In this paper, we present direct mass measurements of neutron-rich S6Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry （IMS） method. The new mass e...In this paper, we present direct mass measurements of neutron-rich S6Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry （IMS） method. The new mass excesses of ^52-54Sc nuclides are determined to be -40492（82）, -38928（114）, -34654（540） keV, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012 （AME12）. In particular, ^53Sc and ^54sc are more bound by 0.8 MeV and 1.0 MeV, respectively. The behavior of the two neutron separation energy with neutron numbers indicates a strong sub-shell closure at neutron number N=32 in Sc isotopes.展开更多
等时性质量谱仪(Isochronous Mass Spectrometry,IMS)是测量短寿命核素质量的有效实验装置。在IMS核素质量测量实验过程中,目标核素通过弹核碎裂反应产生,并被次级束流线分离、传输后注入到储存环内。由于远离稳定线的目标核素产额非常...等时性质量谱仪(Isochronous Mass Spectrometry,IMS)是测量短寿命核素质量的有效实验装置。在IMS核素质量测量实验过程中,目标核素通过弹核碎裂反应产生,并被次级束流线分离、传输后注入到储存环内。由于远离稳定线的目标核素产额非常低,经常伴随大量杂质核素产生,这些杂质离子会加重飞行时间探测器(Time of Flight,TOF)系统的工作负担。在HIRFL-CSR利用IMS进行核素质量测量实验过程中,发展了一种进一步纯化筛选次级离子的方法,以减轻TOF系统的工作负担。基于次级离子在束流线中飞行速度的差异性,利用HIRFL-CSR踢轨磁铁(Kicker)系统,调节次级束流注入CSRe的时间,使次级离子得到进一步筛选和纯化后注入到CSRe内。在实验中,我们测试并验证了该方法的可行性,并讨论了它在纯化次级束流方面的作用。展开更多
The concept of isochronous mass spectrometry （IMS） applying two time-of-flight （TOF） detectors originated many years ago at GSI. However, the corresponding method for data analysis has never been discussed in deta...The concept of isochronous mass spectrometry （IMS） applying two time-of-flight （TOF） detectors originated many years ago at GSI. However, the corresponding method for data analysis has never been discussed in detail. Recently, two TOF detectors have been installed at CSRe and the new working mode of the ring is under test. In this paper, a data analysis method for this mode is introduced and tested with a series of simulations. The results show that the new IMS method can significantly improve mass resolving power via the additional velocity information of stored ions. This improvement is especially important for nuclides with Lorentz factor γ-value far away from the transition point yt of the storage ring CSRe.展开更多
Breakup reactions of the double borromean nucleus ^(8)He were measured at 82.3 MeV/u on CH2 and C targets.The coincident detection of two decaying neutrons and the high performance for neutron cross talk rejection are...Breakup reactions of the double borromean nucleus ^(8)He were measured at 82.3 MeV/u on CH2 and C targets.The coincident detection of two decaying neutrons and the high performance for neutron cross talk rejection are realized in this experiment.The relative energy spectrum for ^(8)He was reconstructed with good statistics.The spectrum exhibits a structure of two resonant peaks,one at an excitation energy of about 3.0 and the other at about 4.14 MeV,respectively.Substantially larger cross section for the first resonance is observed in comparison to the results reported previously.展开更多
Differential cross sections for the elastic scattering of halo nucleus 6He on proton target were measured at 82.3 MeV/u. The experimental results axe well reproduced by optical model calculations using global potentia...Differential cross sections for the elastic scattering of halo nucleus 6He on proton target were measured at 82.3 MeV/u. The experimental results axe well reproduced by optical model calculations using global potential KD02 with a reduction of the depth of real volume part by a factor of 0.7. A systematic analysis shows that this behavior might be related to the weakly bound property of unstable nuclei.展开更多
A knockout reaction experiment was carried out by using the 6He beam at 82.5 MeV/nucleon impinging on CH2 and C targets. The a core fragments at forward angles were detected in coincidence with the recoiled protons at...A knockout reaction experiment was carried out by using the 6He beam at 82.5 MeV/nucleon impinging on CH2 and C targets. The a core fragments at forward angles were detected in coincidence with the recoiled protons at larger angles. From this exclusive measure- ment the valence nucleon knockout mechanism and the core knockout mechanism are separated. This study provides a basis for the exclusive spectroscopic investigation of the exotic nuclei.展开更多
