Lawrence Berkeley National Laboratory
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Scientific Requirements Demand a New Generation of Light Source

In order to have a major impact on the fundamental questions, scientific goals and research objectives of the future, a new generation of light source is required. The necessary capabilities of such a source is substantially beyond those of both third-generation storage rings and the x-ray FELs that are now planned or under construction. The two most challenging performance requirements that must be met simultaneously are: ultrafast temporal resolution (driven by the fundamental time scales of correlation phenomena in matter), and high average flux (driven by the required measurement precision/resolution). Table 1 specifies the various performance requirements and summarizes the research areas that are the primary drivers of each requirement.

Table 1

Table 1 Performance requirements and research needs driving specifications for future light sources

 

Performance Category

Quantification

Required for:

Ultrafast Time Resolution
and Laser Synchronization

<100 fs
and ~100 as

All dynamics studies

- attosecond to picosecond time scales

- duration/bandwidth control

High Repetition Rate

10-100 KHz

Time-resolved spectroscopy

 - high repetition rate for signal averaging

 - repetition rate limited by sample recovery/replacement

 - flux per pulse limited by damage and non-linear efffects

Inelastic x-ray scattering

Lensless imaging

High Average Flux

~1015 ph/s/0.1% BW
(~ 3rd Gen. SR)

Time-resolved spectroscopy

X-ray emission spectroscopy—RIXS/XES

 (at 0.5 eV resolution)

 - flux per pulse limited by damage and nonlinear effects

Very High Average Flux

>>1015 ph/s/0.1% BW
(>> 3rd Gen. SR)

Inelastic x-ray scattering—IXS

X-ray emission spectroscopy—RIXS/XES

(<10 meV resolution)

Lensless imaging

 - flux per pulse limited by damage and nonlinear effects

Tunability

100 eV – 10 KeV

X-ray spectroscopy (electronic/atomic structure)

 - soft x-ray: XANES, EXAFS (TM L-edges)

 - hard x-ray: EXAFS (TM K-edges)

Polarization Control

adjustable circular/linear

All x-ray dichroism spectroscopy

Coherence

Full transverse and longitudinal

Energy resolution (temporal transform limit)

Chirped/shaped pulse experiments

Lensless imaging (transverse coherence)

Stability

<10% pulse amplitude

<0.1sx,y alignment

Extraction of small signals from background