Isochronous mass spectrometry(IMS)of heavyion storage rings is a powerful tool for the mass measurements of short-lived nuclei.In IMS experiments,masses are determined through precision measurements of the revolution ...Isochronous mass spectrometry(IMS)of heavyion storage rings is a powerful tool for the mass measurements of short-lived nuclei.In IMS experiments,masses are determined through precision measurements of the revolution times of the ions stored in the ring.However,the revolution times cannot be resolved for particles with nearly the same mass-to-charge(m/q)ratios.To overcome this limitation and to extract the accurate revolution times for such pairs of ion species with very close m/q ratios,in our early work on particle identification,we analyzed the amplitudes of the timing signals from the detector based on the emission of secondary electrons.Here,the previous data analysis method is further improved by considering the signal amplitudes,detection efficiencies,and number of stored ions in the ring.A sensitive Z-dependent parameter is introduced in the data analysis,leading to a better resolution of ^(34)Ar^(18+) and ^(51)Co^(27+) with A/Z=17/9.The mean revolution times of ^(34)Ar^(18+) and ^(51)Co^(27+) are deduced,although their time difference is merely 1.8 ps.The uncorrected,overlapped peak of these ions has a full width at half maximum of 7.7 ps.The mass excess of ^(51)Co was determined to be-27;332e41T keV,which is in agreement with the previous value of-27;342e48T keV.展开更多
Precision mass measurements of neutron-deficient 152Sm projectile fragments were conducted in 2005 at theFRS-ESR facility at GSI Helmholtz centre[1, 2], employing the time-resolved Schottky Mass Spectrometry[3]. A new...Precision mass measurements of neutron-deficient 152Sm projectile fragments were conducted in 2005 at theFRS-ESR facility at GSI Helmholtz centre[1, 2], employing the time-resolved Schottky Mass Spectrometry[3]. A newmass evaluation method has been developed in the data analysis. The systematic error in the mass determinationwas significantly reduced with the new method[4].Exotic nuclei, produced by projectile fragmentation of a 615 AMeV 152Sm primary beam in a 4.009 g/cm2beryllium target, were transmitted and B-separated by the fragment separator FRS and then injected and storedin the experimental storage ring ESR. In ESR the electron-cooling process was continuously applied to the storedions. To first order approximation, the revolution-frequencies (f) of the stored ions in the ESR are related to theirvelocities (v) and mass-to-charge ratios (m=q) of the ions in rest frame:展开更多
In conventional isochronous mass spectrometry (IMS), single time-of-flight (TOF) method is adopted to measurethe ions' revolution times in a storage ring which can then be used to calculate the ions' masses. H...In conventional isochronous mass spectrometry (IMS), single time-of-flight (TOF) method is adopted to measurethe ions' revolution times in a storage ring which can then be used to calculate the ions' masses. However, themass-to-charge ratio (m=q) is only related to the revolution time (T) under the condition that is equal to taccording to the following equation:展开更多
The masses of neutron-defcient nuclides play a critical role in the calculation of astrophysical rapid proton-capture processes[1].Neutron-defcient nuclides with mass number∧around 80 are the last set of nuclides wit...The masses of neutron-defcient nuclides play a critical role in the calculation of astrophysical rapid proton-capture processes[1].Neutron-defcient nuclides with mass number∧around 80 are the last set of nuclides with unknown masses on the pathway of vp-process[2].The mass measurement of nuclides would be very useful.In 2016,masses of neutron-defcient nuclides 79Y,81Zr,82Zr,83Nb and 84Nb nuclei were precisely measured directly by the experimental storage-ring CSRe at Lanzhou.展开更多
At a certain high temperature,this cycle will be dominant and end the rp-process to heavier region[2].It provides an upper temperature limit for rp-process along the proton drip line to produce nuclides beyond A=84,in...At a certain high temperature,this cycle will be dominant and end the rp-process to heavier region[2].It provides an upper temperature limit for rp-process along the proton drip line to produce nuclides beyond A=84,including the light p nuclides of 92;94Mo,96;94Ru.The existence of Zr-Nb cycle is an important question in rp-process[2].α-separation energy(Sα)of 84Mo plays an important role in the formation of this cycle.A strong enhancement of 83Nb(p,α)reaction rate is due to a very low Sαof 84Mo[1].展开更多
We have reported the mass measurements of neutron-deficient nuclides 79Y,81;82Zr,83;84Nb in this year’s Annual Report.However,for the N=Z nuclides close to A=80,the yield is much lower and even if they can be produce...We have reported the mass measurements of neutron-deficient nuclides 79Y,81;82Zr,83;84Nb in this year’s Annual Report.However,for the N=Z nuclides close to A=80,the yield is much lower and even if they can be produced,there is still great difficult to identify them because of their quite similar mass-to-charge ratio and revolution times.However,their mass are extremely important for rapid proton capture process,for example,80Zr and 84Mo are waiting points of rp-process.Their masses can greatly effect the reaction flow of proton capture on them and then the abundance of the heavier nuclides.In addition,the separation energy of 84Mo(determined by the mass of 80Zr and 84Mo)has a strong impact on the 83Nb(p,α)reaction rate and plays a key role in the formation of Zr-Nb Fig.展开更多
基金This work was supported by the National Key R&D Program of China(Nos.2016YFA0400504 and 2018YFA0404401)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB34000000)+4 种基金the National Natural Science Foundation of China(Nos.11905261,11805032,11975280,and 11605248)the CAS "Light of West China" Program,the China Postdoctoral Science Foundation(No.2019M660250)the FRIB-CSC Fellowship,China(No.201704910964)the International Postdoctoral Exchange Fellowship Program 2017 by the Office of China Postdoctoral Council(No.60 Document of OCPC,2017)the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Programme(No.682841 "ASTRUm").
