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  • 51.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Blomqvist, Jan
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Bäck, Torbjörn
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Cederwall, Bo
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Johnson, Arne
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Spin-aligned neutron-proton pair mode in atomic nuclei2011Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 84, nr 2, s. 021301-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Shell-model calculations using realistic interactions reveal that the ground and low-lying yrast states of the N = Z nucleus (92)(46)Pd are mainly built upon isoscalar neutron-proton pairs, each carrying the maximum angular momentum J = 9 allowed by the shell 0g(9/2), which is dominant in this nuclear region. This structure is different from that found in the ground and low-lying yrast states of all other even-even nuclei studied so far. The low-lying spectrum of excited states generated by such correlated neutron-proton pairs has two distinctive features: (i) the levels are almost equidistant at low energies and (ii) the transition probability I -> I - 2 is approximately constant and strongly selective. This unique mode is shown to replace normal isovector pairing as the dominant coupling scheme in N = Z nuclei approaching the doubly magic nucleus (100)Sn.

  • 52.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Chen, T.
    Exact solution of the pairing problem for spherical and deformed systems2015Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 92, nr 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There has been increasing interest in studying the Richardson model from which one can derive the exact solution for certain pairing Hamiltonians. However, it is still a numerical challenge to solve the nonlinear equations involved. In this paper we tackle this problem by employing a simple hybrid polynomial approach. The method is found to be robust and is valid for both deformed and nearly spherical nuclei. It also provides important and convenient initial guesses for spherical systems with large degeneracy. As an example, we apply the method to study the shape coexistence in neutron-rich Ni isotopes.

  • 53.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Delion, Doru S.
    Liotta, Roberto J.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Effects of formation properties in one-proton radioactivity2012Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 85, nr 1, s. 011303-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is shown that the proton formation probability, extracted from experimental data corresponding to one-proton radioactivity, is divided into two regions when plotted as a function of an universal parameter. This parameter is derived from a microscopic description of the decay process. In this way we explain the systematics of proton emission half-lives. At the same time the formation probability is shown to be a useful quantity to determine the deformation property of the mother nucleus.

  • 54.
    Qi, Chong
    et al.
    Peking University.
    Du, R.
    Gao, Y.
    Pei, J.
    Zhu, J.
    Xu, F.
    Proton resonance properties in light nuclei with mean-field type potentials2008Inngår i: INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS, 2008, s. 1955-1964Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The properties of proton resonances in the p and sd shells are studied with a single-particle potential generated by self-consistent-mean field calculations. Besides, we also propose to calculate the proton-nucleus interaction by a double-folding procedure with the density of the daughter nucleus represented by the result of the same mean-field model. With out raising any adjustable parameter, these calculations provide reasonable estimates for the widths of observed proton resonances in light nuclei. The mean-field-based calculation is particularly useful for the predications of the properties of resonances in light exotic nuclei and the direct proton capture reactions of astrophysics.

  • 55.
    Qi, Chong
    et al.
    Peking University.
    Du, R.
    Gao, Y.
    Zhu, J.
    Xu, F.
    Theoretical studies of proton capture reactions in A similar to 25 proton-rich nuclei2009Inngår i: Science in China Series G: Physics Mechanics and Astronomy, ISSN 1672-1799, E-ISSN 1862-2844, Vol. 52, nr 10, s. 1464-1470Artikkel i tidsskrift (Fagfellevurdert)
  • 56.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Jia, L. Y.
    Fu, G. J.
    Large-scale shell-model calculations on the spectroscopy of N < 126 Pb isotopes2016Inngår i: PHYSICAL REVIEW C, ISSN 2469-9985, Vol. 94, nr 1, artikkel-id 014312Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Large-scale shell-model calculations are carried out in the model space including neutron-hole orbitals 2p(1/2), 1f(5/2), 2p(3/2), 0i(13/2), 1f(7/2), and 0h(9/2) to study the structure and electromagnetic properties of neutron-deficient Pb isotopes. An optimized effective interaction is used. Good agreement between full shell-model calculations and experimental data is obtained for the spherical states in isotopes Pb194-206. The lighter isotopes are calculated with an importance-truncation approach constructed based on the monopole Hamiltonian. The full shell-model results also agree well with our generalized seniority and nucleon-pair-approximation truncation calculations. The deviations between theory and experiment concerning the excitation energies and electromagnetic properties of low-lying 0(+) and 2(+) excited states and isomeric states may provide a constraint on our understanding of nuclear deformation and intruder configuration in this region.

  • 57.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    NUCLEAR CLUSTERING AND GENERALIZATION OF THE GEIGER-NUTTALL LAW2012Inngår i: Romanian Journal of Physics, ISSN 1221-146XArtikkel i tidsskrift (Fagfellevurdert)
  • 58.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Competition of different coupling schemes in atomic nuclei2012Inngår i: Advanced Many-Body And Statistical Methods In Mesoscopic Systems, Institute of Physics Publishing (IOPP), 2012, Vol. 338, nr 012027, s. 012027-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Shell model calculations reveal that the ground and low-lying yrast states of the N = Z nuclei Pd-92(46) and Cd-96 are mainly built upon isoscalar spin - aligned neutron - proton pairs each carrying the maximum angular momentum J = 9 allowed by the shell 0g(9)/(2) which is dominant in this nuclear region. This mode of excitation is unique in nuclei and indicates that the spin - aligned pair has to be considered as an essential building block in nuclear structure calculations. In this contribution we will discuss this neutron - proton pair coupling scheme in detail. In particular, we will explore the competition between the normal monopole pair coupling and the spin - aligned coupling schemes. Such a coupling may be useful in elucidating the structure properties of N = Z and neighboring nuclei.

