Antenna-Coupled Magnetic Microbolometers for CMB Polarization Surveys

Abstract In this work, we propose a magnetic bolometer to be employed in the search of primordial B-modes in the CMB. These magnetic bolometers are an adaptation of the well-known metallic magnetic calorimeters used in particle physics. They rely on the magnetization dependence on temperature of alloys such as Au:Er and Ag:Er. In addition to the low intrinsic noise a magnetic bolometer of this nature offers, the broad and smooth temperature-dependent magnetization of metallic magnetic sensors ultimately translates to a high dynamic range and straightforward calibration. Their intrinsic noise equivalent power (NEP) is estimated to be in the range of 10–100 aW/ $$\sqrt{(}\text {Hz})$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mo>(</mml:mo> </mml:msqrt> <mml:mrow> <mml:mtext>Hz</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> . We outline here a workable design for such a detector utilizing an antenna-coupled approach and present the simulated power transfer ratio that was attained; the detector’s performance is discussed by combining this result with its responsivity.