Isotope 223U synthesized and identified[1;2].αenergy of 8 780(40)keV and a half-life of 55(10)μs.Theαenergy was calculated by subtracting knownαenergy of 219Th from measured decay sum energy of 223U and its daught...Isotope 223U synthesized and identified[1;2].αenergy of 8 780(40)keV and a half-life of 55(10)μs.Theαenergy was calculated by subtracting knownαenergy of 219Th from measured decay sum energy of 223U and its daughter 219Th.Based on the advanced digital pulse processing technique,a new measurement forα-particle energy and half-life of 223U was performed at the gas-filled recoil separator,Spectrometer for Heavy Atoms and Nuclear Structure(SHANS).The isotope 223U was produced in the fusion-evaporation reaction 187Re(40Ar,p3n)223U.展开更多
The study on the decay properties of new isotopes located far from the beta stability line is current the focus of nuclear physics. For isotopes in the region Z >82 and N <126, -emission prevails as radioactive ...The study on the decay properties of new isotopes located far from the beta stability line is current the focus of nuclear physics. For isotopes in the region Z >82 and N <126, -emission prevails as radioactive decay mode and -spectroscopy is the most important tool to obtain information on the nuclear structure. In the heavy nuclei region with N=124 and 126 isotones, an intruder state (h9=2.f7=2)8+ based on the attractive interaction of f7=2 protons and f5=2 neutrons has been significantly observed, which increases the binding energy of this configuration with increasing proton number.展开更多
Lifetime measurements of low-lying excited states in 87Zr and 87Nb have been performed via and coincidences. The 124 MeV 32S beam was delivered from the Sector-Focusing Cyclotron (SFC) of the Heavy Ion R-esearch Facil...Lifetime measurements of low-lying excited states in 87Zr and 87Nb have been performed via and coincidences. The 124 MeV 32S beam was delivered from the Sector-Focusing Cyclotron (SFC) of the Heavy Ion R-esearch Facility in Lanzhou (HIRFL). The parent nuclei 87Nb and 87Mo were produced by the respective reactions 58Ni (32S, 3p) and 58Ni (32S, 2p1n), at a beam energy 100 MeV through the 8 m Al degrader.展开更多
An attempt has been made recently to synthesize very neutron-decient 216U isotope in 40Ca+natHf reaction atthe gas-lled recoil separator SHANS[1]. A beam of 40Ca12+ at an energy of Elab=194.6 MeV was delivered by thes...An attempt has been made recently to synthesize very neutron-decient 216U isotope in 40Ca+natHf reaction atthe gas-lled recoil separator SHANS[1]. A beam of 40Ca12+ at an energy of Elab=194.6 MeV was delivered by thesector focusing cyclotron of the Heavy Ion Research Facility in Lanzhou (HIRFL). The average beam intensity wasabout 100 pnA. Self-support targets of natural hafnium foils with thickness of 420 g/cm2 was mounted in a edframe. Evaporation residues recoiled from the target were separated from the primary beam by the separator andthen implanted into the Si-box detector (consist of three position sensitive silicon detectors and eight non-positionsensitive silicon detectors)[2]. In order to distinguish the -decay events from the implantation events, two multi-wire proportional counters (MWPCs) were mounted upstream from the Si-box detector. Behind the Si-box detectora fourfold segmented Clover detector was installed for -ray studies.展开更多
Over the past years,experimentalists have launched an expedition to explore the predicted,centered near the double-magic Z=114,N=184 nucleus.With their remarkable e orts,elements from hydrogen up to element 118 at pre...Over the past years,experimentalists have launched an expedition to explore the predicted,centered near the double-magic Z=114,N=184 nucleus.With their remarkable e orts,elements from hydrogen up to element 118 at present.The discovery of the superheavy elements o ers the possibilities to study properties of nuclei under extremely strong Coulomb elds and to explore the limits of existence of nuclei.The fusion evaporation reactions induced by low-energy heavy ions are employed for synthesis and study of superheavy isotopes,and the gas-lled recoil separator technique is always used to e ectively separate the produced evaporation residues from projectile-like and target-like products.展开更多
Proton-andα-decay spectroscopy can provide valuable information on the nuclear structure and masses of neutron-de cient isotopes.In 1994,the proton drip line of Ac was reached by the detection of^(207)Ac which was id...Proton-andα-decay spectroscopy can provide valuable information on the nuclear structure and masses of neutron-de cient isotopes.In 1994,the proton drip line of Ac was reached by the detection of^(207)Ac which was identified via the-decay spectroscopy.Four years later,the neighboring proton-unbound nucleus ^(206)Ac was discov-ered.展开更多
The new thorium isotope ^(207)Th has been produced in the 5n evaporation channel of the fusion reaction ^(36)Ar+^(176)Hf.The 197-199 MeV ^(36)Ar^(11+)beam with a typical intensity of0.4 pμA was delivered by the Secto...The new thorium isotope ^(207)Th has been produced in the 5n evaporation channel of the fusion reaction ^(36)Ar+^(176)Hf.The 197-199 MeV ^(36)Ar^(11+)beam with a typical intensity of0.4 pμA was delivered by the Sector Focusing Cyclotron of the Heavy Ion Research Facility in Lanzhou(HIRFL),China.展开更多
Alpha decay,as a pervasive decay mode of unstable heavy nuclei,plays a crucial role in the identification of new superheavy elements and investigation on nuclear structure of exotic nuclei near the proton drip line.