  • 59.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Generalization of the Geiger-Nuttall law and alpha clustering in heavy nuclei2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 381, s. 012131-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A generalization of the Geiger-Nuttall law is deduced, which is valid for the radioactivity of all clusters (including alpha particles), by considering the clusterization and subsequent decay of nucleons within the nucleus. This universal decay law (UDL) is a linear relation between the half-lives of the decaying clusters and the corresponding Q-values. In this universal decay law (UDL) the penetrability is still a dominant quantity. By using three free parameters only, one finds that all known ground state to ground state radioactive decays are explained rather well. This allows us to search for new cluster decay modes and to carry out a simple and model-independent study of the decay properties of nuclei over the whole nuclear chart. It also helps in distinguishing the role played by pairing collectivity in the clustering process in heavy nuclei.

  • 60.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Spin-aligned neutron-proton pair coupling in the era of large scale computing2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 381, nr 1, s. 012106-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Shell model calculations reveal that the ground and low-lying yrast states of the N = Z nuclei Pd-92(46) and Cd-96(48) are mainly built upon isoscalar spin-aligned neutron-proton pairs each carrying the maximum angular momentum J = 9 allowed by the shell 0g(9/2) which is dominant in this nuclear region. This mode of excitation is unique in nuclei and indicates that the spin-aligned pair has to be considered as an essential building block in nuclear structure calculations. In this contribution we will discuss this neutron-proton pair coupling scheme in detail. It may help in understanding the intrinsic structure of the shell-model wave function. In particular, we will explore the competition between the normal monopole pair coupling and the spin-aligned coupling schemes.

  • 61.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi (stängd 20110630).
    Wyss, Ramon A.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi (stängd 20110630).
    Nuclear clustering and generalization of the Geiger-Nuttall law 100 years after its formulation2011Inngår i: MANY-BODY CORRELATIONS FROM DILUTE TO DENSE NUCLEAR SYSTEMS (MBC 2011), 2011, Vol. 321Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The formation of clusters in nuclei is discussed and conditions to assess clusterization are formulated. By using these conditions a generalization of the Geiger-Nuttall law is deduced. This universal decay law (UDL) is a linear relation between the half-lives of the decaying clusters (including alpha particles) and the corresponding Q-values. The agreement between the UDL and available experimental data is excellent. This allows us to distinguish the role played by pairing collectivity in the clustering process.

  • 62.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wyss, Ramon A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Recent developments in radioactive charged-particle emissions and related phenomena2019Inngår i: Progress in Particle and Nuclear Physics, ISSN 0146-6410, E-ISSN 1873-2224, Vol. 105, s. 214-251Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The advent and intensive use of new detector technologies as well as radioactive ion beam facilities have opened up possibilities to investigate alpha, proton and cluster decays of highly unstable nuclei. This article provides a review of the current status of our understanding of clustering and the corresponding radioactive particle decay process in atomic nuclei. We put alpha decay in the context of charged-particle emissions which also include one- and two-proton emissions as well as heavy cluster decay. The experimental as well as the theoretical advances achieved recently in these fields are presented. Emphasis is given to the recent discoveries of charged-particle decays from proton-rich nuclei around the proton drip line. Those decay measurements have shown to provide an important probe for studying the structure of the nuclei involved. Developments on the theoretical side in nuclear many-body theories and supercomputing facilities have also made substantial progress, enabling one to study the nuclear clusterization and decays within a microscopic and consistent framework. We report on properties induced by the nuclear interaction acting in the nuclear medium, like the pairing interaction, which have been uncovered by studying the microscopic structure of clusters. The competition between cluster formations as compared to the corresponding alpha-particle formation are included. In the review we also describe the search for super-heavy nuclei connected by chains of alpha and other radioactive particle decays.

  • 63.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wang, X. B.
    Xu, Zhen Xiang
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, F. R.
    Alternate proof of the Rowe-Rosensteel proposition and seniority conservation2010Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 82, nr 1, s. 014304-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For a system with three identical nucleons in a single-j shell, the states can be written as the angular-momentum coupling of a nucleon pair and the odd nucleon. The overlaps between these nonorthonormal states form a matrix that coincides with the one derived by Rowe and Rosensteel [Phys. Rev. Lett. 87, 172501 ( 2001)]. The propositions they state are related to the eigenvalue problems of the matrix and dimensions of the associated subspaces. In this work, the propositions are proven from the symmetric properties of the 6j symbols. Algebraic expressions for the dimension of the states, eigenenergies, as well as conditions for conservation of seniority can be derived from the matrix.

  • 64.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    N = Z nuclei: a laboratory for neutron-proton collective mode2016Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 91, nr 1, artikkel-id 013009Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The neutron-neutron and proton-proton pairing correlations have long been recognized to be the dominant many-body correlation beyond the nuclear mean field since the introduction of pairing mechanism by Bohr, Mottelson and Pines nearly 60 years ago. Nevertheless, few conclusions have been reached concerning the existence of analogous neutron-proton (np) pair correlated state. One can see a renaissance in np correlation studies in relation to the significant progress in radioactive ion beam facilities and detection techniques. The np pairs can couple isospin T = 1 (isovector) or 0 (isoscalar). In the isovector channel, the angular momentum zero component is expected to be the most important one. On the other hand, as one may infer from the general properties of the np two-body interaction, in the isoscalar channel, both the np pairs with minimum (J = 1) and maximum (J = 2j) spin values can be important. In this contribution, we will discuss the possible evidence for np pair coupling from a different perspective and analyze its influence on interesting phenomena including the Wigner effect and mass correlations in odd-odd nuclei. In particular, we will explain the spin-aligned pair coupling scheme and quartet coupling involving pairs with maximum (J = 2j) spin values.

