The PSI UCN Source

At PSI currently a source of ultra cold neutrons (UCN) is being built. This source is based on the spallation process using a high intensity proton beam (Ip ≥ 2 mA) with a low duty cycle (1 %) hitting a heavy metal spallation target. The neutrons will be thermalized in heavy water and down scattered into the UCN regime in a 30 dm 3 solid deuterium (sD2) converter. The UCN will be stored in a large UCN storage volume (2 m 3 ) from where they will be piped to the experiments. We expect a UCN density in the storage volume of 3000 per cm 3 . Start-up is planned for 2007.