Double Chooz Results towards the ND phase Rencontres de Moriond - PowerPoint PPT Presentation

Double Chooz Results towards the ND phase Rencontres de Moriond 2014 EW Interactions and Unified Theories March 2014 La Thuile Pau Novella (CNRS/APC) On behalf of the DC collaboration P. Novella, DC New Results, Moriond 2014 1

Overview ● Reactor neutrinos and θ 13 ● The Double Chooz experiment ● n-Gd and n-H R+S oscillation results ● Reactor Rate Modulation analysis ● Towards the ND+FD phase ● Summary and conclusions P. Novella, DC New Results, Moriond 2014 2

Reactor neutrinos and θ 13 L ~ 1 km P ( ν e → ν x ) In contrast to accelerator experiments... No parameter correlations No matter effects Pure ν e beam Cheap, as source exists High flux and large x-section Low energy 2014: θ 13 measured by DC, DB and RENO → precision phase! P. Novella, DC New Results, Moriond 2014 3

Detecting reactor neutrinos IBD: ν e + p → e + + n Th: 1.8 MeV. D isappearance! Target: scintillator + n-catcher (Gd) γ E ν spectrum E ν spectrum Prompt signal Prompt signal Detector: PMT s (1-8 MeV) (1-8 MeV) e - e + ν e γ p n Gd/H γ γ Delayed signal Delayed signal P. Novella, DC New Results, Moriond 2014 4

Setting up the experiments Reactor neutrinos: <E ν > ~ 4 MeV Solar sector Systematics! Oscillation! ~1 km ~100 m P. Novella, DC New Results, Moriond 2014 5

The Double Chooz Experiment Near Detector L = 400m 10m 3 target 120 m.w.e. Summer 2014 Far Detector L = 1050m 10m 3 target 300 m.w.e. • Pioneered reactor experiments after CHOOZ: • Experimental concept of using two detectors April 2011 ~ Chooz Reactors • New detector structure: 4 layers detector • Low background (S/N ~ 20, proven by reactor OFF) 4.27GW th x 2 cores • Stable Gd loaded LS developed 66 P. Novella, DC New Results, Moriond 2014 6

The DC Collaboration France Germany Japan Russia Spain USA Brazil CBPF APC EKU Tübingen Tohoku U. INR RAS CIEMAT - U. Alabama UNICAMP CEA/DSM/IRF MPIK Tokyo Inst. Tech. IPC RAS Madrid ANL Heidelberg UFABC U: Tokyo Metro. U. RRC U. Chicago SPP RWTH Niigata U. Kurchatov Columbia U. SPhN Aachen Kobe U. UCDavis SEDI TU München Tohoku Gakuin U. Drexel U. SIS U. Hamburg Hiroshima Inst. IIT SENAC Tech. KSU CNRS/IN2P3: LLNL Subatech MIT IPHC U. Notre Dame U. Tennessee Spokesperson: H. de Kerret (IN2P3) Project Manager: Ch. Veyssière (CEA-Saclay) Web Site: www.doublechooz.org/ P. Novella, DC New Results, Moriond 2014 7

Double Chooz Detectors Inner Detector Glove box Steel buffer 2 acrylic vessels µ Outer Veto Buffer Plastic scint. strips Mineral oil Inner Veto 390 10” PMT Scint. (LAB) 78 8” PMTs Gamma Catcher Scintillator (PXE) Iron Shield Target Inner ND and FD Scintillator (PXE) are identical doped with Gd P. Novella, DC New Results, Moriond 2014 8

Detector Calibration 3 Calibration sources: ● Radiactive sources 137 Cs, 68 Ge, 60 Co, 252 Cf 60 Co Natural sources n-H captures, BiPo LED l light injection LED light injection GC Guide Tube Energy Scale PE non-linearity 60 Co Detector uniformity Z-axis Time stability P. Novella, DC New Results, Moriond 2014 9