  • 65.
    Qi, Chong
    et al.
    Peking University.
    Xu, F.
    Peking University.
    Isospin asymmetry effects in mirror nuclei with modern charge-dependent NN potential2008Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 814, nr 1-4, s. 48-65Artikkel i tidsskrift (Fagfellevurdert)
  • 66.
    Qi, Chong
    et al.
    Peking University.
    Xu, F.
    Peking University.
    Isospin symmetry and Gamow Teller transition strengths in mirror nuclei2006Inngår i: International Journal of Modern Physics E, ISSN 0218-3013, Vol. 15, nr 7, s. 1563-1568Artikkel i tidsskrift (Fagfellevurdert)
  • 67.
    Qi, Chong
    et al.
    Peking University.
    Xu, F.
    Peking University.
    Shell-Model Calculations of fp-shell Nuclei with Realistic NN Interactions2010Inngår i: NUCLEAR PHYSICS TRENDS / [ed] Ozawa, A; Liu, WP, 2010, s. 391-397Konferansepaper (Fagfellevurdert)
  • 68.
    Qi, Chong
    et al.
    Peking University.
    Xu, F.
    Peking University.
    Shell-model studies of isomeric states in Fe-51,Fe-52,Fe-532008Inngår i: Chinese Physics C, High Energy Physics & Nuclear Physics, ISSN 1674-1137, E-ISSN 0899-9996, Vol. 32, s. 112-115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The yrast bands of (51,52,53)Fe have been studied with a microscopical effective Hamiltonian derived from the charge-dependent Bonn NN potential. Calculations obtain satisfactory agreements with experimental data, reproducing the observed isomeric states. The possible origins of the isomers are discussed.

  • 69.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, F. R.
    Liotta, Roberto J.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Zhang, M. Y.
    Asawatangtrakuldee, C.
    Hu, D.
    Microscopic mechanism of charged-particle radioactivity and generalization of the Geiger-Nuttall law2009Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 80, nr 4, s. 044326-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A linear relation for charged-particle emissions is presented starting from the microscopic mechanism of the radioactive decay. It relates the logarithms of the decay half-lives with two variables, called. chi' and. rho', which depend upon the Q values of the outgoing clusters as well as the masses and charges of the nuclei involved in the decay. This relation explains well all known cluster decays. It is found to be a generalization of the Geiger-Nuttall law in a radioactivity, and therefore we call it the universal decay law. Predictions of the most likely emissions of various clusters are presented by applying the law over the whole nuclear chart. It is seen that the decays of heavier clusters with nonequal proton and neutron numbers are mostly located in the trans-lead region. The emissions of clusters with equal protons and neutrons, like C-12 and O-16, are possible in some neutron-deficient nuclei with Z >= 54.

  • 70.
    Qi, Chong
    et al.
    Peking University.
    Xu, Furong
    Peking University.
    Shell-model study of spectroscopies and isospin structures in odd-odd N=Z nuclei employing realistic NN interaction2008Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 800, nr 1-4, s. 47-62Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structures of odd-odd N = Z nuclei in the lower fp shell have been investigated with a new microscopic interaction. The interaction is derived from a high-precision charge-dependent Bonn nucleon-nucleon potential using the folded-diagram renormalization method. Reasonable agreements with experimental data have been obtained. Particularly, the relative positions of T = 0 and T = I bands are well reproduced. As examples, the spectroscopies and isospin structures of (46)V and (50)Mn have been discussed in details, with the useful predictions of level structures including electromagnetic properties. Some unique features in these nuclei can be used to increase the understanding of the effective interaction theory. Our calculations show that the realistic effective interaction which is directly related to nucleon-nucleon scattering can give the reasonable descriptions of the collective properties of nuclear many-body system without any empirical modification.

  • 71.
    Qi, Chong
    et al.
    Peking University.
    Xu, Furong
    Peking University.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Universal Decay Law in Charged-Particle Emission and Exotic Cluster Radioactivity2009Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, nr 7, s. 072501-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A linear universal decay formula is presented starting from the microscopic mechanism of the charged-particle emission. It relates the half-lives of monopole radioactive decays with the Q values of the outgoing particles as well as the masses and charges of the nuclei involved in the decay. This relation is found to be a generalization of the Geiger-Nuttall law in α radioactivity and explains well all known cluster decays. Predictions on the most likely emissions of various clusters are presented.

  • 72.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, Zhen Xiang
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto J.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Analytic proof of partial conservation of seniority in j=9/2 shells2012Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 884, s. 21-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A partial conservation of the seniority quantum number in j = 9/2 shells has been found recently in a numerical application. In this paper an analytic proof for this problem is derived as an extension of the work [L. Zamick, P. Van Isacker, Phys. Rev. C 78 (2008) 044327]. We analyze the properties of the non-diagonal interaction matrix elements with the help of the one-particle and two-particle coefficients of fractional parentage (cfp's). It is found that all non-diagonal (and the relevant diagonal) matrix elements can be re-expressed in simple ways and are proportional to certain one-particle cfp's. This remarkable occurrence of partial dynamic symmetry is the consequence of the peculiar property of the j = 9/2 shell, where all it = 3 and 5 states are uniquely defined.

