We describe the use of machine learning algorithms to select high-quality measurements for the Mu2e experiment. This technique is important for experiments with backgrounds that arise due to ...measurement errors. The algorithms use multiple pieces of ancillary information that are sensitive to measurement quality to separate high-quality and low-quality measurements.
A preliminary thermal 1D numerical model for studying the demise behavior of stainless steel 316L, silicon carbide (SiC) and carbon fiber reinforced polymer (CFRP) during uncontrolled atmospheric ...entry is proposed. Test case modeling results are compared to experimental data obtained in the framework of ESA Clean Space initiative: material samples were exposed to different heat flux conditions using the Plasma Wind Tunnel (PWT) facilities at the Institute of Space Systems (IRS) of the University of Stuttgart. This numerical model approximates the heating history of the selected materials by simulating their thermal response and temperature profiles, which have trends similar to the experimental curves that are found. Moreover, when high heat flux conditions are considered, the model simulates the materials' mass loss due to the ablation process: at the end of the simulation, the difference between the experimental and the modeled results is about 17% for CFRP and 35% for stainless steel. To reduce the model's uncertainties, the following analysis suggests the need to consider the influence of adequate material thermophysical properties and the physical-chemical processes that affect the samples' temperature profile and mass loss.
Abstract
It is widely accepted that the next lepton collider beyond a
Higgs factory would require center-of-mass energy of the order of up
to 15 TeV. Since, given reasonable space and cost ...restrictions,
conventional accelerator technology reaches its limits near this
energy, high-gradient advanced acceleration concepts are
attractive. Advanced and novel accelerators (ANAs) are leading
candidates due to their ability to produce acceleration gradients on
the order of 1–100 GV/m, leading to compact acceleration
facilities. However, intermediate energy facilities (IEF) are
required to test the critical technology elements on the way towards
multi-TeV-class collliders. Here a science case for a 20–100 GeV
center-of-mass energy ANA-based lepton collider that can be a
candidate for an intermediate energy facility is presented. The IEF
can provide numerous opportunities for high energy physics studies
including precision Quantum Chromodynamics and Beyond the Standard
Model physics measurements, investigation of charged particle
interactions with extreme electromagnetic fields, and exploring muon
and proton beam acceleration. Possible applications of this collider
include the studies of γγ and electron beam-fixed
target/beamdump collider designs. Thus, the goal of the proposed IEF
is to both carry out particle physics measurements in the
20-100 GeV ranges as well as to serve as an ANA demonstrator
facility.
These proceedings present the method and performance of primary vertex reconstruction at the ATLAS experiment during Runs 1 and 2 at the LHC. The studies presented focus on data taken during 2012 at ...a centre-of-mass energy of s=8TeV, and during 2015-2016 at s=13TeV. Some predictions toward future runs are also presented. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed.
The reconstruction of vertices corresponding to proton-proton collisions in ATLAS is an essential element of event reconstruction used in many performance studies and physics analyses. During Run-1 ...of the LHC, ATLAS has employed an iterative approach to vertex finding. In order to improve the flexibility of the algorithm and ensure continued performance for very high numbers of simultaneous collisions in Run-2 of the LHC and beyond, a new approach to seeding vertex finding has been developed inspired by image reconstruction techniques. This note provides a brief outline of how reconstructed tracks are used to create an image of likely vertex collisions in an event, describes the implementation in the ATLAS software, and presents some preliminary results of the performance of the algorithm in simulation approximating early Run-2 conditions.
Large international collaborations that use decentralized computing models are becoming a custom rather than an exception in High Energy Physics. A good computing model for such big collaborations ...has to deal with the distribution of the experiment-specific software around the world. When the CDF experiment developed its software infrastructure, most computing was done on dedicated clusters. As a result, libraries, configuration files and large executables were deployed over a shared file system. In order to adapt its computing model to the Grid, CDF decided to distribute its software to all European Grid sites using Parrot, a user-level application capable of attaching existing programs to remote I/O systems through the filesystem interface. This choice allows CDF to use just one centralized source of code and a scalable set of caches all around Europe to efficiently distribute its code and requires almost no interaction with the existing Grid middleware or with local system administrators. This system has been in production at CDF in Europe since almost two years. Here, we present CDF implementation of Parrot and some comments on its performances.
Presented in this contribution are methods currently developed and used by the ATLAS collaboration to measure the performance of the primary vertex reconstruction algorithms. With the increasing ...instantaneous luminosity at the LHC, many proton-proton collisions occur simultaneously in one bunch crossing. The correct identification of the primary vertex from a hard scattering process and the knowledge of the number of additional pile-up interactions is crucial for many physics analyses. Under high pile-up conditions, additional effects like splitting one vertex into many or reconstructing several interactions as one also become sizable effects. The mathematical methods, their software implementation, and studies presented in this contribution are methods currently developed and used by the ATLAS collaboration to measure the performance of the primary vertex reconstruction algorithms. Statistical methods based on data and Monte Carlo simulation are both used to disentangle and understand the different contributions.
The mechanism by which asymmetric signals induce left-right-specific morphogenesis has been elusive.
Pitx2 encodes a transcription factor expressed throughout the left lateral plate mesoderm and ...subsequently on the left side of asymmetric organs such as the heart and gut during organogenesis in the chick embryo.
Pitx2 is induced by the asymmetric signals encoded by
Nodal and
Sonic hedgehog, and its expression is blocked by prior treatment with an antibody against Sonic hedgehog. Misexpression of
Pitx2 on the right side of the embryo is sufficient to produce reversed heart looping and heart isomerisms, reversed body rotation, and reversed gut situs.
A study was designed to evaluate nutrient disappearance from three Texas browse species containing condensed tannins (CT;
Acacia angustissima var.
hirta,
Desmodium paniculatum,
Smilax bona-nox, and
...Medicago sativa as control) using the mobile nylon bag technique. Ruminally or duodenally cannulated steers were fed a basal diet of
Sorghum bicolor
×
S. sudanense hay. The proportion of nutrient that disappeared during rumen, pepsin/HCl, or intestinal incubation differed among plant species and nutrient evaluated (
P<0.05) and did not appear to be directly related to relative CT concentrations. Dry matter (DM), inorganic matter (IM), and organic matter (OM) disappearance was greater (
P<0.05) during rumen incubation than at other stages for all plant species evaluated. Of the plants containing CT,
A. angustissima demonstrated the greatest overall disappearance of DM, OM, P, and crude protein (CP). A greater proportion of
A. angustissima and
D. paniculatum CP and P disappearance occurred in the intestinal tract compared to
S. bona-nox and
M. sativa. The presence of CT appears to reduce total P disappearance and shift disappearance site from the rumen to the intestines in some plant species containing CT.
This article presents the full operational experimental capabilities of the plasma wind tunnel facilities at the Institute of Space Systems at the University of Stuttgart. The simulation of the ...aerothermodynamic environment experienced by vehicles entering the atmosphere of Earth is attempted using three different facilities. Utilizing the three different facilities, the recent improvements enable a unique range of flow conditions in relation to other known facilities. Recent performance optimisations are highlighted in this article. Based on the experimental conditions demonstrated a corresponding flight scenario is derived using a ground-to-flight extrapolation approach based on local mass-specific enthalpy, total pressure and boundary layer edge velocity gradient. This shows that the three facilities cover the challenging parts of the aerothermodynamics along the entry trajectory from Low Earth Orbit. Furthermore, the more challenging conditions arising during interplanetary return at altitudes above 70 km are as well covered.
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