Abstract
ESS will be a premier neutron source facility. Unprecedented neutron beam intensities are ensured by spallation reactions of a 5 MW, 2.0 GeV proton beam impinging on a tungsten target equipped with advanced moderators. The work presented here aims at investigating possibilities for installing an ultra cold neutron (UCN) source at the ESS. One consequence of using the recently proposed flat moderators is that they take up less space than the moderators originally foreseen and thus leave more freedom to design a UCN source, close to the spallation hotspot. One of the options studied is to place a large4He UCN source in a through-going tube which penetrates the shielding below the target. First calculations of neutron flux available for UCN production are given, along with heat-load estimates. It is estimated that the flux can give rise to a UCN production at a rate of up to1.5·108 UCN/s. A production in this range potentially allows for a number of UCN experiments to be carried out at unprecedented precision, including, for example, quantum gravitational spectroscopy with UCNs which rely on high phase-space density.
Highlights
The fundamental physics community has expressed strong interest to investigate the possibility of installing source of ultra cold neutrons (UCNs) at the ESS
One consequence of using the recently proposed flat moderators is that they take up less space than the moderators originally foreseen and leave more freedom to design a UCN source, close to the spallation hotspot
This paper focuses on the in-pile option, in particular the possibility that a UCN source could be hosted in a through-going tube that penetrates the monolith shielding as well as the outer and inner reflectors
Summary
The fundamental physics community has expressed strong interest to investigate the possibility of installing source of ultra cold neutrons (UCNs) at the ESS. This paper focuses on the in-pile option, in particular the possibility that a UCN source could be hosted in a through-going tube that penetrates the monolith shielding as well as the outer and inner reflectors. This would allow the UCN converter to come as close as possible to the spallation region, thereby subject to the highest possible input neutron flux. In order not to conflict with the cold/thermal moderators at the ESS, the tube must pass under the lower moderator. In addition first estimates of the possible UCN production rate are given
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