We develop both relativistic mean field and beyond approaches for hypernuclei with possible quadrupole-octupole deformation or pear-like shapes based on relativistic point-coupling energy density functionals. The symm...We develop both relativistic mean field and beyond approaches for hypernuclei with possible quadrupole-octupole deformation or pear-like shapes based on relativistic point-coupling energy density functionals. The symmetries broken in the mean-field states are recovered with parity, particle-number and angular momentum projections. We take_Λ^(21)Ne as an example to illustrate the method, where the Λ hyperon is put on one of the two lowest-energy orbits(labeled as Λ_s, Λ_p), respectively. We find that the Λ hyperon in both cases disfavors the formation of a reflection-asymmetric molecular-like^(16)O+α structure in^(20)Ne, which is consistent with the Nilsson diagram for the hyperon in(β_2, β_3) deformation plane. In particular, we show that the negative-parity states with the configuration^(20)Ne(K~π= 0^-) Λ_s are close in energy to those with the configuration^(20)Ne(K~π= 0^+)Λ_p, even though they have very different structures. The Λ_s(Λ_p) becomes more and more concentrated around the bottom(top) of the"pear" with the increase of octupole deformation.展开更多
A multi-nucleon transfer and cluster decay experiment,^(7)Li(^(11)B,^(14)C^(*)→α+^(10)Be)α,is conducted at an incident beam energy of 55 MeV.This reaction channel has a significantly large 0-value,which favors popu...A multi-nucleon transfer and cluster decay experiment,^(7)Li(^(11)B,^(14)C^(*)→α+^(10)Be)α,is conducted at an incident beam energy of 55 MeV.This reaction channel has a significantly large 0-value,which favors populating the high lying resonant states in ^(14)C.The decay paths,from these resonances to various states of the final nucleus ^(10) Be,can be selected,owing to the experimentally achieved optimal resolution of the Q-value spectrum.A number of resonant states are reconstructed from the forward emitting 10Be+α fragments,and their major molecular structures can be detected according to the selective decay paths and relative decay widths.A state at 22.4(2)MeV validates the previously measured and theoretically predicted band head of the positive-parity σ-bond linear-chain mo-lecular band.Two additional resonances at 22.9(2)and 24.2(2)MeV are identified and consistent with the predicted 2^(+) and 4^(+) members of the same molecular band,thus providing novel evidences for the existence of the exotic clustering chain structure in neutron-rich carbon isotopes.A few high energy resonances,which also indicate the presence of the σ-bond molecular structure,are observed;however,further studies are still required to clarify their ascription in band systematics.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11575148)the support by the Scientific Discovery through Advanced Computing(SciDAC)program funded by the U.S.Department of Energy,Office of Science,Office of Advanced Scientific Computing Research and Office of Nuclear Physics,under Award Number DE-SC0008641(NUCLEI SciDAC Collaboration)
文摘We develop both relativistic mean field and beyond approaches for hypernuclei with possible quadrupole-octupole deformation or pear-like shapes based on relativistic point-coupling energy density functionals. The symmetries broken in the mean-field states are recovered with parity, particle-number and angular momentum projections. We take_Λ^(21)Ne as an example to illustrate the method, where the Λ hyperon is put on one of the two lowest-energy orbits(labeled as Λ_s, Λ_p), respectively. We find that the Λ hyperon in both cases disfavors the formation of a reflection-asymmetric molecular-like^(16)O+α structure in^(20)Ne, which is consistent with the Nilsson diagram for the hyperon in(β_2, β_3) deformation plane. In particular, we show that the negative-parity states with the configuration^(20)Ne(K~π= 0^-) Λ_s are close in energy to those with the configuration^(20)Ne(K~π= 0^+)Λ_p, even though they have very different structures. The Λ_s(Λ_p) becomes more and more concentrated around the bottom(top) of the"pear" with the increase of octupole deformation.
基金Supported by the National Key research and development Program of China(2018YFA0404403)the National Natural Science Foundation of China(11875074,11875073,12027809,11635015,11961141003)the Continuous Basic Scientific Research Project(WDJC-2019-13)。
文摘A multi-nucleon transfer and cluster decay experiment,^(7)Li(^(11)B,^(14)C^(*)→α+^(10)Be)α,is conducted at an incident beam energy of 55 MeV.This reaction channel has a significantly large 0-value,which favors populating the high lying resonant states in ^(14)C.The decay paths,from these resonances to various states of the final nucleus ^(10) Be,can be selected,owing to the experimentally achieved optimal resolution of the Q-value spectrum.A number of resonant states are reconstructed from the forward emitting 10Be+α fragments,and their major molecular structures can be detected according to the selective decay paths and relative decay widths.A state at 22.4(2)MeV validates the previously measured and theoretically predicted band head of the positive-parity σ-bond linear-chain mo-lecular band.Two additional resonances at 22.9(2)and 24.2(2)MeV are identified and consistent with the predicted 2^(+) and 4^(+) members of the same molecular band,thus providing novel evidences for the existence of the exotic clustering chain structure in neutron-rich carbon isotopes.A few high energy resonances,which also indicate the presence of the σ-bond molecular structure,are observed;however,further studies are still required to clarify their ascription in band systematics.