Abstract: A readout system, including a data channel for conveying data, and detector units. Each detector unit includes an input which receives a pulse having a magnitude, a storage buffer which stores an indication of the magnitude, and output circuitry which outputs a request-to-read signal in response to the storage unit receiving the pulse. The units output the indications to the data channel upon receiving a select signal in response to the request-to-read signal. The system includes a processor, which receives the request-to-read signal, and in response transmits the select signal and reads the indication from the data channel. The system also includes selectors, coupled as a tree of hierarchical rows having decreasing numbers of selectors, which convey the request-to-read signals from the detector units to the processor. The selectors also convey the select signals from the processor to the detector units, thereby causing the processor to read the indications.