Remeasurement of the half-life of ^(79)Se has been carried out with the projectile x-ray detection(PXD)in accelerator mass spectrometry.We made two major improvements over our earlier ^(79)Se half-life determination[N...Remeasurement of the half-life of ^(79)Se has been carried out with the projectile x-ray detection(PXD)in accelerator mass spectrometry.We made two major improvements over our earlier ^(79)Se half-life determination[Nucl.Instrum.Methods B 123(1997)403].Fristly,the PXD technique has been used for separation of ^(79)Se and 75Se from 79Br and 75As isobars respectively.Secondly,the half-life of ^(79)Se has been measured relative to the known precise half-life of ^(75)Se(119.79±0.04d).A more reliable half-life of ^(79)Se measured with the PXD technique is(2.95±0.38)×10^(5)y,about a factor of one lower than the previous value,1.1 × 10^(6)y.The problems in the previous measurement are discussed.展开更多
Some interferences are often encountered in accelerator mass spectrometry (AMS) measurements, espe-cially for medium-heavy nuclide measurement. It is difficult for online discrimination of the nuclide of interest from...Some interferences are often encountered in accelerator mass spectrometry (AMS) measurements, espe-cially for medium-heavy nuclide measurement. It is difficult for online discrimination of the nuclide of interest from the interfering ones. In order to solve this problem, we developed a method to simulate the experimental spectra of medium-heavy nuclides in AMS measurements. The results obtained from this method are in good agreement with experimental values.展开更多
It has been claimed that the half-life of radioactive nuclides embedded in metals may be significantly affected by the screening of quasi-free electrons provided by the metals,especially at the cryogenic temperature.W...It has been claimed that the half-life of radioactive nuclides embedded in metals may be significantly affected by the screening of quasi-free electrons provided by the metals,especially at the cryogenic temperature.We determine the α-decay half-life values of 210 po in high purity metallic bismuth at 4.2 K and 293 K.The results show that the α-decay half-life of 210Po at T =4.2 K is about (24 ±8)% shorter than that at room temperature.展开更多
Anomalous ^(3)He/^(4)He ratios in deuterium-loaded titanium samples are observed to be about 1-4×10^(-1),much greater than the values (≤10^(-4)) in natural objects.Control experiments with the deuterium-unloaded...Anomalous ^(3)He/^(4)He ratios in deuterium-loaded titanium samples are observed to be about 1-4×10^(-1),much greater than the values (≤10^(-4)) in natural objects.Control experiments with the deuterium-unloaded titanium sample and original industrial deuterium gas are also carried out,but no anomalous 3He/4He values are observed.In addition,anomalous tritium in deuterium-loaded titanium samples are also observed.To explain the excess 3He and tritium in the deuterium-loaded titanium samples,it is required that the deuteron-induced nuclear reaction occurs in the samples at low temperature.展开更多
The long-lived isotope ^(53)Mn cosmogenically produced in situ is a very useful indicator for geochronological dating.A new ^(53)Mn accelerator−mass-spectrometry(AMS)measurement method is developed based on the HI-13 ...The long-lived isotope ^(53)Mn cosmogenically produced in situ is a very useful indicator for geochronological dating.A new ^(53)Mn accelerator−mass-spectrometry(AMS)measurement method is developed based on the HI-13 Tandem Accelerator andΔE−Q3D detection system at China Institute of Atomic Energy.The performance of ^(53)Cr isobar separation and suppression is tested by a series of ^(53)Mn standards and commercial MnO samples.The results show that theΔE−Q3D detection system brought about an overall suppression factor of more than 107 for the interfering isobar ^(53)Cr.展开更多
High spin states in ^(90)Mo have been populated through the ^(59)Co (^(35)Cl,2p2n) 90Mo reaction at beam energy of 116 MeV. Level lifetimes of the positive-parity decay sequence are measured by using the Doppler shift...High spin states in ^(90)Mo have been populated through the ^(59)Co (^(35)Cl,2p2n) 90Mo reaction at beam energy of 116 MeV. Level lifetimes of the positive-parity decay sequence are measured by using the Doppler shift attenuation method. It is observed that the M1 transition strengths show a substantial enhancement at high spin. This behaviour may be related to occupation of high Ω orbitals by a pair of g9/2 protons. A deformed shape with oblate is suggested above the 13^(+) state.展开更多
In order to carry out the measurement of heavy nuclei in accelerator mass spectrometry, characteristic X-rays of the incident projectile have been explored and used as a method for isobar discrimination. The projectil...In order to carry out the measurement of heavy nuclei in accelerator mass spectrometry, characteristic X-rays of the incident projectile have been explored and used as a method for isobar discrimination. The projectile X-ray combined with AMS technique has been set up in China institute of Atomic Energy. The measurement of 79Se was performed by resorting to the projectile X-ray AMS technique and the detection sensitivity of 79Se was improved more than 2 orders of magnitude. The detection limit was about 3.6x 10-9 for 79Se/Se.展开更多
By using HPGe γ-ray spectrometry, the activity of the long-lived fission product 126Sn in a SnOB2 sample was measured. The number of 126Sn atoms and the ratio of 126Sn to Sn were calculated based on the half-life val...By using HPGe γ-ray spectrometry, the activity of the long-lived fission product 126Sn in a SnOB2 sample was measured. The number of 126Sn atoms and the ratio of 126Sn to Sn were calculated based on the half-life value of 2.35×105a and the chemical stoichiometry. The result of the ratio of 126Sn to Sn, （1.033±0.037）×10-8, is consistent with the results measured by the accelerator mass spectrometry （AMS） within uncertainty limits, which confirms our procedures in the measurement of 126Sn by AMS and lays a foundation for the AMS measurement of 126Sn at much lower levels.展开更多
基金Supported in part by the Nuclear Energy Foundation of China,No.H7010101.
