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Molecular and Ultrafast Science Seminar (MUSS)
No full textCFEL Molecular and Ultrafast Science Seminar (MUSS) series. This is a general topical seminar series on developments in modern molecular and ultrafast science jointly organized by the CFEL Controlled Molecule Imaging group, the Spectroscopy of molecular processes group, the CFEL Attosecond Science group, and the CFEL Ultrafast Optics group. Unless otherwise noted, the seminar talks start at 10:00h in the CFEL seminar rooms I and II, ground floor
On-Chip -Based Non-volatile Resistive Memory for in vitro Neurointerfaces
No full textThe development of highly integrated electrophysiological devices working in directcontact with living neuron tissue opens new exciting prospects in the fields ofneurophysiology and medicine, but imposes tight requirements on the power dissipatedby electronics. On-chip preprocessing of neuronal signals can substantially decrease thepower dissipated by external data interfaces, and the addition of embedded non-volatilememory would significantly improve the performance of a co-processor in real-timeprocessing of the incoming information stream from the neuron tissue. Here, we evaluatethe parameters of TaOx-based resistive switching (RS) memory devices produced bymagnetron sputtering technique and integrated with the 180-nm CMOS field-effecttransistors as possible candidates for on-chip memory in the hybrid neurointerfaceunder development. The electrical parameters of the optimized one-transistor–oneresistor (1T-1R) devices, such as the switching voltage (approx. ±1 V), uniformity ofthe Roff/Ron ratio (∼10), read/write speed (<40 ns), and the number of the writing cycles(up to 1010), are satisfactory. The energy values for writing and reading out a bit ∼30and ∼0.1 pJ, respectively, are also suitable for the desired in vitro neurointerfaces, butare still far too high once the prospective in vivo applications are considered. Challengesarising in the course of the prospective fabrication of the proposed TaOx-based RSdevices in the back-end-of-line process are identified
Double parton distributions in the pion from lattice QCD
No full textWe perform a lattice study of double parton distributions in the pion, using the relationship between their Mellin moments and pion matrix elements of two local currents. A good statistical signal is obtained for almost all relevant Wick contractions. We investigate correlations in the spatial distribution of two partons in the pion, as well as correlations involving the parton polarisation. The patterns we observe depend significantly on the quark mass. We investigate the assumption that double parton distributions approximately factorise into a convolution of single parton distributions
Lateral Variation of the Native Passive Film on Super Duplex Stainless Steel Resolved by Synchrotron Hard X-Ray Photoelectron Emission Microscopy
No full textA native passive film on 25Cr-7Ni super duplex stainless steel was analyzed using synchrotronhard X-ray photoemission electron microscopy, focusing on variations between individualgrains of ferrite and austenite phases. The film consists of an oxide inner layer and anoxyhydroxide outer layer, in total 2.3 nm thick. The Cr content is higher in the outer than theinner layer, ca. 80% on average. The Cr content is higher on ferrite than austenite, whereas thethickness is rather uniform. The grain orientation has a small but detectable influence, ferrite(111) grains have a lower Cr content than other ferrite grains
Kinematically complete experimental study of Compton scattering at helium atoms near the threshold
No full textCompton scattering is one of the fundamental interaction processes of light with matter. When discovered, it was described as a billiard-type collision of a photon ‘kicking’ a quasi-free electron. With decreasing photon energy, the maximum possible momentum transfer becomes so small that the corresponding energy falls below the binding energy of the electron. In this regime, ionization by Compton scattering becomes an intriguing quantum phenomenon. Here, we report on a kinematically complete experiment studying Compton scattering off helium atoms in that regime. We determine the momentum correlations of the electron, the recoiling ion and the scattered photon in a coincidence experiment based on cold target recoil ion momentum spectroscopy, finding that electrons are not only emitted in the direction of the momentum transfer, but that there is a second peak of ejection to the backward direction. This finding links Compton scattering to processes such as ionization by ultrashort optical pulses, electron impact ionization, ion impact ionization and neutron scattering, where similar momentum patterns occur
