Real-Time Control, Acquisition and Data Treatment for Beam Current Transformers in a Transfer Line

Particle beams are transferred from the 1 GeV Booster to the 26 GeV Proton Synchrotron and to an experimental area, ISOLDE. The characteristics of the beams and their destination change on a 1.2 s cycle basis. There are six beam current transformers to measure the beam intensities, i.e. the number of particles passing through the transfer lines. On each pulse of the Booster, a real-time system, called BTTR (Beam Transfer TRansformers), acquires the transformer values, selects the range, executes a calibration, and treats the data. Part of the treatment is the subtraction of the base-value, which includes systematic perturbations, acquired in the absence of beam. The system also handles asynchronous tasks, such as acquisition of base-value, readout of calibration factors and other diagnostic actions. The concept of the BTTR and its design are presented, as well as some practical results

An adaptive hierarchical particle-mesh code with isolated boundary conditions

This article describes a new, fully adaptive Particle-Multiple-Mesh numerical simulation code developed primarily for simulations of small regions (such as a group of galaxies) in a cosmological context. It integrates the equations of motion of a set of particles subject to their mutual gravitational interaction and to an arbitrary external field. The interactions are computed using a hierarchy of nested grids constructed anew at each integration step to enhance the spatial resolution in high-density regions of interest. Significant effort has gone into supporting isolated boundary conditions at the top grid level. This makes our method also applicable to non-cosmological problems, at the cost of some complications which we discuss. We point out the implications of some differences between our approach and those of other authors of similar codes, in particular with respect to the handling of the interface between regions of different spatial resolution. We present a selection of tests performed to verify the correctness and performance of our implementation. The conclusion suggests possible further improvements in the areas of independent time steps and particle softening lengths.Comment: 35 pages, LaTeX, uses aaspp4.sty, 8 figures included ApJ, in press. Only modest changes from earlier posted versio

Cold collapse and the core catastrophe

We show that a universe dominated by cold dark matter fails to reproduce the rotation curves of dark matter dominated galaxies, one of the key problems that it was designed to resolve. We perform numerical simulations of the formation of dark matter halos, each containing \gsim 10^6 particles and resolved to 0.003 times the virial radius, allowing an accurate comparison with rotation curve data. A good fit to both galactic and cluster sized halos can be achieved using the density profile rho(r) \propto [(r/r_s)^1.5(1+(r/r_s)^1.5)]^-1, where r_s is a scale radius. This profile has a steeper asymptotic slope, rho(r) \propto r^-1.5, and a sharper turnover than found by lower resolution studies. The central structure of relaxed halos that form within a hierarchical universe has a remarkably small scatter (unrelaxed halos would not host disks). We compare the results with a sample of dark matter dominated, low surface brightness (LSB) galaxies with circular velocities in the range 100-300 km/s. The rotation curves of disks within cold dark matter halos rise too steeply to match these data which require a constant mass density in the central regions. The same conclusion is reached if we compare the scale free shape of observed rotation curves with the simulation data. It is important to confirm these results using stellar rather than HI rotation curves for LSB galaxies. We test the effects of introducing a cut-off in the power spectrum that may occur in a universe dominated by warm dark matter. In this case halos form by a monolithic collapse but the final density profile hardly changes, demonstrating that the merger history does not play a role in determining the halo structure.Comment: Latex 13 pages, 4 figures. Submitted to MNRAS. High resolution colour version of figure 4 and other N-body images here: http://star-www.dur.ac.uk:80/~moore/images

Acceleration of lead ions in the CERN PS booster and the CERN PS

The new CERN Heavy Ion Accelerating Facility also requires besides a new Linac substantial modifications of existing accelerators. They are imposed by the low speed and the low intensity of the ion beam and, crucially at low energy, by the short lifetime of the partially stripped ions due to charge exchange with the atoms of the residual gas. The upgraded vacuum system hits the limits of a non-bakeable machine and consequently the acceleration had to be sped up by all means. In the Booster this led to injection and RF capture on a fast-rising magnet cycle and a new digital RF beam control system. Beam current transformers had to be replaced by new, heavily shielded ones. Other modifications include a new staircase magnet to distribute ions over the four Booster rings, lengthening of septa and kicker pulses, plus new, bakeable extraction septa and an energy stabilizing RF loop on the flat top in the CPS, and a stripper in the transfer line to the SPS

