Probing neutrino millicharges at the European Spallation Source

We study the potential of a set of future detectors, proposed to be located at the European Spallation Source (ESS), to probe neutrino millicharges through coherent elastic neutrino-nucleus scattering. In particular, we focus on detectors with similar characteristics as those that are under development for operation at the ESS, including detection technologies based on cesium iodine, germanium, and noble gases. Under the considered conditions, we show that the Ge detector, with a lighter nuclear target mass with respect to CsI and a noble gas like Xe, is more efficient to constrain neutrino millicharges, reaching a sensitivity of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mo>∼</a:mo><a:msup><a:mrow><a:mn>10</a:mn></a:mrow><a:mrow><a:mo>−</a:mo><a:mn>9</a:mn></a:mrow></a:msup><a:mi>e</a:mi></a:mrow></a:math> for diagonal neutrino millicharges, and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mo>∼</c:mo><c:msup><c:mrow><c:mn>10</c:mn></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>8</c:mn></c:mrow></c:msup><c:mi>e</c:mi></c:mrow></c:math> for the transition ones. In addition, we study the effects of including electron scattering processes for the CsI detector, achieving an expected sensitivity of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mo>∼</e:mo><e:msup><e:mrow><e:mn>10</e:mn></e:mrow><e:mrow><e:mo>−</e:mo><e:mn>11</e:mn></e:mrow></e:msup><e:mi>e</e:mi></e:mrow></e:math> for the diagonal millicharges.