T HE B OREXINO RECENT RESULTS AND SOX MEASUREMENT PERSPECTIVES Alessio Porcelli on behalf of the Borexino/SOX Collaborations – 27th October, 2017 www.uni-mainz.de EXPERIMENTELLE TEILCHEN- UND ASTROTEILCHEN PHYSIK (ETAP)
Borexino and SOX Collaborations Technische Universität München Joint Institute for Nuclear Research 167 among scientists and students, and 291 produced articles Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 1/22
Physics questions. . . pp cycle CNO cycle d + e + + ν d + ν p + p p + e - + p d + p 3 He + γ 3 He + 3 He α + 2p 3 He + α 7 Be + γ 7 Be + e - 7 Li + ν 7 Be + p 8 B + γ 7 Li + p 2 α 8 B 8 Be + e + + ν 8 Be 2 α Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 2/22
Physics questions. . . pp cycle CNO cycle d + e + + ν d + ν p + p p + e - + p d + p 3 He + γ 3 He + 3 He α + 2p 3 He + α 7 Be + γ 7 Be + e - 7 Li + ν 7 Be + p 8 B + γ 7 Li + p 2 α 8 B 8 Be + e + + ν 8 Be 2 α Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 2/22
Physics questions. . . pp cycle CNO cycle d + e + + ν d + ν p + p p + e - + p d + p 3 He + γ 3 He + 3 He α + 2p 3 He + α 7 Be + γ 7 Be + e - 7 Li + ν 7 Be + p 8 B + γ 7 Li + p 2 α 8 B 8 Be + e + + ν 8 Be 2 α Large Mixing Angle scenario (LMA) Vacuum dominated 2 sin 2 2 θ 12 1 − 1 2 sin θ 12 Matter-enhanced Transition region region Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 2/22
Physics questions. . . pp cycle CNO cycle d + e + + ν d + ν p + p p + e - + p Designed d + p 3 He + γ threshold Designed goal 3 He + 3 He α + 2p 3 He + α 7 Be + γ Designed goal 7 Be + e - 7 Li + ν 7 Be + p 8 B + γ 7 Li + p 2 α 8 B 8 Be + e + + ν 8 Be 2 α Borexino! Large Mixing Angle scenario (LMA) Designed threshold Vacuum dominated 2 sin 2 2 θ 12 1 − 1 2 sin θ 12 Matter-enhanced Transition region region Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 2/22
Borexino Detector Sited beneath Gran Sasso mountain (1400m of rock shielding), Italy. Very low Stainless steel sphere background Scintillator • 2212 PMTs • 270 t PC+PPO • 1350 m 3 buffer (wavelength PC+DMP (light Nitrogen shifter): 1.4 g/l quencher) stripping Distillation Water extraction Outer: 5.5 m Inner: 4.25 m Nylon vessels 25% Coverage Water: 2100 m 2 • 135 μ m thick • γ -shield • Radon barrier Light Yield (LY): • 208 PMTs for • Dynamic μ -veto (uses reconstruction 500 p.e./MeV Cherenkov light) Continuous Carbon steel temperature and 20 legs plates contamination Borexino core is the most radio-clean spot on Earth monitoring with over 10 orders of magnitude below typical radioactivity levels Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 3/22
Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 4/22
Borexino signature Indistinguishable from the natural radioactivity ( β − / γ components) 3 10 Counts / (day x 100 ton x 1 keV) 14 C (3.46 x 10 6 ) ! 2 10 β -like spectrums pp- ν (133) ! 10 210 Po (656) ! 1 7 Be- ν (46) ! 85 Kr (35) ! -1 10 11 C(26) ! 210 Bi(42) ! 10 -2 pep- ν (2.8) ! CNO- ν (5.3) ! -3 10 10 -4 200 400 600 800 1000 1200 1400 1600 1800 Energy [keV] ⇒ Extreme low background required!!! Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 5/22
Data selection p Counts / 740.7 days / 1 N 5 10 1 Raw spectrum 4 10 2 Muon cut 3 Fiducial Volume cut 210 Po ( α ) 3 1 ! 10 (every goal has an 7 Be ( ν ) 11 C ( β + +2 γ ) 2 2 10 optimised FV) 3 ! 14 C ( β - ) 10 ( x -axis: number of PMTs triggered External BG in the event cluster ∼ E · LY) 1 100 200 300 400 500 600 700 800 900 N p Thorough statistical subtraction of cosmogenics, such as: α/β Gatti’s parameter and neural network discrimination (trained on 214 Bi- 214 Po coincidence) 11 C Three Fold Coincidence (TFC): space-time veto applied on µ − n pairs coincidences. Average decay time of 11 C is 30 min. . . . and more [arXiv:1308.0443] Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 6/22
