skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Future of ePix detectors for high repetition rate FELs

Abstract

Free-electron lasers (FELs) made the imaging of atoms and molecules in motion possible, opening new science opportunities with high brilliance, ultra-short x-ray laser pulses at up to 120 Hz. Some new or upgraded FEL facilities will operate at greatly increased pulse rates (kHz to MHz), presenting additional requirements on detection. We will present the ePix platform for x-ray detectors and the current status of the ePix detectors: ePix100 for low noise applications, ePix10k for high dynamic range applications, and ePixS for spectroscopic applications. Then we will introduce the plans to match the ePix detectors with the requirements of currently planned high repetition rate FELs (mainly readout speed and energy range).

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;  [1];  [1];  [2]
  1. SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22608397
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1741; Journal Issue: 1; Conference: SRI2015: 12. international conference on synchrotron radiation instrumentation, New York, NY (United States), 6-10 Jul 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ATOMS; DETECTION; FREE ELECTRON LASERS; IMAGES; MOLECULES; NOISE; PULSES; READOUT SYSTEMS; VELOCITY; X RADIATION; X-RAY LASERS

Citation Formats

Blaj, G., E-mail: blaj@slac.stanford.edu, Caragiulo, P., Carini, G., Dragone, A., Haller, G., Hart, P., Hasi, J., Herbst, R., Kenney, C., Markovic, B., Pines, J., Segal, J., Tamma, C., Tomada, A., Nishimura, K., and Currently at Ultralytics, 1 Appian Way #715-6, South San Francisco, CA, 94080. Future of ePix detectors for high repetition rate FELs. United States: N. p., 2016. Web. doi:10.1063/1.4952884.
Blaj, G., E-mail: blaj@slac.stanford.edu, Caragiulo, P., Carini, G., Dragone, A., Haller, G., Hart, P., Hasi, J., Herbst, R., Kenney, C., Markovic, B., Pines, J., Segal, J., Tamma, C., Tomada, A., Nishimura, K., & Currently at Ultralytics, 1 Appian Way #715-6, South San Francisco, CA, 94080. Future of ePix detectors for high repetition rate FELs. United States. doi:10.1063/1.4952884.
Blaj, G., E-mail: blaj@slac.stanford.edu, Caragiulo, P., Carini, G., Dragone, A., Haller, G., Hart, P., Hasi, J., Herbst, R., Kenney, C., Markovic, B., Pines, J., Segal, J., Tamma, C., Tomada, A., Nishimura, K., and Currently at Ultralytics, 1 Appian Way #715-6, South San Francisco, CA, 94080. Wed . "Future of ePix detectors for high repetition rate FELs". United States. doi:10.1063/1.4952884.
@article{osti_22608397,
title = {Future of ePix detectors for high repetition rate FELs},
author = {Blaj, G., E-mail: blaj@slac.stanford.edu and Caragiulo, P. and Carini, G. and Dragone, A. and Haller, G. and Hart, P. and Hasi, J. and Herbst, R. and Kenney, C. and Markovic, B. and Pines, J. and Segal, J. and Tamma, C. and Tomada, A. and Nishimura, K. and Currently at Ultralytics, 1 Appian Way #715-6, South San Francisco, CA, 94080},
abstractNote = {Free-electron lasers (FELs) made the imaging of atoms and molecules in motion possible, opening new science opportunities with high brilliance, ultra-short x-ray laser pulses at up to 120 Hz. Some new or upgraded FEL facilities will operate at greatly increased pulse rates (kHz to MHz), presenting additional requirements on detection. We will present the ePix platform for x-ray detectors and the current status of the ePix detectors: ePix100 for low noise applications, ePix10k for high dynamic range applications, and ePixS for spectroscopic applications. Then we will introduce the plans to match the ePix detectors with the requirements of currently planned high repetition rate FELs (mainly readout speed and energy range).},
doi = {10.1063/1.4952884},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1741,
place = {United States},
year = {Wed Jul 27 00:00:00 EDT 2016},
month = {Wed Jul 27 00:00:00 EDT 2016}
}
  • A sustained filamentation or density depression phenomenon in an argon gas attenuator servicing a high-repetition femtosecond X-ray free-electron laser has been studied using a finite-difference method applied to the thermal diffusion equation for an ideal gas. A steady-state solution was obtained by assuming continuous-wave input of an equivalent time-averaged beam power and that the pressure of the entire gas volume has reached equilibrium. Both radial and axial temperature/density gradients were found and describable as filamentation or density depression previously reported for a femtosecond optical laser of similar attributes. The effect exhibits complex dependence on the input power, the desired attenuation,more » and the geometries of the beam and the attenuator. Time-dependent simulations were carried out to further elucidate the evolution of the temperature/density gradients in between pulses, from which the actual attenuation received by any given pulse can be properly calculated.« less
  • Newtonian fluid dynamics simulations were performed using the Navier–Stokes–Fourier formulations to elucidate the short time-scale (µs and longer) evolution of the density and temperature distributions in an argon-gas-filled attenuator for an X-ray free-electron laser under high-repetition-rate operation. Both hydrodynamic motions of the gas molecules and thermal conductions were included in a finite-volume calculation. It was found that the hydrodynamic wave motions play the primary role in creating a density depression (also known as a filament) by advectively transporting gas particles away from the X-ray laser–gas interaction region, where large pressure and temperature gradients have been built upon the initial energymore » depositionviaX-ray photoelectric absorption and subsequent thermalization. Concurrent outward heat conduction tends to reduce the pressure in the filament core region, generating a counter gas flow to backfill the filament, but on an initially slower time scale. If the inter-pulse separation is sufficiently short so the filament cannot recover, the depth of the filament progressively increases as the trailing pulses remove additional gas particles. Since the rate of hydrodynamic removal decreases while the rate of heat conduction back flow increases as time elapses, the two competing mechanisms ultimately reach a dynamic balance, establishing a repeating pattern for each pulse cycle. Finally, by performing simulations at higher repetition rates but lower per pulse energies while maintaining a constant time-averaged power, the amplitude of the hydrodynamic motion per pulse becomes smaller, and the evolution of the temperature and density distributions approach asymptotically towards, as expected, those calculated for a continuous-wave input of the equivalent power.« less
  • One of the concepts for the next generation of linacdriven FELs is a CW superconducting linac driving an electron beam with MHz repetition rates. One of the challenges for next generation FELs is improve the stability of the xray pulses by improving the shot-to-shot stability of the energy, charge, peak current, and timing jitter of the electron beam. A high repetition rate FEL with a CW linac presents an opportunity to use a variety of broadband feedbacks to stabilize the beam parameters. To understand the performance of such a feedback system, we are developing a dynamic model of the machinemore » with a focus on the longitudinal beam properties. The model is being developed as an extension of the LITrack code and includes the dynamics of the beam-cavity interaction, RF feedback, beam-based feedback, and multibunch effects. In this paper, we present a detailed description of this model.« less