Atypical energy eigenstates in the Hubbard chain and quantum disentangled liquids

We investigate the implications of integrability for the existence of quantum disentangled liquid (QDL) states in the half-filled one-dimensional Hubbard model. We argue that there exist finite energy-density eigenstates that exhibit QDL behaviour in the sense of J. Stat. Mech. P10010 (2014). These states are atypical in the sense that their entropy density is smaller than that of thermal states at the same energy density. Furthermore, we show that thermal states in a particular temperature window exhibit a weaker form of the QDL property, in agreement with recent results obtained by strong-coupling expansion methods in arXiv:1611.02075. This article is part of the themed issue `Breakdown of ergodicity in quantum systems: from solids to synthetics matter'.Comment: 11 pages, 3 figures. arXiv admin note: text overlap with arXiv:1611.0207

Design of the LHC Beam Dump Entrance Window

7 TeV proton beams from the LHC are ejected through a 600 m long beam dump transfer line vacuum chamber to a beam dump block. The dump block is contained within an inert gas-filled vessel to prevent a possible fire risk. The dump vessel and transfer line are separated by a 600 mm diameter window, which must withstand both the static pressure load and thermal shock from the passage of the LHC beam. In a previous paper [1] the functional requirements and conceptual design of this window were outlined. This paper describes the analysis leading to the final design of the window. The choice of materials is explained and tests performed on the prototype window are summarized

Installation and commissioning of vacuum systems for the LHC particle detectors

The LHC collider has recently completed commissioning at CERN. At four points around the 27 km ring, the beams are put into collision in the centre of the experiments ALICE, ATLAS, CMS and LHCb which are installed in large underground caverns. The ‘experimental vacuum systems’ which transport the beams through these caverns and collision points are a primary interface between machine and experiment and were developed and installed as one project at CERN. Each system has a different geometry and materials as required by the experiment. However, they all have common requirements from the machine, and use many common technologies developed for the project. In this paper we give an overview of the four systems. We explain the technologies that were developed and applied for the installation, test, bakeout and subsequent closure of the experimental vacuum systems. We also discuss lessons learnt from the project

Vacuum Calculations for the LHC Experimental Beam Chambers

The vacuum stability is studied for the LHC experimental beam vacuum chambers of ALICE, ATLAS, and CMS. The present baseline design includes sputtered Non-Evaporable Getter (NEG) coating over the whole chamber inner surface providing distributed pumping and an antimultipactor coating. The data are presented for the dominant gas species (H2, CH4, CO and CO2) in a baked system. It results that the distributed pumping is necessary for vacuum stability of CO. Lumped pumping with Sputter Ion Pumps (SIP) is also indispensable for the stability of CH4. The operational constraints with NEG technology are described

Temporomandibular joint prosthesis in cancer reconstruction preceding radiation therapy

Total joint prostheses are a viable treatment option after removal of malignancies invading the temporomandibular joint, even when adjuvant radiation therapy is required.publishedVersio

Vacuum Stability for Ion Induced Gas Desorption

Ion induced vacuum instability was first observed in the Intersecting Proton Storage Rings (ISR) at CERN and in spite of substantial vacuum improvements, it remained a limitation of the maximum beam current throughout the operation of the machine. Extensive laboratory studies and dedicated machine experiments were made during this period to understand the details of this effect and to identify ways of increasing the limit to higher beam currents. Stimulated by the recent design work for the LHC vacuum system, the interest in this problem has been revived with a new critical review of the parameters which determine the pressure run-away in a given vacuum system with high intensity beams

Microstructural and mechanical characterization of yarns made from carbon nanotubes for the instrumentation of particle beams at CERN

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Incidence of severe retinopathy of prematurity before and after a modest reduction in target oxygen saturation levels

Previous studies suggest that reducing target oxygen saturation levels to 85–93% decreases the incidence of severe retinopathy of prematurity (ROP). Our aim was to determine if a more modest reduction in target oxygen saturation levels also reduces ROP incidence