For the ESS project, an Emittance Measurement Unit (EMU) was developed by CEA Saclay. This EMU, based on Allison scanner design, was installed in a LEBT for the ion source commissioning at INFN-LNS at the beginning of the year 2017. Transverse emittance is one of the key measurements to be performed during the commissioning of the low energy sections of a hadron linac.The good knowledge of the beam transverse phase space allows a safe and efficient operation of the machines by using the results of the measurement for beam dynamic simulations.
For a linear accelerator with high beam power operating in pulsed mode, it is mandatory to have a high-resolution emittance measurement as well as a time resolve measurement. To achieve this, a high dynamic range acquisition chain is needed. During the first measurement campaign, a dynamic range above 103 was demonstrated, showing unexpected background signals that the authors will discuss in this paper. The paper also describes the performance of the EMU, and the results of simulations performed to estimate the effective length of the electrostatic field needed for the particle deflection in the Allison scanner based EMU.