An experiment for knockout reaction induced by SHe beam at 82.5 MeV/nucleon on CH2 and C targets was carried out. The 6He and 4He core fragments at forward angles and the recoiled protons at large angles were detected...An experiment for knockout reaction induced by SHe beam at 82.5 MeV/nucleon on CH2 and C targets was carried out. The 6He and 4He core fragments at forward angles and the recoiled protons at large angles were detected coincidently. From this exclusive measurement the valence nucleon knockout mechanism and the core knockout mechanism are separated, which can be applied to the exclusive spectroscopic study on the structure of exotic nuclei.展开更多
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...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 primary86 Kr ions at a realistic energy of460.65 Me V/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.展开更多
A neutron detector array was used in a breakup reaction experiment at RIKEN with an 82.5 MeV/u SHe beam impinging on the CH2 and C targets. The array was calibrated using the cosmic ray, the 7 ray from the 6He＋Pb rea...A neutron detector array was used in a breakup reaction experiment at RIKEN with an 82.5 MeV/u SHe beam impinging on the CH2 and C targets. The array was calibrated using the cosmic ray, the 7 ray from the 6He＋Pb reaction and the mono-energetic neutrons from the 7Li（p, n）TBe（g.s.＋0.43 MeV） reaction. The position resolution, timing resolution and neutron de- tection efficiency were obtained accordingly. Cross-talk rejection conditions were developed based on analysis of the data taken from the 7Li（p, n）TBe（g.s.＋0.43 MeV） test experiment, and finally a preliminary two-neutron correlation function for the SHe breakup reaction was investigated.展开更多
The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed Bρ-defined isochronous mass spectrometry method at the cooler storage ri...The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed Bρ-defined isochronous mass spectrometry method at the cooler storage ring in Lanzhou.The new mass excess value allowed us to determine the excitation energies of the two low-lying 1+states in ^(22)Al with significantly reduced uncertainties of 51 keV.When compared to the analogue states in its mirror nucleus ^(22)F,the mirror energy differences of the two 1^(+)states in the ^(22)Al-^(22)F mirror pair are determined to be−625(51)keV and−330(51)keV.The excitation energies and mirror energy differences are used to test the state-of-the-art ab initio valence-space in-medium similarity renormalization group calculations with four sets of interactions derived from the chiral effective field theory.The mechanism leading to the large mirror energy differences is investigated and attributed to the occupation of theπs_(1/2) orbital.展开更多
基金Supported by 973 Program of China(2013CB834401)the NSFC(U1232208,U1432125,11205205,11035007)the Helmholtz-CAS Joint Research Group(HCJRG-108)
文摘In this paper, we present direct mass measurements of neutron-rich S6Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry （IMS） method. The new mass excesses of ^52-54Sc nuclides are determined to be -40492（82）, -38928（114）, -34654（540） keV, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012 （AME12）. In particular, ^53Sc and ^54sc are more bound by 0.8 MeV and 1.0 MeV, respectively. The behavior of the two neutron separation energy with neutron numbers indicates a strong sub-shell closure at neutron number N=32 in Sc isotopes.
文摘等时性质量谱仪(Isochronous Mass Spectrometry,IMS)是测量短寿命核素质量的有效实验装置。在IMS核素质量测量实验过程中,目标核素通过弹核碎裂反应产生,并被次级束流线分离、传输后注入到储存环内。由于远离稳定线的目标核素产额非常低,经常伴随大量杂质核素产生,这些杂质离子会加重飞行时间探测器(Time of Flight,TOF)系统的工作负担。在HIRFL-CSR利用IMS进行核素质量测量实验过程中,发展了一种进一步纯化筛选次级离子的方法,以减轻TOF系统的工作负担。基于次级离子在束流线中飞行速度的差异性,利用HIRFL-CSR踢轨磁铁(Kicker)系统,调节次级束流注入CSRe的时间,使次级离子得到进一步筛选和纯化后注入到CSRe内。在实验中,我们测试并验证了该方法的可行性,并讨论了它在纯化次级束流方面的作用。
基金Supported by the 973 Program of China(2013CB834401)National Nature Science Foundation of China(U1232208,U1432125,11205205,11035007)the Helmholtz-CAS Joint Research Group(Group No.HCJRG-108)
文摘The concept of isochronous mass spectrometry （IMS） applying two time-of-flight （TOF） detectors originated many years ago at GSI. However, the corresponding method for data analysis has never been discussed in detail. Recently, two TOF detectors have been installed at CSRe and the new working mode of the ring is under test. In this paper, a data analysis method for this mode is introduced and tested with a series of simulations. The results show that the new IMS method can significantly improve mass resolving power via the additional velocity information of stored ions. This improvement is especially important for nuclides with Lorentz factor γ-value far away from the transition point yt of the storage ring CSRe.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11035001,10975006 and J1103206the National Basic Research Program of China under Grant No 2007CB815002.
