Robert Kieffer
A5040628797- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Radiation Detection and Scintillator Technologies
- Particle Accelerators and Free-Electron Lasers
- Liquid Crystal Research Advancements
- High-Energy Particle Collisions Research
- Advanced X-ray Imaging Techniques
- Supramolecular Self-Assembly in Materials
- Superconducting Materials and Applications
- Gyrotron and Vacuum Electronics Research
- Pickering emulsions and particle stabilization
- Crystallography and Radiation Phenomena
- Surfactants and Colloidal Systems
- Radiation Therapy and Dosimetry
- Muon and positron interactions and applications
- Block Copolymer Self-Assembly
- Optical Systems and Laser Technology
- Medical Imaging Techniques and Applications
- Particle accelerators and beam dynamics
- Mesoporous Materials and Catalysis
- Advanced Optical Sensing Technologies
- Luminescence and Fluorescent Materials
- Astrophysics and Cosmic Phenomena
- Terahertz technology and applications
- Material Dynamics and Properties
European Organization for Nuclear Research
2016-2021
Royal Holloway University of London
2020
Martin Luther University Halle-Wittenberg
2006-2019
Diamond Light Source
2018
Centre National de la Recherche Scientifique
2010-2017
Université Claude Bernard Lyon 1
2010-2017
Institut de Physique
2010
Institute of Nuclear Physics of Lyon
2010
Institut National de Physique Nucléaire et de Physique des Particules
2010
3S Photonics (France)
2005
X-shaped molecules undergo reversible thermal transitions between phase-separated and mixed states.
Abstract The diversity of phase morphologies observed recently in star‐branched liquid‐crystalline and polymeric compounds containing at least three immiscible segments is reviewed. Bolaamphiphiles facial amphiphiles with rodlike aromatic cores, two end‐groups, one (T‐shape) or (X‐shape) chains attached laterally to the core, form numerous honeycomblike liquid‐crystal phases, as well a variety novel lamellar 3D‐ordered mesophases. Molecular self‐organization described bulk phases thin films...
Abstract The single gyroid phase as well the alternating double network gyroid, composed of two networks, hold a significant place in ordered nanoscale morphologies for their potential applications photonic crystals, metamaterials and templates porous ceramics metals. Here, we report first cubic liquid crystals. They form through self‐assembly X‐shaped polyphiles, where glycerol‐capped terphenyl rods lie on surface while semiperfluorinated aliphatic side‐chains fill respective separate...
X-Shaped ternary five-block molecules, composed of a rigid p-terphenyl core, two terminal glycerol groups and flexible n-alkyl or semiperfluorinated chains fixed laterally to opposite sides the terphenyl moiety, form liquid crystalline phases built up honeycomb-like arrays polygonal cylinders, where rod-like aromatic cores cylinder walls with thickness equal width single molecule.
The CALICE Semi-Digital Hadronic Calorimeter (SDHCAL) prototype, built in 2011, was exposed to beams of hadrons, electrons and muons two short periods 2012 on different beam lines the CERN SPS. prototype with its 48 active layers, made Glass Resistive Plate Chambers their embedded readout electronics, run triggerless power-pulsing mode. performance SDHCAL during test found be very satisfactory an efficiency exceeding 90% for almost all layers. A linear response (within 5%) a good energy...
A large prototype of 1.3 m3 was designed and built as a demonstrator the semi-digital hadronic calorimeter (SDHCAL) concept proposed for future ILC experiments. The is sampling 48 units. Each unit an active layer made 1 m2 Glass Resistive Plate Chamber (GRPC) detector placed inside cassette whose walls are stainless steel. contains also electronics used to read out GRPC detector. lateral granularity provided by pick-up pads cm2 each. cassettes inserted into self-supporting mechanical...
A new design of highly granular hadronic calorimeter using Glass Resistive Plate Chambers (GRPCs) with embedded electronics has been proposed for the future International Linear Collider (ILC) experiments. It features a 2-bit threshold semi-digital read-out. Several GRPC prototypes their have successfully built and tested in pion beams. The these detectors is presented along test results on efficiency, pad multiplicity, stability reproducibility.
We report on the observation of incoherent Cherenkov radiation emitted by a 5.3 GeV positron beam circulating in Cornell electron-positron storage ring as passes close vicinity surface fused silica radiator (i.e., at distance larger than 0.8 mm). The shape was designed order to send photons towards detector, consisting compact optical system equipped with an intensified camera. allows both measurements 2D images and angular distribution including polarization study. corresponding light...
T-shaped bolaamphiphiles composed of a 4,4′-disubstituted biphenyl core and terminal diol groups with laterally attached oligo(siloxane) carbosilane units were synthesized investigated respect to their self-assembly into liquid crystalline superstructures (thermotropic mesophases). Two different types investigated: one has two identical glycerol at both ends the core, which are connected by ether linkages in other type is replaced an amide group. The position lateral on was also varied. In...