  • 73.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, Zhenxiang
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Monopole-optimized effective interaction for tin isotopes2012Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 86, nr 4, s. 044323-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a systematic configuration-interaction shell-model calculation on the structure of light tin isotopeswith a global optimized effective interaction. The starting point of the calculation is the realistic CD-Bonnnucleon-nucleon potential. The unknown single-particle energies of the 1d3/2, 2s1/2, and 0h11/2 orbitals and theT = 1 monopole interactions are determined by fitting to the binding energies of 157 low-lying yrast states in102−132Sn. We apply the Hamiltonian to analyze the origin of the spin inversion between 101Sn and 103Sn that wasobserved recently and to explore the possible contribution from interaction terms beyond the normal pairing.

  • 74.
    Qi, Chong
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, Zhen-Xiang
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Shell evolution and its indication on the isospin dependence of the spin-orbit splitting2013Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 724, nr 4-5, s. 247-252Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The available experimental data on shell evolution indicate that the strength of the spin-orbit single-particle potential may be enhanced in neutron-rich nuclei. We observe that such a simple scheme destroys the harmonic oscillator magic numbers N = 8 and 20 and generates new magic numbers like N = 6, 14, 16, 32 and 34. The traditional magic numbers like N = 28 and 50 and N = 14 seen in O-22 are eroded in neutron-rich nuclei due to the sensitivity of larger-l orbitals to the depth of the central potential but they are more robust than the harmonic oscillator magic numbers. The N = 82 shell closure persists in neutron-rich nuclei while the previously proposed shell closures like N = 40 and 70 do not emerge. Both mechanisms contribute to enhancing the N = 56 and 90 gaps by splitting the 1d(5/2) and 0g(7/2) and the 0h(9/2) and 1f(7/2) orbitals.

  • 75.
    Qian, Yibin
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. Nanjing Univ Sci & Technol, Dept Appl Phys, Nanjing 210094, Jiangsu, Peoples R China..
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Partial seniority conservation and solvability of single- j systems2018Inngår i: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 98, nr 6, artikkel-id 061303Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The seniority symmetry is known to be partially conserved in two special cases in the (9/2)(4) system, which can lead to striking features in the corresponding structure and electromagnetic transition properties. However, it is still quite difficult to derive those kind of solvable states, in general, especially towards higher- j orbits. We have developed a novel and effective way to confront this challenge by starting from the m scheme and making use of the angular momentum projection method. It also allows us to explore another special family of seniority conserving states in the midshell besides the specific case of the (9/2)(4) configuration. Moreover, we have studied systemically all states in single- j systems up to j = 15/2 and derived the analytic expressions for the eigenvalues of all solvable states with a focus on those in j = 9/2 and j = 11/2. Such studies can also be useful for the experimental search of relevant states and for the understanding of their electromagnetic transition properties.

  • 76. Sun, M. D.
    et al.
    Liu, Z.
    Huang, T. H.
    Zhang, W. Q.
    Wang, J. G.
    Liu, X. Y.
    Ding, B.
    Gan, Z. G.
    Ma, L.
    Yang, H. B.
    Zhang, Z. Y.
    Yu, L.
    Jiang, J.
    Wang, K. L.
    Wang, Y. S.
    Liu, M. L.
    Li, Z. H.
    Li, J.
    Wang, X.
    Lu, H. Y.
    Lin, C. J.
    Sun, L. J.
    Ma, N. R.
    Yuan, C. X.
    Zuo, W.
    Xu, H. S.
    Zhou, X. H.
    Xiao, G. Q.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Zhang, F. S.
    New short-lived isotope 223Np and the absence of the Z = 92 subshell closure near N = 1262017Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 771, s. 303-308Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The N=130 short-lived isotope 223Np was produced as evaporation residue (ER) in the fusion reaction 40Ar + 187Re at the gas-filled recoil separator Spectrometer for Heavy Atom and Nuclear Structure (SHANS). It was identified through temporal and spatial correlations with α decays of 215Ac and/or 211Fr, the third and fourth members of the α-decay chain starting from 223Np. The pileup signals of ER(223Np)–α(223Np)–α(219Pa) were resolved by using the digital pulse processing technique. An α decay with half-life of T1/2=2.15(52100) μs and energy of Eα=9477(44) keV was attributed to 223Np. Spin and parity of 9/2− were tentatively proposed for the ground state of 223Np by combining the reduced α-decay width and large-scale shell-model calculations. This assignment together with the proton separation energy disprove the existence of a Z=92 subshell closure.

  • 77.
    Sun, M. D.
    et al.
    Chinese Acad Sci, Inst Modern Phys, CAS Key Lab High Precis Nucl Spect, Lanzhou 730000, Gansu, Peoples R China.;Univ Chinese Acad Sci, Sch Nucl Sci & Technol, Beijing 100049, Peoples R China.;Lanzhou Univ, Lanzhou 730000, Gansu, Peoples R China..
    Liu, Z.
    Chinese Acad Sci, Inst Modern Phys, CAS Key Lab High Precis Nucl Spect, Lanzhou 730000, Gansu, Peoples R China.;Univ Chinese Acad Sci, Sch Nucl Sci & Technol, Beijing 100049, Peoples R China..
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Zhang, F. S.
    Beijing Normal Univ, Coll Nucl Sci & Technol, Key Lab Beam Technol & Mat Modificat, Minist Educ, Beijing 100875, Peoples R China.;Beijing Radiat Ctr, Beijing 100875, Peoples R China..
    et al.,
    Fine structure in the alpha decay of U-2232020Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 800, artikkel-id 135096Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fine structure in the alpha decay of U-223 was observed in the fusion-evaporation reaction Re-187(Ar-40, p3n) by using fast digital pulse processing technique. Two alpha-decay branches of U-223 feeding the ground state and 244 keV excited state of Th-219 were identified by establishing the decay chain U-223 (alpha(1)) under right arrow Th-219 (alpha(2)) under right arrow Ra-215 (alpha(3)) under right arrow Rn-211. The alpha-particle energy for the ground-state to ground-state transition of U-223 was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62(-10)(+14) mu s. Evolution of nuclear structure for N = 131 even-Z isotones from Po to U was discussed in the frameworks of nuclear mass and reduced alpha-decay width, a weakening octupole deformation in the ground state of U-223 relative to its lighter isotones Ra-219 and Th-221 was suggested.