文摘Breakup reactions of the double borromean nucleus ^(8)He were measured at 82.3 MeV/u on CH2 and C targets.The coincident detection of two decaying neutrons and the high performance for neutron cross talk rejection are realized in this experiment.The relative energy spectrum for ^(8)He was reconstructed with good statistics.The spectrum exhibits a structure of two resonant peaks,one at an excitation energy of about 3.0 and the other at about 4.14 MeV,respectively.Substantially larger cross section for the first resonance is observed in comparison to the results reported previously.
基金Supported by the National Basic Research Program of China （2007CB815002）, and the National Natural Science Foundation of China （10775003, 10905002 and 10827505）.
文摘Differential cross sections for the elastic scattering of halo nucleus 6He on proton target were measured at 82.3 MeV/u. The experimental results axe well reproduced by optical model calculations using global potential KD02 with a reduction of the depth of real volume part by a factor of 0.7. A systematic analysis shows that this behavior might be related to the weakly bound property of unstable nuclei.
基金supported by the National Basic Research Program of China (No. 2007CB815002)National Natural Science Foundation of China(Nos. 11035001, 10775003, 10827505, 10821140159)
文摘A knockout reaction experiment was carried out by using the 6He beam at 82.5 MeV/nucleon impinging on CH2 and C targets. The a core fragments at forward angles were detected in coincidence with the recoiled protons at larger angles. From this exclusive measure- ment the valence nucleon knockout mechanism and the core knockout mechanism are separated. This study provides a basis for the exclusive spectroscopic investigation of the exotic nuclei.
基金supported by the National Basic Research Program of China (No. 2007CB815002)National Natural Science Foundation of China(Nos. 11035001, 10775003, 10827505, 10821140159)
文摘An experiment for knockout reaction induced by SHe beam at 82.5 MeV/nucleon on CH2 and C targets was carried out. The 6He and 4He core fragments at forward angles and the recoiled protons at large angles were detected coincidently. From this exclusive measurement the valence nucleon knockout mechanism and the core knockout mechanism are separated, which can be applied to the exclusive spectroscopic study on the structure of exotic nuclei.
基金National Basic Research Program of China(973 Program)(2013CB834401)National Natural Science Foundation of China(U1232208,U1432125,11205205,11035007)Western Light Talent Training Program of Chinese Academy Scienus
文摘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 primary86 Kr ions at a realistic energy of460.65 Me V/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.
基金supported by the National Basic Research Program of China (No. 2007CB815002)National Natural Science Foundation of China(Nos. 11035001, 10775003, 10827505, 10821140159)
文摘A neutron detector array was used in a breakup reaction experiment at RIKEN with an 82.5 MeV/u SHe beam impinging on the CH2 and C targets. The array was calibrated using the cosmic ray, the 7 ray from the 6He＋Pb reaction and the mono-energetic neutrons from the 7Li（p, n）TBe（g.s.＋0.43 MeV） reaction. The position resolution, timing resolution and neutron de- tection efficiency were obtained accordingly. Cross-talk rejection conditions were developed based on analysis of the data taken from the 7Li（p, n）TBe（g.s.＋0.43 MeV） test experiment, and finally a preliminary two-neutron correlation function for the SHe breakup reaction was investigated.
基金Supported in part by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB34000000)the CAS Project for Young Scientists in Basic Research (YSBR-002)+4 种基金the National Nature Science Foundation of China (12135017,12121005,11975280,12105333,12205340,12322507,12305126,12305151)the Gansu Natural Science Foundation (22JR5RA123,23JRRA614)the National Key R&D Program of China (2021YFA1601500)Support from the Youth Innovation Promotion Association of Chinese Academy of Sciences (2021419,2022423)support from Young Scholar of Regional Development,CAS ([2023]15).
文摘The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed Bρ-defined isochronous mass spectrometry method at the cooler storage ring in Lanzhou.The new mass excess value allowed us to determine the excitation energies of the two low-lying 1+states in ^(22)Al with significantly reduced uncertainties of 51 keV.When compared to the analogue states in its mirror nucleus ^(22)F,the mirror energy differences of the two 1^(+)states in the ^(22)Al-^(22)F mirror pair are determined to be−625(51)keV and−330(51)keV.The excitation energies and mirror energy differences are used to test the state-of-the-art ab initio valence-space in-medium similarity renormalization group calculations with four sets of interactions derived from the chiral effective field theory.The mechanism leading to the large mirror energy differences is investigated and attributed to the occupation of theπs_(1/2) orbital.
