ESSΝSB DESIGN STUDY FOR THE ESS (EUROPEAN SPALLATION SOURCE) NEUTRINO SUPER BEAM - GEORGE FANOURAKIS INSTITUTE OF NUCLEAR & PARTICLE PHYSICS, NCSR ...
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ESSνSB Design Study
for the ESS (European Spallation Source)
Neutrino Super beam
George Fanourakis
Institute of Nuclear & Particle Physics, NCSR Demokritos
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 1
ESS proton linac empty space for
energy upgrades
• 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).
• Duty cycle 4%.
• 2.0 GeV protons
o up to 3.5 GeV with linac upgrades
• > 2.7x1023 p.o.t/year.
Linac ready by 2023 (full power) –
Exper. areas ready for users by 2025
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 2
The European Spallation Source
as High Intensity Neutrino Facility
for the CP violation observation
ν
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 3
How to add a neutrino facility to ESS?
without disturbing the ESS neutron program
• Double the linac rate (14 Hz → 28 Hz), from 4%
duty cycle to 8%.
• Increase proton energy to 2.5 GeV kinetic
• ESS proton pulse is too long – accumulator ring
(C~400 m) needed to compress each 2.86 ms
proton pulse to four ~ 1.3 μs pulses, otherwise:
• magnetic horns would melt
• atmospheric neutrino background would be
too large for CP violation measurement
• Neutrino optimised target station
• Underground near detector hall
• The neutron program must not be affected and if
possible synergetic modifications.
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 4
ESSνSB at the European level
More information on:
• An H2020 EU Design Study (Call INFRADEV-01-2017) http://essnusb.eu/
• Title of Proposal: Discovery and measurement of leptonic CP violation using an intensive
neutrino Super Beam generated with the exceptionally powerful ESS linear accelerator
• Duration: 4 years (2018-2021) EUROν LAGUNA
(2008-2012) (2008-2010)
• Total cost: 4.7 M€ LAGUNA-
ISS (2005-
LBNO (2010-
2007)
• Requested budget: 3 M€ 2014)
• 15 participating institutes from COST Action
BENE (2004-
11 European countries including CERN and ESS 2008) ESSνSB CA15139
(2015-2019)
• 6 Work Packages
• Approved end of August 2017 Started 1-Jan-2018
decay tunnel near far
linac accumulator target π
p hadrons ν
⨂B
switchyard hadronic collector p ® m +n Detectors physics
(focusing)
WP2 WP3 WP4 WP5 WP6
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 5
ESSνSB collaboration members at the Ruder Boškovic Institute in Zagreb, Croatia G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 6
Demokritos INPP ESSνSB team
George Fanourakis,
George Stavropoulos,
Theodoros Geralis,
Olga Zormpa
Maria-Myrto Prapa
Contributing to WP5 (detectors) and WP6 (Physics) ESSνSB work packages
This project has received funding:
• From the European Union’s Horizon 2020 research and innovation program
under grant agreement No 777419.
• It was also supported (until March 2020) by the COST Action CA15139
``Combining forces for a novel European facility for neutrino-antineutrino
symmetry-violation discovery'' (EuroNuNet).
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 7
ESSνSB-WP5 group members at Consejo Superior de Investigaciones Científicas (CSIC),
Madrid, Spain
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 8
Having access to a powerful
proton beam…
to ESSnuSB
accumulator ring
To be upgraded to include Upgrade
H⁻ source after 2022
What can we do with:
• 5 MW power
• 2.5 GeV energy
• 14 Hz repetition rate
• 1015 protons/pulse
• >2.7x1023 protons/year
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 9
ESSνSB neutrinos energy distribution
(without optimisation using GEANT4 and FLUKA)
neutrinos anti-neutrinos
• almost pure νμ beam at 100 km from the
target and per year
• small νe contamination (in absence of
which could be used to oscillations)
measure νe cross-
sections in a near
detector
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 10Oscillation probability
(neutrino beams)
"atmospheric"
"interference"
"solar"
matter effect
• for antimatter: δCP →-δCP and a→-a
• fake matter/antimatter asymetry due to matter effect • δCP dependence,
• sizable matter effect for
long baselines
Matter-antimatter asymmetry
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 11Use all this ESS linac power to go
to the second oscillation maximum
but why?
