Showing papers on "Time of flight published in 2021"

Visualizing Lithium Distribution and Degradation of Composite Electrodes in Sulfide-based All-Solid-State Batteries Using Operando Time-of-Flight Secondary Ion Mass Spectrometry.

Abstract: Understanding the electrochemical reactions taking place in composite electrodes during cell cycling is essential for improving the performance of all-solid-state batteries. However, comprehensive in situ monitoring of Li distribution, along with measurement of the evolution of degradation, is challenging because of the limitations of the characterization techniques commonly used. This study demonstrates the observation of Li distribution and degradation in composite cathodes consisting of LiNi0.8Co0.15Al0.05O2 (NCA) and 75Li2S·25P2S5 (LPS) during cell operation using operando time-of-flight secondary ion mass spectrometry. The evolution of the nonuniform reaction of NCA particles during charge and discharge cycles was successfully visualized by mapping fragments containing Li. Furthermore, degradation of the NCA/LPS interface was investigated by mapping POx- and SOx- fragments, which are related to the solid electrolyte interphase. We found that during the charge-discharge cycle and application of a high-voltage stress to the composite electrodes, the PO2- and PO3- fragments increased monotonically, whereas the SO3- fragment exhibited a reversible increase-decrease behavior, implying the existence of a redox-active component at the NCA/LPS interface. The demonstrated technique provides insights into both the optimized structures of composite electrodes and the underlying mechanisms of interfacial degradation at active material/solid electrolyte interfaces.

Determination of the tunneling flight time as the reflected phase time

Abstract: Using the time parameter in the time-dependent Schr\"odinger equation, we study the time of flight for a particle tunneling through a square barrier potential. Comparing the mean and variance of the energy and the flight time for transmitted and reflected particles, using both density and flux distributions, we find that, when accounting for momentum filtering, the suitably normalized transmitted and reflected distributions are identical in both the density and flux cases. In contrast to previous studies, we demonstrate that these results do not imply a vanishing tunneling time, but rather that the time it takes to tunnel through a square barrier is precisely given by the reflected phase time. For wide barriers, this becomes independent of the barrier width, as predicted independently by MacColl and Hartman. We show that these conclusions can be reached using a variety of arguments, including purely quantum mechanical ones. Analysis of the shapes of the distributions under consideration reveals that wave-packet reshaping is not an explanation for the MacColl-Hartman effect. The results presented here have direct implications for understanding recent experimental results in the study of the barrier crossing of rubidium atoms. The finite width of an incident wave packet significantly ``masks'' the tunneling time, and induces substantial asymmetry between the flight times of transmitted and reflected atoms.

Time-of-flight photoelectron momentum microscopy with 80–500 MHz photon sources: electron-optical pulse picker or bandpass pre-filter

Abstract: The small time gaps of synchrotron radiation in conventional multi-bunch mode (100–500 MHz) or laser-based sources with high pulse rate (∼80 MHz) are prohibitive for time-of-flight (ToF) based photoelectron spectroscopy. Detectors with time resolution in the 100 ps range yield only 20–100 resolved time slices within the small time gap. Here we present two techniques of implementing efficient ToF recording at sources with high repetition rate. A fast electron-optical beam blanking unit with GHz bandwidth, integrated in a photoelectron momentum microscope, allows electron-optical `pulse-picking' with any desired repetition period. Aberration-free momentum distributions have been recorded at reduced pulse periods of 5 MHz (at MAX II) and 1.25 MHz (at BESSY II). The approach is compared with two alternative solutions: a bandpass pre-filter (here a hemispherical analyzer) or a parasitic four-bunch island-orbit pulse train, coexisting with the multi-bunch pattern on the main orbit. Chopping in the time domain or bandpass pre-selection in the energy domain can both enable efficient ToF spectroscopy and photoelectron momentum microscopy at 100–500 MHz synchrotrons, highly repetitive lasers or cavity-enhanced high-harmonic sources. The high photon flux of a UV-laser (80 MHz, <1 meV bandwidth) facilitates momentum microscopy with an energy resolution of 4.2 meV and an analyzed region-of-interest (ROI) down to <800 nm. In this novel approach to `sub-µm-ARPES' the ROI is defined by a small field aperture in an intermediate Gaussian image, regardless of the size of the photon spot.

