doi: 10.11804/NuclPhysRev.33.02.167
摘要:
The proton radioactivity half-lives are investigated theoretically within a hybrid method.The potential barriers preventing the emission of protons are determined in the quasimolecular shape path within a generalized liquid drop model (GLDM). The penetrability is calculated with the Wentzel-Kramers-Brillouin (WKB) approximation. The spectroscopic factor has been taken into account in halflife calculation, which is obtained by employing the relativistic mean field (RMF) theory combined with the Bardeen-Cooper-Schrieffer (BCS) method. The half-lives within the present hybrid method reproduced the experimental data very well. Some predictions for proton radioactivity are made for future experiments.
Technical Improvements in the Experiment of Isochronous Mass Measurement of 58Ni Projectile Fragments
帅鹏, 涂小林, 张玉虎, 王猛, 徐星, 颜鑫亮, 陈相成
2016, 33(2): 173-179. doi: 10.11804/NuclPhysRev.33.02.173
摘要:
 The combination of in-flight fragment separator and the isochronous mass spectrometry(IMS) in storage rings have been proven to be a powerful tool for the precision mass measurements of shortlived exotic nuclei. In IMS, the mass-over-charge ratio is only related to the revolution period of stored ions, and the relative mass resolution can reach up to the order of 10−6. However, the instability of the magnetic field of storage ring deteriorates the resolution of revolution period, making it very difficult to distinguish the ions with very close mass-over-charge ratio via their revolution periods. To improve the resolution of revolution periods, a new method of weighted shift correction (WSC) has been developed to accurately correct the influence of the magnetic field instabilities in the isochronous mass measurements of 58Ni projectile fragments. By using the new method, the influence of unstable magnetic fields can be greatly reduced, and the mass resolution can be improved by a factor up to 1.7. Moreover, for the ions that still cannot be distinguished after correcting the magnetic field instabilities, we developed a new method of pulse height analysis for particle identification. By analyzing the mean pulse amplitude of each ion from the timing detector, the stored ions with close mass-over-charge ratios but different charge states such as 34Ar and 51Co can be identified, and thus the mass of 51Co can be determined. The charge-resolved IMS may be helpful in the future experiments of isochronous mass measurement even for N =Z nuclei.
Proton Emission---Recent Results and Future Prospects
R. D. Page, D. T. Joss
2016, 33(2): 180-183. doi: 10.11804/NuclPhysRev.33.02.180
摘要:
Considerable progress has been made in the study of proton-emitting nuclei since the first observation of direct proton emission nearly half a century ago. This has led to improvements in our understanding of this rare decay process and provided invaluable nuclear structure data far from the valley of beta stability. This paper reviews the implications of some recent results for exotic iridium, rhenium and tantalum isotopes and considers prospects for future experimental studies of proton-emitting nuclei located at and above the N =82 neutron shell closure.
Theoretical Studies of Proton Radioactivity
Lidia S. Ferreira, Enrico Maglione
2016, 33(2): 184-189. doi: 10.11804/NuclPhysRev.33.02.184
摘要:
In the paper, we will discuss the most recent theoretical approaches developed by our group,to understand the mechanisms of decay by one proton emission, and the structure and shape of exotic nuclei at the limits of stability.
Projected Shell Model Description for the Proton Emitters
卞宝安
2016, 33(2): 190-196. doi: 10.11804/NuclPhysRev.33.02.190
摘要:
Proton radioactivity is an important decay mode for nuclei near the proton drip-line. Studies of this decay mode can reveal valuable information on exotic nuclear structure and provide important information on the stucture of nuclei in extreme conditions. The new experimental data can let us understand the interactions in exotic systems, which motivate further theoretical development. The most recent application of the projected shell model (PSM) for proton emitters is represented. We study the rotational bands of the deformed proton emitter 141Ho by using the PSM. The experimental data are well reproduced. Strongly suppressed γ transition from the low-lying IΠ= 3/2+ state makes this state isomeric. Variations in the dynamical moment of inertia are discussed due to band crossings using the band diagram. The calculated results for proton emitter 151Lu shows it is oblately deformed
Revisit to Two-Proton Radioactivity of 19Mg and Observation of Two-Proton Decay of 30Ar
徐晓栋, I. Mukha, L. Acosta, E. Casarejos, A. A. Ciemny, W. Dominik, et al.
2016, 33(2): 197-202. doi: 10.11804/NuclPhysRev.33.02.197
摘要:
An experiment aimed to investigate the two-proton (2p) decay of the previously unknown nucleus 30Ar was performed at GSI: By tracking the decay products in-flight with silicon micro-strip detectors, the 2p decays of 30Ar were observed for the first time. For the calibration purpose, 2p decays of 19Mg were also remeasured by tracking the coincident 17Ne+p+p trajectories. By comparing the measured angular p-17Ne correlations with those obtained from the corresponding Monte Carlo simulations, the simultaneous 2p decay of 19Mg ground state and the sequential 2p emission of several known excited states of 19Mg were confirmed. One new excited state in 19Mg and two new excited states in 18Na were observed.