In order to systematically investigate the-decay properties of U-isotopes near the N=126 shell and study the fine structures of 218Pa and 211−213Th,enriched targets,180W,182Wand 176Hf,were bombarded by the 36Ar and 40...In order to systematically investigate the-decay properties of U-isotopes near the N=126 shell and study the fine structures of 218Pa and 211−213Th,enriched targets,180W,182Wand 176Hf,were bombarded by the 36Ar and 40Ar beams provided the Heavy Ion Research Facility in Lanzhou(HIRFL).Combinations of beam and target as well as the beam energy,beam intensity,target thickness,irradiation time were listed in Table 1.Fusion-evaporation residues(ERs)were recoiled from the targets and separated from the primary beams using the gas filled recoil separator,SHANS[1].After passing through a multi-wire proportional chamber,the ERs were implanted into a Si-box detector[2]amounted at the focal plane of SHANS.Gamma rays emitted from the ERs were detected by three Ge detectors attached to the Si-box.All-decay and gamma-ray signals were registered and proceeded by a digital data acquisition system.展开更多
Many nuclear theories have predicted the island of stability located around proton number of 114,120 or 126 and neutron number of 184 or 172.The synthesis of nuclei on the island of stability and the study of their ex...Many nuclear theories have predicted the island of stability located around proton number of 114,120 or 126 and neutron number of 184 or 172.The synthesis of nuclei on the island of stability and the study of their exotic decay properties are crucial for the understanding of nuclear structure and properties under extremely strong Coulomb fields,and the discovery of maximum nuclear magic numbers.There is no appropriate method to produce such neutron-rich nuclei except multi-nucleon transfer(MNT)reaction.The target-like fragments(TLF)emit into a wide angular range with a broad energy distribution,which makes it very difficult to collect,separate and identify the nuclei of interest.展开更多
A multi-re ection time-of-ight mass spectrometer(MRTOF-MS)at the spectrometer for heavy atom and nuclear structure(SHANS)[1],which will be used for direct atomic mass measurement and nuclear spectroscopy,is under cons...A multi-re ection time-of-ight mass spectrometer(MRTOF-MS)at the spectrometer for heavy atom and nuclear structure(SHANS)[1],which will be used for direct atomic mass measurement and nuclear spectroscopy,is under construction.展开更多
Lifetime measurements of low-lying excited states in^87Zr have been performed viaβ-γcoincidences.The 127 MeV^32S beam was delivered from the Sector-Focusing Cyclotron(SFC)of the Heavy Ion Research Facility in Lanzho...Lifetime measurements of low-lying excited states in^87Zr have been performed viaβ-γcoincidences.The 127 MeV^32S beam was delivered from the Sector-Focusing Cyclotron(SFC)of the Heavy Ion Research Facility in Lanzhou(HIRFL).The parent nuclei^87Nb were produced by the reaction 58Ni(32S,2p1n),at a beam energy 127 MeV through a 8 um Al degrader.A 200ug/cm^2 layer of 58Ni evaporated onto a 200ug/cm^2 thick carbon foil was employed as the target.After evaporation residues were separated from the projectile beams by the gas-filled recoil separator SHANS[1],the nuclei of interest 87Zr can be obtained with a higher purity and then were implanted into a 300um silicon detector.展开更多
The application of Lanthanum Bromide(LaBr3)detectors provides a unique opportunity to measure lifetime of excited states in picosecond-nanosecond region.Reducing the background is of critical importance to get precise...The application of Lanthanum Bromide(LaBr3)detectors provides a unique opportunity to measure lifetime of excited states in picosecond-nanosecond region.Reducing the background is of critical importance to get precise results.For some excited states feeding from isomers with lifetime longer than 1μs,it can be achieved by the Spectrometer for Heavy Atom and Nuclear Structure(SHANS)[1].143Eu nuclei were populated via the 123Sb(24Mg,4n)fusion-evaporation reaction.Most of the evaporation residues at ground state or long-lived isomers were transferred to detection terminal after a flight of about 1.4μs in SHANS.In the case of 143Eu,three transitions have been observed(Fig.1).展开更多
文摘Isotope 223U synthesized and identified[1;2].αenergy of 8 780(40)keV and a half-life of 55(10)μs.Theαenergy was calculated by subtracting knownαenergy of 219Th from measured decay sum energy of 223U and its daughter 219Th.Based on the advanced digital pulse processing technique,a new measurement forα-particle energy and half-life of 223U was performed at the gas-filled recoil separator,Spectrometer for Heavy Atoms and Nuclear Structure(SHANS).The isotope 223U was produced in the fusion-evaporation reaction 187Re(40Ar,p3n)223U.
