A prospective pulsed source of ultracold neutrons for experiments in fundamental neutron physics

Since their discovery, ultracold neutrons (UCNs) have been a unique tool for the investigation of fundamental properties of the free neutron and its interactions. The succesfull installation of a new pulsed superthermal source for ultracold neutrons based on solid deuterium at the TRIGA Mainz reactor is described. In a combination of solid hydrogen acting as pre-moderator and a solid deuterium converter of around 160 cm(3), this new UCN source should provide at the experimental area >= 370000UCN to the storage volume with the reactor operated in the pulse mode. In a storage experiment, a UCN density of 18 +/- 2UCN/cm(3) was measured applying 1.5 $ pulses with a nominal power of 7 MJ. Assuming a linear behaviour of the UCN output as a function of reactor power this corresponds to a UCN density of 25 +/- 3UCN/cm(3) for 2 $ (10 MJ) pulses.