UCN sources in external beams of thermal or cold neutrons
Vendredi 26 juin 2015 15:00
- Duree : 1 heure
Lieu : ILL 1 - Seminar Room, 71 avenue des Martyrs - Grenoble
Orateur : E. LYCHAGIN (Joint Institute for Nuclear Research, Dubna, Russia)
We discuss a new method to produce ultracold neutrons (UCNs). UCN source at the PIK reactor is chosen as the best example of its application. The main idea of the method was published in refs. [1,2] : a helium UCN source is placed in a cavity in a moderator-reflector installed at the end position of an external beam of thermal or cold neutrons. The moderator-reflector is the source of cold neutrons feeding the helium UCN source ; the cold neutron flux in the source can exceed by several times the incident neutron flux due to multiple reflection of neutrons from the moderator-reflector.
We show that a source of this type at the PIK and ILL reactors would largely exceed parameters of existing or projected UCN sources. As sources of this type do not require modifications in the reactor/spallation source, as well as even the presence of a standard cold source inside the reactor/spallation source, they could be used also at all other neutron facilities.
We estimate parameters of a source with the moderator-reflector from solid methane and liquid deuterium. Installation of such a source with a methane moderator-reflector in а beam of thermal neutrons at the PIK reactor allows achieving the UCN density of 105 cm-3 ; the UCN production rate would be 107 s-1. Higher UCN density would be achieved using deuterium moderator-reflector in a beam of cold neutrons at the PIK reactor ; it is above 8⋅105 cm-3, with the UCN production rate above 3⋅108 s-1.
1. S. Baessler, A.M. Gagarski, E.V. Lychagin, A. Mietke, A.Yu. Muzychka, V.V. Nesvizhevsky, G. Pignol, A.V. Strelkov, B.P. Toperverg, and K. Zhernenkov, “New methodical developments for GRANIT”, Compt. Rend. Phys. 12 (2011) 729.
2. E.V. Lychagin, A.Yu. Muzychka, G.V. Nekhaev, V.V. Nesvizhevsky, E.I. Sharapov, and A.V. Strelkov, “UCN source at an external beam of thermal neutrons”, Adv. High En. Phys. 2015 (2015) 547620.
Contact : pollitt@ill.fr
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