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The design of an angular array of electron time-of-flight (eToF) spectrometers is reported, intended for non-invasive spectral, temporal, and polarization characterization of single shots of high-repetition rate, quasi-continuous, short-wavelength free-electron lasers (FELs) such as the LCLS II at SLAC. This array also enables angle-resolved, high-resolution eToF spectroscopy to address a variety of scientific questions on ultrafast and nonlinear light–matter interactions at FELs. The presented device is specifically designed for the time-resolved atomic, molecular and optical science endstation (TMO) at LCLS II. In its final version, the spectrometer comprises up to 20 eToF spectrometers aligned to collect electrons from the interaction point, which is defined by the intersection of the incoming FEL radiation and a gaseous target. The full composition involves 16 spectrometers forming a circular equiangular array in the plane normal to the X-ray propagation and four spectrometers at 54.7° angle relative to the principle linear X-ray polarization axis with orientations in the forward and backward direction of the light propagation. The spectrometers are capable of independent and minimally chromatic electrostatic lensing and retardation, in order to enable simultaneous angle-resolved photo- and Auger–Meitner electron spectroscopy with high energy resolution. They are designed to ensure an energy resolution of 0.25 eV across an energy window of up to 75 eV, which can be individually centered via the adjustable retardation to cover the full range of electron kinetic energies relevant to soft X-ray methods, 0–2 keV. The full spectrometer array will enable non-invasive and online spectral-polarimetry measurements, polarization-sensitive attoclock spectroscopy for characterizing the full time–energy structure of SASE or seeded LCLS II pulses, and support emerging trends in molecular-frame spectroscopy measurements.

Energetic electron measurements and spacecraft charging are of great significance for theoretical research in space physics and space weather applications. In this paper, the energetic electron detection package (EEDP) deployed on three Chinese navigation satellites in medium Earth orbit (MEO) is reviewed. The instrument was developed by the space science payload team led by Peking University. The EEDP includes a pinhole medium-energy electron spectrometer (MES), a high-energy electron detector (HED) based on ΔE-E telescope technology, and a deep dielectric charging monitor (DDCM). The MES measures the energy spectra of 50−600 keV electrons from nine directions with a 180°×30° field of view (FOV). The HED measures the energy spectrum of 0.5−3.0 MeV electrons from one direction with a 30° cone-angle FOV. The ground test and calibration results indicate that these three sensors exhibit excellent performance. Preliminary observations show that the electron spectra measured by the MES and HED are in good agreement with the results from the magnetic electron-ion spectrometer (MagEIS) of the Van Allen Probes spacecraft, with an average relative deviation of 27.3% for the energy spectra. The charging currents and voltages measured by the DDCM during storms are consistent with the high-energy electron observations of the HED, demonstrating the effectiveness of the DDCM. The observations of the EEDP on board the three MEO satellites can provide important support for theoretical research on the radiation belts and the applications related to space weather.

Bu çalışmada, elektron spektrometresi kullanılarak, Helyum (He) atomunun rezonans düzeylerinin açısal değişimleri ölçülmüştür. 200 eV enerjili elektron demeti, yüksek vakum ortamında He atomları ile çarpıştırılarak koparılan ve saçılan elektronlar dedekte edilmiştir. Elektron spektrometresi deney düzeneği; vakum sistemi, elektron tabancası, hedef gaz He, saçılan ve koparılan elektronları dedekte eden iki elektron enerji analizörü, elektron dedektörleri, sinyal işleme ünitesi ve Faraday Elektron Toplayıcıdan (FET) oluşmaktadır. Bu çalışmada, soygaz element serisinde olan Helyum atomunun kendiliğinden iyonlaşma enerji seviyeleri 10o-80o açı aralığında incelenmiştir. Enerji değerleri 32,5-35 eV olarak alınmıştır. Küçük açılarda rezonans profillerinin simetri durumlarının daha baskın olduğu görülürken, büyük açılara doğru kayıldıkça hem simetrik hem asimetrik yapıda oldukları görülmüştür., In this work, the angular variations of the He atom for the resonance levels were experimentally measured by electron spectrometer. 200 eV energetic electron beam collided with Helium (He) gas in high vacuum and scattered electrons were detected. Measurements were taken for angular variation for fixed incident electron energy. The experimental setup in the electron collision laboratory consists of an electron gun, as target He atom, two electron energy analyzers, electron detectors, signal processing units and Faraday Electron Cup (FEC). Here, the auto ionization energy levels of the He atom (in the rare gas element series) for 10o-800 angular range were examined. Differential cross section measurements (DCS) of resonance energy levels were inspected for 32,5-35 eV. Although the symmetry states of resonance profiles are more dominant in the small angle range, both symmetrical and asymmetrical structures are observed for larger angles.

We present multi-period modulation of energetic electron flux observed by the BeiDa Imaging Electron Spectrometer (BD-IES) on board a Chinese navigation satellite on 13 October 2015. Electron flux oscillations were observed at a dominant period of ∼190 s in consecutive energy channels from ∼50 to ∼200 keV. Interestingly, flux modulations at a secondary period of ∼400 s were also unambiguously observed. The oscillating signals at different energy channels were observed in sequence, with a time delay of up to ∼900 s. This time delay far exceeds the oscillating periods, by which we speculate that the modulations were caused by localized ultra-low-frequency (ULF) waves. To verify the wave–particle interaction scenario, we revisit the classic drift-resonance theory. We adopt the calculation method therein to derive the electron energy change in a multi-period ULF wave field. Then, based on the modeled energy change, we construct the flux variations to be observed by a virtual spacecraft. The predicted particle signatures well agree with the BD-IES observations. We demonstrate that the particle energy change might be underestimated in the conventional theories, as the Betatron acceleration induced by the curl of the wave electric field was often omitted. In addition, we show that azimuthally localized waves would notably extend the energy width of the resonance peak, whereas the drift-resonance interaction is only efficient for particles at the resonant energy in the original theory.