Practical Aspects of Focused Ion Beam Time-of-Flight Secondary Ion Mass Spectrometry Analysis Enhanced by Fluorine Gas Coinjection

Abstract: The interest in using high vacuum-compatible time-of-flight secondary ion mass spectrometry (TOF-SIMS) detectors integrated within focused ion beam instruments (FIB) has increased due to the possib...

Time of flight measurements of energy and density of laser induced Mg plasma ions and investigation of ablated surface morphology

Abstract: The energy and density measurements of laser induced Mg plasma ions have been performed by employing a Faraday cup as an ion collector by using the time of flight method. A Nd:YAG laser (532 nm, 8 ns) has been employed as an irradiation source at irradiances ranging from 4.5 GW/cm2 to 8.1 GW/cm2. For the first time, two distinct peaks of ions with the time delay of ns and μs have been identified for low-Z metal corresponding to fast and slow ions. It is revealed that both the energy and density of Mg plasma ions are increased with increasing laser irradiance and are decreased with the increasing distance between the collector and the target. The density of slow ions is 4–12 times higher than the density of fast ions for the selected irradiances. However, the energy of slow ions is in the range of 100's of eV and the energy of fast ions is in the range of 10's of keV. The anisotropic behavior and forward peaking of plasma are confirmed by the investigation of the angular distribution of ions. The plasma assisted laser ablated morphology is investigated by scanning electron microscopy (SEM) analysis. SEM analysis reveals the formation of cavities, cones, and spikes. The increasing trend of ion density and energy with increasing laser irradiance is correlated with the increased ablated areas and number density of cones.

Charge identification of nuclear fragments with the FOOT Time-Of-Flight system

Abstract: FOOT (FragmentatiOn Of Target) is an applied nuclear physics experiment conceived to conduct high-precision cross section measurements of nuclear fragmentation processes relevant for particle therapy and radiation protection in space. These measurements are important to estimate the physical and biological effects of nuclear fragments, which are produced when energetic particle beams penetrate human tissue. A component of the FOOT experiment is the Δ E -TOF system. It is designed to measure energy loss and time-of-flight of nuclear fragments produced in particle collisions in thin targets in order to extract their charge and velocity. The Δ E -TOF system is composed of a start counter, providing the start time for the time-of-flight, and a 40 × 40 cm 2 wall of thin plastic scintillator bars, providing the arrival time and energy loss of the fragments passing through the detector. Particle charge discrimination can be achieved by correlating the energy loss in the scintillator bars with the measured time-of-flight. Recently, we have built a full-size Δ E -TOF detector. In this work, we describe the energy and time-of-flight calibration procedure and assess the performance of this system. We use data acquired during beam tests at CNAO with proton and 12C beams and at GSI with 16O beams in the energy range relevant for particle therapy, i.e., from 60 to 400 MeV/u. For heavy fragments (C and O), we obtain energy and time resolutions ranging from 4.0 to 5.2% and from 54 to 76 ps, respectively. The procedure is also applied to a fragmentation measurement of a 400 MeV/u 16O beam on a 5 mm carbon target, showing that the system is able to discriminate the charges of impinging fragments.

Influence of sub-nanosecond time of flight resolution for online range verification in proton therapy using the line-cone reconstruction in Compton imaging.

Abstract: Online ion range monitoring in hadron therapy can be performed via detection of secondary radiation, such as prompt γ-rays, emitted during treatment. The prompt γ emission profile is correlated with the ion depth-dose profile and can be reconstructed via Compton imaging. The line-cone reconstruction, using the intersection between the primary beam trajectory and the cone reconstructed via a Compton camera, requires negligible computation time compared to iterative algorithms. A recent report hypothesised that time of flight (TOF) based discrimination could improve the precision of the γ fall-off position measured via line-cone reconstruction, where TOF comprises both the proton transit time from the phantom entrance until γ emission, and the flight time of the γ-ray to the detector. The aim of this study was to implement such a method and investigate the influence of temporal resolution on the precision of the fall-off position. Monte Carlo simulations of a 160 MeV proton beam incident on a homogeneous PMMA phantom were performed using GATE. The Compton camera consisted of a silicon-based scatterer and CeBr3 scintillator absorber. The temporal resolution of the detection system (absorber + beam trigger) was varied between 0.1 and 1.3 ns RMS and a TOF-based discrimination method applied to eliminate unlikely solution(s) from the line-cone reconstruction. The fall-off position was obtained for varying temporal resolutions and its precision obtained from its shift across 100 independent γ emission profiles compared to a high statistics reference profile. The optimal temporal resolution for the given camera geometry and 108 primary protons was 0.2 ns where a precision of 2.30 ± 0.15 mm (1σ) on the fall-off position was found. This precision is comparable to current state of-the-art Compton imaging using iterative reconstruction methods or 1D imaging with mechanically collimated devices, and satisfies the requirement of being smaller than the clinical safety margins.

