Ionoacoustic monitoring of relativistic heavy ion beams

The performance of ionoacoustic detectors is investigated with respect to application of high-precision range and energy loss measurements for relativistic heavy ions. The technique is based on the generation of a pressure wave when a microsecond-pulsed relativistic ion beam is stopped in a water container. The acoustic signal from in-dividual ion pulses is registered by a piezoelectric detector and analyzed in the time/frequency domain to identify the location of pressure wave generation. The experiments were performed at the SIS18 synchrotron at GSI Helmholtzzentrum (Darmstadt, Germany) with Xe, Pb and U ions of energies between 200 MeV/u and 1 GeV/u. We show that the signal amplitude of the acoustic pressure pulse has a linear correlation with the beam intensity within a range of at least 104 to 109 particles/spill. By determining the delay time of the primary and reflected acoustic signal in the water reservoir, the ion-oacoustic technique provides information on ion ranges of 1 % accuracy. By an energy-range calibration in combination with a simulation code such as FLUKA, the range data can be used to determine the beam energy. As demonstrated, inserting targets of known thickness in front of the detector is a simple approach for measuring the energy loss of relativistic ions. The advantage of the ionoacoustic technique is the rather simple experimental setup, the huge dynamic range, the information available online by means of only a single pulse and its radiation hardness. Ionoacoustic detectors have great potential as intensity and energy monitor for short-pulsed light and heavy ion beams at existing or future high-energy ion facilities.