M. Hofmann
A5019835006- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Semiconductor materials and devices
- Atmospheric Ozone and Climate
- Quantum, superfluid, helium dynamics
- Advancements in Semiconductor Devices and Circuit Design
- Diamond and Carbon-based Materials Research
- Atomic and Subatomic Physics Research
- Semiconductor materials and interfaces
- Spectroscopy and Laser Applications
- Innovative Microfluidic and Catalytic Techniques Innovation
- Scientific Research and Discoveries
- Noncommutative and Quantum Gravity Theories
- Nuclear Physics and Applications
- Advanced Chemical Physics Studies
- Nanowire Synthesis and Applications
- Radiation Detection and Scintillator Technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Particle Detector Development and Performance
- Nanofabrication and Lithography Techniques
- Advanced Materials and Mechanics
- Advanced Electron Microscopy Techniques and Applications
- Rheology and Fluid Dynamics Studies
ETH Zurich
2009-2024
Regensburg University of Applied Sciences
2017
Technical University of Munich
2010-2016
RWTH Aachen University
2014
Institute for Biomedical Engineering
2009
University of Calgary
2009
The Double Chooz experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. An observed-to-predicted ratio events 0.944±0.016(stat)±0.040(syst) was obtained in 101 days running at the nuclear power plant France, two 4.25 GW(th) reactors. results were from a single 10 m(3) fiducial volume detector located 1050 m cores. flux prediction used Bugey4 measurement after correction for differences core composition. deficit can be...
The Double Chooz experiment has observed 8249 candidate electron antineutrino events in 227.93 live days with 33.71 GW-ton-years ($\mathrm{\text{reactor power}}\ifmmode\times\else\texttimes\fi{}\mathrm{\text{detector mass}}\ifmmode\times\else\texttimes\fi{}\mathrm{\text{live time}}$) exposure using a $10.3\text{ }\text{ }{\mathrm{m}}^{3}$ fiducial volume detector located at 1050 m from the reactor cores of nuclear power plant France. expectation case ${\ensuremath{\theta}}_{13}=0$ is 8937...
The Double Chooz experiment presents improved measurements of the neutrino mixing angle θ 13 using data collected in 467.90 live days from a detector positioned at an average distance 1050 m two reactor cores nuclear power plant. Several novel techniques have been developed to achieve significant reductions backgrounds and systematic uncertainties with respect previous publications, whereas efficiency $$ {\overline{\nu}}_e signal has increased. value is measured be sin2 2θ = 0.090 − 0.029 +...
The Double Chooz experiment has determined the value of neutrino oscillation parameter $\theta_{13}$ from an analysis inverse beta decay interactions with neutron capture on hydrogen. This uses a three times larger fiducial volume than standard assessment, which is restricted to region doped gadolinium (Gd), yielding exposure 113.1 GW-ton-years. data sample used in this distinct that Gd analysis, and systematic uncertainties are also largely independent, some exceptions, such as reactor flux...
An experiment was performed at the scientific neutron source FRM II in Garching to determine cumulative antineutrino spectrum of fission products U238. Target foils natural uranium were irradiated with a thermal and fast beam emitted β spectra recorded γ-suppressing electron telescope. The obtained U235 normalized data magnetic spectrometer BILL. This method strongly reduces systematic errors U238 measurement. converted into corresponding ν¯e spectrum. final is given 250 keV bins range from...
The Double Chooz collaboration presents a measurement of the neutrino mixing angle θ 13 using reactor $$ \overline{\nu_{\mathrm{e}}} observed via inverse beta decay reaction in which neutron is captured on hydrogen. This based 462.72 live days data, approximately twice as much data previous such analysis, collected with detector positioned at an average distance 1050 m from two cores. Several novel techniques have been developed to achieve significant reductions backgrounds and systematic...
An elastoviscoplastic constitutive equation is proposed to describe both the elastic and rate-dependent plastic deformation behavior of Carbopol® dispersions, commonly used study yield-stress fluids. The model, a variant nonlinear Maxwell model with stress-dependent relaxation time, eliminates need for separate Herschel–Bulkley yield stress. stress dependence viscosity was determined experimentally by evaluating steady-state flow at constant applied shear rate measuring creep Experimentally,...
We present a search for Lorentz violation with 8249 candidate electron antineutrino events taken by the Double Chooz experiment in 227.9 live days of running. This analysis, featuring sidereal time dependence events, is first test invariance using reactor-based source. No variation data and disappearance results are consistent independent oscillations. Under Standard-Model Extension, we set limits on 14 violating coefficients associated transitions between tau flavor, two competitive muon flavor.
A spectroscopic study of liquid argon from the vacuum ultraviolet at 110 nm to 1000 is presented. Excitation was performed using continuous and pulsed 12 keV electron beams. The emission dominated by analogue so-called 2nd excimer continuum. Various additional features were found. time structure light has been measured for a set well-defined wavelength positions. results help interpret literature data in context rare-gas detectors which information lost due use shifters.