文摘Remeasurement of the half-life of ^(79)Se has been carried out with the projectile x-ray detection(PXD)in accelerator mass spectrometry.We made two major improvements over our earlier ^(79)Se half-life determination[Nucl.Instrum.Methods B 123(1997)403].Fristly,the PXD technique has been used for separation of ^(79)Se and 75Se from 79Br and 75As isobars respectively.Secondly,the half-life of ^(79)Se has been measured relative to the known precise half-life of ^(75)Se(119.79±0.04d).A more reliable half-life of ^(79)Se measured with the PXD technique is(2.95±0.38)×10^(5)y,about a factor of one lower than the previous value,1.1 × 10^(6)y.The problems in the previous measurement are discussed.
基金Supported by the National Natural Science Foundation of China (No.10175094) and the Science Foundation of Guangxi University (X022013)
文摘Some interferences are often encountered in accelerator mass spectrometry (AMS) measurements, espe-cially for medium-heavy nuclide measurement. It is difficult for online discrimination of the nuclide of interest from the interfering ones. In order to solve this problem, we developed a method to simulate the experimental spectra of medium-heavy nuclides in AMS measurements. The results obtained from this method are in good agreement with experimental values.
基金Supported by the National Natural Science Foundation of China under Grant No 10875177.
文摘It has been claimed that the half-life of radioactive nuclides embedded in metals may be significantly affected by the screening of quasi-free electrons provided by the metals,especially at the cryogenic temperature.We determine the α-decay half-life values of 210 po in high purity metallic bismuth at 4.2 K and 293 K.The results show that the α-decay half-life of 210Po at T =4.2 K is about (24 ±8)% shorter than that at room temperature.
基金Supported by President Foundation of the China Institute of Atomic Energy(No YZ-0704).
文摘Anomalous ^(3)He/^(4)He ratios in deuterium-loaded titanium samples are observed to be about 1-4×10^(-1),much greater than the values (≤10^(-4)) in natural objects.Control experiments with the deuterium-unloaded titanium sample and original industrial deuterium gas are also carried out,but no anomalous 3He/4He values are observed.In addition,anomalous tritium in deuterium-loaded titanium samples are also observed.To explain the excess 3He and tritium in the deuterium-loaded titanium samples,it is required that the deuteron-induced nuclear reaction occurs in the samples at low temperature.
基金the National Natural Science Foundation of China under Grant Nos 11075221 and 10705054.
文摘The long-lived isotope ^(53)Mn cosmogenically produced in situ is a very useful indicator for geochronological dating.A new ^(53)Mn accelerator−mass-spectrometry(AMS)measurement method is developed based on the HI-13 Tandem Accelerator andΔE−Q3D detection system at China Institute of Atomic Energy.The performance of ^(53)Cr isobar separation and suppression is tested by a series of ^(53)Mn standards and commercial MnO samples.The results show that theΔE−Q3D detection system brought about an overall suppression factor of more than 107 for the interfering isobar ^(53)Cr.
基金Supported by the National Natural Science Foundation of China under Grant Nos.19675067 and 19975070.
文摘High spin states in ^(90)Mo have been populated through the ^(59)Co (^(35)Cl,2p2n) 90Mo reaction at beam energy of 116 MeV. Level lifetimes of the positive-parity decay sequence are measured by using the Doppler shift attenuation method. It is observed that the M1 transition strengths show a substantial enhancement at high spin. This behaviour may be related to occupation of high Ω orbitals by a pair of g9/2 protons. A deformed shape with oblate is suggested above the 13^(+) state.
基金the Nation Natural Science Foundation of China China Nuclear Industry Corporation
文摘In order to carry out the measurement of heavy nuclei in accelerator mass spectrometry, characteristic X-rays of the incident projectile have been explored and used as a method for isobar discrimination. The projectile X-ray combined with AMS technique has been set up in China institute of Atomic Energy. The measurement of 79Se was performed by resorting to the projectile X-ray AMS technique and the detection sensitivity of 79Se was improved more than 2 orders of magnitude. The detection limit was about 3.6x 10-9 for 79Se/Se.
基金Supported by National Natural Science Foundation of China (10576040)
文摘By using HPGe γ-ray spectrometry, the activity of the long-lived fission product 126Sn in a SnOB2 sample was measured. The number of 126Sn atoms and the ratio of 126Sn to Sn were calculated based on the half-life value of 2.35×105a and the chemical stoichiometry. The result of the ratio of 126Sn to Sn, （1.033±0.037）×10-8, is consistent with the results measured by the accelerator mass spectrometry （AMS） within uncertainty limits, which confirms our procedures in the measurement of 126Sn by AMS and lays a foundation for the AMS measurement of 126Sn at much lower levels.
