An accurate energy calibration of a BC501A liquid scintillator by means of Compton scattering of γ-rays is described.The energy resolution and the position of the Compton edge have been precisely determined using a ...An accurate energy calibration of a BC501A liquid scintillator by means of Compton scattering of γ-rays is described.The energy resolution and the position of the Compton edge have been precisely determined using a γ-γ coincidence technique and fitting the coincidence spectrum with a Gaussian function superimposed on a quadratic polynomial for the background.The position of the Compton edge relative to the position of the maximum and the half height of the distribution in dependence on the relevant energy resolution is discussed in detail.The results indicate that the maximum energy of the recoil Compton electron does not occur at the half height distribution but at 0.90±0.05 of the maximum height in the energy range considered.The energy resolution varies from 15.6% to 8.02% for electrons in the energy region from 0.5 MeV to 3 MeV.展开更多
High spin states of 84Sr were populated through the reaction 70Zn(18O,4n)84Sr at 75 MeV beam energy.Measurement of excitation function,γ-γ coincidences,directional correlation from oriented state (DCO) ratios and γ...High spin states of 84Sr were populated through the reaction 70Zn(18O,4n)84Sr at 75 MeV beam energy.Measurement of excitation function,γ-γ coincidences,directional correlation from oriented state (DCO) ratios and γ-transition intensities were performed using eight anticompton HPGe detectors and one planar HPGe detector.Based on the measured results,a new level scheme of 84Sr was established in which 12 new states and nearly 30 new γ-transitions were identified in the present work.The positive-parity states of the new level scheme were compared with the results from calculations in the framework of the projected shell model (PSM).One negative-parity band was extended to spin Iπ=19-and it can be found that in the high spin states,the γ-transition energies show the nature of signature staggering.The negative-parity band levels are in good agreement with deformed configuration-mixing shell model (DCM) calculations.展开更多
Excited states of ^(206)Rn have been examined via the 197 Au(^(14)N,5n)^(206)Rn fusion reaction at a beam energy of 78 MeV.A number of transitions and levels are identified by the γ-γ coincidence measurement,further...Excited states of ^(206)Rn have been examined via the 197 Au(^(14)N,5n)^(206)Rn fusion reaction at a beam energy of 78 MeV.A number of transitions and levels are identified by the γ-γ coincidence measurement,further enriching the level scheme of ^(206)Rn.The fullconfiguration shell model and nucleon-pair approximation(NPA)were utilized to investigate the single-particle configurations and seniority structures in ^(206)Rn.The results of these two calculations suggest that 2_(1)^(+) and 4_(1)^(+) states exhibit only a 50%component of a seniority-two state associated with a broken neutron pair.The collectivity of these two states primarily arises from configuration mixing due to residual proton-neutron interactions.Furthermore,6_(1)^(+) and 8_(1)^(+) states are predominantly characterized by a seniority-two state marked by a broken proton pair.展开更多
The level structure of ^19Opt has been studied experimentally using the ^176yb （^18O, 4n） reaction at beam energies of 88 and 95 MeV. γ-γ-t coincidence measurements were carried out. Based on the analysis of T-T ...The level structure of ^19Opt has been studied experimentally using the ^176yb （^18O, 4n） reaction at beam energies of 88 and 95 MeV. γ-γ-t coincidence measurements were carried out. Based on the analysis of T-T coincidence relationships, the level scheme of ^190Pt is extended to high-spin states. A new structure built on the 3413.6 keV 14＋ state has been observed, and the ＂vi13/2^-2 vh9/2^-1 vj （j = P3/2 or f5/2） configuration is tentatively assigned to it.展开更多
High-spin states in 139Nd nucleus have been reinvestigated with the reaction 128Te (16O, 5n) at a beam energy of 90 MeV. The level scheme has been expanded with spin up to 47/2 . At the low spin states, the yrast coll...High-spin states in 139Nd nucleus have been reinvestigated with the reaction 128Te (16O, 5n) at a beam energy of 90 MeV. The level scheme has been expanded with spin up to 47/2 . At the low spin states, the yrast collective structure built on the νh11/2-1 multiplet shows a transitional shape with γ ≈ 32° according to calculations of the triaxial rotor-plus-particle model. Three collective oblate bands with γ ～-60° at the high spin states were identified for the first time. A band crossing is observed around ω ～0.4 MeV in one oblate band based on the 25/2-level.展开更多
The decay of the neutron-rich erbium isotope <sup>175</sup>Er is studied by using the reaction<sup>176</sup>Yb（n,2p）<sup>175</sup>Er.A partial decay scheme is proposed on the basi...The decay of the neutron-rich erbium isotope <sup>175</sup>Er is studied by using the reaction<sup>176</sup>Yb（n,2p）<sup>175</sup>Er.A partial decay scheme is proposed on the basis of X-γ and γ-γ coincidencemeasurements,taking into account eight observed gamma rays.A ground rotational band is as-signed to <sup>175</sup>Tm.Some systematic behaviors of 1/2+[411] ground rotational bands in odd-Athulium are described.The experimental and calculated decoupling parameters of these bandsare compared.展开更多
文摘An accurate energy calibration of a BC501A liquid scintillator by means of Compton scattering of γ-rays is described.The energy resolution and the position of the Compton edge have been precisely determined using a γ-γ coincidence technique and fitting the coincidence spectrum with a Gaussian function superimposed on a quadratic polynomial for the background.The position of the Compton edge relative to the position of the maximum and the half height of the distribution in dependence on the relevant energy resolution is discussed in detail.The results indicate that the maximum energy of the recoil Compton electron does not occur at the half height distribution but at 0.90±0.05 of the maximum height in the energy range considered.The energy resolution varies from 15.6% to 8.02% for electrons in the energy region from 0.5 MeV to 3 MeV.
