Directional Sensitivity in Double Chooz

1. Directional Sensitivity in Double Chooz LAUNCH Workshop Heidelberg 23.3.2007 Kathrin A. Hochmuth Max-Planck-Institut für Physik

2. Outline • Neutrino Direction Measurements • CHOOZ measurements • Two Reactors - separation of sources? - monitoring power output? • analytical estimates and maximum likelihood analysis - for Double Chooz setup with 30° separation - for hypothetical setup with 90° separation in collaboration with M. Lindner and G. Raffelt

3. Neutrino Direction = average displacement for reactor energies ~ 1.9 cm Note: uncertainty of locating the positron annihilation and neutron absorption points is large! Uncertainty of displacement

4. Setup CHOOZ determined each of the angles with s ~ 12° with 2,500 events Double Chooz near detector: 160,000 events per year

5. One Reactor CHOOZ event rate (2,500); true values q f

6. One Reactor CHOOZ event rate (2,500); true values q f Double Chooz event rate (160,000)

7. Two Reactors ??? 160,000 events Single Reactor Double Chooz 30° separation Hypothetical setup 90° separation

8. Probability Distribution Function tilt angle w.r.t x-y plane; relative strength of the reactors, where (assume for now: ) displacement: 1.9 cm uncertainty of the displacement: 20 cm Separation angle Central angle For Double Chooz

9. Important Points y-axis distribution gives information on the angular separation x-distribution gives only information on the center of the distribution No distinction from a single Gauss; >10 Mio events needed

10. Important Points y-axis distribution gives information on the angular separation x-distribution gives only information on the center of the distribution No distinction from a single Gauss; >10 Mio events needed

11. Non-Gaussianity Good resolution Bad resolution No clear distinction because cosf1~1

12. Angular Separation of 2 Sources 160,000 events Non-Gaussian behavior No distinction from 0° Reactor 1 Separation angle Central angle well determinded x-distribution behaves like a single Gaussian

13. 7 years Double Chooz Reactor 1 Separation angle 3 s distinction possible after 7 years

14. Hypothetical 90° separation for 160,000 events: Clear separation of the angles f1,f2 with s1~3.2° central angle: sc~2.3° • separation angle: s~4.6° Note:

15. Reactor Strength Reactor strength 1 year Double Chooz: 160,000 events: 5 years: f1=45° after 1 year: True value: b1=b2=0.5 after 1 month

16. Conclusions • Separation of the two Double Chooz reactors challenging, because of small separation angle and • 3 s separation of the two Double Chooz reactors after 7 years • Separation Potential increases with increasing angles=> clear distinction for 90° separation after 1 year • Possible to monitor the strength of each individual reactor; for 1 year Double Chooz with

17. References M. Apollonio et al.(CHOOZ Collaboration), Phys.Rev.D 61 (2000) 012001 [hep-ex/9906011]. M. Apollonio et al. Eur.Phys.J. C 27 (2003) 331 [hep-ex/0301017] F. Ardellier et al.(Double Chooz Collaboration) hep-ex/0606025v4 (26 October 2006). P. Vogel and J. F. Beacom, Phys. Rev. D 60 (1999) 053003 H. O. Back et al. (Borexino Collaboration),physics/0408032. P. H. Frampton and P. Vogel, Phys.Rept. 82 (1982) 339. K. A. Hochmuth et al, Earth Moon Planets 99:253-264,2006 ,[hep-ph/0610048]. K. A. Hochmuth et al, Astropart.Phys.27:21-29,2007 ,[hep-ph/0509136].

18. Thank you! N U L A C H