Collinear laser spectroscopy is a powerful tool for studying the nuclear spins,electromagnetic moments,and charge radii of exotic nuclei.To study the nuclear properties of unstable nuclei at the Beijing Radioactive Io...Collinear laser spectroscopy is a powerful tool for studying the nuclear spins,electromagnetic moments,and charge radii of exotic nuclei.To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion-beam Facility(BRIF)and the future High Intensity Heavy-ion Accelerator Facility(HIAF),we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system.The overall performance of this state-of-the-art technique was evaluated,and the system was commissioned using a bunched stable ion beam.The high-resolution optical spectra for the 4s ^(2)S_(1/2)→4p^(2)P_(3/2)(D2)ionic transition of ^(40;42;44;48)Ca isotopes were successfully measured.The extracted isotope shifts relative to ^(40)Ca showed excellent agreement with the literature values.This system is now ready for use at radioactive ion beam facilities such as the BRIF and paves the way for the further development of higher-sensitivity collinear resonance ionization spectroscopy techniques.展开更多
A prototype thick-GEM-based cooling storage ring external-target experiment(CEE) time projection chamber(TPC) is constructed and tested with the pulsed ultraviolet laser beams. The results indicate that the prototype ...A prototype thick-GEM-based cooling storage ring external-target experiment(CEE) time projection chamber(TPC) is constructed and tested with the pulsed ultraviolet laser beams. The results indicate that the prototype TPC has a good performance in three-dimensional track resolution. In X direction the position resolution is about 0.2 mm, and in Y direction the position resolution is about 0.5 mm. The results also determine that the energy resolution is about 5.4%, which achieve the requirements of the CEE experiment and can be used to study the nuclear state equation and the quantum chromo dynamics.展开更多
A new ^11Be（p,d） transfer reaction experiment is performed in inverse kinematics with a radioactive11 Be beam at26.9 MeV. Three low-lying states, namely the 0＋ground state, the 2^＋ state at Ex = 3.37 MeV, and the ...A new ^11Be（p,d） transfer reaction experiment is performed in inverse kinematics with a radioactive11 Be beam at26.9 MeV. Three low-lying states, namely the 0＋ground state, the 2^＋ state at Ex = 3.37 MeV, and the multiplet at around 6 MeV in10 Be, are populated by this one-neutron transfer reaction. These three states in10 Be are clearly discriminated from the -value spectrum, which is rebuilt from energies and angles of the recoil deuterons in coincidence with10 Be. A spectroscopic factor for each state is extracted by comparing the experimental differential cross sections to the theoretical calculation results using the finite range adiabatic distorted wave approximation method with different global nucleon-nucleus potentials. It is found that the newly extracted spectroscopic factors for the 0＋and 2＋states are consistent with the previous ones, but the factor for the multiplet is smaller than the value in the reference, and the possible reason is discussed.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
An experiment for m p（14C},14C＊→10Be＋α）p inelastic excitation and decay was performed in inverse kinematics at a beam energy of 25.3 MeV/u. A series of 14C excited states, including a new one at 18.3（1） MeV, w...An experiment for m p（14C},14C＊→10Be＋α）p inelastic excitation and decay was performed in inverse kinematics at a beam energy of 25.3 MeV/u. A series of 14C excited states, including a new one at 18.3（1） MeV, were observed which decay to various states of the final nucleus of 10Be. A specially designed telescope system, installed around zero degrees, played an essential role in detecting the resonant states near the α-separation threshold. A state at 14.1（1） MeV is clearly identified, being consistent with the predicted band-head of the molecular rotational band characterized by the π-bond linear chain configuration. Further clarification of the properties of this exotic state is suggested by using appropriate reaction tools.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12027809,U1967201,11875073,11875074 and 11961141003)National Key R&D Program of China(No.2018YFA0404403)+1 种基金China National Nuclear Corporation(No.FA18000201)the State Key Laboratory of Nuclear Physics and Technology,Peking University(No.NPT2019ZZ02).
文摘Collinear laser spectroscopy is a powerful tool for studying the nuclear spins,electromagnetic moments,and charge radii of exotic nuclei.To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion-beam Facility(BRIF)and the future High Intensity Heavy-ion Accelerator Facility(HIAF),we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system.The overall performance of this state-of-the-art technique was evaluated,and the system was commissioned using a bunched stable ion beam.The high-resolution optical spectra for the 4s ^(2)S_(1/2)→4p^(2)P_(3/2)(D2)ionic transition of ^(40;42;44;48)Ca isotopes were successfully measured.The extracted isotope shifts relative to ^(40)Ca showed excellent agreement with the literature values.This system is now ready for use at radioactive ion beam facilities such as the BRIF and paves the way for the further development of higher-sensitivity collinear resonance ionization spectroscopy techniques.
基金supported by the National Key Research and Development Program of China(Nos.2016YFA0400502 and 2015CB856904)the National Natural Science Foundation of China(Nos.U1332129,11475243,11421505,11775288 and 11405005)the ‘‘100-talent plan’’ of Shanghai Institute of Applied Physics from the Chinese Academy of Sciences(Nos.Y290061011 and Y526011011)
文摘A prototype thick-GEM-based cooling storage ring external-target experiment(CEE) time projection chamber(TPC) is constructed and tested with the pulsed ultraviolet laser beams. The results indicate that the prototype TPC has a good performance in three-dimensional track resolution. In X direction the position resolution is about 0.2 mm, and in Y direction the position resolution is about 0.5 mm. The results also determine that the energy resolution is about 5.4%, which achieve the requirements of the CEE experiment and can be used to study the nuclear state equation and the quantum chromo dynamics.
基金Supported by the National Key Research and Development Program of China under Grant No 2018YFA0404403the National Natural Science Foundation of China under Grant Nos 11775004 and 11775036
文摘A new ^11Be（p,d） transfer reaction experiment is performed in inverse kinematics with a radioactive11 Be beam at26.9 MeV. Three low-lying states, namely the 0＋ground state, the 2^＋ state at Ex = 3.37 MeV, and the multiplet at around 6 MeV in10 Be, are populated by this one-neutron transfer reaction. These three states in10 Be are clearly discriminated from the -value spectrum, which is rebuilt from energies and angles of the recoil deuterons in coincidence with10 Be. A spectroscopic factor for each state is extracted by comparing the experimental differential cross sections to the theoretical calculation results using the finite range adiabatic distorted wave approximation method with different global nucleon-nucleus potentials. It is found that the newly extracted spectroscopic factors for the 0＋and 2＋states are consistent with the previous ones, but the factor for the multiplet is smaller than the value in the reference, and the possible reason is discussed.
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.
基金Supported by National Key R&D Program of China(2018YFA0404403)the National Natural Science Foundation of China(11535004,11775004,11405005,11375017)
文摘An experiment for m p（14C},14C＊→10Be＋α）p inelastic excitation and decay was performed in inverse kinematics at a beam energy of 25.3 MeV/u. A series of 14C excited states, including a new one at 18.3（1） MeV, were observed which decay to various states of the final nucleus of 10Be. A specially designed telescope system, installed around zero degrees, played an essential role in detecting the resonant states near the α-separation threshold. A state at 14.1（1） MeV is clearly identified, being consistent with the predicted band-head of the molecular rotational band characterized by the π-bond linear chain configuration. Further clarification of the properties of this exotic state is suggested by using appropriate reaction tools.
