Ho-163 source

The production of a sufficient amount of 163Ho atoms in a radiochemically pure form is of paramount importance for the success of the ECHo experiment. The production methods for 163Ho can mainly be divided into two branches:

  • charged particle activation of suitable targets in reactions that lead to 163Ho or its precursor 163Er which decays to 163Ho (EC and β + decay) with a half-life T1/2 = 75 min;
  • thermal neutron activation of enriched 162Er targets.


The reaction that is typically used for the direct activation with proton beams is natDy(p;xn)163Ho. Another possible direct reaction uses deuteron projectiles, 163Dy(d;2n)163Ho. Examples for indirect 163Ho production are natDy(α;xn)163Er(EC,β +)163Ho and 159Tb(7Li;3n)163Er(EC, β +)163Ho.

In the ECHo experiment all the described methods for production of 163Ho through charged particle activation
processes as well as with neutron irradiation of a 162Er target are being considered, as well as possible new methods.

Typically, in the production of 163Ho, contaminants nuclides with decay properties that interfere with the desired clean 163Ho EC spectrum are produced. These include long-lived β −decaying nuclides like 166mHo. Thus, a careful separation of 163Ho is of paramount importance and will be performed by a combination of chemical and potentially physical separations before as well as after the irradiation of the sample.