The RELEC scientific instrumentation onboard the Vernov spacecraft launched on July 8, 2014, included the DRGE gamma-ray and electron spectrometer. This instrument incorporates a set of scintillation phoswich detectors, including four identical X-ray and gamma-ray detectors in the energy range from 10 keV to 3 MeV with a total area of $\sim$500 $cm^{2}$ directed toward the nadir, and an electron spectrometer containing three mutually orthogonal detector units with a geometry factor of $\sim$2 $cm^{2} sr$, which is also sensitive to X-rays and gamma-rays. The goal of the space experiment with the DRGE instrument was to investigate phenomena with fast temporal variability, in particular, terrestrial gamma-ray flashes (TGFs) and magnetospheric electron precipitations. However, the detectors of the DRGE instrument could record cosmic gamma-ray bursts (GRBs) and allowed one not only to perform a detailed analysis of the gamma-ray variability but also to compare the time profiles with the measurements made by other instruments of the RELEC scientific instrumentation (the detectors of optical and ultraviolet flashes, the radio-frequency and low-frequency analyzers of electromagnetic field parameters). We present the results of our observations of cosmic GRB 141011A and GRB 141104A, compare the parameters obtained in the GBM/Fermi and KONUSWind experiments, and estimate the redshifts and Eiso for the sources of these GRBs. The detectability of GRBs and good agreement between the independent estimates of their parameters obtained in various experiments are an important factor of the successful operation of similar detectors onboard the Lomonosov spacecraft., 19 pages, 8 figures

Multi-electron−ion coincidence spectroscopy is applied for investigating metastability of the dication states formed by the S 2p Auger decay in OCS. The coincidence spectrometer developed in the present work is based on a magnetic-bottle time-of-flight electron spectrometer equipped with electrostatic retardation and ion detection capabilities. Dication spectroscopy with a fairly-high energy resolution and high statistics enables us to inspect the metastability of the individual electronic states in OCS2+.

We describe a magnetic bottle time-of-flight electron spectrometer designed for time-resolved photoemission spectroscopy of a liquid microjet using extreme UV and X-ray radiation. The spectrometer can be easily reconfigured depending on experimental requirements and the energy range of interest. To improve the energy resolution at high electron kinetic energy, a retarding potential can be applied either via a stack of electrodes or retarding mesh grids, and a flight-tube extension can be attached to increase the flight time. A gated electron detector was developed to reject intense parasitic signal from light scattered off the surface of the cylindrically shaped liquid microjet. This detector features a two-stage multiplication with a microchannel plate plus a fast-response scintillator followed by an image-intensified photon detector. The performance of the spectrometer was tested at SPring-8 and SACLA, and time-resolved photoelectron spectra were measured for an ultrafast charge transfer to solvent reaction in an aqueous NaI solution with a 200 nm UV pump pulses from a table-top ultrafast laser and the 5.5 keV hard X-ray probe pulses from SACLA.

The blooming of attosecond science (1 as = $10^{-18}$ s) has raised the need to exquisitely control the delay between two ultrashort light pulses, one of them being intense and in the visible spectral range, while the second is weak and in the Extreme Ultra-Violet spectral range. Here we introduce a robust technique, named LIZARD (Laser-dressed IoniZation for the Adjustment of the pump-pRobe Delay), allowing an active stabilization of this pump-probe delay. The originality of the method lies in an error signal calculated from a two-photon photoelectron signal obtained by photoionizing a gas target in an electronic spectrometer with the two superimposed beams. The modulation of sidebands in phase quadrature allows us to perform an \textit{in situ} measurement of the pump-probe phase, and to compensate for fluctuations with an uniform noise sensitivity over a large range of delays. Despite an interferometer length of several meters, we achieved a long term stability of 28 as RMS over hours. This method could be applied to the stabilization of other types of two-color interferometers, provided that one of the propagating beams is capable of photoionizing a target., 10 pages, 8 figures

We report on the status of a users' end-station, MAC: a Multipurpose station for Atomic, molecular and optical sciences and Coherent diffractive imaging, designed for studies of structure and dynamics of matter in the femtosecond time-domain. MAC is located in the E1 experimental hall on the high harmonic generation (HHG) beamline of the ELI Beamlines facility. The extreme ultraviolet beam from the HHG beamline can be used at the MAC end-station together with a synchronized pump beam (which will cover the NIR/Vis/UV or THz range) for time-resolved experiments on different samples. Sample delivery systems at the MAC end-station include a molecular beam, a source for pure or doped clusters, ultrathin cylindrical or flat liquid jets, and focused beams of substrate-free nanoparticles produced by an electrospray or a gas dynamic virtual nozzle combined with an aerodynamic lens stack. We further present the available detectors: electron/ion time-of-flight and velocity map imaging spectrometers and an X-ray camera, and discuss future upgrades: a magnetic bottle electron spectrometer, production of doped nanodroplets and the planned developments of beam capabilities at the MAC end-station., Comment: 14 pages, 13 figures. This is a preprint of an article published in The European Physical Journal Special Topics, 2021