Neutrino Candidates Selection n from IBD can be captured either in Gd or H n-Gd n-H ● High x-section ● High stats (TG+GC) ● ∆ T ~30 µ s ● ∆ T ~200 µ s n-Gd n-H ● E delay ~8 MeV ● E delay ~2 .2MeV Independent statistical samples: 1) x-check on θ 13 n-Gd n-H 2) Boost statistics Characteristic p-d correlation: Background reduction P. Novella, DC New Results, Moriond 2014 10

Backgrounds (I) µ Events mimicking the IBD prompt-delayed correlation Tagged by OV and IV µ related + radiactivity Uncorrelated (accidentals): n 8 He 9 Li Radioactivity + fast neutrons β p Correlated: n 232 Th Fast neutrons (FN): p recoil + n capture 238 U Stopping- µ ( SM ) : µ + Michel electron cosmogenic isotopes ( 9 Li/ 8 He): n- β decay Background measurements on site P. Novella, DC New Results, Moriond 2014 11

Candidates Selection (II) n-Gd p-d correlation n-Gd n-H E prompt 0.7-12.2 MeV 0.7-12.2 MeV E delayed 6.0-12.0 MeV 1.5-3.0 MeV ∆ T 2-100 µ s 10-600 µ s -- <0.9 m ∆ R BG reduction n-Gd n-H µ veto ∆ T > 1ms n-Gd -- E µ > 600 MeV, ∆ T>0.5s Showering −µ isolation 500 µ s 1600 µ s OV veto Prompt not coincident with OV P. Novella, DC New Results, Moriond 2014 12

Neutrino Candidates Rate Run Time: 251.3 day n-Gd 2 Reactors On BG not subtracted Neutrino Candidates rate (day -1 ) 1 Reactors Off 2 Reactors Off n-Gd n-H Accidental BG subtracted Candidates: 8249 S/B~17 n-H Candidates: 36284 S/B~1 Acc. BG P. Novella, DC New Results, Moriond 2014 13

Backgrounds (II) n-Gd FN/SM n-Gd Accidentals: 0.261±0.002 / day n-Gd Rate and shape form Rate and shape time-uncorrelated Fast-n/Stop- µ : 0.67±0.20 / day from IV and OV candidates coincident events Cosmo. 9 Li/ 8 He: 1.25±0.54 /day Accidental Cosmogenic n-Gd n-H Rate from ∆ T µ Shape: MC Accidentals: 73.45±0.16 / day Fast-n/Stop- µ : 2.50±0.47 / day Cosmo. 9 Li/ 8 He: 2.8±1.2 /day P. Novella, DC New Results, Moriond 2014 14

Systematic Uncertainties ● Dominated by flux error: Rate Error (%) n-Gd n-H – to be canceled by the ND statistics 1.1 1.1 Flux prediction 1.7 1.7 det. efficiency 1.0 1.6 background 1.6 1.7 Total 2.7 3.1 Shape uncertainties 9 Li spectrum Reactor spectrum 9 Li/ 8 He dominates the BG error ● Energy scale FN/SM spectrum – 1.5% for n-Gd, 1.6% for n-H – To be reduced with larger stats P. Novella, DC New Results, Moriond 2014 15