基金supported by the Major State Basic Research Development Program in China (Grant No. 2007CB815003)the National Natural Science Foundation of China (Grant Nos. 11065001, 10547140, 10525520,60476043,10675170,10475002 and 10775064)+4 种基金the U.S. National Science Foundation (Grant No. 0500291)the Southeastern Universities Research Association,the Natural Science Foundation of Jiangxi Province (Grant Nos. 0612003 and 2007GZW0476)the LSU - LNNU Joint Research Program (Grant No. 9961)the Foundation of the Education Department of Jiangxi Province (Grant No. [2007]235)the Liaoning Education Department Fund (Grant No. 20060464)
文摘High spin states of 84Sr were populated through the reaction 70Zn(18O,4n)84Sr at 75 MeV beam energy.Measurement of excitation function,γ-γ coincidences,directional correlation from oriented state (DCO) ratios and γ-transition intensities were performed using eight anticompton HPGe detectors and one planar HPGe detector.Based on the measured results,a new level scheme of 84Sr was established in which 12 new states and nearly 30 new γ-transitions were identified in the present work.The positive-parity states of the new level scheme were compared with the results from calculations in the framework of the projected shell model (PSM).One negative-parity band was extended to spin Iπ=19-and it can be found that in the high spin states,the γ-transition energies show the nature of signature staggering.The negative-parity band levels are in good agreement with deformed configuration-mixing shell model (DCM) calculations.
基金Supported partially by the National Natural Science Foundation of China (10975191,U1867210,11375023,11475014,11575018,12075169,12322506)the National Key R&D program of China (2016YFA0400504)。
文摘Excited states of ^(206)Rn have been examined via the 197 Au(^(14)N,5n)^(206)Rn fusion reaction at a beam energy of 78 MeV.A number of transitions and levels are identified by the γ-γ coincidence measurement,further enriching the level scheme of ^(206)Rn.The fullconfiguration shell model and nucleon-pair approximation(NPA)were utilized to investigate the single-particle configurations and seniority structures in ^(206)Rn.The results of these two calculations suggest that 2_(1)^(+) and 4_(1)^(+) states exhibit only a 50%component of a seniority-two state associated with a broken neutron pair.The collectivity of these two states primarily arises from configuration mixing due to residual proton-neutron interactions.Furthermore,6_(1)^(+) and 8_(1)^(+) states are predominantly characterized by a seniority-two state marked by a broken proton pair.
基金Supported by National Natural Science Foundation of China(10505025,10475097)Chinese Academy of Sciences
文摘The level structure of ^19Opt has been studied experimentally using the ^176yb （^18O, 4n） reaction at beam energies of 88 and 95 MeV. γ-γ-t coincidence measurements were carried out. Based on the analysis of T-T coincidence relationships, the level scheme of ^190Pt is extended to high-spin states. A new structure built on the 3413.6 keV 14＋ state has been observed, and the ＂vi13/2^-2 vh9/2^-1 vj （j = P3/2 or f5/2） configuration is tentatively assigned to it.
基金Supported by National Natural Science Foundation of China (10575057, 10775078)Major State Basic Research Development Program (2007CB815005)Special Program of Higher Education Science Foundation (20070003149)
文摘High-spin states in 139Nd nucleus have been reinvestigated with the reaction 128Te (16O, 5n) at a beam energy of 90 MeV. The level scheme has been expanded with spin up to 47/2 . At the low spin states, the yrast collective structure built on the νh11/2-1 multiplet shows a transitional shape with γ ≈ 32° according to calculations of the triaxial rotor-plus-particle model. Three collective oblate bands with γ ～-60° at the high spin states were identified for the first time. A band crossing is observed around ω ～0.4 MeV in one oblate band based on the 25/2-level.
基金The project supported by the National Natural Scierice Foundation of Chinathe Chinose Academy of Sciences
文摘The decay of the neutron-rich erbium isotope <sup>175</sup>Er is studied by using the reaction<sup>176</sup>Yb（n,2p）<sup>175</sup>Er.A partial decay scheme is proposed on the basis of X-γ and γ-γ coincidencemeasurements,taking into account eight observed gamma rays.A ground rotational band is as-signed to <sup>175</sup>Tm.Some systematic behaviors of 1/2+[411] ground rotational bands in odd-Athulium are described.The experimental and calculated decoupling parameters of these bandsare compared.
