In this way, one can not only determine the lifetime of positrons in a certain positron state, but also the momentum distribution of those electrons which are their annihilationpartners in this state. The AMOC method is especially suited for the observation of positron transitions between different states during their lifetime. AMOC measurements, e.g., make visible how positrons are trapped in vacancies. This detector generates the start signal of the positron-age measurement with an efficiency of nearly 100 per cent.
Most positrons annihilate with two gamma quanta sent out in opposite directions.
The signals are processed by fast electronic intruments and put together by a computer to form a two-dimensional spectrum. The following picture shows an AMOC spectrum, named AMOC relief , of methanol at room temperature. The x-axis displays the positron age. Cuts perpendicular to this axis show Doppler-broadened lines. The y-axis shows the energy of the gamma quanta.