https://doi.org/10.1140/epja/i2017-12428-9
Regular Article - Experimental Physics
Upgrade of the ultracold neutron source at the pulsed reactor TRIGA Mainz
1
Institute of Physics, Johannes Gutenberg University, Mainz, Germany
2
Institute of Nuclear Chemistry, Johannes Gutenberg University, Mainz, Germany
3
Laboratory for Particle Physics, Paul Scherrer Institute (PSI), Villigen, Switzerland
4
Institute for Particle Physics, ETH Zürich, Zürich, Switzerland
* e-mail: wheil@uni-mainz.de
Received:
12
June
2017
Accepted:
11
November
2017
Published online:
28
November
2017
The performance of the upgraded solid deuterium ultracold neutron source at the pulsed reactor TRIGA Mainz is described. The current configuration stage comprises the installation of a He liquefier to run UCN experiments over long-term periods, the use of stainless steel neutron guides with improved transmission as well as sputter-coated non-magnetic 58NiMo alloy at the inside walls of the thermal bridge and the converter cup. The UCN yield was measured in a “standard” UCN storage bottle (stainless steel) with a volume of 32 litres outside the biological shield at the experimental area yielding UCN densities of 8.5/cm3; an increase by a factor of 3.5 compared to the former setup. The measured UCN storage curve is in good agreement with the predictions from a Monte Carlo simulation developed to model the source. The growth and formation of the solid deuterium converter during freeze-out are affected by the ortho/para ratio of the H2 premoderator.
© SIF, Springer-Verlag GmbH Germany, part of Springer Nature, 2017