Magnetic Field and Pressure Phase Diagrams of Uranium Heavy-Fermion Compound U2_2Zn17_{17}

We have performed magnetization measurements at high magnetic fields of up to 53 T on single crystals of a uranium heavy-fermion compound U$_2$Zn$_{17}$ grown by the Bridgman method. In the antiferromagnetic state below the N\'{e}el temperature $T_{\rm N}$ = 9.7 K, a metamagnetic transition is found at $H_c$ $\simeq$ 32 T for the field along the [11$\bar{2}$0] direction ($a$-axis). The magnetic phase diagram for the field along the [11$\bar{2}$0] direction is given. The magnetization curve shows a nonlinear increase at $H_m$ $\simeq$ 35 T in the paramagnetic state above $T_{\rm N}$ up to a characteristic temperature $T_{{\chi}{\rm max}}$ where the magnetic susceptibility or electrical resistivity shows a maximum value. This metamagnetic behavior of the magnetization at $H_m$ is discussed in comparison with the metamagnetic magnetism of the heavy-fermion superconductors UPt$_3$, URu$_2$Si$_2$, and UPd$_2$Al$_3$. We have also carried out high-pressure resistivity measurement on U$_2$Zn$_{17}$ using a diamond anvil cell up to 8.7 GPa. Noble gas argon was used as a pressure-transmitting medium to ensure a good hydrostatic environment. The N\'{e}el temperature $T_{\rm N}$ is almost pressure-independent up to 4.7 GPa and starts to increase in the higher-pressure region. The pressure dependences of the coefficient of the $T^2$ term in the electrical resistivity $A$, the antiferromagnetic gap $\Delta$, and the characteristic temperature $T_{{\rho}{\rm max}}$ are discussed. It is found that the effect of pressure on the electronic states in U$_2$Zn$_{17}$ is weak compared with those in the other heavy fermion compounds

Associations of Insulin and Insulin-Like Growth Factors with Physical Performance in Old Age in the Boyd Orr and Caerphilly Studies

Objective Insulin and the insulin-like growth factor (IGF) system regulate growth and are involved in determining muscle mass, strength and body composition. We hypothesised that IGF-I and IGF-II are associated with improved, and insulin with worse, physical performance in old age. Methods Physical performance was measured using the get-up and go timed walk and flamingo balance test at 63–86 years. We examined prospective associations of insulin, IGF-I, IGF-II and IGFBP-3 with physical performance in the UK-based Caerphilly Prospective Study (CaPS; n = 739 men); and cross-sectional insulin, IGF-I, IGF-II, IGFBP-2 and IGFBP-3 in the Boyd Orr cohort (n = 182 men, 223 women). Results In confounder-adjusted models, there was some evidence in CaPS that a standard deviation (SD) increase in IGF-I was associated with 1.5% faster get-up and go test times (95% CI: −0.2%, 3.2%; p = 0.08), but little association with poor balance, 19 years later. Coefficients in Boyd Orr were in the same direction as CaPS, but consistent with chance. Higher levels of insulin were weakly associated with worse physical performance (CaPS and Boyd Orr combined: get-up and go time = 1.3% slower per SD log-transformed insulin; 95% CI: 0.0%, 2.7%; p = 0.07; OR poor balance 1.13; 95% CI; 0.98, 1.29; p = 0.08), although associations were attenuated after controlling for body mass index (BMI) and co-morbidities. In Boyd Orr, a one SD increase in IGFBP-2 was associated with 2.6% slower get-up and go times (95% CI: 0.4%, 4.8% slower; p = 0.02), but this was only seen when controlling for BMI and co-morbidities. There was no consistent evidence of associations of IGF-II, or IGFBP-3 with physical performance. Conclusions There was some evidence that high IGF-I and low insulin levels in middle-age were associated with improved physical performance in old age, but estimates were imprecise. Larger cohorts are required to confirm or refute the findings