Time-dependent Calculations for Two-proton Decay Width with Schematic Density-dependent  Contact Pairing Interaction
Oishi Tomohiro
2016, 33(2): 203-206. doi: 10.11804/NuclPhysRev.33.02.203
摘要:
We calculate the two-proton decay width of the 6Be nucleus employing the schematic densitydependent contact potential for the proton-proton pairing interaction. The decay width is calculated with a time-dependent method, in which the two-proton emission is described as a time-evolution of a threebody meta-stable state. Model-dependence of the two-proton decay width has been shown by comparing the results obtained with the two different pairing models, schematic density-dependent contact and Minnesota interactions, which have zero and finite ranges, respectively.
Testing CVC and CKM Unitarity via Superallowed Nuclear Beta Decay
J. C. Hardy, I. S. Towner
2016, 33(2): 207-211. doi: 10.11804/NuclPhysRev.33.02.207
摘要:
Superallowed nuclear beta decay between 0+ analog states is a sensitive probe of the weak interaction, with the established strength – or Ft value – of each such transition being a direct measure of the vector coupling constant, GV. Each transition’s Ft value depends on the half-life of the parent nucleus as well as on the Q-value and branching ratio for the transition of interest. It also depends on small (1%) transition-dependent theoretical corrections, of which the most sensitive accounts for isospin symmetry breaking. We have recently published a new survey of world superallowed-decay data, which establishes the Ft values of 14 separate superallowed transitions to a precision of order 0.1% or better. The results from this very robust data set yield the value of Vud, the up-down quark mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, and lead to the most demanding test available of CKM unitarity. The survey results and their outcome are described, as is the current direction of experiments that focus on testing the validity of the isospin-symmetry-breaking corrections.
Neutron and Alpha Structure in Neutron Deficient Nuclei in Astrophysics
S. Kubono, 何建军, H. Yamaguchi, D. M. Kahl, S. Hayakawa, T. Terani, et al.
2016, 33(2): 212-216. doi: 10.11804/NuclPhysRev.33.02.212
摘要:
The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning conditions. The p-process, which is supposed to take place at the very early epoch of type II supernovae, has considerable neutrons and alphas together with protons. The alpha-induced reactions on proton-rich unstable nuclei in the light mass regions is expected to play a crucial role, but very few of them were investigated well yet because of the experimental difficulties. Specifically, I report our recent experimental effort for the breakout process from the pp-chain region, 7Be(α ,γ )11C(α ,p)14N under the p-process. The neutron-induced reactions on proton-rich nuclei, which is even more a challenging subject, were investigated previously for very few nuclei. One possible experimental method is the Trojan Horse Method (THM). We successfully have applied THM to the 18F(n, )14N reaction study with an unstable beam of 18F.
Alpha Decay of the Neutron-deficient Isotopes 215,216U
张志远, 甘再国, 马龙, 杨华彬, 王建国, 郁琳, 姜舰, 田玉林, 丁兵, 郭松, 王永生, 黄天衡, 孙明道, 王凯龙
2016, 33(2): 217-220. doi: 10.11804/NuclPhysRev.33.02.217
摘要:
The most neutron-deficient isotopes 215;216U were produced in the complete-fusion reaction 180W(40Ar, 4-5n)215,216U. Evaporation residues recoiled from the target were separated in-flight from the primary beam by the gas-filled recoil separator SHANS and subsequently identified on the basis of correlated -decay chains. Two -decaying states were identified in 216U, one for the ground state and the other for the isomeric state with 8+(h9=2f7=2) configuration. The -decay properties for 215;216U and the systematics of 8+ isomeric state in N =124,126 isotones were investigated.
β-delayed Multi-particle Emission From 31Ar
A. A. Ciemny, C. Mazzocchi, W. Dominik, Z. Janas, M. Pfutzner, M. Pomorski, et al.
2016, 33(2): 221-224. doi: 10.11804/NuclPhysRev.33.02.221
摘要:
The β+ decay of 31Ar was investigated in an experiment at the GSI-FRS spectrometer.The ions of interest have been produced in the fragmentation of a 36Ar beam at 880 MeV/nucleon and implanted in a time projection chamber with optical readout. In addition to β -delayed one and two proton emission, for the first time the emission of -delayed 3 protons has been observed. The branching ratio for this decay mode is found to be (0.07 ± 0.02)%.