The Cluster mission has produced a large data set of electron flux measurements in the Earth's magnetosphere since its launch in late 2000. Electron fluxes are measured using Research with Adaptive Particle Imaging Detector (RAPID)/Imaging Electron Spectrometer (IES) detector as a function of energy, pitch angle, spacecraft position, and time. However, no adiabatic invariants have been calculated for Cluster so far. In this paper we present a step-by-step guide to calculations of adiabatic invariants and conversion of the electron flux to phase space density (PSD) in these coordinates. The electron flux is measured in two RAPID/IES energy channels providing pitch angle distribution at energies 39.2-50.5 and 68.1-94.5 keV in nominal mode since 2004. A fitting method allows to expand the conversion of the differential fluxes to the range from 40 to 150 keV. Best data coverage for phase space density in adiabatic invariant coordinates can be obtained for values of second adiabatic invariant, K, similar to 10(2), and values of the first adiabatic invariant mu in the range approximate to 5-20 MeV/G. Furthermore, we describe the production of a new data product "LSTAR," equivalent to the third adiabatic invariant, available through the Cluster Science Archive for years 2001-2018 with 1-min resolution. The produced data set adds to the availability of observations in Earth's radiation belts region and can be used for long-term statistical purposes., Zweitver��ffentlichungen der Universit��t Potsdam : Mathematisch-Naturwissenschaftliche Reihe; 1192

An overview of the gas-phase endstation with the multi-coincidence setup at the FinEstBeAMS beamline in the MAX IV 1.5 GeV storage ring is presented. A detailed description of the functional design of the endstation together with the data acquisition concept and first test measurements is given., Since spring 2019 ▸ an experimental setup consisting of an electron spectrometer and an ion time-of-flight mass spectrometer for diluted samples has been available for users at the FinEstBeAMS beamline of the MAX IV Laboratory in Lund, Sweden. The setup enables users to study the interaction of atoms, molecules, (molecular) microclusters and nanoparticles with short-wavelength (vacuum ultraviolet and X-ray) synchrotron radiation and to follow the electron and nuclear dynamics induced by this interaction. Test measurements of N2 and thiophene (C4H4S) molecules have demonstrated that the setup can be used for many-particle coincidence spectroscopy. The measurements of the Ar 3p photoelectron spectra by linear horizontal and vertical polarization show that angle-resolved experiments can also be performed. The possibility to compare the electron spectroscopic results of diluted samples with solid targets in the case of Co2O3 and Fe2O3 at the Co and Fe L 2,3-absorption edges in the same experimental session is also demonstrated. Because the photon energy range of the FinEstBeAMS beamline extends from 4.4 eV up to 1000 eV, electron, ion and coincidence spectroscopy studies can be executed in a very broad photon energy range.

We report experimental results on relativistic electron beam (REB) transport in a set of cold and shock-heated carbon samples using the high-intensity kilojoule-class OMEGA EP laser. The REB energy distribution and transport were diagnosed using an electron spectrometer and x-ray fluorescence measurements from a Cu tracer buried at the rear side of the samples. The measured rear REB density shows brighter and narrower signals when the targets were shock-heated. Hybrid PIC simulations using advanced resistivity models in the target warm-dense-matter (WDM) conditions confirm this observation. We show that the resistivity response of the media, which governs the self-generated resistive fields, is of paramount importance to understand and correctly predict the REB transport.

Background : Autoionization is an indirect ionization process that significantly increases the total ionization cross section of the atom. Measurements of electron autoionizing spectra in a broad range of impact energies and the determination of their total intensity allow obtaining the absolute value of the autoionization contribution (the autoionization cross section) and its energy behavior. Methods : The study of the ejected-electron spectra of strontium atoms were carried out by using an electron spectrometer. It consists of a source of the incident electron beam, an electron energy analyzer (of 127° electrostatic type deflector) and an atomic beam source. To minimize the influence of the anisotropy of the angular distribution of ejected electrons, the measurements were carried out at a "magic" observation angle of 54.7°. The incident and ejected-electron energy resolutions were about 0.4 eV and 0.07 eV, respectively. The increment step of the incident electron energy was 0.1 eV in the near-threshold energy region. The autoionization cross section was determined as the normalized sum of total intensities of ejected-electron spectra measured at different impact energies. Results : Autoionization cross section for 4p 6 shell of strontium atoms was determined in an incident-electron energy range from the lowest autoionization threshold (20,98 eV) up to 600 eV. Energy behavior of the cross section is characterized by the presence of the strong resonance structure in the threshold region of 21-30 eV and a broad maximum at approximately 100 eV. Cross section reaches its maximum value of 1.6×10 -16 сm 2 at 24.8 eV. We analyze the excitation and decay processes of the 4p 5 n 1 l 1 n 2 l 2 n 3 l 3 autoionizing states. They determine the magnitude and the energy behavior of the autoionization cross section. Conclusions : The strong resonant excitation of the levels in 4p 5 4d5s 2 , 4p 5 4d 2 5s, and 4p 5 5s 2 5p configurations determines the resonant behavior of the measured autoionization cross section at low impact energies. Shape and magnitude of the cross section at high impact energies are determined by the total contribution from dipole-allowed and singlets autoionizing levels in the configurations 4p 5 4d5s 2 , 4p 5 4d 2 5s.

