ESSnuSB Project for Leptonic CP Violation Discovery based on the European Spallation Source Linac NOW 2014, 10/9E. Wildner, CERN 2 Elena WILDNER CERN for the ESSnuSB Collaboration

The European Spallation Source (ESS) ESS is a neutron spallation source that will be built by a collaboration of 17 European countries. ESS is located in southern Sweden (Lund) NOW 2014, 10/9 E. Wildner, CERN 3 ESS Technical Design Report, April 23, 2013, ESS-doc-274

ESS as proton driver for spallation NOW 2014, 10/9E. Wildner, CERN 4

European Spallation Source NOW 2014, 10/9E. Wildner, CERN 5 Sweden35%Switzerland3.5% Denmark12.5%Norway2.5% Germany11%Poland2% U.K.10%Hungary1.5% France8%Czech0.3% Italy6%Estonia0.25% Spain5%TBD2.5% Contributions by Member Country The ESS has broken ground last week

ESS 5MW proton linac NOW 2014, 10/9E. Wildner, CERN 6 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, protons) 2.0 GeV protons (up to 3.5 GeV with linac upgrades) >2.7x10 23 p.o.t/year Linac ready by 2023 (full power and energy) ESS Technical Design Report, April 23, 2013 ESS-doc-274

NOW 2014, 10/9 E. Wildner, CERN 7 ESSnuSB on ESS site 2 GeV > 2 GeV Neutron spallation target H-H- p ~1 BEuros for the neutrino facility including detector Preliminary ! Civil engineering to be taken into account for accumulator!

ESS H- acceleration for neutrinos The ESS linac for neutron spallation: proton acceleration 14 Hz Duty factor low (4%); some additional capacity is available Repetition rate can be increased to 70 Hz to permit 4 extra acceleration cycles 2.86 / 4 ms long (= 5 MW) Charge in the accumulator ( ) /4 p, 2 GeV >2.7x10 23 p.o.t/year for neutrinos ESS would accelerate in total 10 MW! NOW 2014, 10/9 8 H- ? ? ? ? E. Wildner, CERN

NOW 2014, 10/9 E. Wildner, CERN 9 ESS Accumulator for neutrino production Constraints on present neutrino target focusing system: short pulses Solution: reduce beam pulse length: – Shorten the linac pulse by accumulating the linac beam Accumulator constraints – Reasonably-sized accumulator ring circumference and apertures – Multiturn injection of high intensity linac beam: we need H- – High intensities in the ring may cause collective effects and beam loss

Linac Pulsing 70 Hz, baseline 13/03/14Nufact14, Glasgow, E. Wildner ms 2.86 ms 28 Hz Neutron (proton pulse) Neutrino (H- -pulse) 71.4 ms, 14 Hz ms 0.7 ms 71.4 ms, 14 Hz 70 Hz 2.86 ms Insert one H- pulse 28 Hz Mitigation of charges in accumulator, 70 Hz, implies some overhead (cavity filling)

NOW 2014, 10/9 E. Wildner, CERN 11 ESSnuSB on ESS site 2 GeV > 2 GeV Neutron spallation target H-H- p τ H 1.5 μs τ 0 = 100 μs Bending Radius: 133 m for 3 GeV (70 m for 2 GeV) Target Station 25 m below ground level Decay tunnel under the linac! URGENT STUDY of ground water!

The Linac has to be upgraded Modulators and infrastructure (C. Martins) E. Wildner, CERN 12 NOW 2014, 10/9 To be prepared for at an early stage

Previous Expertise NOW 2014, 10/9E. Wildner, CERN 13 ESSνSB BENE ( ) ISS ( ) EUROν ( ) LAGUNA ( ) LAGUNA- LBNO ( ) SNS (USA)

The MEMPHYS WC Detector ( MEgaton Mass PHYSics) NOW 2014, 10/9E. Wildner, CERN 14 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/ )

Possible locations for far detector NOW 2014, 10/9E. Wildner, CERN 15 CERN ESS Kongsberg Løkken

Neutrino Oscillations with "large" θ 13 NOW 2014, 10/9E. Wildner, CERN 16 P(ν μ →ν e ) L/E 1 st oscillation maximum 2 nd oscillation maximum θ 13 =1º ("small" θ 13 ) θ 13 =8.8º ("large" θ 13 ) for small θ 13 1 st oscillation maximum is better for "large" θ 13 1 st oscillation maximum is dominated by atmospheric term, CP interference solar atmospheric θ 13 =1º θ 13 =8.8º  CP =-90  CP =0  CP =+90 (arXiv: )arXiv: more sensitivity at 2 nd oscillation max. L/E 1 st oscillation max.: A=0.3sinδ CP 2 nd oscillation max.: A=0.75sinδ CP (see arXiv: and arXiv: )

