A new ultra cold neutron (UCN) production in a spallation neutron source is discussed. The new method uses phonon excitation in He-II, where we can use large phonon phase-space for neutron cooling. The new method is free from the Liouville's theorem which limits the turbine UCN source at Grenoble. The spallation neutron source reduces the phonon up-scattering which depends on temperature, because of small gamma heating compared with the reactor. The phonon up-scattering rate limits the UCN storage time. As a result, higher neutron flux can be applied to He-II, and therefore, an enhancement of 10~3 in the UCN production is expected compared with the turbine UCN-source which is the most intensive at present.
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