Work towards producing a radiation-hard and high temperature tolerant direct detection electron spectrometer is reported. The motivation is to develop a low-mass, low-volume, low-power, multi-mission capable instrument for future space science missions. The resultant prototype electron spectrometer employed a GaAs p+-i-n+ mesa photodiode (10 µm i layer thickness; β00 μm diameter) and a custom-made charge-sensitive preamplifier. The GaAs detector was initially electrically characterized as a function of temperature. The detector-preamplifier assembly was then investigated for its utility in electron spectroscopy across the temperature range 100 °C to 20 °C using a laboratory 63Ni radioisotope - particle source (end point energy = 66 keV). Monte Carlo simulations using the computer program CASINO were conducted and showed that the spectrometer had a quantum detection efficiency which increased with increasing electron energy up to 70 keV; a quantum detection efficiency of 73 % was calculated. The accumulated 63Ni - particle spectra together with CASINO simulations of the detected spectra showed that the GaAs based spectrometer could be used for counting electrons and measuring the energy deposited per electron in the detector’s active region (i layer). The development of a GaAs electron spectrometer of this type may find use in future space missions to environments of intense radiation (such as at the surface of Europa for investigation of electron-driven radiolysis of ice) and high temperature (such as at Mercury, and comets passing close to the Sun).

Background : The presence of a closed valence shell in alkaline-earth atoms makes the processes of their excitation and ionization as a whole much more complicated than for neighboring alkali atoms. In order to find patterns and differences in the course of autoionization in these two groups of atoms, it is interesting to compare their autoionization cross sections. Studies of the latter for alkaline-earth atoms have not been conducted until recently. In this paper, the 5p 6 autoionization cross sections of cesium and barium atoms excited by electrons were investigated in the impact-energy range from the excitation threshold of the 5p 6 subshells to 600 eV. Methods : The measurements of the ejected-electron spectra of Cs and Ba atoms were carried out by using an electron spectrometer consisted of a source of the incident electron beam, an electron energy analyzer (of 127 ° electrostatic type) and an atomic beam source. To minimize the influence of the anisotropy of the angular distribution of ejected electrons, the measurements were carried out at a "magic" observation angle of 54.7 ° . The incident and ejected-electron energy resolutions were about 0.4 eV and 0.07 eV, respectively. The increment step of the incident electron energy was 0.1 eV in the near-threshold energy region. The autoionization cross section of Cs and Ba atoms were determined as the normalized total intensities of ejected-electron spectra measured at different impact energies. Results : The autoionization cross sections for 5p 6 subshells in Cs and Ba atoms were determined in an incident-electron energy range from the lowest autoionization thresholds up to 600 eV. The energy behavior of both cross sections is characterized by the presence of the strong resonance structure in the threshold region of 12-23 eV and a broad maximum at approximately 100 eV. The cross sections reach their maximum value of 4.2×10 -16 сm 2 for cesium and 6.7×10 -16 сm 2 for barium at 14.8 eV and 17.4 eV, respectively. An analysis is made of the excitation and decay processes of the 5p 5 n 1 l 1 n 2 l 2 (Cs) and 5p 5 n 1 l 1 n 2 l 2 n 3 l 3 (Ba) autoionizing states that determine the magnitude and the energy behavior of the autoionization cross sections. Conclusions : The strong resonant excitation of the lowest levels in 5p 5 6s 2 , 5p 5 5d6s configurations in cesium and 5p 5 5d6s 2 , 5p 5 5d 2 6s,6p,6d,7d, 5p 5 6s 2 6p,7s,7d and 5p 5 5d6s6p;7s,7d configurations in barium determines the resonant behavior of the measured autoionization cross sections at low impact energies. The shape and magnitude of the cross sections at high impact energies are determined by the total contribution from doublet autoionizing states in cesium and dipole-allowed autoionizing states in the lowest configurations 5p 5 5d6s 2 and 5p 5 5d 2 6s in barium.

We have developed an on-line magnetic spectrometer to measure energy distributions of fast electrons generated from ultra-intense laser-solid interactions. The spectrometer consists of a sheet of plastic scintillator, a bundle of non-scintillating plastic fibers, and an sCMOS camera recording system. The design advantages include on-line capturing ability, versatility of detection arrangement, and resistance to harsh in-chamber environment. The validity of the instrument was tested experimentally. This spectrometer can be applied to the characterization of fast electron source for understanding fundamental laser-plasma interaction physics and to the optimization of high-repetition-rate laser-driven applications.

Ground-based imaging and in situ sounding rocket data are compared to electron transport modeling for an active inverted-V type auroral event. The Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment (GREECE) mission successfully launched from Poker Flat, Alaska, on 3 March 2014 at 11:09:50 UT and reached an apogee of approximately 335 km over the aurora. Multiple ground-based electron-multiplying charge-coupled device (EMCCD) imagers were positioned at Venetie, Alaska, and aimed toward magnetic zenith. The imagers observed the intensity of different auroral emission lines (427.8, 557.7, and 844.6 nm) at the magnetic foot point of the rocket payload. Emission line intensity data are correlated with electron characteristics measured by the GREECE onboard electron spectrometer. A modified version of the GLobal airglOW (GLOW) model is used to estimate precipitating electron characteristics based on optical emissions. GLOW predicted the electron population characteristics with 20% error given the observed spectral intensities within 10 deg of magnetic zenith. Predictions are within 30% of the actual values within 20 deg of magnetic zenith for inverted-V-type aurora. Therefore, it is argued that this technique can be used, at least in certain types of aurora, such as the inverted-V type presented here, to derive 2-D maps of electron characteristics. These can then be used to further derive 2-D maps of ionospheric parameters as a function of time, based solely on multispectral optical imaging data.