  • 78. Wang, F.
    et al.
    Sun, B. H.
    Liu, Z.
    Page, R. D.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Scholey, C.
    Ashley, S. F.
    Bianco, L.
    Cullen, I. J.
    Darby, I. G.
    Eeckhaudt, S.
    Garnsworthy, A. B.
    Gelletly, W.
    Gomez-Hornillos, M. B.
    Grahn, T.
    Greenlees, P. T.
    Jenkins, D. G.
    Jones, G. A.
    Jones, P.
    Joss, D. T.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Khan, S.
    Kishada, A.
    Leino, M.
    Niikura, M.
    Nyman, M.
    Pakarinen, J.
    Pietri, S.
    Podolyak, Z.
    Rahkila, P.
    Rigby, S.
    Saren, J.
    Shizuma, T.
    Sorri, J.
    Steer, S.
    Thomson, J.
    Thompson, N. J.
    Uusitalo, J.
    Walker, P. M.
    Williams, S.
    Zhang, H. F.
    Zhang, W. Q.
    Zhu, L. H.
    Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151mLu2017Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 770, s. 83-87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The quenching of the experimental spectroscopic factor for proton emission from the short-lived d3/2 isomeric state in 151mLu was a long-standing problem. In the present work, proton emission from this isomer has been reinvestigated in an experiment at the Accelerator Laboratory of the University of Jyväskylä. The proton-decay energy and half-life of this isomer were measured to be 1295(5) keV and 15.4(8) μs, respectively, in agreement with another recent study. These new experimental data can resolve the discrepancy in the spectroscopic factor calculated using the spherical WKB approximation. Using the R-matrix approach it is found that the proton formation probability indicates no significant hindrance for the proton decay of 151mLu.

  • 79. Wang, F.
    et al.
    Sun, B. H.
    Liu, Z.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Zhu, L. H.
    Scholey, C.
    Ashley, S. F.
    Bianco, L.
    Cullen, I. J.
    Darby, I. G.
    Eeckhaudt, S.
    Garnsworthy, A. B.
    Gelletly, W.
    Gomez-Hornillos, M. B.
    Grahn, T.
    Greenlees, P. T.
    Jenkins, D. G.
    Jones, G. A.
    Jones, P.
    Joss, D. T.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Khan, S.
    Kishada, A.
    Leino, M.
    Niikura, M.
    Nyman, M.
    Page, R. D.
    Pakarinen, J.
    Pietri, S.
    Podolyak, Zs.
    Rahkila, P.
    Rigby, S.
    Saren, J.
    Shizuma, T.
    Sorri, J.
    Steer, S.
    Thomson, J.
    Thompson, N. J.
    Uusitalo, J.
    Walker, P. M.
    Williams, S.
    Reinvestigation of the excited states in the proton emitter Lu-151: Particle-hole excitations across the N = Z=64 subshell2017Inngår i: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 96, nr 6, artikkel-id 064307Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The excited states of the proton emitter Lu-151 were reinvestigated in a recoil-decay tagging experiment at the Accelerator Laboratory of the University of Jyvaskyla (JYFL). The level scheme built on the ground state of 151Lu was updated with five new y-ray transitions. Large-scale shell model calculations were carried out in the model space consisting of the neutron and proton orbitals 0g(7/2), Id(5/2), Id(3/2), 2s(1/2), and Oh(1/2) with the optimized monopole interaction in order to interpret the experimental level scheme of Lu-151. It is found that the excitation energies of states above the 27/2(-) and 23/2(+) isomeric levels in Lu-151 can be sensitive to excitations from g(7/2) and d(5/2) to single-particle orbitals above N = Z = 64.

  • 80.
    Wang, S.
    et al.
    Peking University.
    Xu, C.
    Peking University.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, F.
    Peking University.
    Jiang, D.
    Peking University.
    Alpha-particle decays from excited states in Mg-242011Inngår i: Science China: Physics, Mechanics and Astronomy, ISSN 1674-7348, Vol. 54, nr 1, s. S130-S135Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using a cluster model based on the Woods-Saxon potential, alpha-particle decays from excited states in Mg-24 have been systematically investigated. Calculations can in general reproduce experimental data, noticing the fact that the preformation factor P of alpha particle in alpha-decaying nuclei is of order from 10(0) to 10(-2). This can be the evidence for the alpha+Ne-20 structure in Mg-24. Meanwhile, the results also show the existence of other configurations, such as O-16+2 alpha. Since the calculated decay widths are very sensitive to the angular momentum carried by the outgoing cluster (alpha particle), our results could serve as a guide to experimental spin assignments.

