Ultra-Fast Pump-Probe Detection Using Plasmas

The temporal resolution of pump-flash interactions in the femtosecond-attosecond (fs-as) regime is limited by the characteristic time constants of the excited states in the detector material. If the relaxation time constant is appreciably longer that the time interval between the pump and probe signals the response of the detector material to the probe represents a temporal convolution with the pump and probe responses, setting a lower limit on the resolution to which the interval between the two pulses can be measured. In most of the solid state ultrafast detection schemes that are being considered for the ultrashort pulse x-ray sources under current development at SLAC and elsewhere the characteristic time constants are related to the bound states of the atoms comprising the material or to the relaxation times of phase transitions or charge carrier populations of the lattice, setting a probable lower limit on the attainable resolution on the order of {approx}0.1 ps. In this paper we consider a novel detection principle based on the excitation of specially prepared unbound states in an ionized plasma with high pump and probe fields, and estimate its potential for extending the lower limit of resolution into the attosecond (as) regime

Development of an advanced x-ray generator based on Compton back-scattering: a proposal for Science for Peace sub-program of NATO

An extended form of a cooperative project proposal is presented. The main goal of the proposal is the design and construction of a storage ring X-ray generator based on Compton backscattering. The project’s primary objectives and organisation, together with a draft plan for the required N-100 storage ring reconstruction effort, are outlined

Infrared (IR) vs. X-Ray Power Generation in the SLAC Linac Coherent Light Source (LCLS)*

Abstract The LCLS, a Free-Electron Laser (FEL) designed for operation at a first harmonic energy of 300 eV (A. m 40A) in the Self-Amplified Spontaneous Emission (SASE) regime, will utilize electron bunches compressed down to durations of cO.Sps, or lengths of ~150 p. It is natural to inquire whether coherent radiation of this (and longer) wavelength will constitute a significant component of the total coherent output of the FEL. In this paper a determination of a simple upper bound on the IR that can be generated by the compressed bunches is outlined. Under the assumed operating parameters of the LCLS undulator, it is shown that the IR component of the coherent output should be strongly dominated by the x-ray component

LCLS optics: Selected technological issues and scientific opportunities

The Stanford Linac Coherent Light Source (LCLS) promises to generate photon pulses of unprecedented brevity and peak brightness in the soft x-ray range. In this presentation selected limitations and novel opportunities for technology and science associated with the availability of such pulses will be briefly assessed. Special emphasis will be placed on possible techniques for extending the peak power density and the temporal and spectral regimes of the LCLS output radiation by orders of magnitude beyond their nominal (calculated) values, and to the associated instrumentation for processing this radiation

Spectral-Angular Characteristics of the LCLS in the Near and Far Fields

The unusually long insertion devices being prepared for Angstrom-wavelength Free Electron Lasers (FELs) will generate spectral-angular distributions in the proposed experimental areas substantially different from those conventionally calculated for the far field. In this paper we report on computational simulations of near vs. far field distributions for the SLAC linac Coherent Light Source (LCLS) undulator, an insertion device approximately 140 meters long. The properties of the coherent radiation as a limiting case of the near-field emission, for the special condition of a microbunched beam radiating along the undulator axis, are reviewed