We present a newly developed end-station at BESSY II dedicated to in situ Spectroscopic Analysis with Tender X-rays (SpAnTeX). The core of the end-station is a new SPECS PHOIBOS 150 HV NAP electron spectrometer. First, we show that the system has successfully achieved high electron transmission and detection efficiency under gas pressures up to 30 mbar and photon energies ranging between 200 eV and 10 keV. Second, using two features of this spectrometer (a new lateral resolution lens and a 3D delay line detector), we show that the endstation enables collection of the photoelectron spatial distribution under realistic working conditions (p ≥ 20 mbar) with a resolution better than 30 μm and the possibility to perform time resolved studies using a continuous tender X-ray source. We conclude by reporting an example of the possible experiments that can be performed using this new endstation using the Dip-and-Pull technique. Although mainly focused on the characterization of solid/liquid interfaces using AP-HAXPES, the end-station can be used at soft X-ray beamlines for more traditional AP-XPS experiments. The Dip-and-Pull module also demonstrates good electrochemical performance. The wide pressure and photon energy range covered by this end-station also enables investigations of solid/solid, solid/gas, liquid/vapor and liquid/liquid interfaces at pressures up to 30 mbar with tender X-rays.

Jefferson Lab is constructing an 11-Gev/c electron spectrometer called the super high momentum spectrometer (SHMS) as part of the 12-GeV JLAB upgrade for experimental Hall C. Three of the five superconducting SHMS magnets are under construction at SigmaPhi in Vannes, France, as a result of an international competition for design and fabrication. The three magnets Q2 and Q3 60 cm bore quadrupoles and the 60 cm warm bore dipole are complete or near complete and have many design features in common. All three magnets share a common superconductor, collaring system, cryostat design, cold to warm support, cryogenic interface, burnout resistant current leads, dc power supply, quench protection, and instrumentation and controls. The three magnets are collared, installed in cryostats and welded up, and in various stages of final testing. The Q2 quadrupole is due to ship from France to America in August arriving during this ASC conference and has passed all final hipot, leak, and pressure tests. The dipole is in leak and pressure testing as of July 2016, whereas the Q3 quadrupole requires some outer vacuum vessel assembly. Delivery of the Q3 and dipole magnets will follow the Q2 at about one month intervals. Factory testing has included hipot and electrical tests, magnetic tests at low field, mechanical alignments to center the coils, leak tests, and ASME code required pressure tests. Upon installation in Hall C at JLAB cold testing will commence.

The RELEС scientific payload of the Vernov satellite launched on July 8, 2014 includes the DRGE spectrometer of gamma-rays and electrons. This instrument comprises a set of scintillator phoswich-detectors, including four identical X-ray and gamma-ray detector with an energy range of 10 kev to 3 MeV with a total area of ~500 cm2 directed to the atmosphere, as well as an electron spectrometer containing three mutually orthogonal detector units with a geometric factor of ~2 cm2 sr. The aim of a space experiment with the DRGE instrument is the study of fast phenomena, in particular Terrestrial gamma-ray flashes (TGF) and magnetospheric electron precipitation. In this regard, the instrument provides the transmission of both monitoring data with a time resolution of 1 s, and data in the event-by-event mode, with a recording of the time of detection of each gamma quantum or electron to an accuracy of ~15 μs. This makes it possible to not only conduct a detailed analysis of the variability in the gamma-ray range, but also compare the time profiles with the results of measurements with other RELEC instruments (the detector of optical and ultraviolet flares, radio-frequency and low-frequency analyzers of electromagnetic field parameters), as well as with the data of ground-based facility for thunderstorm activity. This paper presents the first catalog of Terrestrial gamma-ray flashes. The criterion for selecting flashes required in order to detect no less than 5 hard quanta in 1 ms by at least two independent detectors. The TGFs included in the catalog have a typical duration of ~400 μs, during which 10–40 gamma-ray quanta were detected. The time profiles, spectral parameters, and geographic position, as well as a result of a comparison with the output data of other Vernov instruments, are presented for each of candidates. The candidate for Terrestrial gamma-ray flashes detected in the near-polar region over Antarctica is discussed.

We investigate the average configuration and structure of Saturn's magnetosphere in the nightside equatorial and high‐latitude regions. Electron data from the Cassini Plasma Spectrometer's Electron Spectrometer (CAPS‐ELS) is processed to produce a signal‐to‐noise ratio for the entire CAPS‐ELS time of operation at Saturn's magnetosphere. We investigate where the signal‐to‐noise ratio falls below 1, to identify regions in the magnetosphere where there is a significant depletion in the electron content. In the nightside equatorial region we use this to find that the most planetward reconnection x‐line location is at 20 – 25 RS downtail from the planet in the midnight to dawn sector. We also find an equatorial dawn‐dusk asymmetry at a radial distance of >20 RS which may indicate the presence of plasma depleted flux tubes returning to the dayside after reconnection in the tail. Furthermore, we find that the high‐latitude magnetosphere is predominantly in a state of constant plasma depletion and located on open field lines. We map the region of high‐latitude magnetosphere that is depleted of electrons to the polar cap to estimate the size and open flux content within the polar caps. The mean open flux content for the northern and southern polar caps are found to be 25±5 and 32±5 GWb, respectively. The average location of the open‐closed field boundary is found at invariant colatitudes of 12.7±0.6° and 14.5±0.6°. The northern boundary is modulated by planetary period oscillations more than the southern boundary.