  • 81. Wang, X. B.
    et al.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, F. R.
    Isovector channel of quark-meson-coupling model and its effect on symmetry energy2011Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 865, nr 1, s. 57-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The non-relativistic approximation Of the quark-meson-coupling model has been discussed and compared with the Skyrme-Hartree-Fock model which includes spin exchanges. Calculations show that the spin-exchange interaction has important effect on the descriptions of finite nuclei and nuclear matter through the Fock exchange. Also in the quark-meson-coupling model, it is the Fock exchange that leads to a nonlinear density-dependent isovector channel and changes the density-dependent behavior of the symmetry energy.

  • 82.
    Wang, X.
    et al.
    Peking University.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, F.
    Peking University.
    Eigen-Property of Single-j System and Seniority Conservation Condition2012Inngår i: Plasma Science and Technology, ISSN 1009-0630, Vol. 14, nr 5, s. 383-385Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we study the system with three nucleons within a single-j shell, which can be described as the angular momentum coupling of a nucleon pair and the odd nucleon. The overlaps between these non-orthonormal states form a special matrix coincidental with the one obtained by Rowe and Rosensteel. They proposed a proposition related to the eigenvalue problems of that matrix and dimensions of the associated subspaces. We prove their proposition with the help of the symmetric properties of the six-j symbols. We also derive algebraic expressions for eigen energies as well as conditions for conservation of seniority through the decomposition of the angular momentum.

  • 83.
    Wang, Yan-Zhao
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. Shijiazhuang Tiedao Univ, Dept Math & Phys, Shijiazhuang 050043, Hebei, Peoples R China.;Shijiazhuang Tiedao Univ, Inst Appl Phys, Shijiazhuang 050043, Hebei, Peoples R China.;China Inst Atom Energy, Beijing 102413, Peoples R China..
    Li, Yang
    Shijiazhuang Tiedao Univ, Dept Math & Phys, Shijiazhuang 050043, Hebei, Peoples R China.;Shijiazhuang Tiedao Univ, Inst Appl Phys, Shijiazhuang 050043, Hebei, Peoples R China..
    Qi, Chong
    Gu, Jian-Zhong
    China Inst Atom Energy, Beijing 102413, Peoples R China..
    Pairing Effects on Bubble Nuclei2019Inngår i: Chinese Physics Letters, ISSN 0256-307X, E-ISSN 1741-3540, Vol. 36, nr 3, artikkel-id 032101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the framework of the Skyrme-Hartree-Fock-Bogoliubov approach with the SkT interaction, the pairing effects on the proton bubble structures of Ar-46 and( 206)Hg are discussed. In calculations, three kinds of pairing forces (volume, surface and mixed pairing interactions) are used. For Ar-46, it is shown that the bubble structure with the volume pairing is almost the same as that with the mixed pairing. The bubble with the surface pairing is less pronounced than those with the volume and mixed pairings. Analyzing the density distributions and occupation probabilities of the proton s states and the quasi-degeneracy between the proton 2s(1/2) and 1d(3/2) orbitals, we explain the difference between the bubble structure with the surface pairing and those with the volume and mixed pairings. For Hg-206, it is seen that the proton density distribution with the surface pairing is different from those with the volume and mixed pairings in the whole region of the radial distance. In addition, it is found that the bubbles with the three pairing forces are different from each other and the least pronounced bubble is obtained with the surface pairing. Thus the selection of the pairing force is important for the study of the nuclear bubble structure.

  • 84.
    Wang, Yan-Zhao
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. Shijiazhuang Tiedao Univ, Dept Math & Phys, Shijiazhuang 050043, Hebei, Peoples R China;Shijiazhuang Tiedao Univ, Inst Appl Phys, Shijiazhuang 050043, Hebei, Peoples R China;China Inst Atom Energy, POB 275 10, Beijing 102413, Peoples R China.
    Su, Xue-Dou
    Shijiazhuang Tiedao Univ, Dept Math & Phys, Shijiazhuang 050043, Hebei, Peoples R China.;Shijiazhuang Tiedao Univ, Inst Appl Phys, Shijiazhuang 050043, Hebei, Peoples R China.;Beihang Univ, Sch Phys & Nucl Energy Engn, Beijing 100191, Peoples R China..
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik. Royal Inst Technol KTH, Dept Phys, SE-10691 Stockholm, Sweden..
    Gu, Jian-Zhong
    China Inst Atom Energy, POB 275 10, Beijing 102413, Peoples R China..
    Tensor force effect on the exotic structure of neutron-rich Ca isotopes*2019Inngår i: Chinese Physics C, High Energy Physics & Nuclear Physics, ISSN 1674-1137, E-ISSN 0899-9996, Vol. 43, nr 11, artikkel-id 114101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure of neutron-rich Ca isotopes is studied in the spherical Skyrme-Hartree-Fock-Bogoliubov (SHFB) approach with SLy5, SLy5+T, and 36 sets of TIJ parametrizations. The calculated results are compared with the available experimental data for the average binding energies, two-neutron separation energies and charge radii. It is found that the SLy5+T, T31, and T32 parametrizations reproduce best the experimental properties, especially the neutron shell effects at N = 20, 28 and 32, and the recently measured two-neutron separation energy of Ca-56. The calculations with the SLy5+T and T31 parametrizations are extended to isotopes near the neutron drip line. The neutron giant halo structure in the very neutron-rich Ca isotopes is not seen with these two interactions. However, depleted neutron central densities are found in these nuclei. By analyzing the neutron mean-potential, the reason for the bubble-like structure formation is given.

