1. International Workshop SDANCA 2015
Current experimental techniques of lifetime measurements and their importance for the nuclear structure
S. Pascu
International Workshop SDANCA 2015
8-10 October 2015

2. Outline: Introduction The new ROSPHERE array in Bucharest;
Lifetime measurements in a deformed nucleus: 168Yb;
Quadrupole and octupole collectivity in a vibrational nucleus: 150Gd;
Conclusions

3. 1. Introduction
C. Ur, private communication

4. 2. The new ROSPHERE array in Bucharest
25 positions;
Usually in a mixed configuration: 14 HPGe and 11 LaBr3;
Fast-timing measurements;
Plunger measurements;
New campaign of experiments (PAC meeting).

5. 2. The new ROSPHERE array in Bucharest

6. 2. The new ROSPHERE array in Bucharest – characteristics

7. 3. Fast-timing method
N. Marginean et al., EPJA 46, 329 (2010)

8. 4. Lifetime measurements in 168Yb
166Er(α,2nγ)168Yb
Eα = 24 MeV
d = 2 mg/cm2
8 HPGe and 11 LaBr3
S. Pascu et al., PRC 91, (2015)

9. Data analysis
Coincidence
168Yb

10. Results of the experiment
S. Pascu et al., PRC 91, (2015)
Very short lifetime for the fast-timing method

11. Comparison with the neighboring isotopes2+ 4+ 6+

12. 5. Recoil distance Doppler shift methodθ
Target E0
Energy d Nr
Stopper Es
DDCM

13. Plunger device

14. 6. Quadrupole and octupole collectivity in Gd nuclei
Octupole vibration
l=2
l=3
Quadrupole vibration

15. 6. Quadrupole and octupole collectivity in Gd nuclei
ROSPHERE + Plunger
140Ce (13C, 3nγ)150Gd
E(13C) = 62 MeV
0.5 mg/cm2 140Ce target
5 pnA 13C beam
1% efficiency of HPGe detectors
11 distances between 20 and 500 μm

16. Experimental results

17. Experimental results

18. Experimental results

19. Experimental results

20. Experimental results

21. Experimental results

22. Experimental results
R. H. Spear and W. N. Catford, PRC 41, R1351 (1990)

23. 5. Conclusions The new ROSPHERE array in Bucharest;
Allows for lifetime measurements;
Fast-timing method: Lifetime measurements 168Yb;
Recoil distance Doppler shift method: quadrupole and octupole collectivity in Gd nuclei using the plunger method.