研制了一种新型的带有阻抗性电极的TGEM——RETGEM(Thick GEM with Resistive Electrodes)探测器,阻抗性电极可以有效地保护探测器和前端电子学免于偶尔放电的损伤。对RETGEM探测器进行了初步测试,其中包括计数率、能量分辨、增益以及...研制了一种新型的带有阻抗性电极的TGEM——RETGEM(Thick GEM with Resistive Electrodes)探测器,阻抗性电极可以有效地保护探测器和前端电子学免于偶尔放电的损伤。对RETGEM探测器进行了初步测试,其中包括计数率、能量分辨、增益以及打火率。结果表明,探测器达到了设计的基本要求。展开更多
Electron-loss cross sections of 0q＋ （q = 1 -4） colliding with He, Ne and Ar atoms are measured in the intermediate velocity regime. The ratios of the cross sections of two-electron loss to that of one-electron loss...Electron-loss cross sections of 0q＋ （q = 1 -4） colliding with He, Ne and Ar atoms are measured in the intermediate velocity regime. The ratios of the cross sections of two-electron loss to that of one-electron loss R21 are presented. It is shown that single-channel analysis is not sufficient to explain the results, but that projectile electron loss, electron capture by the projectile and target ionization must be considered together to interpret the experimental data. The screening and antiscreening effects can account for the threshold velocity results, but cannot explain the dependence of the ratio R21 on velocity quantitatively. In general, the effective charge of the target atom increases with velocity increasing because the high-speed projectile ion can penetrate into the inner electronic shell of target atom. Ne and Ar atoms have similar effective charges in this velocity regime, but He atoms have smaller ones at the same velocities due to its smaller nuclear charge.展开更多
In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^＋ （q = 1 - 4） i...In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^＋ （q = 1 - 4） ions with argon atoms. The partial cross section ratios of the double, triple, quadruplicate ionization to the single ionization （or the single capture） of argon associated with single electron loss （or single electron capture） by the projectile are measured and compared with the previous experimental results. In the present experiment, it is observed that the ratios of ionization cross sections R associated with single loss and single capture depend strongly on the projectile charge state and vary significantly with different reaction channels as impact energy increases. In addition, this paper gets empirical scaling laws for the ionization cross section ratios R corresponding to the projectile single loss and finds that the ratios of the double ionization to the single ionization associated with single electron capture remain constant in the present energy range.展开更多
The ratios of transfer ionization （TI） to single-electron capture （SC） cross sections have been measured for the collisions of partially stripped C^q＋ ions （q = 1-4） with He. The collision velocity ranges from ...The ratios of transfer ionization （TI） to single-electron capture （SC） cross sections have been measured for the collisions of partially stripped C^q＋ ions （q = 1-4） with He. The collision velocity ranges from 0.7 to 4.4 vo （vo is the Bohr velocity）. The projectile-ion and recoil-ion coincidence technique is used to separate the processes of TI and SC. The ratios reach the maximum when the velocity is about 3.7 vo. This can be explained qualitatively based on the two-step mechanism. The experimental results are also compared with the results calculated using the classical trajectory Monte Carlo （CTMC） method. The CTMC results are in agreement with the experimental data basically. The discrepancies in higher velocity region are interpreted by the effective charge effect.展开更多
This paper reports that the ratios of double to single electron loss cross-section （R） of O^2＋ in collision with Ar and He at the velocity of 1 -4 vo（vo is the Bohr velocity） have been obtained by the coincidence...This paper reports that the ratios of double to single electron loss cross-section （R） of O^2＋ in collision with Ar and He at the velocity of 1 -4 vo（vo is the Bohr velocity） have been obtained by the coincidence technique. The trend of R - V in the experiment indicates that the effective charge varies with injected velocity. The effective charge can be obtained by the n-body classical trajectory Monte Carlo method, which is interpreted by the molecular Coulomb over barrier model.展开更多
Target ionization accompanied with projectile electron loss is investigated for 0.2-7 MeV C^q＋ （q = 1 - 4） with He and 0.25-5 MeV O^q＋ （q = 1 - 4） with He collisions. For projectile single-electron loss channel,...Target ionization accompanied with projectile electron loss is investigated for 0.2-7 MeV C^q＋ （q = 1 - 4） with He and 0.25-5 MeV O^q＋ （q = 1 - 4） with He collisions. For projectile single-electron loss channel, the He double-to-single ionization ratio R is nearly independent of projectile charge state but dependent on the nuclear charge of projectile Zp. The results are analysed with atomic structure qualitatively. So far there have not existed the experimental data comparable with our results, to our knowledge. The ratio R is interpreted in terms of the two-step mechanism. This analysis agrees well with similar experiments in the literature.展开更多
The multi-electron processes are investigated for 17.9-120 keV/u C^1＋, 30-323 keV/u C^2＋, 120-438 keV/u ^C3＋, 287-480 keV/u C^4＋ incident on a helium target. The cross-section ratios of double electron （DE） proc...The multi-electron processes are investigated for 17.9-120 keV/u C^1＋, 30-323 keV/u C^2＋, 120-438 keV/u ^C3＋, 287-480 keV/u C^4＋ incident on a helium target. The cross-section ratios of double electron （DE） process to the total of the single electron （SE） and the double electron process （i.e. SE＋DE）, the direct double electron （DDI） to the direct single ionization （DSI） as well as the contributions of DDI to DE and of TI to DE are measured using coincidence techniques. The energy and charge state dependences of the measured cross-section ratios are studied and discussed.展开更多
