1 基于轻核衰变实验的考虑 华 辉 北京大学物理学院 HIRFL-RIBLL1 合作组会议, 中科院近代物理研究所，兰州，

2 二、未来基于轻核衰变实验 的考虑 一、已开展研究工作介绍 报告提纲

3 一、已开展研究工作介绍

4  detector Beam on & Beam off mode

5 Experimental detection system in  Neutron sphere ： 8 identical plastic scintillators curved to a radius of 100 cm. Each (157 cm in length, 40 cm in width at the center, and 20 cm in width at both ends, 2.5 cm in thickness). The total solid angle 30% of 4 .  Neutron wall: 20 short plastic scintillation bars. Each (40.0 cm in length, 4.5 cm in width, and 2.5 cm in thickness).The total solid angle 8.8% of 4 .  Neutron wall: 20 short plastic scintillation bars. Each (40.0 cm in length, 4.5 cm in width, and 2.5 cm in thickness). The total solid angle 8.8% of 4 .  Implantation detector: NE102, 4.0 cm by 5.0 cm by 3.0 mm thick.  4 clover high-purity germanium (HPGe)  NIMA606, 645(2009)

6 Our previous work with this device ? ? Studied at NSCL 17 C 18 C 17 N 18 N 19 N 20 N 22 N 23 O 15 B 16 C Studied at GANIL 11 Li 9 Li 8 He Studied at many Labs 19 C 17 B 14 Be Studied at RIKEN Studied at PKU  Phys. Rev. C 72, (2005),  Phys. Rev. C 75, (2007),  Phys. Rev. C 80, (2009).

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8 For 18 N: an average beam purity of 95%. For 21 N: an average beam purity of 74.5%. Disadvantage of Beam on & Beam off mode

9 Nearly all the implanted nuclide and their daughters and granddaughters need to be considered in the decay calculations. The background from the environment is very large!

10 Disadvantage of Beam on & Beam off mode A lot of radioactive nuclei wasted!

11 Si PIN DSSD Si PIN Veto light particles Continuous Beam mode Implantation DSSD: x-y position (pixel), time Decay DSSD: x-y position (pixel), time Beta Counting System (BCS)

12 e-e- Si Strips Continuous Beam mode

13 Experimental detection system in

14 Preamp Log mode

Bi 源内转换电子能量谱 DSSD 硅微条的能量分辨

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17 Beam ： 40 Ar, 68.9MeV/u, ~60enA RIB: 32 Mg LISE 计算

18 粒子注入位置图 Pixel 粒子最大注入率 0.053pps

19 探测装置能量响应曲线

20 Experimental results DSSD No pixel limitation pixel <4 Space correlation

21 Primary experimental dataDSSD Same pixel pixel <2

22 NNDC T 1/2 =41.7±0.2ms A.C Morton et al PLB (2002) 拟合得到的 33 Al 核  衰变半衰期

23 实验得到的目标核  衰变半衰期

24 31 Mgγ 谱分析 a 669 a a ： 31 Al b ： 31 Si 1626 a 1612 a 2314 b 1695 b

25 连续束研究的不稳定核位置

26 二、未来基于轻核衰变实验的考虑 1 、提高  探测效率 Si PIN DSSD Si PIN Veto light particles DSSD

27 2 、优化整个探测设备布局

28 3 、基于 RIBLL 束流强度的考虑 T 1/2 =92±10ms Nuclide CountsCPS 33 Mg Literature value T 1/2 =90.5±1.6ms A.C Morton et al PLB (2002)

29 Literature value T 1/2 =14.8±0.3ms Vandana Tripathi et al PRC 73, (2006) T 1/2 =18.3±0.8ms Nuclide CountsCPS 29 Ne

30 未来研究目标

31 Nuclide LISE++ 36 Al Mg Mg Mg Na Na Na Ne Ne0.003 Beam ： 40 Ar, 68.9MeV/u, ~60enA RIB: 34 Mg

32 Thank you! Peking University