Search for a sterile neutrino using a short-baseline oscillation experiment at the BR2 research reactor

Moortgat Celine


Ryckbosch Dirk, (UGent),

SCK•CEN Mentor

Popescu Lucia
+32 14 33 34 11

Expert group

Belgian Reactor 2

PhD started


Short project description

Neutrinos are the most enigmatic of the elementary particles. They have several interesting
properties, which are not always well understood. They have a very small mass, which probably is
not coming from the same origin (the Higss field) as that of the other particles. The different types
of neutrinos oscillate into each other: i.e. they morph from one type into another while they travel
through space and/or matter. They interact only very weakly with other matter, which is the
reason why they are very hard to study.
Recent experiments have shown some persistent anomalies that could possibly be explained by
the existence of a fourth type of neutrino, not interacting with other matter (hence the name:
sterile neutrino). The presence of such a sterile neutrino should be observable as the
disappearance of electron neutrinos emitted from a nuclear reactor core over a much shorter
distance (about 5m) than is the case for known oscillations.
Within this project I want to participate in the SoLid experiment which will build and operate a
new type of neutrino detector to be used at the BR2 research reactor at the SCK in Mol to do such
a short-baseline neutrino disappearance experiment.


The experimental high energy physics community is investing heavily in massive
and costly new generation long baseline neutrino experiments, such as the NovA
and LBNE projects in the United States, the LAGUNA-LBNO proposal in Europe and
extensions of the currently running T2K neutrino beam in Japan. These projects
will establish the neutrino mass hierarchy and will measure for the first time
the CP-violating phase, based on global fits including old and new reactor
neutrino data. It is very desirable that the anomalies seen at very short
baselines are resolved in the near future such that a coherent picture of
neutrino oscillations can be established based on global data.
With relatively small costs and manpower, the reactor anomaly can be resolved
by performing experiments with efficient electron anti-neutrino detectors very
close to the core of a nuclear fission reactor or by placing very intense
radioactive sources inside these detectors. Several proposals in these
directions exist, at existing neutrino detectors and for new experiments near
the cores of commercial power and research reactors located in France, Russia,
Korea and China. All very short baseline reactor experiments will attempt an
accurate measurement of the electron anti-neutrino flux at
distances between 5 to 15 meters away from a compact reactor core. The
electron anti-neutrinos are generally detected by exploiting the inverse beta
decay reaction where the anti-neutrino interacts with a proton from the
detector to produce a detectable positron and a neutron. The high neutrino
fluxes close to these cores of 10^{20} electron anti-neutrinos per GigaWatt per
second imply high event rates and short measurement campaigns with very
compact detectors of order 1 Ton of active material.
The international SoLid collaboration, involving the universities of Gent and
Antwerpen, will construct a competitive short baseline reactor neutrino
detector at the BR2 research reactor of the SCK in Mol. The reactor
specifications are nearly ideal due to the small core size, stability and high
power of operation and well known neutrino flux. Neutrino detectors can be
operated at distances between 5 and 15 meters from the core with very low
background noise from gamma and neutron radiation.
The objective of this research is to participate in the construction of the
antineutrino detector, the measurements at the BR2 reactor, and the analysis
of the experiment. Ultimately this will lead to new results, proving or
disproving the existence of the reactor anomaly.