Sergio Pasinelli

The ELENA facility

The CERN Antiproton Decelerator (AD) provides antiproton beams with a kinetic energy of 5.3 MeV to an active user community. The experiments would profit from a lower beam energy, but this extraction energy is the lowest one possible under good conditions with the given circumference of the AD. The Extra Low Energy Antiproton ring (ELENA) is a small synchrotron with a circumference a factor of 6 smaller than the AD to further decelerate antiprotons from the AD from 5.3 MeV to 100 keV. Controlled deceleration in a synchrotron equipped with an electron cooler to reduce emittances in all three planes will allow the existing AD experiments to increase substantially their antiproton capture efficiencies and render new experiments possible. ELENA ring commissioning is taking place at present and first beams to a new experiment installed in a new experimental area are foreseen in 2017. The transfer lines from ELENA to existing experiments in the old experimental area will be installed during CERN Long Shutdown 2 (LS2) in 2019 and 2020. The status of the project and ring commissioning will be reported. This article is part of the Theo Murphy meeting issue ‘Antiproton physics in the ELENA era’.

Beam Loss in the Low Energy Ion Ring (LEIR) in the Light of the LHC Injector Upgrade for Ions (LIU-Ions)

For the LHC injector upgrade for Ions (LIU Ions), the Low Energy Ion Ring (LEIR) is requested to deliver twice the intensity per extraction compared to the last Pb54+ ion run in 2013 [1]. As the number of injected ions has been increased into LEIR, a fast loss is observed during the RFcapture of the electron cooled ion beam, and this loss today leads to an effective saturation of the available ion intensity at extraction. Based on chromaticity measurements with Pb54+ beam in LEIR with bunched beam and during acceleration in February 2013 [2], we suspected the chromaticity of the LEIR machine to be wrong in the vertical plane. To investigate the stationary behavior of the LEIR machine, we have developed a new method to measure the machine chromaticity on the low energy flat bottom of LEIR during a single cycle, where the ion beam is un-bunched and coasting. The new method controls the ion beam momentum by the LEIR electron cooler beam rather than the LEIR RF-system. The new method uses the LEIR Schottky system to measure the applied momentum change rather than the radial beam position offset in dispersive regions. The existing tune measurement system is used to measure the tune in the same way as in the classic way involving the RF-system and bunched ion beam. The new method allows a single-cycle-chromaticity measurement of coasting and un-bunched beam with high accuracy and no dependency of cycle-to-cycle machine variation.