ATF2 spot size tuning using the rotation matrix

The Accelerator Test Facility (ATF2) at KEK aims to experimentally verify the local chromaticity correction scheme to achieve a vertical beam size of 37nm. The facility is a scaled down version of the final focus design proposed for the future linear colliders. In order to achieve this goal, high precision tuning methods are being developed. One of the methods proposed for ATF2 is a novel method known as the ‘rotation matrix’ method. Details of the development and testing of this method, including orthogonality optimisation and simulation methods, are presented

4D Emittance Measurements Using Multiple Wire and Waist Scan Methods in the ATF Extraction Line.

TUPC087International audienceEmittance measurements performed in the diagnostic section of the ATF extraction line since 1998 lead to ver- tical emittances three times larger than the expected ones, with a strong dependence on intensity. An experimental program is pursued to investigate potential sources of emit- tance growth and find possible remedies. This requires ef- ficient and reliable emittance measurement techniques. In the past, several phase-space reconstruction methods devel- oped at SLAC and KEK have been used to estimate the ver- tical emittance, based on multiple location beam size mea- surements and dedicated quadrupole scans. These methods have been shown to be very sensitive to measurement er- rors and other fluctuations in the beam conditions. In this context new emittance measurements have been performed revisiting these methods and newly developed ones with a systematic approach to compare and characterise their per- formance in the ATF extraction line

Plans and progress towards tuning the ATF2 final focus system to obtain a 35 nm IP waist

FR5PFP021International audienceUsing a new extraction line currently being commissioned, the ATF2 experiment plans to test a novel compact final focus optics design using a local chromaticity correction scheme, such as could be used in future linear colliders*. Using a 1.3 GeV beam of ∼30nm normalised vertical emittance extracted from the ATF damping ring, the primary goal is to achieve a vertical IP waist of 35nm. We discuss our planned strategy, implementation details and early experimental results for tuning the ATF2 beam to meet the primary goal. These optics require uniquely tight tolerances on some magnet strengths and positions, we discuss efforts to re-match the optics to meet these requirements using high-precision measurements of key magnet elements. We simulated in detail the tuning procedure using several algorithms and different code implementations for comparison from initial orbit establishment to final IP spot-size tuning. Through a Monte Carlo study of 100's of simulation seeds we find we can achieve a spot-size within 10% of the design optics value in at least 90% of cases. We also ran a simulation to study the long-term performance with the use of beam-based feedbacks

Size and shape constancy in consumer virtual reality

With the increase in popularity of consumer virtual reality headsets, for research and other applications, it is important to understand the accuracy of 3D perception in VR. We investigated the perceptual accuracy of near-field virtual distances using a size and shape constancy task, in two commercially available devices. Participants wore either the HTC Vive or the Oculus Rift and adjusted the size of a virtual stimulus to match the geometric qualities (size and depth) of a physical stimulus they were able to refer to haptically. The judgments participants made allowed for an indirect measure of their perception of the egocentric, virtual distance to the stimuli. The data show under-constancy and are consistent with research from carefully calibrated psychophysical techniques. There was no difference in the degree of constancy found in the two headsets. We conclude that consumer virtual reality headsets provide a sufficiently high degree of accuracy in distance perception, to allow them to be used confidently in future experimental vision science, and other research applications in psychology

An electrically driven, computer controlled robotics platform for orchard use

As automation in agriculture progresses, more automation systems will be placed into farms & orchards. Systems that service the crops directly are likely to have positioning requirements that make traditional tractor-trailer units unsuitable. This paper introduces a platform built for transporting robotics modules through a kiwifruit orchard. Performance figures, design considerations and a general hardware overview are presented. The platform is controlled either by remote or computer generated drive commands - facilitating autonomous navigation. In-orchard testing shows the system is well suited for the target application, achieving stable speed control and repeatable positioning

The effect of wave conditions and surfer ability on performance and the physiological response of recreational surfers.

