Superfluid helium based ultracold neutron source for the PIK reactor

Abstract

The PIK reactor at NRC "Kurchatov Institute"-PNPI is going to be equipped with a high-flux Ultra Cold Neutron (UCN) source for fundamental physics researches. The UCN source will use superfluid helium, which will make possible to achieve the density of UCN 2.2·10^3 cm-3, that has not yet been achieved anywhere in the world. The UCN source will be installed on the GEK-4 channel, which will make possible to obtain a low value of heat influx to cryogenic vessels from reactor radiation. The heat removal from the UCN source vessel will be implemented by using a heat exchanger. The calculated UCN density in the EDM spectrometer chamber at the PIK is going to be 200 cm-3, which is 20 times higher than the existing UCN densities in the world. For a new UCN source based on superfluid helium, an extensive research program has been developed in field of the physics of fundamental interactions, including the search for a nonzero neutron EDM, precision measurement of the neutron lifetime, and search for mirror dark matter. Keywords: ultracold neutrons, neutron sources, superfluid helium, neutron EDM, neutron decay.

Development of UCN sources at PNPI

“…In general, a broad research program is planned. The UCN guide system has been designed to feed up to five experimental facilities [43]. At the start of its operation, it is planned to equip the UCN source with experimental setups already available at PNPI: an nEDM spectrometer [40] and two neutron lifetime experiments, one with a gravitational [42] and one with a magnetic trap [10].…”

“…Each symbol represents the year of (for projects: proposed) start of operation and the finally achieved (for projects: proposed) UCN density. Note that some values quote densities achieved in the source, some in external traps [3][4][5]7,11,13,19,21,30,33,43,46,56].…”