CeSOX sensitivity studies

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1 CeSOX sensitivity studies Ma#hieu VIVIER, Guillaume MENTION CEA- Saclay, DSM/IRFU/SPP CeSOX kick- off meecng Paris, February 5 th

2 CeSOX experimental parameters

3 L/E spectrum modeling and χ 2 Model computes L/E expected anti-ν e spectrum. It includes: o o Production of anti-ν e : 144 Pr beta spectrum (see M. Durero talk about modeling of 144 Pr beta spectrum)+ source finite size effects Detection of anti-ν e : up to date IBD cross-section, number of proton targets, detection efficiency IBD(E e )=apple p e E e (1 + rec + rad + WM ) κ = cm 2 MeV -1 Recoil & WM corrections from Fayans (1985) Radiative corrections from Vogel (1984) o o o Energy and position reconstruction resolutions Systematics uncertainties: Fully correlated normalization uncertainty related to source activity uncertainty (3+1) sterile neutrino model P e! e =1 sin 2 (2 )sin m2 L E χ 2 analysis: X N obs i i (1 + )N exp i (, m ) + stat i where i runs over (L/E) bins

4 Model ingredients: L & E distributions 0.7 AntiNu source energy spectrum, Pr144 O ptwm 144 Pr an%- nu spectrum Counts per 1.00 kev bins True neutrino energy E [MeV] An%- nu path length distribu%on L E

5 Model ingredients: L/E resolution functions 7 6 Normalized L/E resolution function 1.8 MeV < E 3 MeV, 3 m < L < 13 m Solid lines: Eres = 5%/sqrt(E) Vres = 15 cm 5 arbitrary units 4 3 Dot dashed lines: Eres = 5%/sqrt(E) Vres = 50 cm Dashed lines: Eres = 15%/sqrt(E) Vres = 15 cm L rec /E rec [m MeV ]

6 Model ingredients: L/E resolution Width of L/E resolution as a function of L/E: MeV < E < 3 MeV 3 m < L < 13 m E = 5% L = 15 cm 0.8 E = 5% L = 50 cm 0.7 E = 15% L = 15 cm 0.6 L/E [m MeV 1 ] L/E [m MeV 1 ]

7 Number of expected IBD candidates CeSOX R < 4.25 m Distance/ Activity 75 kci 100 kci 140 kci 6 m m m CeSOX nominal CeSOX R < 5.5 m Distance/ Activity 75 kci 100 kci 140 kci 6 m m m CeSOX upgraded

8 L/E spectrum expected in Borexino No oscillations 350 sin 2 (2 ) = 0.29, m 2 = 0.25 ev2 new new sin 2 (2 new ) = 0.10, m 2 new = 3 ev2 Statistical error bars only Counts per 0.10 m MeV 1 bin sin 2 (2 ) = 0.29, m 2 = 10 ev2 new new Average L/E is around 3.2 m MeV -1 : corresponds to resolution of 0.1 m MeV -1 Exponential damping of oscillations because of detector resolution Small Δm 2 ( 0.5 ev 2 ) hardly visible because of detector size, unless mixing is large 0 1 Good for intermediate Δm 2 (0.5 5 ev 2 ) (Osc/no osc) ratio High Δm 2 oscillations averaged because binning size > oscillation length + exponential damping: hardly visible unless large mixing angle L/E (m MeV 1 )

9 CeSOX χ 2 sensitivity Take 0.2 m MeV -1 bins (twice L/E resolution) Compute sensitivity to «no oscillation» hypothesis, according to χ 2 formula shown previously Δχ 2 = χ 2 -χ 2 min follows χ2 distribution with 2 dof In next slides, chose 95% CL, Δχ 2 = 6 Reminder: χ 2 contours are statistically averaged contours. If we perform N realizations, allowing for statistical fluctuations, the average of obtained contours must give the contour displayed on sensitivity plots. CeSOX nominal 100 kci, 8.25 m from center, 1.5 years, 95% CL CeSOX upgraded 100 kci, 8.25 m from center, 1.5 years, 95% CL (ev 2 ) m new 2 (ev 2 ) m new 2 rate + shape shape only Reactor anomaly, PRD (2011), 95% CL Reactor anomaly, PRD (2011), 90% CL sin 2 (2 ) new rate + shape shape only Reactor anomaly, PRD (2011), 95% CL Reactor anomaly, PRD (2011), 90% CL sin 2 (2 new )