We present multi-period modulation of energetic electron flux observed by the BeiDa Imaging Electron Spectrometer (BD-IES) onboard a Chinese navigation satellite on October 13, 2015. Electron flux oscillations were observed at a dominant period of ~ 190 s in consecutive energy channels from ~ 50 keV to ~ 200 keV. Interestingly, flux modulations at a secondary period of ~ 400 s were also unambiguously observed. The oscillating signals at different energy channels were observed in sequence, with a time delay of up to ~ 900 s. This time delay far exceeds the oscillating periods, by which we speculate that the modulations were caused by localized ultra-low frequency (ULF) waves. To verify the wave-particle interaction scenario, we revisit the classic drift-resonance theory. We adopt the calculation scheme therein to derive the electron energy change in a multi-period ULF wave field. Then, based on the modeled energy change, we construct the flux variations to be observed by a virtual spacecraft. The predicted particle signatures well agree with the BD-IES observations. We demonstrate that the particle energy change might be underestimated in the conventional theories, as the Betatron acceleration induced by the curl of the wave electron field was often omitted. In addition, we show that azimuthally localized waves would notably extend the energy width of the resonance peak, whereas the drift-resonance interaction is only efficient for particles at the resonant energy in the original theory.

In this work, a 200 μm diameter InGaP (GaInP) p+-i-n+ mesa photodiode was studied across the temperature range 100 °C to 20 °C for the development of a temperature-tolerant electron spectrometer. The depletion layer thickness of the InGaP device was 5 μm. The performance of the InGaP detector was analysed under dark conditions and then under the illumination of a 183 MBq 63Ni radioisotope beta particle source. The InGaP photodiode was connected to a custom-made low-noise charge-sensitive preamplifier to realise a particle counting electron spectrometer. Beta spectra were collected at temperatures up to 100 °C with the InGaP device reverse biased at 5 V. The spectrum accumulated at 20 °C was compared with the spectrum predicted using Monte Carlo simulations; good agreement was found between the predicted and experimental spectra. The work is of importance for the development of electron spectrometers that can be used for planetary and space science missions to environments of high temperature or extreme radiation (e.g. Mercury, Jupiter’s moon Europa, near-Sun comets), as well as terrestrial applications.

A novel mesoscopic electron spectrometer allows for the probing of relaxation processes in quantum Hall edge channels. The device is composed of an emitter quantum dot that injects energy-resolved electrons into the channel closest to the sample edge, to be subsequently probed downstream by a detector quantum dot of the same type. In addition to inelastic processes in the sample that stem from interactions inside the region between the quantum dot energy filters (inner region), anomalous signals are measured when the detector energy exceeds the emitter energy. Considering finite range Coulomb interactions in the sample, we find that energy exchange between electrons in the current inducing source channel and the inner region, similar to Auger recombination processes, is responsible for such anomalous currents. In addition, our perturbative treatment of interactions shows that electrons emitted from the source, which dissipate energy to the inner region before entering the detector, contribute to the current most strongly when emitter-detector energies are comparable. Charge transfer in which the emitted electron is exchanged for a charge carrier from the Fermi sea, on the other hand, preferentially occurs close to the Fermi level.

With the increase of laser power at facilities reaching petawatt-level, there is a need for accurate electron beam diagnostics of the laser wakefield accelerator (LWFA), which are becoming important tools for a wide range of applications including high field physics. Electrons in the range of several 10 0s of GeV are expected at these power levels. Precise diagnostic systems are required to enable applications such as advanced radiation sources. Accurate measurement of the energy spread of electron beams will help pave the way towards LWFA based free-electron lasers and plasma based coherent radiation sources. We propose an innovative double dipole spectrometer suitable for characterizing bunches produced using a petawatt class laser.

The Cluster mission, launched in 2000, has produced a large database of electron flux intensity measurements in the Earths magnetosphere by the Research with Adaptive Particle Imaging Detector (RAPID)/ Imaging Electron Spectrometer (IES) instrument. However, due to background contamination of the data with high-energy electrons (>400 keV) and inner- zone protons (230-630 keV) in the radiation belts and ring current, the data have been rarely used for inner-magnetospheric science. The current paper presents two algorithms for background correction. The first algorithm is based on the empirical contamination percentages by both protons and electrons. The second algorithm uses simultaneous proton observations. The efficiencies of these algorithms are demonstrated by comparison of the corrected Cluster/RAPID/IES data with Van Allen Probes/Magnetic Electron Ion Spectrometer (MagEIS) measurements for 2012-2015. Both techniques improved the IES electron data in the radiation belts and ring current.Yearly averaged flux intensities of the two missions show the ratio of measurements close to 1. IES corrected measurements were also compared with Arase Medium-Energy Particle Experiments-Electron Analyzer (MEP-e) electron data during two conjunction periods in 2017 and also exhibited ratio close to 1. We demonstrate a scientific application of the corrected IES electron data analyzing its evolution during solar cycle. Spin-averaged yearly mean IES electron intensities in the outer belt for energies 40-400 keV at L-shell between 4 and 6 showed high positive correlation with AE index and solar wind dynamic pressure during 2001- 2016. Relationship between solar wind dynamic pressure and IES electron measurements in the outer radiation belt was derived as a uniform linear-logarithmic equation.

TIGER (aka Torino Integrated Gem Electronics for Readout) is the ASIC designed at INFN-Torino for the front-end electronics of a cylindrical triple GEM detector, proposed to replace the inner tracker of BESIII spectrometer (Beijing Electron Spectrometer). The high luminosity of the collider, operational at the Institute of High Energy Physics in Beijing (IHEP), allows to measure states of charmonium and open charm, to carry out light hadrons spectroscopy and to study $\tau$ lepton physics, but it caused aging and degradation problems to the tracking performance. The 64-channel chip in analog-digital mixed mode has been designed using CMOS 110 nm UMC technology in order to be exported to China. Each channel has two branches: branch E for charge measurements and branch T for time measurements.

