LEP Performance at 91.5 GeV

The 1997 LEP collider run was the first year of the LEP2 program devoted to stable high luminosity running. The good performance of the LEP superconducting RF system allowed to run at beam energies of 91.5 GeV. In addition to the to usual optimisation procedures to minimise the vertical beam emittances, the horizontal beam sizes were reduced by increasing the horizontal damping partition number and reducing the betatron function at the interaction points. Vertical beam-beam tune shifts in excess of 0.05 were achieved with total beam currents of 5 mA. The total integrated luminosity of 73 pb-1 is the highest ever recorded in a single year of LEP operation

Operational procedures to obtain high beam-beam tune shifts in LEP pretzel operation

During the running period 1994 the luminosity of LEP has been improved without colliding higher bunch currents. This paper describes the main procedures used by the operations group for luminosity optimization. Separator scans in the vertical plane and orbit interpolations in the horizontal plane are used to adjust settings for electrostatic separators in order to ensure head-on collisions. The closed orbit is corrected towards a reference orbit (called "golden" orbit) which has been found empirically to produce good luminosity. The settings of the skew quadrupoles for coupling compensation is obtained by measuring the closest tune approach of the horizontal and vertical betatron tunes

Report on the Working Group set up to Study the Requirements for Operating the SPS within the INB Framework (INBOPS)

The convention signed with the French authorities for the LHC defines a new Installation Nucléaire de Base (INB). The LHC machine tunnel, the experiments, some buildings which cover access shafts to the machine and the SPS with its extraction lines up to the targets are all inside the new perimeter. The new convention came into effect in September 2000 and therefore the SPS fell within the new context from that time. As a consequence, SL has to operate the SPS within this new regulatory framework and a small working group was set up to look at the requirements and to estimate the resources required. The conclusions of the working group are reported in this paper

Overview of LEP operation in 1998

After the installation of 32 additional RF cavities in the 1997-1998 shutdown LEP was operated at a beam energy of 94.5 GeV. The total integrated luminosity for the year 1998 clearly surpassed its target and reached 198 pb-1. Vertical beam-beam tuneshiftsof more than 0.07 were obtained. The performance did not seem to be beam-beam limited, but the total beam current was limited by power dissipation problems to around 6 mA. A high phase advance optics (102o, 90o), with a smaller natural emittance, was used for regular operation in 1998. This contributed to the excellent performance of LEP, together with the further reduction of both the horizontal and vertical beta function at the interaction points. No dynamic aperture problems were encountered

'Reaching the hard to reach' - lessons learned from the VCS (voluntary and community Sector). A qualitative study.

Background The notion 'hard to reach' is a contested and ambiguous term that is commonly used within the spheres of social care and health, especially in discourse around health and social inequalities. There is a need to address health inequalities and to engage in services the marginalized and socially excluded sectors of society. Methods This paper describes a pilot study involving interviews with representatives from eight Voluntary and Community Sector (VCS) organisations . The purpose of the study was to explore the notion of 'hard to reach' and perceptions of the barriers and facilitators to accessing services for 'hard to reach' groups from a voluntary and community sector perspective. Results The 'hard to reach' may include drug users, people living with HIV, people from sexual minority communities, asylum seekers, refugees, people from black and ethnic minority communities, and homeless people although defining the notion of the 'hard to reach' is not straight forward. It may be that certain groups resist engaging in treatment services and are deemed hard to reach by a particular service or from a societal stance. There are a number of potential barriers for people who may try and access services, including people having bad experiences in the past; location and opening times of services and how services are funded and managed. A number of areas of commonality are found in terms of how access to services for 'hard to reach' individuals and groups could be improved including: respectful treatment of service users, establishing trust with service users, offering service flexibility, partnership working with other organisations and harnessing service user involvement. Conclusions: If health services are to engage with groups that are deemed 'hard to reach' and marginalised from mainstream health services, the experiences and practices for engagement from within the VCS may serve as useful lessons for service improvement for statutory health services

The SPS as accelerator of Pb82+^{82+} ions

In 1994 the CERN SPS was used for the first time to accelerate fully stripped ions of the Pb208 isotope from the equivalent proton momentum of 13 GeV/c to 400 GeV/c. In the CERN PS, which was used as injector, the lead was accelerated as Pb53+ ions and then fully stripped in the transfer line from PS to SPS. The radio frequency swing which is needed in order to keep the synchronism during acceleration is too big to have the SPS cavities deliver enough voltage for all frequencies. For that reason a new technique of fixed frequency acceleration was used. With this technique up to 70% of the injected beam could be captured and accelerated up to the extraction energy, the equivalent of 2.2 1010 charges. The beam was extracted over a 5 sec. long spill and was then delivered to different experiments at the same time