文摘The study on the decay properties of new isotopes located far from the beta stability line is current the focus of nuclear physics. For isotopes in the region Z >82 and N <126, -emission prevails as radioactive decay mode and -spectroscopy is the most important tool to obtain information on the nuclear structure. In the heavy nuclei region with N=124 and 126 isotones, an intruder state (h9=2.f7=2)8+ based on the attractive interaction of f7=2 protons and f5=2 neutrons has been significantly observed, which increases the binding energy of this configuration with increasing proton number.
文摘Lifetime measurements of low-lying excited states in 87Zr and 87Nb have been performed via and coincidences. The 124 MeV 32S beam was delivered from the Sector-Focusing Cyclotron (SFC) of the Heavy Ion R-esearch Facility in Lanzhou (HIRFL). The parent nuclei 87Nb and 87Mo were produced by the respective reactions 58Ni (32S, 3p) and 58Ni (32S, 2p1n), at a beam energy 100 MeV through the 8 m Al degrader.
文摘An attempt has been made recently to synthesize very neutron-decient 216U isotope in 40Ca+natHf reaction atthe gas-lled recoil separator SHANS[1]. A beam of 40Ca12+ at an energy of Elab=194.6 MeV was delivered by thesector focusing cyclotron of the Heavy Ion Research Facility in Lanzhou (HIRFL). The average beam intensity wasabout 100 pnA. Self-support targets of natural hafnium foils with thickness of 420 g/cm2 was mounted in a edframe. Evaporation residues recoiled from the target were separated from the primary beam by the separator andthen implanted into the Si-box detector (consist of three position sensitive silicon detectors and eight non-positionsensitive silicon detectors)[2]. In order to distinguish the -decay events from the implantation events, two multi-wire proportional counters (MWPCs) were mounted upstream from the Si-box detector. Behind the Si-box detectora fourfold segmented Clover detector was installed for -ray studies.
基金Strategic Priority Research Program of Chinese Academy of Sciences(XDB34010000)Guangdong Major Project of Basic and Applied Basic Research(2021B0301030006)+1 种基金National Key R&D Program of China(2018YFA0404402)Frontier Science Key Project of Chinese Academy of Sciences(ZDBS-LY-SLH017)。
文摘Over the past years,experimentalists have launched an expedition to explore the predicted,centered near the double-magic Z=114,N=184 nucleus.With their remarkable e orts,elements from hydrogen up to element 118 at present.The discovery of the superheavy elements o ers the possibilities to study properties of nuclei under extremely strong Coulomb elds and to explore the limits of existence of nuclei.The fusion evaporation reactions induced by low-energy heavy ions are employed for synthesis and study of superheavy isotopes,and the gas-lled recoil separator technique is always used to e ectively separate the produced evaporation residues from projectile-like and target-like products.
基金Strategic Priority Research Program of Chinese Academy of Sciences(XDB34010000)Guangdong Major Project of Basic and Applied Basic Research(2021B0301030006)+1 种基金National Key R&D Program of China(2018YFA0404402)National Natural Science Foundation of China(U1932139,12105328,12035011,U2032135,11975279),Youth Innovation Promotion Association CAS(2020409),CAS Project for Young Scientists in Basic Research(YSBR-002)and Special Research Assistant Project of Chinese Academy of Sciences。
文摘Proton-andα-decay spectroscopy can provide valuable information on the nuclear structure and masses of neutron-de cient isotopes.In 1994,the proton drip line of Ac was reached by the detection of^(207)Ac which was identified via the-decay spectroscopy.Four years later,the neighboring proton-unbound nucleus ^(206)Ac was discov-ered.
