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Supported by: DPG Spring Meeting Dresden 2013 Arnd Sörensen, Valentina Lozza, Nuno Barros, Belina von Krosigk, Laura Neumann, Johannes Petzoldt, Axel Boeltzig,

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Presentation on theme: "Supported by: DPG Spring Meeting Dresden 2013 Arnd Sörensen, Valentina Lozza, Nuno Barros, Belina von Krosigk, Laura Neumann, Johannes Petzoldt, Axel Boeltzig,"— Presentation transcript:

1 supported by: DPG Spring Meeting Dresden 2013 Arnd Sörensen, Valentina Lozza, Nuno Barros, Belina von Krosigk, Laura Neumann, Johannes Petzoldt, Axel Boeltzig, Felix Krüger and Kai Zuber

2 2  SNO+ = SNO + Liquid Scintillator ?  Liquid Scintillator  From SNO to SNO+  Phases of Operation  Neodymium loaded Phase (0νββ with 150 Nd)  Pure Scintillator Phase  TU Dresden  Summary & Outlook

3 3 SNOLab in Creighton Mine, Sudbury, Canada  deepest underground laboratory  2 km ≈ 6000 meter water equivalent flat overburden  muon rate:

4 4 acrylic vessel 12 m diameter 5 cm thickness 780 t liquid scintillator (LAB) ≈ 9100 PMTs in support structure (~ 54% coverage) light-water shielding: 1700 t inside 5700 t outside urylon liner and radon seal

5  fluor: 2 g/L PPO (= 2,5-Diphenyloxazol)  chemically compatible with acrylic  long scattering length & high optical transparency  high light yield (≈ 10,000 photons/MeV)  high purity available  inexpensive & safe 5 LAB + PPO + (Nd)

6 SNO SNO+ 6 LAB lighter than water: rope hold up system + rope hold down system

7 7 General rope-net hold down system new calibration (source manipulation) system scintillator purification plant

8 8 Electronics DAQ boards refurbished improved data flow replace & repair broken PMTs PMTs remapped

9 9 Calibration new low energy sources optical calibration via fibre- injected lasers and LEDs variety of gamma, alpha, beta and neutron sources

10 detector commissioning water phase 150 Nd loaded into liquid scintillator reactor-, geo- and supernova- neutrinos (neutrinoless-) double beta decay search for solar neutrinos: pep and CNO reactor-, geo- and supernova- neutrinos pure scintillator /? ?

11 11 large isotope mass, low background poor energy resolution neutrinoless 0vββ search with liquid scintillator 150 Nd high Q-value: MeV  low background fastest calculated decay rate complementary to other 0vββ experiments ( 76 Ge, 136 Xe …) in SNO+ LS successfully loaded with Neodymium 0.1% loading optimisation: 0.3% loading

12 12 0.1% Nd loading  (43.7 kg 150 Nd) m ee = 350 meV 6.4% MeV IBM ‐ 2 matrix element 3 years running and 50% fiducial Volume (≈ 0.4 kt) Borexino background levels + efficient tagging:  214 Bi: 99.9% reduction  208 Tl: 90.0% reduction Background despite low Q-value through pile-up of e.g. 144 Nd, 176 Lu, 138 La, 14 C  99% pile-up rejection while keeping 90% signal in ROI

13 assuming Borexino background levels are reached and efficient tagging:  214 Bi: 99.9% reduction  208 Tl: 90.0% reduction 13 [Nucl. Phys. B. (Proc. Supp.), S143:229, 2005] Claim of Klapdor m ee ≈ 170 – 530 meV 0.3% Nd (9.0% 3.37 MeV)0.1% Nd (6.4% 3.37 MeV)

14 14 Complete our understanding of the solar neutrino fluxes:  Super-K and SNO measured 8 B neutrinos  Borexino measured 7 Be and first probed pep neutrinos  pp was observed with Ga experiments  improve pep measurement  still missing CNO (probe for solar metallicity)

15  single energy: MeV  very well predicted flux (≈ 2% uncertainty)  new physics models (NSI) predict different survival probabilities in vacuum matter transition regions 15 [PLB 594, (2004)] SNO, [arXiv: ]

16 16 [Peña-Garay & Serenelli, arXiv: ]  No direct observation of CNO neutrinos yet !  probe for solar core metallicity  new solar physics developments suggest 30% lower metallicity old (high Z) new (low Z)

17 Flux is 5 times less than KamLAND BUT  SNO+ reactor spectrum, including oscillations, have sharp peaks and minima, that increase the parameter- fitting sensitivity for Δm no Oscillation 308 events no Oscillation 1186 events Oscillation 176 events Oscillation 710 events

18 18 Signal: from β-decays in Earth’s mantle and continental crust ( 238 U, 232 Th, 40 K)  local region extremely well studied due to mining  low reactor-v background in SNO+: Reactor/Geo ≈ 1.1  check Earth heat production models / chemical composition (multi-site measurement in combination with Borexino, KamLAND)

19 0vββ Phase design, development and test of 48 Sc calibration source (3.33 MeV - ROI)  T – Axel Boeltzig study of cosmogenic (n,p)- activation of Nd and LAB first measurement of nat Nd(p,x) cross sections [PRC 85, (2012)] study of underground- and thermal- neutron activation of Nd pure scintillator phase sensitivity study to solar neutrinos and neutrino oscillation parameters design, development and test of 57 Co low energy (122 keV) calibration source to test the detector threshold and the low energy response alpha and proton quenching factor measurements [arXiv: ] cosmogenic muons and muon induced background tagging investigation of the 14 C background 19

20 20  SNO+ succeeds the SNO experiment by replacing heavy water with liquid scintillator  LS has higher light yield and lower threshold allows to investigate lower energy range ( E < 3.5 MeV )  two phases planned:  Nd loaded phase to search for 0vββ decay of 150 Nd  pure scintillator phase to observe pep and CNO solar neutrinos  reactor neutrino oscillation confirmation, geo neutrino investigation at geologically-interesting site, supernova neutrino watch …  SNO+ will be filled with water this year  0vββ search starts next year

21 Thank you for your attention ! 21

22 more 22

23  radio purity:  14 C is not a problem  pep signal is at higher energy  U, Th not a problem if one can repeat KamLAND scintillator purity  40 K, 210 Bi (Radon daughter)  85 Kr, 210 Po not a problem  pep signal is at higher energy 23 SNO + Borexino pep 11 C CNO 11 C pep

24 24 p-p solar fusion chain CNO cycle

25 (stat)1 year2 years pep9.1%6.5% 8B8B7.5%5.4% 7 Be4%2.8% ppA few %? CNO~ 15%? Assuming Borexino-level backgrounds are reached

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