10 CeSOX contours features CeSOX nominal 100 kci, 8.25 m from center, 1.5 years, 95% CL Sensitivity to oscillations is degraded because of exponential damping + size of oscillations < binning size. Compensated by rate information: P 1 ½ sin 2 (2θ) (ev 2 ) m new 2 Detector contains more than 1 oscillation period, best performances are here. L osc comparable to detector size, but still less than 1 oscillation period is contained in the detector. rate + shape shape only Reactor anomaly, PRD (2011), 95% CL Reactor anomaly, PRD (2011), 90% CL sin 2 (2 new ) L osc much bigger than detector size P 1 α sin 2 (2θ) Δm 2

11 Different confidence levels With different confidence 90, 95 and 99 %: Rate + shape Shape only CeSOX nominal 100 kci, 8.25 m from center, 1.5 years CeSOX nominal 100 kci, 8.25 m from center, 1.5 years m 2 [ev 2 ] m 2 [ev 2 ] 90% C.L 90% C.L 95% C.L 99% C.L sin 2 (2 ) 95% C.L 99% C.L sin 2 (2 )

12 Impact of source-detector distance Rate + shape Shape only CeSOX 1.5 years, 95% CL CeSOX 1.5 years, 95% CL D = 6 m D = 8.25 m D = 12 m D = 6 m D = 8.25 m D = 12 m

13 Impact of source extension Take a spherical source and increase radius: Rate + shape Shape only CeSOX 1.5 years, 95% CL CeSOX 1.5 years, 95% CL Point like source R source = 7.5 cm R source = 50 cm Point like source R source = 7.5 cm R source = 50 cm Source extension doesn t make any differences

14 Impact of energy resolution Rate + shape Shape only CeSOX 1.5 years, 95% CL CeSOX 1.5 years, 95% CL E = 2.5% = 5% E = 10% E E = 2.5% = 5% E = 10% E

15 Impact of position resolution Rate + shape Shape only CeSOX 1.5 years, 95% CL CeSOX 1.5 years, 95% CL R = 5 cm R = 15cm R = 50 cm R = 5 cm R = 15cm R = 50 cm

16 Impact of source activity Rate + shape Shape only CeSOX 1.5 years, 95% CL CeSOX 1.5 years, 95% CL A = 75 kci A = 100 kci A = 140 kci A = 75 kci A = 100 kci A = 140 kci

17 CeSOX vs CeLAND CeSOX vs CeLAND 1.5 years, 95% CL CeSOX upgraded vs CeLAND 1.5 years, 95% CL (ev 2 ) m new 2 (ev 2 ) m new 2 CeSOX 100 KCi, 8.25 m from center, R < 4.25 m CeLAND 65 kci, 9.6 m from center, R < 6.5 m Reactor anomaly, PRD (2011), 95% CL Reactor anomaly, PRD (2011), 90% CL sin 2 (2 new ) CeSOX 100 KCi, 8.25 m from center, R < 5.5 m CeLAND 65 kci, 9.6 m from center, R < 6.5 m Reactor anomaly, PRD (2011), 95% CL Reactor anomaly, PRD (2011), 90% CL sin 2 (2 new )

18 Conclusions Competitive limits with CeSOX nominal scenario. Most of the anomaly parameter space is covered at 95% C.L. Very good limits with upgraded Borexino detector: better than KamLAND taking into account the transport constraints (higher activity is achievable if deploying at Borexino). Contours more sensitive to energy resolution than vertex resolution. Source extension does not impact the sensitivity Other systematic uncertainty studies ongoing o o o o Effect of fiducial volume uncertainty (what is the fiducial volume uncertainty in Borexino?) Effect of a «radius scale» uncertainty? (Is there any systematic bias associated to the vertex reconstruction in Borexino?) KamLAND collaboration claimed one in their volume calibration paper (Berger et al. (2009)). Effect of an energy scale uncertainty? (What is the energy scale uncertainty in Borexino?) Any backgrounds systematics that we should include in the sensitivity study? Strongly depends on source impurities content

19 Backup slides

20 KamLAND systematic bias in position reconstruction From Berger et al. (2009): «The KamLAND full-volume calibration system»

PROSPECT: Precision Reactor Oscillation and Spectrum experiment

PROSPECT: Precision Reactor Oscillation and Spectrum experiment DAVID MARTINEZ CAICEDO on behalf of PROSPECT collaboration ILLINOIS INSTITUTE OF TECHNOLOGY NUFACT 2015 AUGUST 14th 2015 1 Outline Motivations: