1. The Lifetime Measurement of First 2+ State in 174Os with LaBr3(Ce)
李聪博1,2 等
指导教师：吴晓光1，李险峰2
1中国原子能科学研究院
2吉林大学
浙江湖州

2. CONTENTS
Introduction
LaBr3:Ce Crystals and Test
Experimental Electronics and Data analysis method
Off-line Test with 152Eu
In-beam Experiments
Conclusions

3. Introduction Os
174Os
Neutron mid-shell
A Large error bar

4. Introduction 174Os(21+) with lifetime 505(60) ps (RDM).
Recoil distance method (RDM) with Plunger devices. (ps - ~1ns)
Triple-βγγ (t) coincidence method using a mix of Ge, plastic, BaF2 or LaBr3(Ce) in β decay experiment. (>several Ps) H. Mach et al, Nucl. Instrum. Meth. A 280, 49 (1989).
3. A new experimental method Triple-γγγ (t) with LaBr3(Ce) and Ge in-beam experiments. (>several Ps)
N. Mărginean, et al., Eur.Phys.J.A 46,329(2010)
174Os(21+) with lifetime 505(60) ps (RDM).
J. Gascon et al., Nucl. Phys. A 470, 230 (1987).

5. LaBr3:Ce Crystals and Test
Dendity（gcm-3）
Light yield（ph/keV）
Decay time（ns）
maximum emission（nm）
Energy resolution（%）662keV
NaI:Tl
3.67 41
230
410
5.6
CsI:Na
4.51 40
630
420
7.4 66
1000x800/6
550
6.6
LaCl3:Ce
3.79 49 28
350
3.8
LaBr3:Ce
5.0 63 16
380
2.8
BGO
7.1 9
300
480
9.0
LSO 26
7.9
GSO
6.7 8 60
440
7.8
YAP
5.5 21 30
4.3
BaF2
4.9 2
0.8
225 10

6. LaBr3:Ce Crystals and Test
characteristics
Volume:
Four 30 × 30mm Three 1 × 1 inch cylinder

7. LaBr3:Ce Crystals and Test
Energy Resolution

8. LaBr3:Ce Crystals and Test
Time Resolution
22Na

9. Experimental Electronics and Data analysis method

10. Experimental Electronics and Data analysis method
Sloping method
H. Mach, R.L. Gill and M.Moszyinski, Nucl. Instrum. Meth. A 280, 49 (1989).

11. Off-line Test with 152Eu

12. Off-line Test with 152Eu Deconvolution Fitting 1.39（3）ns
T1/2=1.42(2)ns

13. In-beam Experiments

14. In-beam Experiments
Cascade

15. In-beam Experiments Beams: 140 MeV 28Si
Target: 0.9mg/cm2 152Sm rolled onto a12.5mg/cm2 Pb backing
10 HPGe-BGO , 2 Planar HPGe and 7 LaBr3(Ce)

16. In-beam Experiments
J.L. DURELL et al. Phys. Letter. B (1982)

17. In-beam Experiments
508(16)ps

18. In-beam Experiments
Jing-ye Zhang et al., Phys. Rev. C 73, (2006)

19. In-beam Experiments A large increase A subshell
structure in the evolution of W and Os isotopic chains.
M. Rudigier et al., Nucl. Phys. A 847, 89 (2010).

20. In-beam Experiments N.V. Zamfir et al. Phys. Letter. B357 515(1995)
P.Moller,J.R.Nix,W.D.Myers,W.J.Swiatecki,At.DataNucl.DataTables59(1995)185–381.

21. In-beam Experiments

22. In-beam Experiments Suggested as +0.117 +0.145
P.Moller,J.R.Nix,W.D.Myers,W.J.Swiatecki,At.DataNucl.DataTables59(1995)185–381.
M. Rudigier et al., Nucl. Phys. A 847, 89 (2010).

23. Conclusions
The lifetime of the first excited 2+ state in 174Os has been remeasured in fast time experiment and determined to be a greater accuracy, to be 508(16)ps.
A deviation of the B(E2) value systematics in 174Os may hint a nuclear structure change, resulting a large increase in hexadecapole deformation (with ).
These explanations, from phenomenology at least, modify the expected trends. Other explanations, especially with microscopic model calculations, are needed.

24. Thanks for your attention!