Nuclear orientation of 3H with ionisation and calorimetric detectors at low temperatures and in high fields

As a new nuclear physics application of low temperature detectors we propose the measurement of the beta asymmetry parameter for the allowed beta decay of 3H by means of low temperature nuclear orientation in high external fields. Since 3H is the lightest mirror nucleus these experiments are of particular interest in connection with the search for physics beyond the standard electroweak model. accurate measurement of the low energy beta particles, low thresholds and good energy resolution are equally important. Two types of detectors are discussed. The first type is based on the “standard” ionisation detectors and operates at 4.2 K. The low threshold is achieved by cooling the first stage of the preamplifier thereby reducing the electronic noise. More accurate results can be obtained with calorimetric detectors. We have shown that the use of bolometers in high magnetic fields is possible, with a very low threshold and a good energy resolution.