The oscillation results published by the Double Chooz Collaboration in 2011 and 2012 rely on background models substantiated reactor-on data. In this analysis, we present a background-model-independent measurement of mixing angle θ13 including 7.53 days reactor-off A global fit observed antineutrino rates for different reactor power conditions is performed, yielding both total rate. are improved significantly data fit, as it provides direct This rate modulation analysis considers candidates...
Arrays of black silicon field emission pillar structures were fabricated on p-type substrates. Two types samples with the same number pillars (arrays 10 × 10) but different heights (8 and 20 μm) prepared as well a reference sample without pillars. The properties these cathodes investigated both by means integral current-voltage measurements scanning microscopy. Samples height μm revealed onset fields low 6.4 V/μm, enhancement factors up to 800, currents 8 μA at an applied V/μm. Due material,...
Double Chooz is unique among modern reactor-based neutrino experiments studying $\bar \nu_e$ disappearance in that data can be collected with all reactors off. In this paper, we present from 7.53 days of reactor-off running. Applying the same selection criteria as used reactor-on oscillation analysis, a measured background rate 1.0$\pm$0.4 events/day obtained. The model for accidentals, cosmogenic $\beta$-$n$-emitting isotopes, fast neutrons cosmic muons, and stopped-$\mu$ decays analysis...
Polymer hydrogels, water-laden 3D cross-linked networks, find broad application as advanced biomaterials and functional materials because of their biocompatibility, stimuli responsiveness, affordability. The cross-linking density reports material properties such elasticity, permeability, swelling propensity. However, this critical design parameter can be challenging to template locally. Here, we report a continuous processing scheme that uses laminar flow direct the organization across...
We report on a method to stabilize the transmitted electron flux in field-emission source using an external regulation circuit. The was realized with array of silicon (Si) nanowhiskers top elongated pillar structures, mica spacer, and extraction grid made Si. As for most applications, emitted current from cathode is not as crucial through toward anode. investigated which allows directly by merely current. By this method, we were able our down values below 1%. Simultaneously, it shown that...
The spectral and temporal light emission properties of liquid argon have been studied in the context its use large rare-gas detectors for detecting Dark Matter particles astronomy. A table-top setup has developed. Continuous pulsed low energy electron beam excitation is used to stimulate emission. range from 110 1000 nm wavelength covered by detection system with a time resolution on order 1 ns.
In the present work, black-silicon field emitter arrays (FEAs) are investigated regarding influence of residual gas pressure on characteristics and lifetime in high voltage triode setup. Current-voltage-characteristics at different levels recorded show a decreasing emission current with rising pressure. This decrease can be explained by an increase work function charging surface caused adsorbates. The restored to its initial value heating FEA up 110 °C during active emission. With this...
For liquid-scintillator neutrino detectors of kiloton scale, the transparency organic solvent is central importance. The present paper reports on laboratory measurements optical scattering lengths solvents PXE, LAB, and Dodecane which are under discussion for next-generation experiments like SNO+, Hanohano, or LENA. Results comprise wavelength range from 415 to 440nm. contributions Rayleigh Mie as well absorption/re-emission processes discussed. Based results, LAB seems be preferred a...
In this contribution, the authors will present an algorithm to extract characteristics of nonideal field emission circuit elements from saturation-limited measurement data. The method for calculating voltage drop on current-limiting is based theory as well Newton's method. Since only assumption make a connection in series, applicable most data showing saturation. To be able determine significance any parameter output, uncertainties and extracted parameters correlations are fully taken into...
The Double Chooz experiment measures the neutrino mixing angle θ 13 by detecting reactor $$ {\overline{\nu}}_e via inverse beta decay. positron-neutron space and time coincidence allows for a sizable background rejection, nonetheless liquid scintillator detectors would profit from positron/electron discrimination, if feasible in large detector, to suppress remaining background. Standard particle identification, based on dependent profile of photon emission scintillator, can not be used given...
Semiconductor field emitters are suitable candidates for applications, which require a very stable emission (FE) current and high uniformity over the entire area. By using different materials geometries, we able to vary FE characteristics within wide range. Each specific application requires its own optimized design cathode as well other parts of electron source. To meet many these requirements possible while only limited number prefabricated components, established modular system concept...
Using the Double Chooz detector, designed to measure neutrino mixing angle ${\ensuremath{\theta}}_{13}$, products of ${\ensuremath{\mu}}^{\ensuremath{-}}$ capture on $^{12}\mathrm{C},^{13}\mathrm{C},^{14}\mathrm{N}$, and $^{16}\mathrm{O}$ have been measured. Over a period 489.5 days, $2.3\ifmmode\times\else\texttimes\fi{}{10}^{6}$ stopping cosmic collected, which $1.8\ifmmode\times\else\texttimes\fi{}{10}^{5}$ captured carbon, nitrogen, or oxygen nuclei in inner detector scintillator acrylic...