Detector design proposal for a cosmic magnetic monopole search experiment

A magnetic monopole is a well-motivated class of beyond-Standard-Model particles that could provide insights into the long-standing puzzle of the quantization of electric charge. These hypothetical particles are likely to be super heavy (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mo>∼</a:mo><a:mrow><a:msup><a:mrow><a:mn>10</a:mn></a:mrow><a:mrow><a:mn>15</a:mn></a:mrow></a:msup></a:mrow><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>GeV</a:mi></a:math>) and may have been produced during the very early stages of the Universe’s evolution. We propose a novel detection scenario for the search for such cosmic magnetic monopoles, utilizing a hybrid approach that combines radio-frequency atomic magnetometers and plastic scintillators. Such a setup allows one to detect both the induction and scintillation signals of monopoles with velocities larger than about <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:msup><c:mrow><c:mn>10</c:mn></c:mrow><c:mrow><c:mo>−</c:mo><c:mn>6</c:mn></c:mrow></c:msup></c:mrow></c:math> light speed (assuming a signal-to-noise ratio of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mo>∼</e:mo><e:mn>4</e:mn></e:math>) and their masses larger than approximately <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:msup><g:mrow><g:mn>10</g:mn></g:mrow><g:mrow><g:mn>7</g:mn></g:mrow></g:msup></g:mrow><g:mtext> </g:mtext><g:mtext> </g:mtext><g:mi>GeV</g:mi></g:math> (at <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>β</i:mi><i:mo>∼</i:mo><i:msup><i:mn>10</i:mn><i:mrow><i:mo>−</i:mo><i:mn>3</i:mn></i:mrow></i:msup></i:math>). The proposed detector design has the potential to be scaled up to large areas, enabling the exploration of the parameter space of the cosmic magnetic monopoles beyond the current experimental and astrophysical constraints. It is estimated that such a detector can reach the current most stringent limits on the flux set by previous searches, with a signal-to-noise ratio of the induction signal larger than about 4.5, assuming an effective exposure being <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mrow><k:mn>20</k:mn><k:mo>,</k:mo><k:mn>000</k:mn><k:mtext> </k:mtext><k:mtext> </k:mtext><k:mi>year</k:mi><k:mo>·</k:mo><k:mtext> </k:mtext><k:msup><k:mrow><k:mi mathvariant="normal">m</k:mi></k:mrow><k:mrow><k:mn>2</k:mn></k:mrow></k:msup></k:mrow></k:math> and at least three coil layers.