Time-of-flight modulated intensity small-angle neutron scattering measurement of the self-diffusion constant of water

Abstract: The modulated intensity by zero effort small-angle neutron scattering (MI-SANS) technique is used to measure scattering with a high energy resolution on samples normally ill-suited for neutron resonance spin echo. The self-diffusion constant of water is measured over a q–t range of 0.01–0.2 A−1 and 70–500 ps. In addition to demonstrating the methodology of using time-of-flight MI-SANS instruments to observe diffusion in liquids, the results support previous measurements on water performed with different methods. This polarized neutron technique simultaneously measures the intermediate scattering function for a wide range of time and length scales. Two radio frequency flippers were used in a spin-echo setup with a 100 kHz frequency difference in order to create a high-resolution time measurement. The results are compared with self-diffusion measurements made by other techniques and the general applicability of MI-SANS at a pulsed source is assessed.

Time-of-flight apparatus for the measurement of slow positronium emitted by nanochannel converters at cryogenic temperatures

Abstract: Silicon nanochannel plates (NCPs) are efficient positron to positronium converters and are employed as sources of abundant cold positronium. Characterization of the emitted positronium energy spectrum is crucial to assess the NCP performance and support their further optimization. We present here a Time-of-Flight (ToF) system optimized to measure the energy spectrum of positronium produced by NCP converters held at cryogenic temperatures. The ToF-apparatus was tested by implanting 7 keV positrons into NCPs at room temperature before performing ToF experiments using positron implantation energies of 7 and 11 keV into NCPs held at 20 K. At these conditions we succeeded in determining the energy spectrum of the positronium escaping from the nanochannels into the vacuum down to an energy of 10 meV.

Development of a miniature time-of-flight mass spectrometer coupled with an improved substrate-enhanced laser-induced acoustic desorption source (SE-LIAD/TOF-MS)

Abstract: A novel, compact and sensitive SE-LIAD/TOF-MS has been described. It facilitates fast sample preparation, and a full mass spectrum is acquired efficiently and sensitively. More importantly, it features the detection of non-acidic and non-basic or non-polar species, which is not suitable for determination by ESI and MALDI techniques. In this technique, standard samples, carbazole and melamine, are prepared on a Ti foil with a quartz plate attached to the backside of the Ti foil to perform a laser-induced acoustic desorption experiment (SE-LIAD) coupled to TOF-MS for analysis. Enhanced signals are observed with about 5.6 to 13.8 times higher than that obtained in the standard LIAD method, dependent on different ionization techniques. Compared to the EI spectra, the PI spectra for both species show intact and sharp molecular peaks. The limits of detection (LOD) of melamine were evaluated experimentally in the range from ∼2-6 pg (EI/MS mode) to ∼0.3-0.5 ng (VUV-SPI/MS mode). Thus, the method in this study exhibits rapid qualitative and quantitative analysis with good sensitivity, being free of the complex matrix influences.

Single ion thermal wave packet analyzed via time-of-flight detection

Abstract: A single $^{40}$Ca ion is confine in the harmonic potential of a Paul trap and cooled to a temperature of a few mK, with a wave packet of sub-m spatial and sub-m/s velocity uncertainty. Deterministically extracted from the Paul trap, the single ion is propagating over a distance of 0.27 m and detected. By engineering the ion extraction process on the initial wave packet, theoretically modeling the ion trajectories, and studying experimentally the time-of-flight distribution, we directly infer the state of the previously trapped ion. This analysis allows for accurate remote sensing of the previous motional excitation in the trap potential, both coherently or incoherently. Our method paves a way to extract, manipulate and design quantum wave packets also outside of the Paul trap.