A prototype silicon-tungsten electromagnetic calorimeter for an ILC detector was tested in 2007 at the CERN SPS test beam. Data were collected with electron and hadron beams energy range 8 to 80 GeV. The analysis described here focuses on interactions of pions calorimeter. One main objectives CALICE program is validate Monte Carlo tools available design a full-sized detector. Si-W are therefore confronted predictions various physical models implemented GEANT4simulation framework.
In recent years, there has been an increasing demand for noninvasive beam size monitoring on particle accelerators. Ideally, these monitors should be cost effective and require little or no maintenance. These also suitable both linear circular machines. Here, the experimental setup is described in detail, results from a diffraction radiation monitor are presented. This tested Cornell Electron Storage Ring using 1 mA ($1.6\ifmmode\times\else\texttimes\fi{}{10}^{10}$ particles per bunch)...
We present the observation and detailed investigation of coherent Cherenkov diffraction radiation (CChDR) in terms spectral-angular characteristics. Electromagnetic simulations have been performed to optimize design a prismatic dielectric radiator performance detection system with aim providing longitudinal beam diagnostics. Successful experimental validations organized on CLEAR CLARA facilities based at CERN Daresbury laboratory respectively. With ps sub-ps long electron bunches, emitted...
The high granularity of the CALICE Semi-Digital Hadronic CALorimeter (SDHCAL) provides capability to reveal track segments present in hadronic showers. These are then used as a tool probe behaviour active layers situ, better reconstruct energy these showers and also distinguish them from electromagnetic ones. In addition, comparison data simulation helps discriminate among different shower models simulation. To extract recorded SDHCAL, Hough Transform is after being adapted presence dense...
The CERN Linear Electron Accelerator for Research (CLEAR) has now finished its second year of operation, providing a testbed new accelerator technologies and versatile radiation source. Hosting varied experimental program, this beamline provides flexible test facility users both internal external to CERN, as well being an excellent physics training ground. energy can be between 60 220 MeV, bunch length 1 4 ps, charge in the range 10 pC 2 nC, number bunches 200, at repetition rate 0.8 Hz....
We present recent achievements in the application of optical diffraction radiation (ODR) to measurement transverse beam size a 1.3 GeV micrometer-size electron performed with an instrument installed extended extraction line KEK Accelerator Test Facility. ODR is technique for and emittance highly relativistic particle beams. has advantage being noninvasive relatively inexpensive candidate operation linear accelerators, where no simple alternatives (e.g., synchrotron radiation) are available....
Abstract Aggregation in Langmuir films is usually understood as being a disorderly grouping of molecules turning into chaotic three‐dimensional aggregates and considered an unwanted phenomenon causing irreversible changes. In this work we present the studies 11 compounds from group specific surfactants, known bolaamphiphiles, that exhibit reversible aggregation and, many cases, transition to well‐defined multilayers, which can be layering transition. These bolaamphiphiles incorporate rigid...
Showers produced by positive hadrons in the highly granular CALICE scintillator-steel analogue hadron calorimeter were studied. The experimental data collected at CERN and FNAL for single particles with initial momenta from 10 to 80 GeV/c. response resolution spatial characteristics of shower development proton- pion-induced showers test beam simulations using Geant4 version 9.6 are compared.
Langmuir films of four X-shaped bolaamphiphiles were studied using surface pressure and Kelvin potential measurements, Brewster angle microscopy X-ray reflectivity. The partially fluorinated exhibit an unusual reversibility reproducibility isotherms, create very stable well defined single- or triple layers which can be transferred to solid substrates.
The spatial development of hadronic showers in the CALICE scintillator-steel analogue hadron calorimeter is studied using test beam data collected at CERN and FNAL for single positive pions protons with initial momenta range 10–80 GeV/c. Both longitudinal radial are parametrised two-component functions. parametrisation fit to simulations QGSP_BERT FTFP_BERT physics lists from GEANT4 version 9.6. parameters extracted simulated samples compared two types hadrons. response ratio...
The use of grazing incidence small and intermediate angle X-ray scattering in the study structure alignment thermotropic liquid crystals is illustrated on selected examples. These include columnar LC phases a star-shaped mesogen, several honeycomb T-shaped X-shaped bolaamphiphilic LCs, gold nanoparticles coated with mesogenic ligands. Sharp Bragg reflections from systems 2-d 3-d periodicities are obtained through annealing. Due to nearly perfect surface most cases, indexing complex...
The CALICE Semi-Digital Hadron Calorimeter (SDHCAL) technological prototype is a sampling calorimeter using Glass Resistive Plate Chamber detectors with three-threshold readout as the active medium. This technology one of two options proposed for hadron International Large Detector Linear Collider. was exposed to beams muons, electrons and pions different energies at CERN Super Proton Synchrotron. To be able study performance such in future experiments it important ensure reliable simulation...