8 research outputs found
Detector Technologies for CLIC
The Compact Linear Collider (CLIC) is a high-energy high-luminosity linear
electron-positron collider under development. It is foreseen to be built and
operated in three stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3
TeV, respectively. It offers a rich physics program including direct searches
as well as the probing of new physics through a broad set of precision
measurements of Standard Model processes, particularly in the Higgs-boson and
top-quark sectors. The precision required for such measurements and the
specific conditions imposed by the beam dimensions and time structure put
strict requirements on the detector design and technology. This includes
low-mass vertexing and tracking systems with small cells, highly granular
imaging calorimeters, as well as a precise hit-time resolution and power-pulsed
operation for all subsystems. A conceptual design for the CLIC detector system
was published in 2012. Since then, ambitious R&D programmes for silicon vertex
and tracking detectors, as well as for calorimeters have been pursued within
the CLICdp, CALICE and FCAL collaborations, addressing the challenging detector
requirements with innovative technologies. This report introduces the
experimental environment and detector requirements at CLIC and reviews the
current status and future plans for detector technology R&D.Comment: 152 pages, 116 figures; published as CERN Yellow Report Monograph
Vol. 1/2019; corresponding editors: Dominik Dannheim, Katja Kr\"uger, Aharon
Levy, Andreas N\"urnberg, Eva Sickin
Higgs Physics at the CLIC Electron-Positron Linear Collider
The Compact Linear Collider (CLIC) is an option for a future e+e- collider operating at centre-of-mass energies up to 3 TeV, providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper is the first comprehensive presentation of the Higgs physics reach of CLIC operating at three energy stages: sqrt(s) = 350 GeV, 1.4 TeV and 3 TeV. The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung (e+e- -> ZH) and WW-fusion (e+e- -> Hnunu), resulting in precise measurements of the production cross sections, the Higgs total decay width Gamma_H, and model-independent determinations of the Higgs couplings. Operation at sqrt(s) > 1 TeV provides high-statistics samples of Higgs bosons produced through WW-fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes e+e- -> ttH and e+e- -> HHnunu allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of the precision achievable with Higgs measurements at CLIC and describes the interpretation of these measurements in a global fit.The Compact Linear Collider (CLIC) is an option for a future collider operating at centre-of-mass energies up to , providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper is the first comprehensive presentation of the Higgs physics reach of CLIC operating at three energy stages: , 1.4 and . The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung ( ) and -fusion ( ), resulting in precise measurements of the production cross sections, the Higgs total decay width , and model-independent determinations of the Higgs couplings. Operation at provides high-statistics samples of Higgs bosons produced through -fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes and allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of the precision achievable with Higgs measurements at CLIC and describes the interpretation of these measurements in a global fit
The forward physics facility at the high-luminosity LHC
High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential
Study of tau-neutrino production at the CERN SPS
The DsTau project proposes to study tau-neutrino production in high-energy proton interactions. The outcome of this experiment are prerequisite for measuring the charged-current cross section that has never been well measured. Precisely measuring the cross section would enable testing of lepton universality in scattering and it also has practical implications for neutrino oscillation experiments and high-energy astrophysical observations. mesons, the source of tau neutrinos, following high-energy proton interactions will be studied by a novel approach to detect the double-kink topology of the decays and . Directly measuring decays will provide an inclusive measurement of the production rate and decay branching ratio to . The momentum reconstruction of will be performed by combining topological variables. This project aims to detect 1,000 decays in proton interactions in tungsten target to study the differential production cross section of mesons. To achieve this, state-of-the-art emulsion detectors with a nanometric-precision readout will be used. The data generated by this project will enable the cross section from DONUT to be re-evaluated, and this should significantly reduce the total systematic uncertainty. Furthermore, these results will provide essential data for future experiments such as the program in the SHiP project at CERN. In addition, the analysis of proton interactions, combined with the expected high yield of charmed decays as by-products, will enable the extraction of additional physical quantities.The DsTau project proposes to study tau-neutrino production in high-energy proton interactions. The outcome of this experiment are prerequisite for measuring the charged-current cross section that has never been well measured. Precisely measuring the cross section would enable testing of lepton universality in scattering and it also has practical implications for neutrino oscillation experiments and high-energy astrophysical observations. mesons, the source of tau neutrinos, following high-energy proton interactions will be studied by a novel approach to detect the double-kink topology of the decays and . Directly measuring decays will provide an inclusive measurement of the production rate and decay branching ratio to . The momentum reconstruction of will be performed by combining topological variables. This project aims to detect 1,000 decays in proton interactions in tungsten target to study the differential production cross section of mesons. To achieve this, state-of-the-art emulsion detectors with a nanometric-precision readout will be used. The data generated by this project will enable the cross section from DONUT to be re-evaluated, and this should significantly reduce the total systematic uncertainty. Furthermore, these results will provide essential data for future experiments such as the program in the SHiP project at CERN. In addition, the analysis of proton interactions, combined with the expected high yield of charmed decays as by-products, will enable the extraction of additional physical quantities
In vitro capture and characterization of embryonic rosette-stage pluripotency between naive and primed states.
