Abstract
The disappearance of reactor antineutrinos into a new neutral state (called
sterile neutrino) has been proposed as a possible explanation for the recent
reactor and Gallium anomalies arising from the re-analysis of reactor flux
and calibration data of previous neutrino experiments. One way to test this
hypothesis is to look for distortions of the anti-neutrino energy caused by
oscillation from active to sterile neutrino at close stand-off (~ 6-8m) of a
compact reactor core. Due to the small anti-neutrino cross-section, the main
challenge in achieving a precise measurement is to control the high level of
gamma rays and neutron background that are present at close stand off and to
the surface.
The SoLid experiment intends to search for active-to-sterile anti-neutrino
oscillation at very short baseline of the SCK CEN BR2 research reactor. A
novel approach to measuring reactor anti-neutrinos was developed based on an
innovative sandwich of composite Polyvynil-Toluene and 6LiF:ZnS
scintillators. The system is highly segmented and read out by a network of
wavelength shifting fibers and MPPCs. High experimental sensitivity can be
achieved with the combination of high granularity, high neutron-gamma
discrimination using 6LiF:ZnS(Ag) scintillator and precise localisation of
the inverse beta decay products. We will describe the principle of
detection, the detector design and we will focus on the performance of the
first full scale SoLid module 1 (SM1) installed at BR2 early 2015
demonstrating the technology.