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 12Neutrino Oscillations with "large" θ13
solar
atmospheric
for "large" θ13
for small θ13 1st oscillation
atmospheric solar
1st oscillation maximum is
maximum is L/E L/E dominated by
better atmospheric
CP interference
(arXiv:1110.4583) CP interference term
θ13=1º θ13=8.8º
solar 2nd oscillation maximum
P(νμ→νe)
1st oscillation maximum
θ13=8.8º
θ13=1º dCP=-90 ("large" θ13)
("small" θ13) dCP=0
dCP=+90
L/E L/E
• 1st
oscillation max.: A=0.3sinδCP
more sensitivity at 2nd oscillation max.
• 2nd oscillation max.: A=0.75sinδCP
(see arXiv:1310.5992 and arXiv:0710.0554)
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 13Oscillations to be studied
e and e CP violation:
The good
In vaccum, this ratio depends only on neutrino mass square differences
You get less statistics because you have to either:
The bad
• Move 3x further than 1st maximum - flux 9x smaller
• Reduce energy 3x – cross-section at least 3x smaller
The optimal • Depends on the systematic error – assume similar at 1st and
2nd oscillation maximum
• 3x signal at 2nd osc. maximum is less obscured by systematics, but we have
less statistics (measured appearance events).
• If the signal at 2nd maximum is not obscured by larger statistical error,
then 2nd maximum is better.
• Intense beam helps here, as does having larger θ13 because Pμ→e and
Pμ→e are larger and we get more events.
• With 0 systematic error, first maximum is better
• more statistics, even though the effect is smaller.
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 14Neutrino
baseline
Baseline:
• Garpenberg mine, 540 km from
the neutrino source,
corresponding to 2nd oscillation
maximum.
Alternatives:
• Zinkgruvan mine, 340 km from
source
• Garpenberg and Zinkgruvan,
250 kt each
2 active mines aligned…
Garpenberg
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 15Near detectors
Super Fine Grained Detector,
sFGD, 1 t target mass
0.5 kt water Cherenkov detector
Possible addition:
NINJA-like water-
emulsion detector
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 16Far detectors
Baseline
• 2 x 270 kt fiducial volume (~20xSuperK)
• Readout: 2 x 38k 20” PMTs
• 30% optical coverage
Can also be used for other purposes:
• Proton decay
• Astroparticles
• Galactic SN ν
• Supernovae "relics"
• Solar Neutrinos
• Atmospheric Neutrinos
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 172nd Oscillation max. coverage
2nd oscillation max.
well covered by the ESS
neutrino spectrum
1st oscillation max.
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 18Physics Performance
540 km
• little dependence on mass hierarchy,
• δCP coverage at 5 σ C.L. up to 60%,
• δCP accuracy down to 6° at 0° and 180°
(absence of CPV for these two values),
• not yet optimized facility,
• 5/10% systematic errors on signal/background.
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 19CPV performance comparison between ESSnuSB, DUNE
and Hyper-K assuming 3% systematic errors for ESSnuSB
in line with the other two.
ESSνSB 500 kt tank at 540 km.
ESSνSB 500 kt tank at 360 km.
(degrees)
ESSνSB 250 kt tank at 540 km
and 250 kt tank at 360 km.
See also: K. Chakraborty et al. / Nuclear Physics B 937 (2018) 303–332
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 20Fraction of δCP
Garpenberg
(540 km) (E. Martinez-Fernandez)
Zinkgruvan
(360 km)
Lund
2 active mines aligned…
these scenarios may be too
optimistic for all facilities
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 21Possible ESSνSB schedule
Nucl. Phys. B 885 (2014) 127
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 22INPP in WP5 detector studies
Next talk by Olga Zormpa
“ESSνSB project studies
for the Far detector”
HyperK 260 kton water Cherenkov
far detector. Equipped with 40000
photo sensors
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 23Conclusions • ESS will be the most powerful neutron facility for a plethora of research and applications. • ESS can also become a powerful neutrino facility with enough protons to go to the 2nd oscillation maximum and increase the CPV sensitivity. • CPV: 5 σ could be reached over 60% of δCP range by ESSνSB with large physics potential. • Large associated detectors have a rich astroparticle physics program. • The European Spallation Source Linac will be ready by 2025, upgrade decisions by this moment. • This project is currently supported by a EU-H2020 Design Study. • The INPP team is participating in the far detector studies. G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 24
G.K. Fanourakis INPP Anoual meeting, 14-15/01/2021 25
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