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Publikationen von
Andreas Seidel

Alle Publikationen des HI Jena


F. C. Salgado, N. Cavanagh, M. Tamburini, D. W. Storey, R. Beyer, P. H. Bucksbaum, Z. Chen, A. Di Piazza, E. Gerstmayr, . Harsh, E. Isele, A. R. Junghans, C. H. Keitel, S. Kuschel, C. F. Nielsen, D. A. Reis, C. Roedel, G. Sarri, A. Seidel, C. Schneider, I. Uggerhoj, J. Wulff, V. Yakimenko, C. Zepter, S. Meuren, and M. Zepf
Single particle detection system for strong-field QED experiments
New Journal of Physics 24, 015002 (2022)

Abstract: Measuring signatures of strong-field quantum electrodynamics (SF-QED) processes in an intense laser field is an experimental challenge: it requires detectors to be highly sensitive to single electrons and positrons in the presence of the typically very strong x-ray and gamma-photon background levels. In this paper, we describe a particle detector capable of diagnosing single leptons from SF-QED interactions and discuss the background level simulations for the upcoming Experiment-320 at FACET-II (SLAC National Accelerator Laboratory). The single particle detection system described here combines pixelated scintillation LYSO screens and a Cherenkov calorimeter. We detail the performance of the system using simulations and a calibration of the Cherenkov detector at the ELBE accelerator. Single 3 GeV leptons are expected to produce approximately 537 detectable photons in a single calorimeter channel. This signal is compared to Monte-Carlo simulations of the experiment. A signal-to-noise ratio of 18 in a single Cherenkov calorimeter detector is expected and a spectral resolution of 2% is achieved using the pixelated LYSO screens.


B. Kettle, D. Hollatz, E. Gerstmayr, G. M. Samarin, A. Alejo, S. Astbury, C. Baird, S. Bohlen, M. Campbell, C. Colgan, D. Dannheim, C. Gregory, H. Harsh, P. Hatfield, J. Hinojosa, Y. Katzir, J. Morton, C. D. Murphy, A. Nurnberg, J. Osterhoff, G. Pérez-Callejo, K. Põder, P. P. Rajeev, C. Roedel, F. Roeder, F. C. Salgado, G. Sarri, A. Seidel, S. Spannagel, C. Spindloe, S. Steinke, M. J. V. Streeter, A. G. R. Thomas, C. Underwood, R. Watt, M. Zepf, S. J. Rose, and S. P. D. Mangles
A laser–plasma platform for photon–photon physics: the two photon Breit–Wheeler process
New Journal of Physics 23, 115006 (2021)
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F. C. Salgado, K. Grafenstein, A. Golub, A. Dopp, A. Eckey, D. Hollatz, C. Muller, A. Seidel, D. Seipt, S. Karsch, and M. Zepf
Towards pair production in the non-perturbative regime
New Journal of Physics 23, 105002 (2021)

Abstract: The interaction of light with the quantum-vacuum is predicted to give rise to some of the most fundamental and exotic processes in modern physics, which remain untested in the laboratory to date. Electron-positron pair production from a pure vacuum target, which has yet to be observed experimentally, is possibly the most iconic. The advent of ultra-intense lasers and laser accelerated GeV electron beams provide an ideal platform for the experimental realisation. Collisions of high energy gamma-ray photons derived from the GeV electrons and intense laser fields result in detectable pair production rates at field strengths that approach and exceed the Schwinger limit in the centre-of-momentum frame. A detailed experiment has been designed to be implemented at the ATLAS laser at the centre of advanced laser applications. We show full calculations of the expected backgrounds and beam parameters which suggest that single pair events can be reliably generated and detected.

A. Seidel, J. Osterhoff, and M. Zepf
Characterizing ultralow emittance electron beams using structured light fields
Physical Review Accelerators and Beams 24, 012803 (2021)

Abstract: Novel schemes for generating ultralow emittance electron beams have been developed in past years and promise compact particle sources with excellent beam quality suitable for future high-energy physics experiments and free-electron lasers. Current methods for the characterization of low emittance electron beams such as pepperpot measurements or beam focus scanning are limited in their capability to resolve emittances in the sub 0.1 mm mrad regime. Here we propose a novel, highly sensitive method for the single shot characterization of the beam waist and emittance using interfering laser beams. In this scheme, two laser pulses are focused under an angle creating a gratinglike interference pattern. When the electron beam interacts with the structured laser field, the phase space of the electron beam becomes modulated by the laser ponderomotive force and results in a modulated beam profile after further electron beam phase advance, which allows for the characterization of ultralow emittance beams. 2D PIC simulations show the effectiveness of the technique for normalized emittances in the range of epsilon(n) = 1/20.01; 1] mm mrad.