  • 85.
    Wu, Zheying
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Changizi, Sara
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Empirical residual neutron-proton interaction in odd-odd nuclei2016Inngår i: PHYSICAL REVIEW C, ISSN 2469-9985, Vol. 93, nr 3, artikkel-id 034334Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two types of average neutron-proton interaction formulas are compared: In the first type, neutron-proton interactions for even-even and odd-A nuclei extracted from experimental binding energies show a smooth behavior as a function of mass number A and are dominated by the contribution from the symmetry energy. Whereas in the second type large systematic staggering is seen between even-A and odd-A nuclei. This deviation is understood in terms of the additional neutron-proton interaction in odd-odd nuclei relative to the neighboring even-even and odd-A systems. We explore three possible ways to extract this additional interaction from the binding energy difference of neighboring nuclei. The extracted interactions are positive in nearly all cases and show weak dependence on the mass number. The empirical interactions are also compared with theoretical values extracted from recent nuclear mass models where large unexpected fluctuations are seen in certain nuclei. The reproduction of the residual neutron-proton interaction and the correction of those irregular fluctuations can be a good criterion for the refinement of those mass models.

  • 86.
    Wu, Zhe-Ying
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liu, Hong-Liang
    Global calculations of microscopic energies and nuclear deformations: Isospin dependence of the spin-orbit coupling2015Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 92, nr 2, artikkel-id 024306Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: The deviation between different model calculations that may occur when one goes toward regions where the masses are unknown is getting increased attention. This is related to the uncertainties of the different models which may have not been fully understood. Purpose: To explore in detail the effect of the isospin dependence of the spin-orbital force in the Woods-Saxon potential on global binding energy and deformation calculations. Method: The microscopic energies and nuclear deformations of about 1850 even-even nuclei are calculated systematically within the macroscopic-microscopic framework using three Woods-Saxon parametrizations, with different isospin dependencies, which were constructed mainly for nuclear spectroscopy calculations. Calculations are performed in the deformation space (beta(2), gamma, beta(4)). Both the monopole and doubly stretched quadrupole interactions are considered for the pairing channel. Results: The ground-state deformations obtained by the three calculations are quite similar to each other. Large differences are seen mainly in neutron-rich nuclei and in superheavy nuclei. Systematic calculations on the shape-coexisting second minima are also presented. As for the microscopic energies of the ground states, the results are also very close to each other. Only in a few cases the difference is larger than 2 MeV. The total binding energy is estimated by adding the macroscopic energy provided by the usual liquid drop model with its parameters fitted through the least square root and minimax criteria. Calculations are also compared with the results of other macroscopic-microscopic mass models. Conclusions: All the three calculations give similar values for the deformations, microscopic energies, and binding energies of most nuclei. One may expect to have a better understanding of the isospin dependence of the spin-orbital force with more data on proton- and neutron-rich nuclei.

  • 87. Xu, Chen
    et al.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Wang, S. M.
    Xu, F. R.
    Jiang, D. X.
    Molecular structure of highly excited resonant states in Mg-24 and the corresponding Be-8+O-16 and C-12+C-12 decays2010Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 81, nr 5, s. 054319-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exotic Be-8 and C-12 decays from high-lying resonances in Mg-24 are analyzed in terms of a cluster model. The calculated quantities agree well with the corresponding experimental data. It is found that the calculated decay widths are very sensitive to the angular momentum carried by the outgoing cluster. It is shown that this property makes cluster decay a powerful tool to determine the spin as well as the molecular structures of the resonances.

  • 88.
    Xu, Zhen Xiang
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Blomqvist, Jan
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Multistep shell model description of spin-aligned neutron-proton pair coupling2012Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 877, s. 51-58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The recently proposed spin-aligned neutron-proton pair coupling scheme is studied within a non-orthogonal basis in term of the multistep shell model. This allows us to identify simultaneously the roles played by other configurations such as the normal pairing term. The model is applied to four-, six- and eight-hole N = Z nuclei below the core Sn-100.

  • 89.
    Xu, Zhen Xiang
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Multistep shell model in the complex energy plane2012Inngår i: Advanced Many-Body And Statistical Methods In Mesoscopic Systems, Institute of Physics Publishing (IOPP), 2012, s. 012029-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We have adopted the multistep shell model in the complex energy plane to study nuclear excitations occurring in the continuum part of the spectrum. In this method one proceeds by solving the shell model equations in a successive manner. That is, in each step one constructs the building blocks to be used in future steps. We applied this formalism to analyze the unbound nuclei Li-12,Li-13 starting from the one - particle states in Li-10 and two - particle states in Li-11. In the former case the excitations correspond to the motion of three particles partitioned as the product of a one - particle and two - particle systems. The ground state of Li-12 is thus calculated to be an antibound (virtual) state. In the four - particle system Li-13 the states can be constructed as the coupling of two correlated pairs. We found that there is no bound or antibound state in Li-13.

  • 90.
    Xu, Zhenxiang
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Liotta, Roberto J.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Roger, T.
    GANIL, France.
    Roussel-Chomaz, P.
    GANIL, France.
    Savajols, H.
    GANIL, France.
    Wyss, Ramon
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Analysis of the unbound spectrum of 12Li.2011Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 850, s. 53-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The unbound nucleus 12Li is evaluated by studying three-neutron one-proton excitations within the multistepshell model in the complex energy plane. It is found that the ground state of this system consists of anantibound 2− state. A number of narrow states at low energy are found which ensue from the coupling ofresonances in 11Li to continuum states close to threshold.