Characterization of stilbene-d12 for neutron spectroscopy without time of flight

Abstract: We have experimentally characterized the light-output response of a deuterated trans-stilbene (stilbene-d12 ) crystal to quasi-monoenergetic neutrons in the 0.8 to 4.4 MeV energy range. These data allowed us to perform neutron spectroscopy measurements of a DT 14.1 MeV source and a 239PuBe source by unfolding the impinging neutron spectrum from the measured light-output response. The stilbene-d12 outperforms a 1 H − stilbene of similar size when comparing the shape of the unfolded spectra and the reference ones. These results confirm the viability of non-hygroscopic stilbene-d12 crystal for direct neutron spectroscopy without need for time-of-flight measurements. This capability makes stilbene-d12 a well suited detector for fast-neutron spectroscopy in many applications including nuclear reaction studies, radiation protection, nuclear non-proliferation, and space travel.

Probing Surface Information of Alloy by Time of Flight-Secondary Ion Mass Spectrometer

Abstract: In recent years, time of flight-secondary ion mass spectrometer (ToF-SIMS) has been widely employed to acquire surface information of materials. Here, we investigated the alloy surface by combining the mass spectra and 2D mapping images of ToF-SIMS. We found by surprise that these two results seem to be inconsistent with each other. Therefore, other surface characteristic tools such as SEM-EDS were further used to provide additional supports. The results indicated that such differences may originate from the variance of secondary ion yields, which might be affected by crystal orientation.

Temporal and spatial study of differently charged ions emitted by ns-laser-produced tungsten plasmas using time-of-flight mass spectroscopy

Abstract: Tungsten (W) is an important material in tokamak walls and divertors. The W ion charge state distribution and the dynamic behavior of ions play important roles in the investigation of plasma–wall interactions using laser-ablation-based diagnostics such as laser-induced breakdown spectroscopy and laser-induced ablation spectroscopy. In this work, we investigate the temporal and spatial evolutions of differently charged ions in a nanosecond-laser-produced W plasma in vacuum using time-of-flight mass spectroscopy. Ions with different charge states from 1 to 7 (W+ to W7+) are all observed. The temporal evolutions of the differently charged ions show that ions with higher charge states have higher velocities, indicating that space separation occurs between the differently charged ion groups. Spatially-resolved mass spectroscopy measurements further demonstrate the separation phenomenon. The temporal profile can be accurately fitted by a shifted Maxwell–Boltzmann distribution, and the velocities of the differently charged ions are also obtained from the fittings. It is found that the ion velocities increase continuously from the measured position of 0.75 cm to 2.25 cm away from the target surface, which indicates that the acceleration process lasts through the period of plasma expansion. The acceleration and space separation of the differently charged ions confirm that there is a dynamic plasma sheath in the laser-produced plasma, which provides essential information for the theoretical laser-ablation model with plasma formation and expansion.

Mass Spectrometric Identification of Proteins Enhanced by the Atomic Force Microscopy Immobilization Surface.

Abstract: An approach to highly-sensitive mass spectrometry detection of proteins after surface-enhanced concentrating has been elaborated. The approach is based on a combination of mass spectrometry and atomic force microscopy to detect target proteins. (1) Background: For this purpose, a technique for preliminary preparation of molecular relief surfaces formed as a result of a chemical or biospecific concentration of proteins from solution was developed and tested on several types of chip surfaces. (2) Methods: mass spectrometric identification of proteins using trailing detectors: ion trap, time of flight, orbital trap, and triple quadrupole. We used the electrospray type of ionization and matrix-assisted laser desorption/ionization. (3) Results: It is shown that when using locally functionalized atomically smooth surfaces, the sensitivity of the mass spectrometric method increases by two orders of magnitude as compared with measurements in solution. Conclusions: It has been demonstrated that the effective concentration of target proteins on specially prepared surfaces increases the concentration sensitivity of mass spectrometric detectors-time-of-flight, ion trap, triple quadrupole, and orbital ion trap in the concentration range from up to 10-15 M.

Dynamics of the 6Li/7Li Exchange at a Graphite–Solid Electrolyte Interphase: A Time of Flight–Secondary Ion Mass Spectrometry Study

Abstract: The isotopic Li-ion exchange occurring in the solid electrolyte interphase (SEI) of a graphite electrode is studied by time of flight secondary ions mass spectrometry analysis (ToF-SIMS) of Li isot...