$^{229}$Th is the only known nucleus with an excited state that offers the possibility for a direct laser excitation using existing laser technology. Its excitation energy has been measured indirectly to be 7.8(5) eV ($\approx$160 nm). The energy and lifetime of the isomeric state make it the presently only suitable candidate for a nuclear optical clock, the uncertainty of the excitation energy is, however, still too large to allow for a direct laser excitation in a Paul trap. Therefore, a major goal during the past years has been an improved energy determination. One possible approach is to measure the kinetic energy of electrons which are emitted in the internal conversion decay of the first isomeric state in $^{229}$Th. For this reason an electron spectrometer based on a magnetic bottle combined with electrical retarding fields has been built. Its design, as well as first test measurements are presented, which reveal a relative energy resolution of 3 % and thus enable to measure the electrons' expected kinetic energy to better than 0.1 eV. This is sufficiently precise to specify a laser system able to drive the nuclear clock transition in $^{229}$Th.

XXI International Conference on Ultrafast Phenomena 2018 (UP 2018), UP2018, Hamburg, Germany, 15 Jul 2018 - 20 Jul 2018; The European physical journal / Web of Conferences 205, 3007 (2019). doi:10.1051/epjconf/201920503007, We present a design combining a velocity map imaging electron spectrometer with a reflectron mass spectrometer. Since the two spectrometer sides have different intrinsic requirements for the electric field in the central region, a large number of electrodes and a reflectron-geometry of the mass spectrometer were employed to achieve simultaneous high resolutions. Together with femtosecond and attosecond pump-probe methods it will enable studies of ultrafast dynamics in large molecular systems., Published by EDP Sciences, Les Ulis

Real experimental measurements in high-radiation environments often suffer from a high-flux of background noise which can limit the retrieval of the underlying signal. It is important to have an effective method to properly remove unwanted noise from measurement images. Machine learning methods using a multilayer neural network (deep learning) have been shown to be effective for extracting features from images. However, the efficacy of such methods is often restricted by a lack of high-quality training data. Here, we demonstrate the application for noise removal by performing simulations to generate virtual training data for a denoising deep-learning model. We first apply the model to simulations of an electron spectrometer measuring the energy spectra of electron beams accelerated from the interaction of an intense laser with a thin foil. By considering the chi-squared test and image test-indexes, namely the peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM), we found our method to be highly effective. We then used the trained model to denoise real experimental measurements of the electron beam spectra from experiments performed at a state-of-the-art high-power laser facility. This application is offered as a new method for effectively removing noise from experimental data in high-flux radiation background environment.

An electron beam derived from stripping of ultrarelativistic lead ions has been used to perform calibration measurements on the electron spectrometer of the Advanced Wakefield experiment at CERN. As part of this study, new measurements of the stripping cross-section for ultrarelativistic hydrogen-like lead ions passing through aluminium and silicon have been obtained which demonstrate good agreement with existing measurements and theory. Improvements in terms of electron beam quality and ion beam diagnostic capability, as well as further applications of such an electron beam, are discussed.

The cornerstone of the Chinese experimental particle physics program is a series of experiments performed in the τ-charm energy region. China began building e+e− colliders at the Institute for High Energy Physics in Beijing more than three decades ago. Beijing Electron Spectrometer (BES) is the common root name for the particle physics detectors operated at these machines. We summarize the development of the BES program and highlight the physics results across several topical areas.

There is a proposal to search for a sterile neutrino in a few keV mass range by the “Troitsk nu-mass” facility. In order to estimate sterile neutrino mixing one needs to make precision spectrum measurements well below the endpoint using the existing electrostatic spectrometer with a magnetic adiabatic collimation, or MAC-E filter. The expected signature will be a kink in the electron energy spectrum in tritium beta-decay. In this paper we consider the systematic effect of electron backscattering on the detector used in the spectrometer. For this purpose we provide a set of Monte-Carlo simulation results of electron backscattering on a silicon detector with a thin golden window with realistic electric and magnetic fields in the spectrometer. We have found that the probability of such an effect reaches up to 20–30%. The scattered electron could be reflected backwards to the detector by electrostatic field or by magnetic mirror. There is also a few percent probability to escape from the spectrometer through its entrance. A time delay between the scattering on the detector and the return of the reflected electron can reach a couple of microseconds in the Troitsk spectrometer. Such estimations are critical for the planning upgrades of the detector and the registration electronics. All considered effects are relevant to any MAC-E type spectrometer with solid detector.

A technique to determine the isotopic constituents of a mixed actinide sample has been proposed by a coincident alpha-conversion electron measurement. This presents a unique signature to allow the unfolding of isotopes that possess overlapping alpha particle energy and reduce backgrounds of an unseparated sample. The work presented here are results of conversion electron spectroscopy of 241 Am, 238 Pu and 239 Pu using a dual-stage peltier-cooled 25 mm 2 silicon drift detector and alpha spectroscopy with a passivated ion implanted planar silicon detector. The conversion electron spectra were evaluated from 20–55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information and calibration to aid in the coincident measurement approach. Furthermore, an alpha-conversion electron spectrometer was assembled using the silicon based detectors described and results of a coincident spectrum analysis is reported for 241 Am.

A common feature of top hat space plasma analyzers are electrostatic "deflector plates" mounted externally to the aperture which steer the incoming particles and permit the sensor to rapidly scan the sky without moving. However, the electric fields generated by these plates can penetrate the mesh or grid on the outside of the sensor, potentially violating spacecraft electromagnetic cleanliness requirements. In this brief report we discuss how this issue was addressed for the Dual Electron Spectrometer for the Magnetospheric Multiscale Mission using a double-grid system and the simple modeling technique employed to assure the safe containment of the stray fields from its deflector plates.

