Following the restart of the first elements in CERN’s accelerator complex in June (CERN Courier July/August 2014 p5), beams are now being delivered to experiments from the Proton Synchrotron (PS) and the PS Booster.
First in line were experiments in the East Area of the PS, where the T9 and T10 beam lines are up and running. These test beams serve projects such as the Advanced European Infrastructures for Detectors at Accelerators (AIDA), which looks at new detector solutions for future accelerators, and the ALICE collaboration’s tests of components for their inner tracking system. By the evening of 14 July, beam was hitting the East Area’s target and the next day, beams were back in T9 and T10.
Next to receive beams for physics were experiments at the neutron time-of-flight facility, n_TOF, and the Isotope mass Separator On-Line facility, ISOLDE. On 25 July, detectors measured the first neutron beam in n_TOF’s new Experimental Area 2 (EAR2). It was a low-intensity beam, but it showed that the whole chain – from the spallation target to the experimental hall, including the sweeping magnet and the collimators – is working well. Built about 20 m above the neutron production target, EAR2 is a bunker connected to the underground facilities via a vertical flight path through a duct 80 cm in diameter, where the beamline is installed. At n_TOF, neutron-induced reactions are studied with high accuracy, thanks to the high instantaneous neutron flux that the facility provides. The first experiments will be installed in EAR2 this autumn and the schedule is full until the end of 2015.
A week later, on 1 August, ISOLDE restarted its physics programme with beams from the PS Booster, after a shutdown of almost a year and a half during which many improvements were made. One of the main projects was the installation of new robots for handling the targets that become very radioactive. The previous robots were more than 20 years old and beginning to suffer from the effects of radiation. The long shutdown of CERN’s accelerator complex, LS1, provided the perfect opportunity to replace them with more modern robots with electronic-sensor feedback. On the civil engineering side, three ISOLDE buildings have been demolished and replaced with a single building that includes a new control room, a data-storage room, three laser laboratories, and a biology and materials laboratory. In the ISOLDE hall, new permanent experimental stations have also been installed. Almost 40 experiments are planned for the remainder of 2014.
After the PS, the Super Proton Synchrotron (SPS) will be next to receive beam. On 27 June, the SPS closed its doors to the LS1 engineers, bringing almost 17 months of activities to an end. The machine has now entered the hardware-testing phase, in preparation for a restart in October.
Meanwhile at the LHC, early August saw the start of the cool down of a third sector – sector 1-2. By the end of August, five sectors of the machine should be in the process of cooling down, with one (sector 6-7) already cold. Meanwhile, the copper stabilizer continuity measurements (CSCM) have been completed in the first sector (6-7), with no defect found. CSCM tests are to start in the second sector in mid-August. Elsewhere in the machine, the last pressure tests were carried out on 31 July, and the last short-circuit tests should be complete by mid-August.