1. 0nbb decay to the excited state 0 + of 130 Xe Comparison of the GE and SC analyses S. Di Domizio, December 2010

2. 2 Part 1: comparison of the methods In the following slides I will evaluate the efficiencies using the SC cuts with the GE and SC algorithms

3. 3 Efficiency – scenario1 – SC – 536 e = (0.82 +/- 0.03)%

4. 4 Efficiency – scenario1 – SC – 734 e = (0.82 +/- 0.02)%

5. 5 Efficiency – scenario1 – SC – 1257 e = (0.80 +/- 0.03)%

6. 6 Efficiency – scenario2 – SC - 1257 e = (2.58 +/- 0.04)%

7. 7 Efficiency – scenario2 – SC – 1270 e = (2.56 +/- 0.03)%

8. 8 Efficiency – scenario3 – SC – 536 e = (1.72 +/- 0.03)%

9. 9 Efficiency – scenario3 – SC – 1991 e = (1.76 +/- 0.03)%

10. 10 GE – scenario1 - 1257 Using GE algorithms and SC cuts

11. 11 GE – scenario2 - 1270 Using GE algorithms and SC cuts

12. 12 GE – scenario3 - 1257 Using GE algorithms and SC cuts

13. 13 Part 2: comparison of the results In the following slides I will summarize the differences in the two approaches and will extract the half life limits

14. 14 Comparison scenario 1 scenario 2 scenario 3 GESC N·t = 9.11 x 10 25 y N·t = 8.74 x 10 25 y N·t = 8.96 x 10 25 y 0.60 % 2.29 % 1.41 % 0.80 % 2.58 % 1.75 % scenario 1 scenario 2 scenario 3 GESC 0.48 % 1.93 % 1.19 % 0.64 % 2.18 % 1.48 % Geometric only total (with psa, noise, etc.) statistics N·t = 9.50 x 10 25 y values reported in the note Forgot to include the three “dead” channels 2, 3 and 50 “My” evaluation with “SC” method efficienc y GESC

15. 15 Result (GE) Posterior pdf for G G < 6.74 x 10 -25 y -1 90%CL T 1/2 > 1.03 x 10 24 y 90%CL

16. 16 Result (SC) Posterior pdf for G G < 5.98 x 10 -25 y -1 90%CL T 1/2 > 1.16 x 10 24 y 90%CL

17. 17 Part 3: the approach proposed by Frank In the following slides I will show the method and the results I obtained by treating the difference between GE and SC analysis as a systematic error

18. 18 Treating the differences as syst errors Use the approach discussed in Adam's internal note 1 2 3 efficienc y (0.56+/- 0.08)% (2.06+/- 0.13)% (1.34+/- 0.15)% scenari o Statistics: N·t = (9.23 +/- 0.27) x 10 25 y

19. 19 Result (combined) Posterior pdf for G G < 6.39 x 10 -25 y -1 90%CL T 1/2 > 1.09 x 10 24 y 90%CL

20. 20 Summary GE: T 1/2 > 1.0 x 10 24 y @90%CL SC: T 1/2 > 1.2 x 10 24 y @90%CL GE+SC: T 1/2 > 1.1 x 10 24 y @90%CL

21. 21 Method comparison Consider the limit case of an experiment with two crystals where one has 100% dead time and the other has 0 dead time. Since no coincidences can be recorded in these conditions, the number of signal and background counts will be zero. The SC approach would give a finite value for both the efficiency and the accumulated statistics, thus resulting in a non trivial limit for the half life of the process. The GE approach would give a finite value for the statistics and a null value for the efficiency, therefore nothing can be said about the half life of the process.

22. 22 Treating the differences as syst errors