DICE (Delft Internal Conversion Experiment)
Anomalies in the IPC spectrum have been found by de Boer et al., they are interpreted as the creation and decay of isoscalar neutral bosons. This provided the motivation to start the DICE experiment.
The DICE detector has a 2 cm drift gap and is flushed with CO2 DME and is placed in a 0.3 T permanent magnetic field. Monte-Carlo studies show a vertex resolution of 100 micron for a 1 MeV electron in such a 0.3T field. From the energy measurements the energy resolution is extracted to be 0.08 MeV over a 15 mm track length. The DICE detector is surrounded by four trigger scintillators.
At the Reactor Institute in Delft, the radioactive source 24Na (half-life is 15 hours) will be produced. The small source, less than 1mm diameter, will be placed in the centre of the DICE detector. 24Na decays with a 1.39MeV e- to an excited state of 24Mg with an energy of 4.12MeV. This state decays via two transitions of 2.75MeV and 1.37MeV to the ground state. Both transitions can have an IPC with 10-3 probability resulting in e+e- pairs with respectively 1.73MeV and 0.35MeV sum energy. If an exotic boson is created in the transition, the e+e- pair will show a peak in the angular correlation corresponding to the boson mass, while the typical IPC distribution is a monotone decreasing function of the angle.