文摘Isochronous mass spectrometry(IMS)of heavyion storage rings is a powerful tool for the mass measurements of short-lived nuclei.In IMS experiments,masses are determined through precision measurements of the revolution times of the ions stored in the ring.However,the revolution times cannot be resolved for particles with nearly the same mass-to-charge(m/q)ratios.To overcome this limitation and to extract the accurate revolution times for such pairs of ion species with very close m/q ratios,in our early work on particle identification,we analyzed the amplitudes of the timing signals from the detector based on the emission of secondary electrons.Here,the previous data analysis method is further improved by considering the signal amplitudes,detection efficiencies,and number of stored ions in the ring.A sensitive Z-dependent parameter is introduced in the data analysis,leading to a better resolution of ^(34)Ar^(18+) and ^(51)Co^(27+) with A/Z=17/9.The mean revolution times of ^(34)Ar^(18+) and ^(51)Co^(27+) are deduced,although their time difference is merely 1.8 ps.The uncorrected,overlapped peak of these ions has a full width at half maximum of 7.7 ps.The mass excess of ^(51)Co was determined to be-27;332e41T keV,which is in agreement with the previous value of-27;342e48T keV.
文摘Precision mass measurements of neutron-deficient 152Sm projectile fragments were conducted in 2005 at theFRS-ESR facility at GSI Helmholtz centre[1, 2], employing the time-resolved Schottky Mass Spectrometry[3]. A newmass evaluation method has been developed in the data analysis. The systematic error in the mass determinationwas significantly reduced with the new method[4].Exotic nuclei, produced by projectile fragmentation of a 615 AMeV 152Sm primary beam in a 4.009 g/cm2beryllium target, were transmitted and B-separated by the fragment separator FRS and then injected and storedin the experimental storage ring ESR. In ESR the electron-cooling process was continuously applied to the storedions. To first order approximation, the revolution-frequencies (f) of the stored ions in the ESR are related to theirvelocities (v) and mass-to-charge ratios (m=q) of the ions in rest frame:
文摘In conventional isochronous mass spectrometry (IMS), single time-of-flight (TOF) method is adopted to measurethe ions' revolution times in a storage ring which can then be used to calculate the ions' masses. However, themass-to-charge ratio (m=q) is only related to the revolution time (T) under the condition that is equal to taccording to the following equation:
文摘The masses of neutron-defcient nuclides play a critical role in the calculation of astrophysical rapid proton-capture processes[1].Neutron-defcient nuclides with mass number∧around 80 are the last set of nuclides with unknown masses on the pathway of vp-process[2].The mass measurement of nuclides would be very useful.In 2016,masses of neutron-defcient nuclides 79Y,81Zr,82Zr,83Nb and 84Nb nuclei were precisely measured directly by the experimental storage-ring CSRe at Lanzhou.
文摘At a certain high temperature,this cycle will be dominant and end the rp-process to heavier region[2].It provides an upper temperature limit for rp-process along the proton drip line to produce nuclides beyond A=84,including the light p nuclides of 92;94Mo,96;94Ru.The existence of Zr-Nb cycle is an important question in rp-process[2].α-separation energy(Sα)of 84Mo plays an important role in the formation of this cycle.A strong enhancement of 83Nb(p,α)reaction rate is due to a very low Sαof 84Mo[1].
文摘We have reported the mass measurements of neutron-deficient nuclides 79Y,81;82Zr,83;84Nb in this year’s Annual Report.However,for the N=Z nuclides close to A=80,the yield is much lower and even if they can be produced,there is still great difficult to identify them because of their quite similar mass-to-charge ratio and revolution times.However,their mass are extremely important for rapid proton capture process,for example,80Zr and 84Mo are waiting points of rp-process.Their masses can greatly effect the reaction flow of proton capture on them and then the abundance of the heavier nuclides.In addition,the separation energy of 84Mo(determined by the mass of 80Zr and 84Mo)has a strong impact on the 83Nb(p,α)reaction rate and plays a key role in the formation of Zr-Nb Fig.
