An intense source of very cold neutrons using solid deuterium and nanodiamonds for the European Spallation Source

Nicola Rizzi, Ben Folsom, Mina Akhyani, Mads Bertelsen, Peter Böni, Yannick Beßler, Tomasz Bryś, Amalia Chambon, Valentin Czamler, Bent Lauritzen, Jose Ignacio Márquez Damián, Valery Nesvizhevsky, Blahoslav Rataj, Stavros Samothrakitis, Valentina Santoro, Ha Shuai, Markus Strobl, Mathias Strothmann, Alan Takibayev, Richard WagnerLuca Zanini*, Oliver Zimmer

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


The European Spallation Source (ESS), currently under construction, is based on a high-brightness, bi-spectral, low-dimensional moderator placed above a spallation target, intended to initially serve fifteen neutron scattering instruments. Within the upgrade path of ESS, the HighNESS project aims at designing a source complementary to this upper moderator, focusing on delivering a higher intensity and a colder spectrum of neutrons. We have investigated the use of solid ortho-deuterium at 5 K as a source of very cold neutrons (VCNs). This source performs competitively as a high-intensity cold-neutron moderator, while also showing an order-of-magnitude flux increase in the very cold range above 40 ̊ A compared to a liquid deuterium moderator of similar volume and shape, also designed within HighNESS. The long-wavelength performance of the source can be improved further by encasing it in a thin layer of nanodiamonds. The cooling of a solid deuterium moderator placed so close to the spallation target of a high-power neutron source like ESS is very challenging, but may be feasible by augmenting the heat conductivity with the addition of low-density metallic foam structures within the moderator vessel. Such a source could provide unprecedented opportunities in fundamental physics research and neutron scattering using VCNs.

Original languageEnglish
Article number169215
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Number of pages15
Publication statusPublished - 2024


  • European spallation source
  • Moderators
  • Nanodiamonds
  • Solid deuterium
  • Very cold neutrons


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