Miniball experiment

[1][2][3][4] Miniball is a high-resolution germanium detector array, specifically designed to work with low-intensity radioactive ion beams post-accelerated by HIE-ISOLDE (High Intensity and Energy-ISOLDE), to analyse gamma radiation emitted by short-lived nuclei.

Studying transfer reactions is useful in nuclear astrophysics as it replicates stellar evolution and can test theoretical models.

Each cryostat is shared by three capsules, which are installed in a common vacuum chamber connected to a single dewar.

Depending on the dimensions of the reaction chamber placed in the centre of the array, the clusters can be arranged in various configurations to provide optimum solid angle coverage.

The setup consists of a silicon barrel with forward and backward CD detectors, covering a solid angle of 66% of 4π.

Using this technique, electric dipole, quadrupole and octupole moments of electromagnetic transitions in several radioactive nuclei have been determined.

[11] As an example, in one of the first transfer-reaction experiments performed with Miniball an excited state of spin-parity 0+ having a spherical shape has been identified in the "island of inversion" nucleus 32Mg.