Center for Underground Physics in Pyhäsalmi
Neutrino Physics in Finland
Strategic outlook of the Finnish Neutrino Physics community
from the Universities of Jyväskylä, Oulu and Helsinki
July 25, 2012
Importance of neutrino physics
Many of the significant discoveries in particle physics over the past few decades
have come from the study of neutrinos. They include the detection of neutrino
oscillations indicating a non-zero neutrino mass, detection of supernova- and
geo neutrinos, and the spectroscopy of solar neutrinos. European scientists and
research facilities have played an important role in these discoveries. By so far,
neutrinos (with a mass) are the only particles known to disobey the predictions
of the Standard Model hinting the likely path towards the next major
breakthrough in physics. It is therefore important that neutrino physics becomes
one of the high-priority areas in the European Strategy for Particle Physics.
Deep underground science facility of the next generation
LAGUNA and LAGUNA-LBNO design studies has shown that the Pyhäsalmi mine
in Finland is in many respects the most suitable site to host large volume
neutrino detectors for long baseline neutrino oscillation experiments,
astroparticle research, and for proton decay measurements. The Pyhäsalmi mine
is the preferred location of both the liquid argon detector (GLACIER) and of the
liquid scintillator detector (LENA). Finnish Neutrino Physics community
together with the municipality of Pyhäjärvi, regional government, and the
relevant industrial partners are strongly committed to build deep underground
science facility of the next generation in the Pyhäsalmi mine.
Neutrino mass hierarchy and CP violation with LAGUNA-LBNO
The scientific motivations for building new large-scale research infrastructures
for neutrino physics are strong. During the past year the value of the neutrino
mixing angle 13 was measured with a good accuracy and it was found to be close
to the upper bound of the allowed range of the previous measurements. With
this knowlegde, the strategy should now focus on the next milestones:
determination of the neutrino mass hierarchy and the phase δ of the CP violation
in the leptonic sector. The fastest path towards these goals is being prepared by
LAGUNA-LBNO – a consortium of 300 scientists and engineers from 13 countries
making plans for a very long baseline flavor oscillations experiment with
neutrino beams from CERN to Pyhäsalmi mine. The recently submitted
Expression of Interest to CERN SPS Committee is the first major milestone
towards the realization of this project. The Finnish Neutrino physics community
gives this project the highest strategic priority.
LAGUNA-LBNO and the High Intensity Frontier
Progress in experimental particle physics relies on the increase in energy and
intensity of the accelerated ions. It is clear that without the improved luminosity
at LHC the recent discovery of the new (Higgs) boson would not have been
possible. The proposed neutrino beam from CERN to Pyhäsalmi (CN2PY) would
generate the drive to boost the beam power of the existing facilities and pave the
way towards the ultimate high-intensity neutrino research facility, the Neutrino
Factory. The distance between CERN and Pyhäsalmi mine is not just well suited
for CN2PY, the 2300 km long baseline would be ideal for the beams produced by
a Neutrino Factory as well.
Significance of LENA to LBNO and astroparticle physics
Although the primary detector for LBNO experiment is a liquid argon detector
with ancillary magnetized iron detector modules behind it, there is a lot of
synergy and sound physics reasons to provide the underground laboratory also
with a 50 kton liquid scintillator detector LENA. There is a very rich astroparticle
program to be accomplished by LENA that includes solar, supernova and geo
neutrinos. Also some of the proton decay channels can be best explored with a
large scintillator. Even for the beam measurements LENA would have, with a
longer run time, the capability of an independent verification of the mass
hierarchy and a limited capacity to probe of the range of the leptonic CP phase δ.
Last but certainly not least, a liquid scintillator detector is considered to be an
excellent tool to investigate the hypothesis of sterile neutrinos produced with
high-strength radioactive sources.
Kimmo Kainulainen, Jukka Maalampi, Jouni Suhonen and Wladyslaw Trzaska
Department of Physics, University of Jyväskylä
Marko Aittola, Timo Enqvist, Eelis Kokko and Pasi Kuusiniemi
Oulu Southern Institute, University of Oulu
Katri Huitu and Kari Rummukainen
Department of Physics, University of Helsinki
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