Measurement of the inclusive and differential Higgs boson production cross sections in the leptonic WW decay mode at 13 TeV
No full textMeasurement of the fiducial inclusive and differential production cross sections of the Higgs boson in proton-proton collisions at 13 TeV are performed using events where the Higgs boson decays into a pair of W bosons that subsequently decay into a final state with an electron, a muon, and a pair of neutrinos. The analysis is based on data collected with the CMS detector at the LHC during 2016-2018, corresponding to an integrated luminosity of 137 fb. Production cross sections are measured as a function of the transverse momentum of the Higgs boson and the associated jet multiplicity. The Higgs boson signal is extracted and simultaneously unfolded to correct for selection efficiency and resolution effects using maximum-likelihood fits to the observed distributions in data. The integrated fiducial cross section is measured to be 86.5 9.5 fb, consistent with the Standard Model expectation of 82.5 4.2 fb. No significant deviation from the Standard Model expectations is observed in the differential measurements
Measurements with silicon photomultipliers of dose-rate effects in the radiation damage of plastic scintillator tiles in the CMS hadron endcap calorimeter
No full textMeasurements are presented of the reduction of signal output due to radiation damage for two types of plastic scintillator tiles used in the hadron endcap (HE) calorimeter of the CMS detector. The tiles were exposed to particles produced in proton-proton (pp) collisions at the CERN LHC with a center-of-mass energy of 13 TeV, corresponding to a delivered luminosity of 50 fb−1. The measurements are based on readout channels of the HE that were instrumented with silicon photomultipliers, and are derived using data from several sources: a laser calibration system, a movable radioactive source, as well as hadrons and muons produced in pp collisions. Results from several irradiation campaigns using 60Co sources are also discussed. The damage is presented as a function of dose rate. Within the range of these measurements, for a fixed dose the damage increases with decreasing dose rate
Identification of heavy, energetic, hadronically decaying particles using machine-learning techniques
No full textMachine-learning (ML) techniques are explored to identify and classify hadronic decays of highly Lorentz-boosted W/Z/Higgs bosons and top quarks. Techniques without ML have also been evaluated and are included for comparison. The identification performances of a variety of algorithms are characterized in simulated events and directly compared with data. The algorithms are validated using proton-proton collision data at &surd;s = 13TeV, corresponding to an integrated luminosity of 35.9 fb−1. Systematic uncertainties are assessed by comparing the results obtained using simulation and collision data. The new techniques studied in this paper provide significant performance improvements over non-ML techniques, reducing the background rate by up to an order of magnitude at the same signal efficiency
High-frequency Graviton from Inflaton Oscillation
No full textWe point out that there is a high-frequency tail of the stochastic inflationary gravitational wave background that scales as with frequency . This contribution comes from the graviton vacuum fluctuation amplified by the inflaton coherent oscillation during the reheating stage. It contains information on inflaton properties such as the inflaton mass as well as the thermal history of the early Universe
anomalies under the lens of electroweak precision
No full textThe measurements carried out at LEP and SLC projected us into the precision era of electroweak physics. This has also been relevant in the theoretical interpretation of LHCb and Belle measurements of rare semileptonic decays, paving the road for new physics with the inference of lepton universality violation in ratios. The simplest explanation of these flavour anomalies -- sizeable one-loop contributions respecting Minimal Flavour Violation -- is currently disfavoured by electroweak precision data. In this work, we discuss how to completely relieve the present tension between electroweak constraints and one-loop minimal flavour violating solutions to . We determine the correlations in the Standard Model Effective Field Theory that highlight the existence of such a possibility. Then, we consider minimal extensions of the Standard Model where our effective-field-theory picture can be realized. We discuss how these solutions to anomalies, respecting electroweak precision and without any new source of flavour violation, may point to the existence of a boson at around the TeV scale, within the discovery potential of LHC, or to leptoquark scenarios