M. B. Schwab, E. Siminos, T. Heinemann, D. Ullmann, F. Karbstein, S. Kuschel, A. Sävert, M. Yeung, D. Hollatz, A. Seidel, J. Cole, S. P. D. Mangles, B. Hidding, M. Zepf, S. Skupin, and M. C. Kaluza
Visualization of relativistic laser pulses in underdense plasma
Physical Review Accelerators and Beams 23, 032801 (2020)

Abstract: We present experimental evidence of relativistic electron-cyclotron resonances (RECRs) in the vicinity of the relativistically intense pump laser of a laser wakefield accelerator (LWFA). The effects of the RECRs are visualized by imaging the driven plasma wave with a few-cycle, optical probe in transverse geometry. The probe experiences strong, spectrally dependent and relativistically modified birefringence in the vicinity of the pump that arises due to the plasma electrons’ relativistic motion in the pump’s electromagnetic fields. The spectral birefringence is strongly dependent on the local magnetic field distribution of the pump laser. Analysis and comparison to both 2D and 3D particle-in-cell simulations confirm the origin of the RECR effect and its appearance in experimental and simulated shadowgrams of the laser-plasma interaction. The RECR effect is relevant for any relativistic, magnetized plasma and in the case of LWFA could provide a nondestructive, in situ diagnostic for tracking the evolution of the pump’s intensity distribution with propagation through tenuous plasma.


S. Kuschel, M. B. Schwab, M. Yeung, D. Hollatz, A. Seidel, W. Ziegler, A. Sävert, M. C. Kaluza, and M. Zepf
Controlling the Self-Injection Threshold in Laser Wakefield Accelerators
Physical Review Letters 121, 154801 (2018)

Abstract: Controlling the parameters of a laser plasma accelerated electron beam is a topic of intense research with a particular focus placed on controlling the injection phase of electrons into the accelerating structure from the background plasma. An essential prerequisite for high-quality beams is dark-current free acceleration (i.e., no electrons accelerated beyond those deliberately injected). We show that small-scale density ripples in the background plasma are sufficient to cause the uncontrolled (self-)injection of electrons. Such ripples can be as short as ∼50  μm and can therefore not be resolved by standard interferometry. Background free injection with substantially improved beam characteristics (divergence and pointing) is demonstrated in a gas cell designed for a controlled gas flow. The results are supported by an analytical theory as well as 3D particle in cell simulations.

G. A. Becker, S. Tietze, S. Keppler, J. Reislöhner, J. H. Bin, L. Bock, F.-E. Brack, J. Hein, M. Hellwing, P. Hilz, M. Hornung, A. Kessler, S. D. Kraft, S. Kuschel, H. Liebetrau, W. Ma, J. Polz, H.-P. Schlenvoigt, F. Schorcht, M. B. Schwab, A. Seidel, K. Zeil, U. Schramm, M. Zepf, J. Schreiber, S. Rykovanov, and M. C. Kaluza
Ring-like spatial distribution of laser accelerated protons in the ultra-high-contrast TNSA-regime
Plasma Physics and Controlled Fusion 60, 055010 (2018)

Abstract: The spatial distribution of protons accelerated from submicron-thick plastic foil targets using multi-terawatt, frequency-doubled laser pulses with ultra-high temporal contrast has been investigated experimentally. A very stable, ring-like beam profile of the accelerated protons, oriented around the target’s normal direction has been observed. The ring’s opening angle has been found to decrease with increasing foil thicknesses. Two-dimensional particle-in-cell simulations reproduce our results indicating that the ring is formed during the expansion of the proton density distribution into the vacuum as described by the mechanism of target-normal sheath acceleration. Here—in addition to the longitudinal electric fields responsible for the forward acceleration of the protons—a lateral charge separation leads to transverse field components accelerating the protons in the lateral direction.


