LHC@home: a Volunteer Computing System for Massive Numerical Simulations of Beam Dynamics and High Energy Physics Events

Recently, the LHC@home system has been revived at CERN. It is a volunteer computing system based on BOINC which allows boosting the available CPU-power in institutional computer centers by the help of individuals that donate the CPU-time of their PCs. Currently two projects are hosted on the system, namely SixTrack and Test4Theory. The first is aimed at performing beam dynamics simulations, while the latter deals with the simulation of high-energy events. In this paper the details of the global system, as well a discussion of the capabilities of either project will be presented. Milestones of progress of the projects will also be discussed

Feasibility Experiment Of Granular Target Options for Future Neutrino Facilities

Fragmented solid targets made of either fluidised tungsten powder or static pebble bed of tungsten spheres, have been long proposed and are being studied as an alternative configuration towards high-power (>1 MW of beam power) target systems, suitable for a future Super Beam or Neutrino Factory. Such assemblies offer many advantages as better thermal and inertial stress absorption, thermal cooling and, if in the fluidised form, regeneration. We propose to perform a validation test of a tungsten powder target. The proposed feasibility experiment will try on a pulse-by-pulse basis to address the effect of the impact of a high-power pulsed beam in such an assembly using both online diagnostic tools with high-speed cameras, laser vibrometry and acoustic measurements, as well as offline, post-irradiation analysis of the target material

Feasibility Experiment of a Granular Target for Future Neutrino Facilities

Granular, solid targets made of fluidized tungsten powder or static pebble bed of tungsten spheres, have been proposed and are being studied as an alternative configurations towards high-power (1MW of beam power) target systems, suitable for a future Super Beam or Neutrino Factory. With the lack of experimental data on this field, a feasibility experiment was performed in HiRadMat facility of CERN/SPS that tried on a pulse-by-pulse basis to address the effect of the impact of the SPS beam (440GeV/c) on a static tungsten granular target. Online instrumentation such as high-speed photography and laser-Doppler vibrometry was employed. Preliminary results show a powder disruption speed of less than 0.6 m/s at 3E11 protons/pulse while the disruption speed appears to be scaling proportionally with the beam intensity

A FEASIBILITY EXPERIMENT OF A W-POWDER TARGET IN THE HIRADMAT FACILITY AT CERN

Granular solid targets made of fluidized tungsten powder or a static pebble bed of tungsten spheres, have been proposed and are being studied as an alternative configuration for high-power (>1MW of beam power) target systems, suitable for a future Super Beam or Neutrino Factory. Due to the lack of experimental data on this field, a feasibility experiment was performed in HiRadMat facility of CERN to address the effect of the impact of the SPS beam (440 GeV/c) on a static tungsten powder target. Online instrumentation such as high-speed photography and laser-Doppler vibrometry was employed. Preliminary results show a powder disruption speed of less than 0.6 m/s at 3 1011 protons/pulse while the disruption speed appears to scale with the beam intensity

Application of machine learning techniques at the CERN Large Hadron Collider

Machine learning techniques have been used extensively in several domains of Science and Engineering for decades. These powerful tools have been applied also to the domain of high-energy physics, in the analysis of the data from particle collisions, for years already. Accelerator physics, however, has not started exploiting machine learning until very recently. Several activities are flourishing in this domain, in view of providing new insights to beam dynamics in circular accelerators, in different laboratories worldwide. This is, for instance, the case for the CERN Large Hadron Collider, where since a few years exploratory studies are being carried out. A broad range of topics have been addressed, such as anomaly detection of beam position monitors, analysis of optimal correction tools for linear optics, optimisation of the collimation system, lifetime and performance optimisation, and detection of hidden correlations in the huge data set of beam dynamics observables collected during the LHC Run 2. Furthermore, very recently, machine learning techniques are being scrutinised for the advanced analysis of numerical simulations data, in view of improving our models of dynamic aperture evolution.peer-reviewe

The lifespan and kinetics of human dendritic cell subsets and their precursors in health and inflammation

Dendritic cells (DC) are specialized mononuclear phagocytes that link innate and adaptive immunity. They comprise two principal subsets: plasmacytoid DC (pDC) and conventional DC (cDC). Understanding the generation, differentiation, and migration of cDC is critical for immune homeostasis. Through human in vivo deuterium-glucose labeling, we observed the rapid appearance of AXL+ Siglec6+ DC (ASDC) in the bloodstream. ASDC circulate for ∼2.16 days, while cDC1 and DC2 circulate for ∼1.32 and ∼2.20 days, respectively, upon release from the bone marrow. Interestingly, DC3, a cDC subset that shares several similarities with monocytes, exhibits a labeling profile closely resembling that of DC2. In a human in vivo model of cutaneous inflammation, ASDC were recruited to the inflammatory site, displaying a distinctive effector signature. Taken together, these results quantify the ephemeral circulating lifespan of human cDC and propose functions of cDC and their precursors that are rapidly recruited to sites of inflammation

Comparison of the Kinematics Following Gait Perturbation in Individuals Who Did or Did Not Undergo Total Knee Replacement

We aimed to compare the spatiotemporal parameters and joint kinematics during unperturbed and perturbed gait between individuals with osteoarthritis (OA) who did or did not undergo total knee replacement (TKR) one year post a baseline evaluation. OA subjects scheduled for TKR (TKR group; n = 14) and not scheduled for TKR (NTKR group; n = 17) were age-matched. Outcome measures included: joint range of motion, timed up and go, joint pain levels, Oxford score, and the Activities-specific Balance Confidence Scale. In addition, spatiotemporal gait parameters and joint kinematics were recorded during perturbed and unperturbed gait. After one year, most of the TKR group (71%), but only 41% of the NTKR group, increased their gait velocity by more than 0.1m/sec, which is the meaningful clinical important difference for gait velocity. After perturbation of the contralateral limb, the TKR group showed a greater decrease in the maximal extension of the OA hip compared to the NTKR group (p = 0.031). After perturbation of the OA limb, more subjects decreased their OA knee flexion–extension range in the NTKR group compared to the TKR group (p = 0.011) and more subjects decreased their maximal ankle plantar flexion in the TKR group (p = 0.049). Although the surgery was successful in terms of pain reduction and increased functionality, individuals following TKR exhibited unique compensatory strategies in response to the perturbation of both limbs. These findings might suggest that balance deficits remain in individuals following TKR and therefore are associated with a risk of falls