THE NOISE OF THE MAGNETIC BOLOMETER

We discuss a thermal detector consisting Of an absorber of pure insulating material and a sensor being a paramagnetic sample in a small magnetic field. Upon absorption of a particle and thermalization of its energy the magnetic moment M of the sensor decreases and DELTAM is measured very sensitively with a SQUID. This detector has the unique property that no power of measurement is applied and therefore it is possible and favourable to make the signal decay time much longer than the signal rise time. With that we obtain frequency spectra of the noise and of the signal, which show that the uncertainty of energy deltaE is not limited by the so-called thermodynamic limit. The limits of energy resolution are estimated in particular with respect to high detector masses.