Data selection p Counts / 740.7 days / 1 N 5 10 1 Raw spectrum 4 10 2 Muon cut 3 Fiducial Volume cut 210 Po ( α ) 3 1 ! 10 (every goal has an 7 Be ( ν ) 11 C ( β + +2 γ ) 2 2 10 optimised FV) 3 ! 14 C ( β - ) 10 ( x -axis: number of PMTs triggered External BG in the event cluster ∼ E · LY) 1 100 200 300 400 500 600 700 800 900 N p Thorough statistical subtraction of cosmogenics, such as: α/β Gatti’s parameter and neural network discrimination (trained on 214 Bi- 214 Po coincidence) 11 C Three Fold Coincidence (TFC): space-time veto applied on µ − n pairs coincidences. Average decay time of 11 C is 30 min. . . . and more [arXiv:1308.0443] Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 6/22
Data selection p Counts / 740.7 days / 1 N 5 10 1 Raw spectrum 4 10 2 Muon cut 3 Fiducial Volume cut 210 Po ( α ) 3 1 ! 10 (every goal has an 7 Be ( ν ) 11 C ( β + +2 γ ) 2 2 10 optimised FV) 3 ! 14 C ( β - ) 10 ( x -axis: number of PMTs triggered External BG in the event cluster ∼ E · LY) 1 100 200 300 400 500 600 700 800 900 N p Thorough statistical subtraction of cosmogenics, such as: α/β Gatti’s parameter and neural network discrimination (trained on 214 Bi- 214 Po coincidence) 11 C Three Fold Coincidence (TFC): space-time veto applied on µ − n pairs coincidences. Average decay time of 11 C is 30 min. . . . and more [arXiv:1308.0443] Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 6/22
pp chain result After first measurements of ν s from 7 Be (862 keV) � 2 /d.o.f. = 172.3/147 pp � : 144 ± 13 (free) 210 Po: 583 ± 2 (free) [PRL107(2011)141302], pep (1440 7 Be � : 46.2 ± 2.1 (constrained) 14 C: 39.8 ± 0.9 (constrained) pep � : 2.8 ( f xed) Pile-up: 321 ± 7 (constrained) CNO � : 5.36 ( f xed) 210 Bi: 27 ± 8 (free) keV) [PRL108(2012)051302] and 214 Pb: 0.06 ( f xed) 85 Kr: 1 ± 9 (free) a 10 4 CNO (most stringent upper limit) pp � 10 3 Events (c.p.d. per 100 t per keV) [PRL108(2012)051302] 14 C 10 2 210 Po CNO � Synthetic 10 85 Kr pile-up 210 Bi 1 7 Be � First direct observation of the low 10 –1 energy neutrinos coming from the 10 –2 10 –3 pp fusion in the core of the Sun 214 Pb pep � 10 –4 exposure of 408 days × 71.3 ton 10 –5 150 200 250 300 350 400 450 500 550 Energy (keV) b 5 Residuals, (data – f t)/ � 4 3 2 1 0 –1 –2 –3 –4 –5 150 200 250 300 350 400 450 500 550 Energy (keV) Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 7/22
pp chain result After first measurements of ν s from 7 Be (862 keV) � 2 /d.o.f. = 172.3/147 pp � : 144 ± 13 (free) 210 Po: 583 ± 2 (free) [PRL107(2011)141302], pep (1440 7 Be � : 46.2 ± 2.1 (constrained) 14 C: 39.8 ± 0.9 (constrained) pep � : 2.8 ( f xed) Pile-up: 321 ± 7 (constrained) CNO � : 5.36 ( f xed) 210 Bi: 27 ± 8 (free) keV) [PRL108(2012)051302] and 214 Pb: 0.06 ( f xed) 85 Kr: 1 ± 9 (free) a BREAKTHROUGH 10 4 CNO (most stringent upper limit) pp � 10 3 Events (c.p.d. per 100 t per keV) [PRL108(2012)051302] 14 C 10 2 TOP 10 210 Po CNO � Synthetic 10 85 Kr pile-up 210 Bi 1 7 Be � First direct observation of the low 10 –1 energy neutrinos coming from the 10 –2 10 –3 pp fusion in the core of the Sun 2014 214 Pb pep � 10 –4 exposure of 408 days × 71.3 ton 10 –5 150 200 250 300 350 400 450 500 550 Energy (keV) b 5 Expected: 131 ± 2 cpd/100 t Residuals, (data – f t)/ � 4 3 2 Rate: 144 ± 12 | stat ± 10 | syst cpd/100 t 1 0 –1 Null hypothesis rejection: 10 σ –2 –3 –4 [Nature512(2014)383] –5 150 200 250 300 350 400 450 500 550 Energy (keV) Motivations Borexino ν -sol Modulation NMM Geo- ν . . . and more SOX Outlook Backups A. Porcelli | The Borexino and SOX experiments 27.10.2017 7/22
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