For most Cassini passes through the inner magnetosphere of Saturn, the hot electron population (> few hundred eVs) largely disappears inside of some cutoff L shell. Anode-and-actuation-angle averages of hot electron fluxes observed by the Cassini Electron Spectrometer are binned into 0.1 Rs bins in dipole L to explore the properties of this cutoff distance. The cutoff L shell is quite variable from pass to pass (on timescales as short as 10–20 h). At energies of 5797 eV, 2054 eV, and 728 eV, 90% of the inner boundary values lie between L ~ 4.7 and 8.4, with a median near L = 6.2, consistent with the range of L values over which discrete interchange injections have been observed, thus strengthening the case that the interchange process is responsible for delivering the bulk of the hot electrons seen in the inner magnetosphere. The occurrence distribution of the inner boundary is more sharply peaked on the nightside than at other local times. There is no apparent dependence of the depth of penetration on large-scale solar wind properties. It appears likely that internal processes (magnetic stress on mass-loaded flux tubes) are dominating the injection of hot electrons into the inner magnetosphere.

A special electrostatic electron spectrometer designed for precise and unique experiments and an intensity calibration method for universal application in electron spectroscopy are presented. The upgrade of the analyzer enables the intensity calibration at arbitrary electron energies using elastically scattered electrons. In order to test the calibration procedure the double differential (in energy and angle) ionization cross sections (DDCS) of electrons ejected from 300 keV proton-argon collisions were measured and compared with the data of Rudd et al. [1]. The good agreement between the two data sets verifies the applicability of the calibration method.

The paper describes cases of observations of narrow energy spectrum electron flows up to 500 eV on the INTERBALL Tail Probe. About 30 events were registered in 1996 on the night side of the Earth predominantly in 03h–06h local time sector. Quasimonochromatic electrons (QME) were registered by all 8 spectrometer channels oriented along the spacecraft meridian with angles of the field of view centers relative to sunward direction from 11° to 169°. Quasimonochromatic electrons were observed simultaneously with large fluxes of high temperature magnetospheric electrons. The dependences of QME energy on both fluxes and energy of high-energy magnetospheric electrons were observed in every event. The ratio of full width at half height (FWHH) to mean energy of QME was ~20%. This electron component with quasimonochromatic energy probably was originated on the spacecraft surface. The registered energy of QME was apparently due to difference of potentials between spacecraft surface from which electron beam originated and the location of electron spectrometer.

Laser Wakefield plasma acceleration of electrons to energies above 10 GeV, may be possible in the new high power Laser beam facilities. The design of an Electron Spectrometer with an electro-magnet with adjustable magnetic field is proposed for the characterization of electron energy spectrum with a precision better than 10% for the entire energy range from 0.5 GeV to 38 GeV. The expected precision in the measurement of the electron energy is calculated as a function of the magnetic field, of the electron energy and of the magnet length. To outline the advantages offered by a pulsed electromagnet with high magnetic fields, the mass and the electric power lost in the coils of a 4 m long electromagnet with continuous current and Iron yoke are calculated.

Single photon simultaneous core ionization/core excitation (K−2V) of the Benzene molecule has been observed experimentally, using synchrotron radiation, by electron coincidence spectroscopy with a magnetic bottle time-of-flight electron spectrometer and reveals a rich spectrum. DFT and Post–Hartree–Fock calculations provide detailed assignments of K−2V states. The specific Auger decay of these states has also been determined experimentally with a new technique to improve the energy resolution.

X-ray photoelectron spectroscopy (XPS) is used to analyze the chemistry of the Ru(0001) film surface and the Ru/SiO2 interfacial region at different annealing conditions. The XPS spectra are collected under ultrahigh vacuum (base pressure of ∼5 × 10−10 Torr) condition using a SPECS electron spectrometer with a PHOIBOS 100 hemispherical energy analyzer and an XR 50 Al Kα x-ray source (1486.67 eV). High-resolution spectra of O 1s, Ru 3d/C 1s, and Si 2p together with survey scans are presented. The presence of 1 × 1 low energy diffraction pattern, collected from a 950 °C Ar/H2 step-annealed Ru(0001) sample, confirms the hexagonal periodicity of Ru(0001) surfaces.

We study the distribution of magnetospheric electrons using data from the BeiDa Imaging Electron Spectrometer (BD-IES) onboard a Chinese navigation spacecraft and the Magnetic Electron Ion Spectrometer (MagEIS) onboard the Van Allen Probes (VAP). While the MagEIS instrument monitors electron flux in the inner magnetosphere ( L ∗ 6 ), the BD-IES instrument extends the range of measurement beyond the geosynchronous distance ( 6 L ∗ 9 ). Utilizing one year of the multi-spacecraft data, the distribution of electron phase space density (PSD) of wide spatial and energy coverage is statistically derived for the first time. Evident peaks are identified in the radial PSD profiles of energetic electrons ( μ > 50 M e V / G ) at L ∗ ~ 5.5 , with the inner and outer sides of the PSD peaks unambiguously observed by MagEIS and BD-IES respectively. These peaked distributions confirm that local acceleration plays an important role in the electron dynamics. Besides, the electron spectra in the vicinity of the PSD peak are harder, with spectral indexes of ~ − 2.5 . The spectral index drops to ~ − 4 inside L ∗ ~ 3 . This softer spectrum indicates less acceleration and/or more loss in the most inner part of the magnetosphere. The new observational results from the BD-IES, incorporated with VAP data, provide us with a more comprehensive view of the energetic electrons in the near Earth space.