ESS neutrino energy distribution NOW 2014, 10/9E. Wildner, CERN 17 at 100 km from the target and per year

Neutrino spectra NOW 2014, 10/9E. Wildner, CERN km (2 GeV) below ν τ production neutrinosanti-neutrinos 2 years8 years δ CP =0 E. Fernandez

δ CP accuracy performance (USA snowmass process, P. Coloma) NOW 2014, 10/9E. Wildner, CERN 19 for systematic errors see: Phys. Rev. D 87 (2013) 3, [arXiv: [hep-ph]] arXiv: [hep-ex] Neutrino "snowmass" group conclusions "default" column

Results including nuSTORM E. Wildner, CERNNOW 2014, 10/9 20 Pilar Coloma et al. LBNF (40 kton detector, 1.2MW beam power) Systematics are basically the same as before. nuSTORM plots assume that cross sections are determined at the 1% level of precision, removing the constraint between the cross sections for different flavors, they are all allowed to vary independently in the fit.

2nd Oscillation max. coverage NOW 2014, 10/9E. Wildner, CERN 21 2 nd oscillation max. well covered by the ESS neutrino spectrum 1 st oscillation max. E. Fernandez

Which baseline? NOW 2014, 10/9E. Wildner, CERN 22 Zinkgruvan Garpenberg Zinkgruvan is better for 2 GeV 360 km Garpenberg is better for > 2.5 GeV 540 km systematic errors: 5%/10% (signal/backg.) CPVMH Zinkgruvan is better atmospheric neutrinos are needed (at least at low energy) E. Fernandez

Systematic errors NOW 2014, 10/9E. Wildner, CERN 23 Phys. Rev. D 87 (2013) 3, [arXiv: [hep-ph]]

Systematic errors and exposure NOW 2014, 10/9E. Wildner, CERN 24 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 years20 years (courtesy P. Coloma) High potentiality

Effect of the unknown MH on CPV performance NOW 2014, 10/9E. Wildner, CERN 25 "default" case for systematics small effectpractically no need to re-optimize when MH will be known

ESS Neutrino Super Beam NOW 2014, 10/9 26 arXiv: arXiv: participating institutes from 10 different countries, among them ESS and CERN EU H2020 Design Study application has been submitted recently !

When and to what price ? NOW 2014, 10/9E. Wildner, CERN 27 Total price of ESSnuSB including the detector is 1.2 BEUR: 100 MEUR linac 200 MEUR accumulator 200 MEUR target station 700 MEUR the far detector If we have our CDR in 2018 and if we convince everybody to build this facilities, we could start construction at the moment when the neutron facility will be ready, i.e., The construction could last up to when we will be able to start data taking. If LBNE starts earlier (e.g ), in one or two years ESSnuSB will accumulate more protons on the target than LBNE.

Conclusions NOW 2014, 10/9E. Wildner, CERN 28 For MH and mainly for CP Violation intense neutrino beams are needed. Better CPV sensitivity at the 2 nd oscillation maximum. EU FP7 LAGUNA-LBNO Design Study is finishing. The European Spallation Source Linac will be ready in less than 10 years ESS will have enough protons to go to the 2 nd oscillation maximum and increase its CPV sensitivity. CPV: 5 σ could be reached over 60% of δ CP range (ESSνSB) with large potentiality. Large associated detectors have a rich astroparticle physics program. Full complementarity with a long baseline experiment on the 1 st oscillation maximum using a LAr detector. A feasibility Design Study for ESSnuSB is now proposed (H2020).

Backup NOW 2014, 10/9E. Wildner, CERN 29

CP Violating Observables NOW 2014, 10/9E. Wildner, CERN 30 matter effect ⇒ accessibility to mass hierarchy ⇒ long baseline Non-CP terms CP violating ≠0 ⇒ CP Violation be careful, matter effects also create asymmetry atmospheric solar interference

Neutrino Oscillations with "large" θ 13 NOW 2014, 10/9E. Wildner, CERN 31 (see arXiv: and arXiv: ) 2 nd oscillation maximum is better at the 1 st oscillation max.: A=0.3sinδ CP at the 2 nd oscillation max.: A=0.75sinδ CP

Physics Performance for ESSνSB (Enrique Fernantez, Pilar Coloma) NOW 2014, 10/9E. Wildner, CERN 32 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 δ CP resolution around these values is needed 1º gain around these values increase the discovery δ CP range by ~4x5x1º (1 st approx.) δ CP precision (unknown MH)