Study on the measurement method of wet gas flow velocity by ultrasonic flow meter

Abstract: Wet gas widely exists in energy, chemical, electric power and other industries. Accurate measurement of gas flow velocity in pipelines is related to economic and trade benefits. In this paper, a measurement method of wet gas velocity by ultrasonic flow meter is explored. Ultrasonic propagation in wet gas will be affected by liquid film and droplet, resulting in strong attenuation of signal and drastic change of envelope. It is difficult to obtain accurate measurement results by common time of flight calculation method. In order to solve this problem, a primary envelope normalized cross-correlation method based on statistical average is proposed. The statistical average method is used to overcome the problem of large signal fluctuations. At the same time, based on the analysis of the characteristics of the received signal under different working conditions, the primary envelope of the received signal and the reference waveform are used for cross-correlation calculations. A set of complete gas velocity measurement system is built, and three real flow experiments are carried out on a 50mm diameter horizontal pipe at ambient temperature and pressure. In the working conditions that the gas superficial velocity is from 5 m/s to 20m/s, and the liquid volume fraction is from 0.2% to 5%, the maximum standard uncertainty of this method is 0.515%, which is a relatively accurate calculation method of wet gas velocity.

Measurements of neutral particle energy spectrum on EAST using a time-of-flight low-energy neutral particle analyzer

Abstract: The neutral particles generated by charge exchange reactions can play an important role in erosion of first wall materials in fusion devices. In order to measure the flux and energy of neutral particles to the first wall, a low-energy neutral particle analyzer (LENPA) based on the time-of-flight method has been developed and successfully applied on the Experimental Advanced Superconducting Tokamak (EAST)' to measure the neutrals with an energy of 20–3000 eV. The LENPA works in the counting mode, and the signal of photons is used as the reference for the flight time of neutrals. The energy spectrum of low-energy neutral particles on EAST has been obtained for the first time. The new diagnostics can help in understanding the neutral particle generation and deposition on the first wall materials in tokamaks under different plasma conditions.

Time-Of-Flight methodologies with large-area diamond detectors for ion characterization in laser-driven experiments

Abstract: Time-Of-Flight (TOF) technique coupled with semiconductor detectors is a powerful instrument to provide real-time characterization of ions accelerated because of laser-matter interactions. Nevertheless, the presence of strong electromagnetic pulses (EMPs) generated during the interactions, can severely hinder its employment. For this reason, the diagnostic system must be designed to have high EMP shielding. Here we present a new advanced prototype of detector, developed at ENEA-Centro Ricerche Frascati (Italy), with a large area (15 mm x 15 mm) polycrystalline diamond sensor having 150 microns thickness. The tailored detector design and testing ensure high sensitivity and, thanks to the fast temporal response, high energy resolution of the reconstructed ion spectrum. The detector was offline calibrated and then successfully tested during an experimental campaign carried out at the PHELIX laser facility at GSI (Germany). The high rejection to EMP fields was demonstrated and suitable calibrated spectra of the accelerated protons were obtained.

Detection of Au+ Ions During Fluorine Gas-Assisted Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) for the Complete Elemental Characterization of Microbatteries.

Abstract: Due to excellent electric conductivity and chemical inertness, Au can be used in new microdevices for energy applications, microelectronics, and biomedical solutions. However, the chemical analysis of Au-containing systems using time-of-flight secondary ion mass spectrometry (TOF-SIMS) can be difficult because of the negative ionization of Au, as most metals form positive ions, and therefore cannot be detected from the same analytical volume. In this work, we present the potential of fluorine gas coinjection for altering the polarity, from the negative to positive, of Au secondary ions generated under Ga+ beam bombardment. The importance of detecting Au+ ions and representing their spatial distribution in nanoscale was demonstrated using a novel solid electrolyte for Li-ion solid-state batteries, amorphous Li7La3Zr2O12 (aLLZO). This allowed for assessing the migration of mobile Li+ ions outside the aLLZO layer and alloying the Au layer with Li, which explained the presence of an internal electric field observed during the polarization measurements. Remarkably, during fluorine gas-assisted TOF-SIMS measurements, the trace amount of Au content (5 ppm) was detected in a Pt layer (unattainable under standard vacuum conditions). In conclusion, fluorine gas-assisted TOF-SIMS can help understanding operation mechanisms and potential degradation processes of microdevices and therefore help optimizing their functionality.

New method for time alignment and time calibration of the TOFOR time-of-flight neutron spectrometer at JET.