S. Kuschel, D. Hollatz, T. Heinemann, O. Karger, M. B. Schwab, D. Ullmann, A. Knetsch, A. Seidel, C. Rödel, M. Yeung, M. Leier, A. Blinne, H. Ding, T. Kurz, D. J. Corvan, A. Sävert, S. Karsch, M. C. Kaluza, B. Hidding, and M. Zepf
Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch
Physical Review Accelerators and Beams 19, 071301 (2016)

Abstract: We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matched to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. Its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.


M. Hornung, G. Becker, A. Seidel, J. Reislöhner, H. Liebetrau, L. Bock, S. Keppler, A. Kessler, M. Zepf, J. Hein, and M. Kaluza
Generation of 25-TW Femtosecond Laser Pulses at 515 nm with Extremely High Temporal Contrast
Applied Sciences 5, 1970 (2015)

Abstract: We report on the frequency doubling of femtosecond laser pulses at 1030 nm center wavelength generated from the fully diode-pumped laser system POLARIS. The newly generated pulses at a center wavelength of 515 nm have a pulse energy of 3 J with a pulse duration of 120 fs. On the basis of initially ultra-high contrast seed pulses we expect a temporal intensity contrast better 10^17 200 ps before the peak of the main pulse. We analyzed the temporal intensity contrast from milliseconds to femtoseconds with a dynamic range covering more than 20 orders of magnitude. The pulses were focussed with a f/2-focussing parabola resulting in a peak intensity exceeding 10^20 W/cm2. The peak power and intensity are to the best of our knowledge the highest values for 515 nm-laser-pulses achieved so far.


H. Liebetrau, M. Hornung, A. Seidel, M. Hellwing, A. Kessler, S. Keppler, F. Schorcht, J. Hein, and M. C. Kaluza
Ultra-high contrast frontend for high peak power fs-lasers at 1030 nm
Optics Express 22, 24776 (2014)

Abstract: We present the results from a new frontend within a double-chirped pulse amplification architecture (DCPA) utilizing crossed-polarized wave generation (XPW) for generating ultra-high contrast, 150 μJ-level, femtosecond seed pulses at 1030 nm. These pulses are used in the high energy class diode-pumped laser system Polaris at the Helmholtz Institute in Jena. Within this frontend, laser pulses from a 75 MHz oscillator-pulse train are extracted at a repetition rate of 1 Hz, temporally stretched, amplified and then recompressed reaching a pulse energy of 2 mJ, a bandwidth of 12 nm and 112 fs pulse duration at a center wavelength of 1030 nm. These pulses are temporally filtered via XPW in a holographic-cut BaF2 crystal, resulting in 150 μJ pulse energy with an efficiency of 13 %. Due to this non-linear filtering, the relative intensity of the amplified spontaneous emission preceding the main pulse is suppressed to 2×10^−13. This is, to the best of our knowledge, the lowest value achieved in a high peak power laser system operating at 1030 nm center wavelength.

M. Hornung, H. Liebetrau, A. Seidel, S. Keppler, A. Kessler, J. Körner, M. Hellwing, F. Schorcht, D. Klöpfel, A. K. Arunachalam, G. A. Becker, A. Sävert, J. Polz, J. Hein, and M. C. Kaluza
The all-diode-pumped laser system POLARIS – an experimentalist’s tool generating ultra-high contrast pulses with high energy
High Power Laser Science and Engineering 2, e20 (2014)

Abstract: The development, the underlying technology and the current status of the fully diode-pumped solid-state laser system POLARIS is reviewed. Currently, the POLARIS system delivers 4 J energy, 144 fs long laser pulses with an ultra-high temporal contrast of 5×10^12 for the ASE, which is achieved using a so-called double chirped-pulse amplification scheme and cross-polarized wave generation pulse cleaning. By tightly focusing, the peak intensity exceeds 3.5×10^20 W cm^{−2}. These parameters predestine POLARIS as a scientific tool well suited for sophisticated experiments, as exemplified by presenting measurements of accelerated proton energies. Recently, an additional amplifier has been added to the laser chain. In the ramp-up phase, pulses from this amplifier are not yet compressed and have not yet reached the anticipated energy. Nevertheless, an output energy of 16.6 J has been achieved so far.