Wikipedia
MiniGRAIL is a type of Resonant Mass Antenna, which is a massive sphere that used to detect gravitational waves. The MiniGRAIL is the first such detector to use a spherical design. It is located at Leiden University in the Netherlands. The project is being managed by the Kamerlingh Onnes Laboratory. A team from the Department of Theoretical Physics of the University of Geneva, Switzerland, is also heavily involved.
Gravitational waves are a type of radiation that is emitted by objects that have mass and are undergoing acceleration. The strongest sources of gravitational waves are expected to be compact objects such as neutron stars and black holes. This detector may be able to detect certain types of instabilities in rotating single and binary neutron stars, and the merger of small black holes or neutron stars.