The CERN PS East Area in the LHC Era

Experiments planned at the CERN Large Hadron Collider (LHC) will require a well-equipped test area with low momentum (<15 Gev/c) secondary particle beams. These beams will be used to test some of the LHC detectors components (ALICE, ATLAS, CMS, LHCb). In addition another recently approved experiment (DIRAC) will be installed in the PS East Area. This experiment will require a primary proton beam of 24 GeV/c to test QCD predictions. In this context, the EHNL project (East Hall New Look) has been launched. The major modifications include (i) an extension of the present area with a primary 24 GeV/c beam line, (ii) a new secondary beam line lay-out with test areas at 3.5, 7, 10 and 15 GeV/c, (iii) an additional irradiation area, (iv) an improved facility for beam sharing between the various users. This paper describes the scope of the project, its new features, the planned facilities and its installation schedul

Measuring the Loschmidt amplitude for finite-energy properties of the Fermi-Hubbard model on an ion-trap quantum computer

Calculating the equilibrium properties of condensed matter systems is one of the promising applications of near-term quantum computing. Recently, hybrid quantum-classical time-series algorithms have been proposed to efficiently extract these properties from a measurement of the Loschmidt amplitude $\langle \psi| e^{-i \hat H t}|\psi \rangle$ from initial states $|\psi\rangle$ and a time evolution under the Hamiltonian $\hat H$ up to short times $t$. In this work, we study the operation of this algorithm on a present-day quantum computer. Specifically, we measure the Loschmidt amplitude for the Fermi-Hubbard model on a $16$-site ladder geometry (32 orbitals) on the Quantinuum H2-1 trapped-ion device. We assess the effect of noise on the Loschmidt amplitude and implement algorithm-specific error mitigation techniques. By using a thus-motivated error model, we numerically analyze the influence of noise on the full operation of the quantum-classical algorithm by measuring expectation values of local observables at finite energies. Finally, we estimate the resources needed for scaling up the algorithm.Comment: 18 pages, 12 figure

An Antiproton Decelerator in the CERN PS Complex

The present CERN PS low-energy antiproton complex involves 4 machines to collect, cool, decelerate and supply experiments with up to 1010 antiprotons per pulse and per hour of momenta ranging from 0.1 to 2 GeV/c. In view of a possible future physics programme requiring low energy antiprotons, mainly to carry out studies on antihydrogen, a simplified scheme providing at low cost antiprotons at 100 MeV/c has been studied. It requires only one machine, the present Antiproton Collector (AC) converted into a cooler and decelerator (Antiproton Decelerator, AD) and delivering beam to experiments in the hall of the present Antiproton Accumulator Complex (AAC) [1]. This paper describes the feasibility study of such a scheme [2]

The antiproton decelerator (AD), a simplified antiproton source (feasibility study)

In view of a possible future physics programme concerning antihydrogen a simplified scheme for the provision of antiprotons of a few MeV has been studied. It uses the present target area and the modified Antiproton Collector (AC) in its present location. In this report all the systems are reviewed and their modifications discussed

The antiproton decelerator: AD

A simplified scheme for the provision of antiprotons at 100 MeV/c based on fast extraction is described. The scheme uses the existing production target area and the modified Antiproton Collector Ring in their current location. The physics programme is largely based on capturing and storing antiprotons in Penning traps for the production and spectroscopy of antihydrogen. The machine modifications necessary to deliver batches of 1 107 /min at 100 MeV/c are described. Details of the machine layout and the experimental area in the existing AAC Hall are given

Primates, Provisioning and Plants: Impacts of Human Cultural Behaviours on Primate Ecological Functions

Human provisioning of wildlife with food is a widespread global practice that occurs in multiple socio-cultural circumstances. Provisioning may indirectly alter ecosystem functioning through changes in the eco-ethology of animals, but few studies have quantified this aspect. Provisioning of primates by humans is known to impact their activity budgets, diets and ranging patterns. Primates are also keystone species in tropical forests through their role as seed dispersers; yet there is no information on how provisioning might affect primate ecological functions. The rhesus macaque is a major human-commensal species but is also an important seed disperser in the wild. In this study, we investigated the potential impacts of provisioning on the role of rhesus macaques as seed dispersers in the Buxa Tiger Reserve, India. We studied a troop of macaques which were provisioned for a part of the year and were dependent on natural resources for the rest. We observed feeding behaviour, seed handling techniques and ranging patterns of the macaques and monitored availability of wild fruits. Irrespective of fruit availability, frugivory and seed dispersal activities decreased when the macaques were provisioned. Provisioned macaques also had shortened daily ranges implying shorter dispersal distances. Finally, during provisioning periods, seeds were deposited on tarmac roads that were unconducive for germination. Provisioning promotes human-primate conflict, as commensal primates are often involved in aggressive encounters with humans over resources, leading to negative consequences for both parties involved. Preventing or curbing provisioning is not an easy task as feeding wild animals is a socio-cultural tradition across much of South and South-East Asia, including India. We recommend the initiation of literacy programmes that educate lay citizens about the ill-effects of provisioning and strongly caution them against the practice

In situ EBSD investigation of deformation processes and strain partitioning in bi-modal Ti-6Al-4V using lattice rotations

International audienceIdentification of operating deformation processes and assessment of the resulting strain partitioning are critical concerns for mechanical properties prediction and microstructure optimization in complex alloys such as α/β titanium alloys. Lattice rotation relative to the initial orientation was presently used as a marker of slip activity. A Ti-6Al-4V specimen with a bi-modal microstructure was tested in tension in a scanning electron microscope. Crystallographic orientations were characterized in situ using electron back-scattered diffraction (EBSD). A successful prediction of activated slip systems was achieved using the rotation axis associated with plastic activity. The combination of this procedure and slip traces analysis offers an insight into the determination of both slip plane and slip direction of active slip systems. Based on classical crystal plasticity formulations, the magnitude of the rotation relative to the initial orientation was interpreted in terms of plastic shear magnitude. A quantitative assessment of plastic strain at the microstructure scale was then carried out using lattice rotation data. This approach enabled to discuss strain partitioning in Ti-6Al-4V considering the influence of microstructural features and active slip modes

In situ SEM investigation of slip transfer in Ti-6Al-4V: Effect of applied stress

International audienceSlip transfer is a major concern to understand fatigue behavior and damage, especially in titanium alloys. The presently reported investigation focused on the influence of the applied stress through the use of in situ tensile tests carried out inside a scanning electron microscope. Slip transfer between primary α nodules in Ti-6Al-4V was studied using slip trace analysis combined with the electron backscattered diffraction technique to consider crystallographic aspects. The influence of the resolved shear stress and the alignment between slip systems on slip transmission was thoroughly characterized considering a large number of blocked or transferred slip bands. In particular, the evolution of alignment and stress related indicators was assessed with respect to the applied stress

Concurrent operation of ⟨c + a⟩ slip and twinning under cyclic loading of Ti-6Al-4V

International audienceDeformation processes operating in hard/soft grain pairs were characterized in Ti-6Al-4V specimens with a bimodal microstructure submitted to fatigue and dwell fatigue loadings. Concurrent operation of 1st order ⟨c + a⟩ pyramidal slip and slip-stimulated deformation twinning was observed in hard grains, resulting from multi-scale strain incompatibilities. The former constitutes a direct experimental evidence of stress redistribution under cyclic loadings while the latter, which is triggered by local stress concentrations due to dislocations pile ups, is detected for the first time. Insights into the crack initiation processes are then discussed