Abstract: The TOFOR time-of-flight (TOF) neutron spectrometer at the Joint European Torus (JET) is composed of 5 start (S1) and 32 stop (S2) scintillation detectors. Recently, the data acquisition system (DAQ) of TOFOR was upgraded to equip each of the 37 detectors with its own waveform digitizer to allow for correlated time and pulse height analysis of the acquired data. Due to varying cable lengths and different pulse processing pathways in the new DAQ system, the 160 (5 · 32) different TOF pairs of start–stop detectors must be time-aligned to enable the proper construction of a summed TOF spectrum. Given the time (energy) resolution required by the entire spectrometer system to measure different plasma neutron emission components, it is of importance to align the detector pairs to each other with sub-nanosecond precision. Previously, the alignment partially depended on using fusion neutron data from Ohmic heating phases of JET experimental pulses. The dependence on fusion neutron data in the time alignment process is, however, unsatisfactory as it involves data one would wish to include in an independent analysis for physics results. In this work, we describe a method of time-aligning the detector pairs by using gamma rays. Given the known geometry and response of TOFOR to gamma rays, the time alignment of the detector pairs is found by examining gamma events interacting in coincidence in both S1–S1 and S1–S2 detector combinations. Furthermore, a technique for separating neutron and gamma events in the different detector sets is presented. Finally, the time-aligned system is used to analyze neutron data from Ohmic phases for different plasma conditions and to estimate the Ohmic fuel ion temperature.

FT-ICR mass spectrometry: Superconducting magnet, external ion source, ion-molecule reactions, and ion-ion traps.

Abstract: The world of Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry has witnessed, especially in the last 30 years significant advances in many fields of science, such as electronics, magnets, new ICR cell designs, developed ICR event sequences, modern external ionization sources, and linear ion beam guides, as well as modern vacuum technology. In this review, a brief account is given focusing especially on the studies performed in Wanczek's group and ICR research laboratory at the University of Bremen. An FT-ICR mass spectrometer has been developed with a high magnetic field superconducting magnet, operating at 4.7 T. At this magnetic field, a trapping time of 13.5 h was obtained with 30% efficiency. For the tetrachloromethane molecular ion, m/z 166, a mass-resolving power m/Δm = 1.5 × 106 was measured at a pressure of 2 × 10-8 Torr. The transition from magnet sweep to frequency sweep and the application of Fourier-transform has greatly enhanced the ICR technology. External ion sources were invented and differential pumping schemes were developed for enabling ultrahigh vacuum condition for ICR detection, while guiding ions at relatively higher pressures, during their flight to the ICR cell. With the external ion source, a time-of-flight ICR tandem instrument is built. A method to measure the ion flight time and to trap the ions in the ICR cell is described. Many ICR cell characteristics such as z-axis ion ejection and coupling of radial and axial ion motions in a superposed homogeneous magnetic and inhomogeneous trapping electric field were extensively studied. Gas-phase ion-molecule reactions of several reactive inorganic compounds with a focus on phosphorous and sulfur as well as silicon chemistry were also studied in great detail. The gas-phase ion chemistry of several trifluoromethyl-reagents such as trifluoromethyltrimethylsilane and tris(trifluoromethyl)phosphine were also investigated in ICR. Dual polarities multisegmented ICR cells were invented and deeply characterized. Sophisticated ICR pulse event programs were developed to enable long-range ion-ion interactions between simultaneously trapped positive and negative ions.

Cost-Effective Sensor for Flow Monitoring in Biologic Microreactors

Abstract: Continuous nutrient supply of cell cultures in perfused bioreactors requires reliable flow monitoring. This work presents an approach for the flow rate measurement based on low temperature ceramic technology, which allows the direct integration of temperature sensors in the center of fluid channels. Thick film thermistors detect the flow rate in two different operation modes: the calorimetric addresses flow rates from $20~\mu \text{l}$ /min to $80~\mu \text{l}$ /min and the time of flight flow such as up to 1.5 ml/min. The design takes advantage of highly sensitive thermistors with negative temperature coefficient, and optimized heat exchange due to the direct thermal contact between fluid and temperature probe. In addition to calorimetric evaluation, the temperature course as a function of time is used to detect the time of flight. This allows the tracking of the flow rate independent from the thermistor’s temperature characteristic using the temperature maximum as marker. Cross-correlation applied to this temperature problem significantly improves the detection accuracy for the time of flight. Based on temperature and flow measurement data, it was proven that a fit function could replicate the flow rate as a function of the difference in time of flight between two thermistor positions with a deviation less than 4 %. The evaluation of time of flight data can extend the operation range of the sensor by two orders of magnitude. Applying this signal processing, the same method can be applied even for low flow rates, with a measurement range from $30~\mu \text{l}$ /min to $1500~\mu \text{l}$ /min.