https://doi.org/10.1140/epja/i2007-10494-2
Regular Article - Experimental Physics
First production of ultracold neutrons with a solid deuterium source at the pulsed reactor TRIGA Mainz⋆
1
Physics Department, Technische Universität München, James-Franck-Strasse, D-85748, Garching, Germany
2
Institute for Physics, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, D-55128, Mainz, Germany
3
Institute for Nuclear Chemistry, Johannes Gutenberg-Universität Mainz, Fritz-Strassmann-Weg 2, D-55128, Mainz, Germany
4
Walther-Meissner-Institut der Bayerischen Akademie der Wissenschaften, Walther-Meissner-Str. 8, D-85748, Garching, Germany
5
Joint Institute for Nuclear Research, 141980, Dubna, Moscow Region, Russia
6
STEAG Encotec GmbH, Rüttenscheider Str. 1-3, D-45128, Essen, Germany
* e-mail: wheil@uni-mainz.de
Received:
11
September
2007
Accepted:
19
October
2007
Published online:
12
November
2007
The production rates of ultracold neutrons (UCN) with a solid deuterium converter have been measured at the pulsed reactor TRIGA Mainz. Exposed to a thermal neutron fluence of 
n·cm^-2·pulse^-1, the number of detected very cold and ultracold neutrons ranges up to 200 000 at 7mol of solid deuterium (sD2) in combination with a pre-moderator (mesitylene). About 50% of the measured neutrons can be assigned to UCN with energies E of 
where V
F(sD
2) = 105 neV and V
F(guide) = 190 neV are the Fermi potentials of the sD2 converter and our stainless steel neutron guides, respectively. Thermal cycling of solid deuterium, which was frozen out from the gas phase, considerably improved the UCN yield, in particular at higher amounts of sD2.
PACS: 28.20.Gd Neutron transport: diffusion and moderation – / 14.20.Dh Protons and neutrons – / 29.25.Dz Neutron sources –
© Società Italiana di Fisica and Springer-Verlag, 2007
