Introduction to Laser Physics

This paper is a basic introduction to laser physics, especially that relevant to accelerator science. It presents the essential physics of a laser, some of the different types of laser system available, the propagation of laser beams, and the key diagnostics that are used for lasers

The Coherent Combination of Fibre Lasers - Towards Realistic Applications

To drive a laser-plasma wakefield, high peak-power laser pulses are required. For useful accelerator applications, it is also necessary to have driving lasers with high efficiency, repetition rates, and average power. The coherent combination of Ytterbium-doped fibre laser amplifiers is a promising potential solution, and previous work has demonstrated the successful combination of near-identical ultrafast fibre lasers. We report here the combination of significantly mismatched Ytterbium-doped photonic crystal fibre amplifiers with a combined efficiency of 96%, while the locked power output remained stable for 6 hours. The combined output of the system had a total gain of 12 dB, with no detrimental effect on the compressed pulse width observed

Reconciling surveillance systems with limited resources: an evaluation of passive surveillance for rabies in an endemic setting

Surveillance systems for rabies in endemic regions are often subject to severe constraints in terms of resources. The World Organisation for Animal Health (OIE) and the World Health Organisation (WHO) propose the use of an active surveillance system to substantiate claims of disease freedom, including rabies. However, many countries do not have the resources to establish active surveillance systems for rabies and the testing of dead dogs poses logistical challenges. This paper explores the potential of using a scenario tree model parameterised with data collected via questionnaires and interviews to estimate the sensitivity of passive surveillance, assessing its potential as a viable low-cost alternative to active surveillance systems. The results of this explorative study illustrated that given a large enough sample size, in this case the entire population of Colombo City, the sensitivity of passive surveillance can be 100% even at a low disease prevalence (0.1%), despite the low sensitivity of individual surveillance components (mean values in the range 4.077×10(-5)-1.834×10(-3) at 1% prevalence). In addition, logistic regression was used to identify factors associated with increased recognition of rabies in dogs and reporting of rabies suspect dogs. Increased recognition was observed amongst dog owners (OR 3.8 (CI, 1.3-10.8)), people previously bitten by dogs (OR 5.9 (CI, 2.2-15.9)) and people who believed they had seen suspect dogs in the past (OR 4.7 (CI, 1.8-12.9)). Increased likelihood of reporting suspect dogs was observed amongst dog owners (OR 5.3 (CI, 1.1-25)). Further work is required to validate the data collection tool and the assumptions made in the model with respect to sample size in order to develop a robust methodology for evaluating passive rabies surveillance

OH detection by absorption of frequency-doubled diode laser radiation at 308nm

Radiation at 308 nm has been obtained by frequency doubling the output of a commercial diode laser cooled to 165 K. A single pass through a crystal of LiIO3 converted 1 mW of 616 nm radiation to 50 pW of UV, and this was used to detect the OH radical in absorption in a flow tube. Possible extensions of the method for detection of OH in the atmosphere are discussed

The role of values in collaborative consumption: insights from a product-service system for lending and borrowing in the UK

Collaborative consumption is an emerging socio-economic model based on sharing, renting, gifting, bartering, swapping, lending and borrowing. Made possible through community interaction and, increasingly, use of network technologies, these alternative and more sustainable ways of consuming have attracted growing attention for their potential to prevent new purchases, intensify the use of idle assets and promote reuse of possessions that are no longer wanted. Nonetheless, the uptake of Product- Service Systems (PSSs) that enable collaborative consumption is still very limited. This paper investigates how consumers' values can influence the acceptance, adoption and diffusion of collaborative consumption. It reviews two theoretical frameworks used to understand pro-environmental behaviour, social psychological models of behaviour and social practice theory. Coming from contrasting disciplinary perspectives, these approaches conceptualise values differently. The paper evaluates the possibility of resolving these differences through a mixed methods study. It examines values empirically through a case study of Ecomodo, a UK-based online marketplace where people can lend and borrow each other's objects, spaces and skills, and present the results of a quantitative study which identified and measured value priorities among Ecomodo users through Schwartz's Portrait Value Questionnaire. It concludes with a discussion of the role of values in relation to the introduction and scaling up of PSSs that enable collaborative consumption

Micron-scale laser-wire scanner for the KEK Accelerator Test Facility extraction line

A laser-wire transverse electron beam size measurement system has been constructed and operated at the Accelerator Test Facility (ATF) extraction line at KEK. The construction of the system is described in detail along with the environment of the ATF related to the laser wire. A special set of electron beam optics was developed to generate an approximately 1 mu m vertical focus at the laser-wire location. The results of our operation at the ATF extraction line are presented, where a minimum rms electron beam size of 4: 8 +/- 0: 3 mu m was measured, and smaller electron beam sizes can be measured by developing the method further. The beam size at the laser-wire location was changed using quadrupoles and the resulting electron beam size measured, and vertical emittance extracted

Abstracts from the NIHR INVOLVE Conference 2017

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