This study investigated the effects of wave conditions on performance and the physiological responses of surfers. After institutional ethical approval 39 recreational surfers participated in 60 surfing sessions where performance and physiological response were measured using global positioning system (GPS) heart rate monitors. Using GPS, the percentage time spent in surfing activity categories was on average 41.6, 47.0, 8.1, and 3.1% for waiting, paddling, riding, and miscellaneous activities, respectively. Ability level of the surfers, wave size, and wave period are significantly associated with the physiological, ride, and performance parameters during surfing. As the ability level of the surfers increases there is a reduction in the relative exercise intensity (e.g., average heart rate as a percentage of laboratory maximum, rpartial = -0.412, p < 0.01) which is in contrast to increases in performance parameters (e.g., maximum ride speed (0.454, p < 0.01). As the wave size increased there were reductions in physiological demand (e.g., total energy expenditure rpartial = -0.351, p ≤ 0.05) but increases in ride speed and distance measures (e.g., the maximum ride speed, 0.454, p < 0.01). As the wave period increased there were increases in intensity (e.g., average heart rate as a percentage of laboratory maximum, rp = 0.490, p < 0.01) and increases in ride speed and distance measures (e.g., the maximum ride speed, rpartial = 0.371, p < 0.01). This original study is the first to show that wave parameters and surfer ability are significantly associated with the physiological response and performance characteristics of surfing

Infrared Spectroscopy of Symbiotic Stars. IV. V2116 Ophiuchi/GX 1+4, The Neutron Star Symbiotic

We have computed, based on 17 infrared radial velocities, the first set of orbital elements for the M giant in the symbiotic binary V2116 Ophiuchi. The giant's companion is a neutron star, the bright X-ray source GX 1+4. We find an orbital period of 1161 days by far the longest of any known X-ray binary. The orbit has a modest eccentricity of 0.10 with an orbital circularization time of less than 10^6 years. The large mass function of the orbit significantly restricts the mass of the M giant. Adopting a neutron-star mass of 1.35M(Sun), the maximum mass of the M giant is 1.22M(Sun), making it the less massive star. Derived abundances indicate a slightly subsolar metallicity. Carbon and nitrogen are in the expected ratio resulting from the red-giant first dredge-up phase. The lack of O-17 suggests that the M-giant has a mass less than 1.3M(Sun), consistent with our maximum mass. The red giant radius is 103R(Sun), much smaller than the estimated Roche lobe radius. Thus, the mass loss of the red giant is via a stellar wind. Although the M giant companion to the neutron star has a mass similar to the late-type star in low-mass X-ray binaries, its near-solar abundances and apparent runaway velocity are not fully consistent with the properties of this class of stars.Comment: In press to The Astrophysical Journal (10 April 2006 issue). 23 page

Exploring ultra-low β* values in ATF2 - R&D Programme proposal

We propose to explore the beam sizes and performance of the ATF2 Final Focus System for reduced IP beta functions up to a factor between 2 and 4 below its design. The results will demonstrate the feasibility of the system in a chromaticity regime of interest for CLIC and ILC

Optimal Duration and Timing of Adjuvant Chemotherapy After Definitive Surgery for Ductal Adenocarcinoma of the Pancreas: Ongoing Lessons From the ESPAC-3 Study

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Antibiotics modulate biofilm formation in fish pathogenic isolates of atypical Aeromonas salmonicida

Atypical Aeromonas salmonicida causes furunculosis infections of non‐salmonid fish, which requires antibiotic therapy. However, antibiotics may induce biofilm in some bacteria, which protects them against hostile conditions while allowing them to persist on surfaces, thus forming a reservoir for infection. The aim of this study was to determine whether atypical isolates of A. salmonicida increased biofilm in the presence of two antibiotics, florfenicol and oxytetracycline. A microtitre plate assay was used to quantify biofilm in the presence and absence of each antibiotic. Fifteen of 28 isolates formed biofilms under control conditions, while 23 of 28 isolates increased biofilm formation in the presence of at least one concentration of at least one antibiotic. For oxytetracycline, the most effective concentration causing biofilm to increase was one‐quarter of that preventing visible bacterial growth, whereas for florfenicol it was one‐half of this value. This is the first study to demonstrate that a bacterial pathogen of fish increases biofilm in response to antibiotics. Biofilm formation may increase the risk of re‐infection in culture systems and this lifestyle favours the transmission of genetic material, which has implications for the dissemination of antibiotic‐resistance genes and demonstrates the need for enhanced disease prevention measures against atypical A. salmonicida