Following implantation, the naive pluripotent epiblast of the mouse blastocyst generates a rosette, undergoes lumenogenesis and forms the primed pluripotent egg cylinder, which is able to generate the embryonic tissues. How pluripotency progression and morphogenesis are linked and whether intermediate pluripotent states exist remain controversial. We identify here a rosette pluripotent state defined by the co-expression of naive factors with the transcription factor OTX2. Downregulation of blastocyst WNT signals drives the transition into rosette pluripotency by inducing OTX2. The rosette then activates MEK signals that induce lumenogenesis and drive progression to primed pluripotency. Consequently, combined WNT and MEK inhibition supports rosette-like stem cells, a self-renewing naive-primed intermediate. Rosette-like stem cells erase constitutive heterochromatin marks and display a primed chromatin landscape, with bivalently marked primed pluripotency genes. Nonetheless, WNT induces reversion to naive pluripotency. The rosette is therefore a reversible pluripotent intermediate whereby control over both pluripotency progression and morphogenesis pivots from WNT to MEK signals
Measurement of shower development and its MoliĂšre radius with a four-plane LumiCal test set-up
A prototype of a luminometer, designed for a future collider detector, and consisting at present of a four-plane module, was tested in the CERN PS accelerator T9 beam. The objective of this beam test was to demonstrate a multi-plane tungsten/silicon operation, to study the development of the electromagnetic shower and to compare it with MC simulations. The MoliÚre radius has been determined to be 24.0 ± 0.6 (stat.) ± 1.5 (syst.) mm using a parametrization of the shower shape. Very good agreement was found between data and a detailed Geant4 simulation.A prototype of a luminometer, designed for a future e+e- collider detector, and consisting at present of a four-plane module, was tested in the CERN PS accelerator T9 beam. The objective of this beam test was to demonstrate a multi-plane tungsten/silicon operation, to study the development of the electromagnetic shower and to compare it with MC simulations. The Moli\`ere radius has been determined to be 24.0 +/- 0.6 (stat.) +/- 1.5 (syst.) mm using a parametrization of the shower shape. Very good agreement was found between data and a detailed Geant4 simulation
Energy dependence of coherent photonuclear production of J/Ï mesons in ultra-peripheral Pb-Pb collisions at = 5.02 TeV
International audienceThe cross section for coherent photonuclear production of J/Ï is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of = 5.02 TeV. Cross sections are presented in five different J/Ï rapidity ranges within |y| < 4, with the J/Ï reconstructed via its dilepton decay channels. In some events the J/Ï is not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range 17 < W < 920 GeV, where W is the centre-of-mass energy per nucleon of the ÎłPb system. This range corresponds to a Bjorken-x interval spanning about three orders of magnitude: 1.1 Ă 10 < x < 3.3 Ă 10. In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies.[graphic not available: see fulltext
Accessing the strong interaction between Î baryons and charged kaons with the femtoscopy technique at the LHC
The interaction between Î baryons and kaons/antikaons is a crucial ingredient for the strangeness S=0 and S=â2 sector of the mesonâbaryon interaction at low energies. In particular, the ÎK⟠might help in understanding the origin of states such as the Î(1620), whose nature and properties are still under debate. Experimental data on ÎâK and ÎâK⟠systems are scarce, leading to large uncertainties and tension between the available theoretical predictions constrained by such data. In this Letter we present the measurements of ÎâKâ+ÎâŸâKâ and ÎâKââÎâŸâK+ correlations obtained in the high-multiplicity triggered data sample in pp collisions at s=13 TeV recorded by ALICE at the LHC. The correlation function for both pairs is modeled using the LednickĂœâLyuboshits analytical formula and the corresponding scattering parameters are extracted. The ÎâKââÎâŸâK+ correlations show the presence of several structures at relative momenta kâ above 200 MeV/c, compatible with the Ω baryon, the Î(1690), and Î(1820) resonances decaying into ÎâKâ pairs. The low kâ region in the ÎâKââÎâŸâK+ also exhibits the presence of the Î(1620) state, expected to strongly couple to the measured pair. The presented data allow to access the ÎK+ and ÎKâ strong interaction with an unprecedented precision and deliver the first experimental observation of the Î(1620) decaying into ÎKâ