Studies with slow and ultracold neutrons

Ultracold neutron storage and transport experiments performed at a pulsed reactor are described. Mean storage time amounted to 140s at ultracold neutron density of 100 n/l. The possibility of increasing both ultracold neutron number and density is provided by increasing the solid angle used and cooling the neutron converter. Some results of theoretical investigations related to an abnormal leakage of ultracold neutrons from a trap are presented. An analytical expression is obtained for the probability of ultracold neutron coherent heating due to inelastic interaction with thermal vibrations of the trap wall. Major characteristics of a gravitational spectrometer are described which is designed for the neutron energy range of 10-4-10-8 eV at 5-20% resolution. The neutron spectrum is presented