基金Strategic Priority Research Program of Chinese Academy of Sciences(XDB34010000)Guangdong Major Project of Basic and Applied Basic Research(2021B0301030006)+1 种基金National Key R&D Program of China(2018YFA0404402)Frontier Science Key Project of Chinese Academy of Sciences(ZDBS-LY-SLH017)。
文摘The new thorium isotope ^(207)Th has been produced in the 5n evaporation channel of the fusion reaction ^(36)Ar+^(176)Hf.The 197-199 MeV ^(36)Ar^(11+)beam with a typical intensity of0.4 pμA was delivered by the Sector Focusing Cyclotron of the Heavy Ion Research Facility in Lanzhou(HIRFL),China.
基金National Key R&D Program of China(2018YFA0404402)。
文摘Alpha decay,as a pervasive decay mode of unstable heavy nuclei,plays a crucial role in the identification of new superheavy elements and investigation on nuclear structure of exotic nuclei near the proton drip line.
文摘In order to systematically investigate the-decay properties of U-isotopes near the N=126 shell and study the fine structures of 218Pa and 211−213Th,enriched targets,180W,182Wand 176Hf,were bombarded by the 36Ar and 40Ar beams provided the Heavy Ion Research Facility in Lanzhou(HIRFL).Combinations of beam and target as well as the beam energy,beam intensity,target thickness,irradiation time were listed in Table 1.Fusion-evaporation residues(ERs)were recoiled from the targets and separated from the primary beams using the gas filled recoil separator,SHANS[1].After passing through a multi-wire proportional chamber,the ERs were implanted into a Si-box detector[2]amounted at the focal plane of SHANS.Gamma rays emitted from the ERs were detected by three Ge detectors attached to the Si-box.All-decay and gamma-ray signals were registered and proceeded by a digital data acquisition system.
基金National Natural Science Foundation of China(11675224,11405243,11605268,11735017)Chinese Academy of Sciences(113462KYSB20150026,QYZDJ-SSW-SLH041)National Basic Research Program of China(973 Program)(2013CB834400)。
文摘Many nuclear theories have predicted the island of stability located around proton number of 114,120 or 126 and neutron number of 184 or 172.The synthesis of nuclei on the island of stability and the study of their exotic decay properties are crucial for the understanding of nuclear structure and properties under extremely strong Coulomb fields,and the discovery of maximum nuclear magic numbers.There is no appropriate method to produce such neutron-rich nuclei except multi-nucleon transfer(MNT)reaction.The target-like fragments(TLF)emit into a wide angular range with a broad energy distribution,which makes it very difficult to collect,separate and identify the nuclei of interest.
基金National Natural Science Foundation of China(11405243,11675224,11605268,11805254)Chinese Academy of Sciences(113462KYSB20150026,QYZDJ-SSW-SLH041)National Key R&D Program of China(2018YFA0404402)。
文摘A multi-re ection time-of-ight mass spectrometer(MRTOF-MS)at the spectrometer for heavy atom and nuclear structure(SHANS)[1],which will be used for direct atomic mass measurement and nuclear spectroscopy,is under construction.
文摘Lifetime measurements of low-lying excited states in^87Zr have been performed viaβ-γcoincidences.The 127 MeV^32S beam was delivered from the Sector-Focusing Cyclotron(SFC)of the Heavy Ion Research Facility in Lanzhou(HIRFL).The parent nuclei^87Nb were produced by the reaction 58Ni(32S,2p1n),at a beam energy 127 MeV through a 8 um Al degrader.A 200ug/cm^2 layer of 58Ni evaporated onto a 200ug/cm^2 thick carbon foil was employed as the target.After evaporation residues were separated from the projectile beams by the gas-filled recoil separator SHANS[1],the nuclei of interest 87Zr can be obtained with a higher purity and then were implanted into a 300um silicon detector.
文摘The application of Lanthanum Bromide(LaBr3)detectors provides a unique opportunity to measure lifetime of excited states in picosecond-nanosecond region.Reducing the background is of critical importance to get precise results.For some excited states feeding from isomers with lifetime longer than 1μs,it can be achieved by the Spectrometer for Heavy Atom and Nuclear Structure(SHANS)[1].143Eu nuclei were populated via the 123Sb(24Mg,4n)fusion-evaporation reaction.Most of the evaporation residues at ground state or long-lived isomers were transferred to detection terminal after a flight of about 1.4μs in SHANS.In the case of 143Eu,three transitions have been observed(Fig.1).
