Beam losses from ultra-peripheral nuclear collisions between Pb ions in the Large Hadron Collider and their alleviation

Electromagnetic interactions between colliding heavy ions at the Large Hadron Collider (LHC) at CERN will give rise to localized beam losses that may quench superconducting magnets, apart from contributing significantly to the luminosity decay. To quantify their impact on the operation of the collider, we have used a three-step simulation approach, which consists of optical tracking, a Monte-Carlo shower simulation and a thermal network model of the heat flow inside a magnet. We present simulation results for the case of Pb ion operation in the LHC, with focus on the ALICE interaction region, and show that the expected heat load during nominal Pb operation is 40% above the quench level. This limits the maximum achievable luminosity. Furthermore, we discuss methods of monitoring the losses and possible ways to alleviate their effect.Comment: 17 pages, 20 figure

Initial evidence for the criterion-related and structural validity of the long versions of the direct and meta-perspectives of the Coach-Athlete Relationship Questionnaire

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 Taylor & Francis.The aim of the present study was to develop and initially validate a longer version of the direct (Jowett & Ntoumanis, 2004) and meta-perspectives (Jowett, 2009a, 2009b) of the Coach-Athlete Relationship Questionnaire (CART-Q). In Study 1, instruments (e.g. questionnaires, scales, and inventories) that have been used to assess relationship quality in the broader psychological literature were examined and items potentially relevant to the coach-athlete relationship were identified. The content validity of the identified items was then assessed using expert panels. A final questionnaire was subsequently prepared and administered to 693 participants (310 coaches and 383 athletes). Confirmatory factor analysis was employed to assess the multidimensional nature of the questionnaire based on the 3Cs (i.e. closeness, commitment, and complementarity) model of the coach-athlete relationship. The findings indicated that the direct and meta-perspective items of the long versions of the CART-Q approached an adequate data fit. Moreover, evidence for the internal consistency and criterion validity of the new instruments was also obtained. In Study 2, the newly developed measure was administered to an independent sample of 251 individuals (145 athletes and 106 coaches). Further statistical support was gained for the factorial validity and reliability of the longer version of the CART-Q

Physics Opportunities with the FCC-hh Injectors

In this chapter we explore a few examples of physics opportunities using the existing chain of accelerators at CERN, including potential upgrades. In this context the LHC ring is also considered as a part of the injector system. The objective is to find examples that constitute sensitive probes of New Physics that ideally cannot be done elsewhere or can be done significantly better at theCERN accelerator complex. Some of these physics opportunities may require a more flexible injector complex with additional functionality than that just needed to inject protons into the FCC-hh at the right energy, intensity and bunch structure. Therefore it is timely to discuss these options concurrently with the conceptual design of the FCC-hh injector system.Comment: 13 pages, chapter 5 in Physics at the FCC-hh, a 100 TeV pp collide

Measurements of heavy ion beam losses from collimation

The collimation efficiency for Pb ion beams in the LHC is predicted to be lower than requirements. Nuclear fragmentation and electromagnetic dissociation in the primary collimators create fragments with a wide range of Z/A ratios, which are not intercepted by the secondary collimators but lost where the dispersion has grown sufficiently large. In this article we present measurements and simulations of loss patterns generated by a prototype LHC collimator in the CERN SPS. Measurements were performed at two different energies and angles of the collimator. We also compare with proton loss maps and find a qualitative difference between Pb ions and protons, with the maximum loss rate observed at different places in the ring. This behavior was predicted by simulations and provides a valuable benchmark of our understanding of ion beam losses caused by collimation.Comment: 12 pages, 20 figure

Optics Considerations for the PS2

CERN envisages replacing the existing Proton Synchrotron (PS) with a larger synchrotron (PS2) capable of injecting at higher energy into the SPS. Since it should increase the performance not only of the LHC but also CNGS and other users of beams from CERN's hadron injector complex, the new accelerator must retain much of the flexibility of the present complex. A number of candidate optics, with and without transition crossing, have been evaluated systematically and compared

Linear Optics Design for PS2

The design considerations and key parameters for the replacement of the CERN Proton Synchrotron (PS) with a new ring (PS2), as part of the upgrade of the LHC injector complex are summarized. Classical linear optics solutions including standard FODO, doublet and triplet cells with real transition energy, are studied. Particular emphasis is given to the tuning and optimisation of Negative Momentum Compaction (NMC) cells with imaginary transition energy. The optics of the high energy transfer line is also presented

Developing a best practice framework for musculoskeletal outpatient physiotherapy delegation: the MOPeD mixed-methods research study protocol.