R+S Oscillation Results Phys. Rev. D86 (2012) 052008 Phys. Lett. B723 (2013) 66-70 1 1 4 4 0 0 0 0 V V Ba ckg ro u nd -s u b tra cte d s ig n a l ts ts Me Me V n n s Ba c kg ro u nd-s u btra cte d s ig n a l Me t e e n Ev Ev 5 5 No o s cilla tio n e .2 .2 No o s c illa tio n Ev 1 2 0 0 1 1 2 2 0 0 0 0 .5 0 0 2 θ 0 Be s t fjt: s in (2 ) = 0 .1 0 9 2 θ Be s t fjt: s in (2 ) = 0 .0 9 7 1 3 1 3 a t ∆ m 2 = 0 .0 0 2 3 2 e V 2 ( χ 2 /d.o .f. = 4 2 .1 /3 5 ) 3 1 ∆ 2 2 a t m = 0 .0 0 2 3 1 e V 1 0 0 0 1 1 0 0 0 0 0 0 Sys te m a tic e rro r Sys te m a tic e rro r 8249 IBDs (with BG) 8 8 0 0 0 0 8 0 0 228 live days 36284 IBDs (with BG) 240 live days χ 2 /dof = 42.1/35 6 6 0 0 0 0 6 0 0 χ 2 /dof = 38.9/30 4 4 0 0 0 0 4 0 0 n-Gd n-H 2 2 0 0 0 0 2 0 0 d d 1 1 .2 .2 d 1 .2 e e e t t t ic ic V V ic V d d Me Me 1 1 .0 .0 d 1 Me / Pre / Pre / Pre 5 5 0 0 .8 .8 .5 0 .8 .2 .2 0 a a a 0 0 t t t Da Da Da 0 .6 0 0 .6 .6 2 4 6 8 1 0 1 2 d d d te e e 0 t t dic ic ic V V 0 0 V d d Me Me Me -5 0 - Pre - Pre - Pre -1 -1 0 0 0 0 .5 -1 0 0 5 5 .2 .2 0 ta ta ta 0 0 -1 5 0 -2 -2 0 0 0 0 Da Da Da 2 4 6 8 1 0 1 2 2 2 4 4 6 6 8 8 1 1 0 0 1 1 2 2 En e rg y (Me V) En En e e rg rg y (Me y (Me V) V) DC-II(Gd): sin 2 2θ 13 = 0.109 ± 0.039 [0.030 stat ± 0.025 syst ] DC-II(H): sin 2 2θ 13 = 0.097 ± 0.048 [0.034 stat ± 0.034 syst ] P. Novella, DC New Results, Moriond 2014 16

Reactor-Off: BG measurement 2011 and 2012 reactor-off samples: 7.53 days P n-Gd 2012 h y s . R e v . D 8 n-Gd 2011 7 ( 2 n-Gd 0 1 3 ) 0 1 1 1 0 2 ● n-Gd selection: R BG =1.0±0.4 events/day Consistent with BG model ● n-H selection: R BG =10.8±3.4 events/day (acc. sub.) used in R+S fit P. Novella, DC New Results, Moriond 2014 17

3 1 0 Gd-H Combined Result 2 d n o i r o M e c n i s w e N ● Taking the most from DC: n-Gd + n-H + Reactor-Off: Rate+Shape: sin 2 2 θ 13 =0.109±0.035 Rate-Only: sin 2 2 θ 13 =0.107±0.045 ● To be compared with n-Gd “only” : Rate+Shape: sin 2 2 θ 13 =0.109±0.039 DC Prelminary Rate-Only: sin 2 2 θ 13 =0.170±0.052 ● n-H will be a powerful handle to improve the θ 13 results P. Novella, DC New Results, Moriond 2014 18

3 Reactor Rate Modulation 1 0 2 d n o i r o M e c n i s w ● New θ 13 /BG analysis e N – Different reactor powers (2-Off!) Both ● No background model assumed Reactors On 1) BG-independent θ 13 measurement 1 Reactor On 2) cross-check of the BG model Both ● RRM unique in DC: Reactors Off ● 2 reactors only ● Reactor-Off data ● n-Gd and n-H samples P. Novella, DC New Results, Moriond 2014 19

! 3 3 n-Gd RRM Analysis 1 1 0 0 2 2 d d n n o o i i r r o o M M e e ArXiv:1401.5981, submitted to PLB c c n n i i s s w w e e N N ● θ 13 from the slope, while BG from extrapolation to 0 power w/o 2-Off n-Gd 2-Off Independent BG measurement P. Novella, DC New Results, Moriond 2014 20

Gd-H Combined RRM Result New since Moriond 2013 ArXiv:1401.5981, submitted to PLB Taking the most from DC: n-Gd + n-H + Reactor-Off: ● ● θ 13 consistent with R+S fit, BG consistent with BG model used in R+S fit P. Novella, DC New Results, Moriond 2014 21