1. Marcos DRACOS IPHC-IN2P3/CNRS Université de Strasbourg
ESSνSB Project for Leptonic CP Violation Discovery based on the European Spallation Source Linac
Marcos DRACOS
IPHC-IN2P3/CNRS Université de Strasbourg
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

2. European Spallation Source
under pre-construction phase
(~1.8 B€ facility)
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

3. M. Dracos IPHC/CNRS-UdS
ESS proton linac
The ESS will be a copious source of spallation neutrons
5 MW average beam power
125 MW peak power
14 Hz repetition rate (2.86 ms pulse duration, 1015 protons)
2.0 GeV protons (up to 3.5 GeV with linac upgrades)
>2.7x1023 p.o.t/year
Linac ready by 2023 (full power and energy)
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

4. How to add a neutrino facility?
The neutron program must not be affected and if possible synergetic modifications
Linac modifications: double the rate (14 Hz → 28 Hz), from 4% duty cycle to 8%.
Accumulator (ø 143 m) needed to compress to few μs the 2.86 ms proton pulses, affordable by the magnetic horn (350 kA, power consumption, Joule effect)
H- source (instead of protons)
space charge problems to be solved
~300 MeV neutrinos
Target station (studied in EUROnu)
Underground detector (studied in LAGUNA)
Short pulses (~μs) will also allow DAR experiments
neutrino flux at 100 km (similar spectrum than for EU FP7 EUROν SPL SB)
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

5. M. Dracos IPHC/CNRS-UdS
Previous Expertise
ESSνSB
BENE ( )
ISS ( )
EUROν ( )
LAGUNA ( )
LAGUNA-LBNO ( )
SNS (USA)
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

6. ESS neutrino energy distribution
at 100 km from the target and per year
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

7. Possible locations for far detector
ESS
Kongsberg
Løkken
CERN
LAGUNA sites
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

8. The MEMPHYS WC Detector (MEgaton Mass PHYSics)
Proton decay
Astroparticles
Understand the gravitational collapsing: galactic SN ν
Supernovae "relics"
Solar Neutrinos
Neutrino Oscillations (Super Beam, Beta Beam)
Atmospheric Neutrinos
500 kt fiducial volume (~20xSuperK)
Readout: ~240k 8” PMTs
30% optical coverage
(arXiv: hep-ex/ )
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

9. M. Dracos IPHC/CNRS-UdS
Neutrino spectra
540 km (2 GeV)
below ντ production
neutrinos
anti-neutrinos
δCP=0
2 years
8 years
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

10. CP Violating Observables
atmospheric
Non-CP terms
solar
interference
CP violating
matter effect
⇒ accessibility to mass hierarchy
⇒ long baseline
≠0 ⇒ CP Violation
be careful, matter effects also create asymmetry
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

11. Neutrino Oscillations with "large" θ13
2nd oscillation maximum
P(νμ→νe)
1st oscillation maximum
θ13=8.8º
("large" θ13)
θ13=1º
("small" θ13)
dCP=-90
dCP=0
dCP=+90
L/E
L/E
solar
atmospheric
for "large" θ13 1st oscillation maximum is dominated by atmospheric term,
for small θ13 1st oscillation maximum is better
atmospheric
solar
L/E
L/E
CP interference
CP interference
(arXiv: )
θ13=1º
θ13=8.8º
1st oscillation max.: A=0.3sinδCP
2nd oscillation max.: A=0.75sinδCP
more sensitivity at 2nd oscillation max.
(see arXiv: and arXiv: )
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

12. ESS Neutrino Super Beam
arXiv:
arXiv:
14 participating institutes form 10 different countries,
among them ESS and CERN
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

13. M. Dracos IPHC/CNRS-UdS
Which baseline?
CPV MH
Garpenberg
Zinkgruvan
Zinkgruvan is better for 2 GeV
Garpenberg is better for > 2.5 GeV
systematic errors: 5%/10% (signal/backg.)
Zinkgruvan is better
atmospheric neutrinos are needed (at least at low energy)
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

14. 2nd Oscillation max. coverage
well covered by the ESS neutrino spectrum
1st oscillation max.
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

15. M. Dracos IPHC/CNRS-UdS
Systematic errors
Phys. Rev. D 87 (2013) 3, [arXiv: [hep-ph]]
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

16. δCP accuracy performance (USA snowmass process, P. Coloma)
"default" column
for systematic errors see:
Phys. Rev. D 87 (2013) 3, [arXiv: [hep-ph]]
arXiv: [hep-ex] Neutrino "snowmass" group conclusions
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

17. Systematic errors and exposure
for ESSnuSB systematic errors see [hep-ph] (lower limit "default" case, upper limit "optimistic" case)
P5 requirement: 75% at 3 σ
Neutrino Factory reach
10 years
20 years
High potentiality
(courtesy P. Coloma)
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

18. M. Dracos IPHC/CNRS-UdS
Conclusions
For CP Violation intense neutrino beams are needed.
Significantly better sensitivity at the 2nd oscillation maximum.
The European Spallation Source Linac will be ready in 10 years
Neutrino Super Beam based on ESS linac is very promising.
ESS will have enough protons to go to the 2nd oscillation maximum and increase its CPV sensitivity.
CPV: 5 σ could be reached over 60% of δCP range (ESSνSB) with large potentiality.
Large associated detectors have a rich astroparticle physics program.
Full complementarity with a long baseline experiment on the 1st oscillation maximum using a LAr detector.
A feasibility Design Study is now proposed.
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

19. M. Dracos IPHC/CNRS-UdS
Backup
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

20. Asymmetry due to matter effects
Eν=3 GeV
δCP=0
Normal Hierarchy (NH)
Inverted Hierarchy (IH)
distance [km]
good position to measure MH
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

21. Neutrino Oscillations with "large" θ13
at the 1st oscillation max.: A=0.3sinδCP
at the 2nd oscillation max.: A=0.75sinδCP
2nd oscillation maximum is better
(see arXiv: and arXiv: )
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

22. Neutrino Oscillations with "large" θ13
2nd oscillation max.
P(νμ→νe)
10º
1st oscillation max.
30º
using present oscillation parameters
60º
90º
L/E
more sensitive to 2nd oscillation max.
But, to go to the 2nd oscillation max. we must be very rich in protons…
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

23. Physics Performance for ESSνSB (Enrique Fernantez, Pilar Coloma)
δCP precision (unknown MH)
for 2 GeV
optimum km
for 3.5 GeV
optimum km
but the variation is small
CPV discovery implies exclusion at 5 σ of 0º and 180º
high δCP resolution around these values is needed
1º gain around these values increase the discovery δCP range by ~4x5x1º (1st approx.)
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

24. M. Dracos IPHC/CNRS-UdS
Which baseline?
discovery potential
(unknown mass hierarchy)
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

25. The MEMPHYS Detector (Proton decay)
(arXiv: hep-ex/ )
ICHEP 2014
M. Dracos IPHC/CNRS-UdS

26. The MEMPHYS Detector (Supernova explosion)
SUPERK
Diffuse Supernova Neutrinos
(10 years, 440 kt)
For 10 kpc: ~105 events
ICHEP 2014
M. Dracos IPHC/CNRS-UdS