The Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory is a second generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.Comment: 58 pages, 12 figures, submitted to Nucl. Inst. Meth. Uses elsart and epsf style files. For additional information about SNO see http://www.sno.phy.queensu.ca . This version has some new reference

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

Growth, production and fin damage in cage-held 0+ Atlantic salmon pre-smolts (Salmo salar L.) fed either a) on-demand, or b) to a fixed satiation-restriction regime: Data from a commercial farm

This experiment investigated the impact of feeding regime upon the growth performance, production efficiency and fin damage of cage-held 0+ Atlantic salmon pre-smolts. Six groups of pre-smolts (n= 61847 +/- 2620 fish group(-1)) were held in six 12 x 12 x 4 in production cages for 64 days (23rd August until 26th October) at initial and final densities of 4.6 +/- 0.2 kg m(-3) and 9.5 +/- 0.5 kg m(-3), respectively (mean +/- SEM). Fish were subjected to ambient photoperiod (11.67-16.05 h min-max) until 16th October, before being held under 24 h light. Fish were fed throughout the light phase and comparisons were made between three groups fed to an imposed regime (scheduled fixed ration feeding every 10 min) and three groups fed on-demand using commercial interactive feedback systems. The study was divided into primary and secondary phases: during the primary phase (part I) each regime was fed to satiation, whereas during the secondary phase (part II) fish under the imposed regime received a restricted ration that was ca. 20% less than those fed on-demand. During part I there were no differences in ration (g fish(-1)), fish condition and Specific Growth Rate (G,) between regimes (G(w): 1.45 +/- 0.06 vs. 1.44 +/- 0.04 for imposed vs. on-demand fed fish, respectively). During part 11 underfeeding in the imposed regime had a significant and deleterious impact upon fish condition, FCR and growth (G(w): 0.45 +/- 0.04 vs. 0.84 +/- 0.09 for imposed vs. on-demand fed fish, respectively). Fish under the imposed regime also had significantly more dorsal fin splitting than those fed on demand for the duration of the study, and significantly more dorsal fin erosion at the end of Parts I and II. In addition, the smallest fish within each cage suffered the greatest amount of fin splitting and erosion at the end of Parts I and II, irrespective of feeding regime. Daily ration amongst the on-demand cages decreased as winter approached; stepwise multiple regression analyses demonstrated that this was significantly related to a seasonal decrease in temperature