Each Laboratory of the Institute has its own prehistory and destiny. If DLNP and VBLHE had gone a long way before the foundation of JINR and served as a basis for its establishment, the Laboratory of Neutron Physics first appeared as a line in the Convention on the establishment of JINR signed by the founding countries. In late 1955 in IPPE (Obninsk) a Seminar was held, where American scientists’ work studying the neutron energy dependence of uranium-235 fission cross-section was discussed. In this experiment a uranium-coated disk rotating synchronously with a beam chopper was used and the radioactivity of uranium on a wheel rim was measured. Suddenly DI (D.I.Blokhintsev, IPPE Director at that time) raised his hand and said “what if a part of the reactor active zone is fixed on a rim of such disk so that at each revolution this part passes near the stationary zone and creates a supercritical mass for a short time?” These are the recollections of the creators of the theory of this reactor (IPPE scientists) about the beginning of work on the design of the pulsed fast (more precisely  using fast neutrons) reactor (IBR). The advantages of pulsed reactors over mechanical selectors used at that time on stationary reactors were clear from the very beginning: to set the reactor power into pulsation is much more economic than to chop off a neutron beam by a chopper. Later D.I.Blokhintsev explained that it was these considerations that guided the creators of IBR. In the mid-1956 D.I.Blokhintsev was suggested to head the International Institute organized in Dubna, but he set a condition to Minister Ye.P.Slavskii responsible for the establishment of JINR: to take a decision on the construction of a new facility in Dubna – IBR. In order for physical investigations to be carried out on this reactor, the Laboratory of Neutron Physics was established, and I.M.Frank was elected its Director… The "wheel" began to turn. In 1957  1958 about ten rooms in DLNP building ?3 were allotted to FLNP and its staff vacancies began to be filled. Besides Director, Chief Engineer was also appointed at once and then first specialists were taken on. By late 1958 the number of employees increased up to 75. In November 1960 I.M.Frank made a report at the IXth Session of the JINR Scientific Council, which was devoted to the results of the commissioning work on the FLNP first pulsed reactor. The pace of development was amazing – only three years passed from the conceiving of the idea to its realization. The construction of the reactor required the solution of many engineering problems, including the creation of a machine that would make possible fast repeating changes of reactivity. Such machine was designed, manufactured and tested in three months in the Central Institute of Aircraft Engine Engineering. The reactor was equipped with various originally designed devices allowing for fine adjustment of the reactor reactivity. For the first time the equipment was developed, which made it possible to control the reactor power in a pulsed mode. A lot of design offices and institutes participated in this work. By late 1959 the construction of the reactor building, control room, measuring halls with neutronguides from 100 to 1000 meters was completed. By then the critical assembly was carried out and the IBR basic parameters were experimentally estimated: critical mass, reactivity dependence of the position of the zone moving part relative to the fixed one, and thereby the expected neutron pulse width was refined. The FLNP specialists also carried out a large amount of work on the preparation of the reactor for the start-up. Soviet specialists and Chinese scientists took part in the refinement of the reactor theory, in necessary calculations and in the commissioning phase. The IBR start-up took place on June 23, 1960. That day, undoubtedly, remains vivid in the memory of all participants. Yu.Ya.Stavisskii, the responsible for the start-up, frequently came running from the control panel room on the second floor to the time analyzer to watch himself what was happening with the form of a neutron pulse. The pulse width was reducing excitingly, as the reactivity increased. In the control panel room D.I.Blokhintsev worried about his brainchild. In the evening the reactor reached a critical state in a pulsed mode  the start-up came true! The reactor was tested by the physicists under the guidance of F.L.Shapiro. In July the reactor operated at its designed power of 1 kW, the neutron pulse width was 36 s, close to the value estimated after the critical assemblies.