Comparison of β-decay and Charge-exchange Reactions in Mirror T =2 Nuclei and Isospin Mixing
B. Rubio, S. E. A. Orrigo, A. Algora, B. Blank, Y. Fujita, H. Fujita, et al.
2016, 33(2): 225-229. doi: 10.11804/NuclPhysRev.33.02.225
摘要:
We have carried out β decay studies of proton rich nuclei in the fp shell at different laboratories.Here we present our recent results on the decay of Tz =-2 nuclei performed at GANIL and compare them with the Charge Exchange reactions on their stable, mirror-partner targets, performed at RCNP. In one of the cases, the 56Zn - 56Fe pair, a strong isospin mixing has been observed. The results are well reproduced in the framework of Shell Model calculations
An Implantation and Detection System for Spectroscopy of 22,24Si
孙立杰, 徐新星, 林承键, 王建松, 方德清, 李智焕, 王玉廷, 李晶, 杨磊, 马南茹, 王康, 臧宏亮,
2016, 33(2): 230-234. doi: 10.11804/NuclPhysRev.33.02.230
摘要:
A new decay detection system with high detection efficiency and low detection threshold has been developed for charged-particle decay studies, including -delayed proton, decay or direct proton emission from proton-rich nuclei. The detection system was tested by using the -delayed proton emitter 24Si and was commissioned in the decay study of 22Si produced by projectile fragmentation at the First Radioactive Ion Beam Line in Lanzhou. Under a continuous-beam mode, the isotopes of interest were implanted into two double-sided silicon strip detectors, where the subsequent decays were measured and correlated to the preceding implantations by using position and time information. The system allows to measure protons with energies down to about 200 keV without obvious background in the proton spectrum. Further application of the detection system can be extended to the measurements of -delayed proton decay and the direct proton emission of other exotic proton-rich nuclei.
Alpha Decay as a Probe of the Structure of Neutron-deficient Nuclei Around Z =82
亓冲
2016, 33(2): 235-241. doi: 10.11804/NuclPhysRev.33.02.235
摘要:
In this contribution I would like to review briefly our recent studies on nuclear α formation probabilities in heavy nuclei and their indication on the underlying structure of the nuclei involved. In particular, I will show that the empirical α-formation probabilities, which can be extracted from experimental half-lives, exhibit a rather smooth function with changing proton or neutron numbers. This allows us to distinguish the role played by pairing collectivity in the clustering process. The sudden hindrance of the clustering of the nucleons around the N = 126 shell closure is due to the fact that the configuration space does not allow a proper manifestation of the pairing collectivity. The influence of the Z = 82 shell closure on the α formation properties will also be discussed. Moreover, we have evaluated the α-decay fine structure to excited 0+ states in Hg and Rn isotopes as well as the α-decay from the excited 0+ states in the mother nucleus. It is thus found that the α decay is sensitive to the mixture of configurations corresponding to different nuclear shapes.
Large-Scale Shell Model for Nuclear Structure and Nuclear Astrophysics Studies
王韩奎, 金华, 孙扬, 何翊绮, 秦伟, 王高亮
2016, 33(2): 242-245. doi: 10.11804/NuclPhysRev.33.02.242
摘要:
The study of neutron-rich nuclei near 132Sn is interesting and important for both nuclear  structure and nuclear astrophysics. For a considerably large model space allowing cross-shell excitations, a new effective Hamiltonian is determined by employing the extended pairing-plus-quadrupole model with monopole corrections. Calculations for two mass regions, for the north-east quadrant of 132Sn with Z > 50 and N > 82 and for the south-west quadrant with Z < 50 and N < 82, have been performed recently. The structure of these nuclei is analyzed in detail, and the role of the monopole corrections can
be clearly seen.
Two-nucleon Excitation from p to sd Shell in 12,14C
袁岑溪, 张敏, 兰念吾, 方尤俊
2016, 33(2): 246-249. doi: 10.11804/NuclPhysRev.33.02.246
摘要:
The effect of the two-nucleon excitation from p to sd shell is discussed on 12C and 14C in the frame work of the nuclear shell model. The recently suggested shell-model Hamiltonian YSOX provides an suitable tool to investigate the 2 ~! excitation in psd region. Because the strength of the < pp|V |sdsd > interaction, which represents the interaction between the 0 and 2 ~! configurations, is considered in the construction of the Hamiltonian YSOX. The level of 12C is almost independent on the <pp|V |sdsd> interaction, but excitation energies of certain states in 14C are strongly affected by it. Further investigation shows that the percentage of 2 ~! configuration in these states is quite different from that of the ground state. The non-linear effects of the < pp|V |sdsd > interaction on the configurations and transition rates are also discussed.