Characterization of REX/HIE-ISOLDE RFQ longitudinal acceptance and transmission

The Isotope mass Separator On-Line DEvice (ISOLDE) based at CERN, is a Radioactive Ion Beam (RIB) facility where rare isotopes are produced from 1.4 GeV-proton collisions onto a target then are manipulated and transported to user experimental stations for studies, notably in the domain of nuclear physics. The RIB of interest is delivered to a dedicated experimental station either at low (up to 60 keV) or high energy (MeV/u range) after acceleration through the recently completed REX/HIE-ISOLDE linac upgrade. The first stage of the linac consists of normal-conducting IH and spiral-resonators and is preceded by a Radio-Frequency Quadrupole (RFQ). A description of the experimental setup and the specifications of the RFQ will serve as an introduction for the presentation of recent results about the transmission efficiency of the RFQ. Furthermore, a newly developed technique will be demonstrated, that allow for the capture of ion beam intensities below the femto-Ampere range. In fine, a measurement of the longitudinal acceptance of the RFQ will be included.