  • 91.
    Xu, Zhenxiang
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Novel Monte Carlo representation for shell model in the complex energy planeManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    A Monte Carlo method is presented to evaluate quantum states with many particles moving inthe continuum. The scattering state is generated at each time by a Monte Carlo random samplingalgorithm. The same calculation are repeated until the average energies of all calculations converge.For systems with one and two particles, our calculations show that the exact solution can beapproached with around only one hundred iterations.

  • 92. Yuan, C.
    et al.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Recent shell-model studies of light and medium-mass nuclei2014Inngår i: He Jishu/Nuclear Techniques, ISSN 0253-3219, Vol. 37, nr 10, artikkel-id 100503Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Nuclear shell model is widely applied in the studies of light and medium-mass nuclei. The ground and excited state energies, electromagnetic properties and β decay properties of these nuclei can be well understood by solving many body Schrödinger equation with effective shell-model Hamiltonian in the model space. Purpose: The aim is to introduce the framework of shell model and its application in nuclei. Methods: The nuclear shell model is used to study properties of selected nuclei. Results: In psd region, a new effective shell-model Hamiltonian is introduced. The neutron drip-line of C, N, and O isotopes can be given with such Hamiltonian. The nuclei around A=20 with weakly bound proton are investigated through a modified shell model Hamiltonian. N=Z nucleus is good for studying the effect of proton-neutron pair. 46V and 50Mn have both T=0 and 1 rotational band. 92Pd can be understood under a spin alignment isoscalar scheme of proton-neutron pair. Mirror nuclei around N=Z in fp region can be used for the investigation of charge symmetry breaking effect of nuclear force. Conclusion: Nuclear shell model is proper and useful for the description of light and medium-mass nuclei.

  • 93.
    Yuan, C.
    et al.
    Peking University.
    Qi, Chong
    Peking University.
    Xu, F.
    Peking Unversity.
    Shell-model studies of the N=14 and 16 shell closures in neutron-rich nuclei2009Inngår i: Chinese Physics C, High Energy Physics & Nuclear Physics, ISSN 1674-1137, E-ISSN 0899-9996, Vol. 33, s. 55-57Artikkel i tidsskrift (Fagfellevurdert)
  • 94. Yuan, C. X.
    et al.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, F. R.
    Shell evolution in neutron-rich carbon isotopes: Unexpected enhanced role of neutron-neutron correlation2012Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 883, s. 25-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Full shell-model diagonalization has been performed to study the structure of neutron-rich nuclei around C-20. We investigate in detail the roles played by the different monopole components of the effective interaction in the evolution of the N = 14 shell in C, N and O isotopes. It is found that the relevant neutron neutron monopole terms, V-d5/2d5/2(nn) and V-s1/2s1/2(nn) contribute significantly to the reduction of the N = 14 shell gap in C and N isotopes in comparison with that in O isotopes. The origin of this unexpectedly large effect, which is comparable with (sometimes even larger than) that caused by the proton neutron interaction, is related to the enhanced configuration mixing in those nuclei due to many-body correlations. Such a scheme is also supported by the large B(E2) value in the nucleus C-20 which has been measured recently.

  • 95. Yuan, C. X.
    et al.
    Xu, F. R.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Configuration mixing effects in neutron-rich carbon isotopes2013Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 420, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Shell model calculations are done to study the structure of neutron-rich carbon isotopes. For both even-A and odd-A neutron-rich carbon isotopes, the energy levels are strongly affected by the configuration mixing of valence neutrons. The calculated energy levels in the nucleus 17C are significantly improved compared with experimental values when the model space of the three valence neutrons is enlarged from pure v(0d5/2) 3 configuration to full sd space. We also investigate the configuration mixing effect on the B(E2) values in even-even nuclei 16-20C.

  • 96. Yuan, Cenxi
    et al.
    Qi, Chong
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Xu, Furong
    Suzuki, Toshio
    Otsuka, Takaharu
    Mirror energy difference and the structure of loosely bound proton-rich nuclei around A=202014Inngår i: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 89, nr 4, s. 044327-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The properties of loosely bound proton-rich nuclei around A = 20 are investigated within the framework of the nuclear shell model. In these nuclei, the strength of the effective interactions involving the loosely bound proton s(1/2) orbit is significantly reduced in comparison with that of those in their mirror nuclei. We evaluate the reduction of the effective interaction by calculating the monopole-based-universal interaction (V-MU) in the Woods-Saxon basis. The shell-model Hamiltonian in the sd shell, such as USD, can thus be modified to reproduce the binding energies and energy levels of the weakly bound proton-rich nuclei around A = 20. The effect of the reduction of the effective interaction on the structure and decay properties of these nuclei is also discussed.

  • 97.
    Zheng, S.
    et al.
    Peking University.
    Xu, F.
    Yuan, C.
    Qi, Chong
    Peking University.
    Alignments in the nobelium isotopes2009Inngår i: Chinese Physics C, High Energy Physics & Nuclear Physics, ISSN 1674-1137, E-ISSN 0899-9996, Vol. 33, nr 2, s. 107-109Artikkel i tidsskrift (Fagfellevurdert)
  • 98.
    Zhu, J.
    et al.
    Peking University.
    Qi, Chong
    Peking University.
    Liu, Meng
    Cui, X.
    Xu, F.
    Shape transitions in proton-rich Ho and Tm isotopes2009Inngår i: Chinese Physics C, High Energy Physics & Nuclear Physics, ISSN 1674-1137, E-ISSN 0899-9996, Vol. 33, s. 9-11Artikkel i tidsskrift (Fagfellevurdert)
12 51 - 98 of 98
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