INTRODUCTION: Physiotherapy assistants/support workers are an important part of the physiotherapy workforce in the UK. Many of them work in National Health Service (NHS) physiotherapy outpatient services treating patients with musculoskeletal (MSK) conditions. In many services, they take responsibility, under professional supervision, for types of clinical work traditionally undertaken by physiotherapists such as leading exercise classes and treating individual patients. Nevertheless, their role(s) are relatively undefined and as such, there is considerable variation in the duties and tasks they undertake. This study aims to design a framework of 'best practice' in delegation to guide the work of clinicians in NHS physiotherapy MSK services and facilitate standardisation of practice to ensure that patients receive safe and effective treatment by the most appropriate person. METHODS AND ANALYSIS: This mixed-methods study will be conducted in four stages. In stage 1, a focused ethnography in two MSK outpatient physiotherapy services will explore how the current use of delegation is informed by the culture within the clinical setting as well as views, attitudes about, and experiences of, delegation among clinicians, managers and patients. In stage 2a, nominal group technique will be used with three separate groups (physiotherapists/physiotherapy assistants/support workers, managers) to reach a consensus about what components should be included in a best practice framework of delegation. In stage 2b, a discrete choice experiment will elicit patients' preferences between care from physiotherapists and physiotherapy assistants/support workers within MSK physiotherapy services. In the final stage, the results of all previous stages will be triangulated to inform the development of a best practice delegation framework for future testing and use within NHS MSK outpatient physiotherapy services. ETHICS AND DISSEMINATION: Ethical approval has been granted by the South West-Frenchay Research Ethics Committee. The findings will be disseminated in peer-reviewed journals, conference presentations, the lay press and social media

Delegation of workload from musculoskeletal physiotherapists to physiotherapy assistants/support workers: A UK online survey.

PURPOSE: There are approximately 9000 physiotherapy assistants/support workers in the UK. Many of them work in NHS physiotherapy outpatient services treating patients with musculoskeletal conditions, but their role(s) are relatively undefined and as such there is considerable variation in the duties and tasks they undertake. This study aimed to explore current practice of UK musculoskeletal physiotherapists in relation to delegation to physiotherapy assistants/support workers. METHODS: An online cross-sectional descriptive survey was designed and collected data on delegation practice and training in delegation. The survey was piloted with 10 physiotherapists. The final questionnaire was distributed via the interactive Chartered Society of Physiotherapy's website and the authors' professional networks via Twitter. Responses were collected over a five-week-period from October to November 2020. RESULTS: Of 302 survey responses, 232 were analysed (46 incomplete, 24 ineligible). The majority of respondents (66.3%, 154/232) had worked as physiotherapists for over 10 years. Most respondents indicated they had neither formal training (84%, 195/232) nor informal training (60.3%, 140/232) regarding how to delegate tasks. The clinical tasks most commonly delegated by physiotherapists were supervision of exercises (81.0%, 188/232) and walking aid provision (78.5%, 182/232) whereas the least delegated clinical task was the application of electrotherapy (19.8%, 46/232). CONCLUSION: These survey results provide evidence for the need to improve training in delegation for both physiotherapists and physiotherapy assistants, and to ensure clearer delegation processes to facilitate good delegation practice in the musculoskeletal setting

Design of beam optics for the Future Circular Collider e+e- -collider rings

A beam optics scheme has been designed for the Future Circular Collider-e+e- (FCC-ee). The main characteristics of the design are: beam energy 45 to 175 GeV, 100 km circumference with two interaction points (IPs) per ring, horizontal crossing angle of 30 mrad at the IP and the crab-waist scheme [1] with local chromaticity correction. The crab-waist scheme is implemented within the local chromaticity correction system without additional sextupoles, by reducing the strength of one of the two sextupoles for vertical chromatic correction at each side of the IP. So-called "tapering" of the magnets is applied, which scales all fields of the magnets according to the local beam energy to compensate for the effect of synchrotron radiation (SR) loss along the ring. An asymmetric layout near the interaction region reduces the critical energy of SR photons on the incoming side of the IP to values below 100 keV, while matching the geometry to the beam line of the FCC proton collider (FCC-hh) [2] as closely as possible. Sufficient transverse/longitudinal dynamic aperture (DA) has been obtained, including major dynamical effects, to assure an adequate beam lifetime in the presence of beamstrahlung and top-up injection. In particular, a momentum acceptance larger than +/-2% has been obtained, which is better than the momentum acceptance of typical collider rings by about a factor of 2. The effects of the detector solenoids including their compensation elements are taken into account as well as synchrotron radiation in all magnets. The optics presented in this paper is a step toward a full conceptual design for the collider. A number of issues have been identified for further study