A novel Micro-pattern gaseous detector （MPGD）, thick GEM with electrodes made of a resistive material （RETGEM） is presented. In this paper we mainly investigate the energy resolution of a RETGEM in Ar＋CO2 with di...A novel Micro-pattern gaseous detector （MPGD）, thick GEM with electrodes made of a resistive material （RETGEM） is presented. In this paper we mainly investigate the energy resolution of a RETGEM in Ar＋CO2 with different gas mixtures. The results indicate that an energy resolution 30% in single and double mode can be obtained. The existence of an optimum energy resolution is discussed.展开更多
文摘研制了一种新型的带有阻抗性电极的TGEM——RETGEM(Thick GEM with Resistive Electrodes)探测器,阻抗性电极可以有效地保护探测器和前端电子学免于偶尔放电的损伤。对RETGEM探测器进行了初步测试,其中包括计数率、能量分辨、增益以及打火率。结果表明,探测器达到了设计的基本要求。
基金supported by the Special Foundation for Key Programs of Basic Research at its earlier stage,Ministry of Science and Technology,China(Grant No. 2002CCA00900)the Foundation for the Doctors of University of South China (GrantNo. 5-2007-XQD-001)
文摘Electron-loss cross sections of 0q＋ （q = 1 -4） colliding with He, Ne and Ar atoms are measured in the intermediate velocity regime. The ratios of the cross sections of two-electron loss to that of one-electron loss R21 are presented. It is shown that single-channel analysis is not sufficient to explain the results, but that projectile electron loss, electron capture by the projectile and target ionization must be considered together to interpret the experimental data. The screening and antiscreening effects can account for the threshold velocity results, but cannot explain the dependence of the ratio R21 on velocity quantitatively. In general, the effective charge of the target atom increases with velocity increasing because the high-speed projectile ion can penetrate into the inner electronic shell of target atom. Ne and Ar atoms have similar effective charges in this velocity regime, but He atoms have smaller ones at the same velocities due to its smaller nuclear charge.
文摘In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^＋ （q = 1 - 4） ions with argon atoms. The partial cross section ratios of the double, triple, quadruplicate ionization to the single ionization （or the single capture） of argon associated with single electron loss （or single electron capture） by the projectile are measured and compared with the previous experimental results. In the present experiment, it is observed that the ratios of ionization cross sections R associated with single loss and single capture depend strongly on the projectile charge state and vary significantly with different reaction channels as impact energy increases. In addition, this paper gets empirical scaling laws for the ionization cross section ratios R corresponding to the projectile single loss and finds that the ratios of the double ionization to the single ionization associated with single electron capture remain constant in the present energy range.
文摘The ratios of transfer ionization （TI） to single-electron capture （SC） cross sections have been measured for the collisions of partially stripped C^q＋ ions （q = 1-4） with He. The collision velocity ranges from 0.7 to 4.4 vo （vo is the Bohr velocity）. The projectile-ion and recoil-ion coincidence technique is used to separate the processes of TI and SC. The ratios reach the maximum when the velocity is about 3.7 vo. This can be explained qualitatively based on the two-step mechanism. The experimental results are also compared with the results calculated using the classical trajectory Monte Carlo （CTMC） method. The CTMC results are in agreement with the experimental data basically. The discrepancies in higher velocity region are interpreted by the effective charge effect.
基金supported by the Special Foundation for State Major Basic Research Program of China (Grant No 2002CCA00900)
文摘This paper reports that the ratios of double to single electron loss cross-section （R） of O^2＋ in collision with Ar and He at the velocity of 1 -4 vo（vo is the Bohr velocity） have been obtained by the coincidence technique. The trend of R - V in the experiment indicates that the effective charge varies with injected velocity. The effective charge can be obtained by the n-body classical trajectory Monte Carlo method, which is interpreted by the molecular Coulomb over barrier model.
文摘Target ionization accompanied with projectile electron loss is investigated for 0.2-7 MeV C^q＋ （q = 1 - 4） with He and 0.25-5 MeV O^q＋ （q = 1 - 4） with He collisions. For projectile single-electron loss channel, the He double-to-single ionization ratio R is nearly independent of projectile charge state but dependent on the nuclear charge of projectile Zp. The results are analysed with atomic structure qualitatively. So far there have not existed the experimental data comparable with our results, to our knowledge. The ratio R is interpreted in terms of the two-step mechanism. This analysis agrees well with similar experiments in the literature.
基金Supported by the National Natural Science Foundation of China with Grant No 10304019.
文摘The multi-electron processes are investigated for 17.9-120 keV/u C^1＋, 30-323 keV/u C^2＋, 120-438 keV/u ^C3＋, 287-480 keV/u C^4＋ incident on a helium target. The cross-section ratios of double electron （DE） process to the total of the single electron （SE） and the double electron process （i.e. SE＋DE）, the direct double electron （DDI） to the direct single ionization （DSI） as well as the contributions of DDI to DE and of TI to DE are measured using coincidence techniques. The energy and charge state dependences of the measured cross-section ratios are studied and discussed.
基金Supported by Knowledge Innovation Project of Chinese Academy of Sciences (KJCX1-YW-004,YFKJCX3.SYW.N5)Major State Basic Research Developing Program (2008CB817702)
文摘A novel Micro-pattern gaseous detector （MPGD）, thick GEM with electrodes made of a resistive material （RETGEM） is presented. In this paper we mainly investigate the energy resolution of a RETGEM in Ar＋CO2 with different gas mixtures. The results indicate that an energy resolution 30% in single and double mode can be obtained. The existence of an optimum energy resolution is discussed.
