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udkm1Dsim toolbox
A Simulation Toolkit for
1D Ultrafast Dynamics
in Condensed Matter


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Bessy Beamline

Joint Research Group at HZB

Beamline Setup

General Beamline Parameters

Photon Energy Range: 2 - 14 keV
Photon Flux: 1011 ph/s (monochromatic)
Energy Resolution: 1/1000 - 1/5000 
X-Ray Pulse Duration: 100
> 10
ps (hybrid mode)
ps (low-α mode)
X-Ray Spot Size: 150 µm

Source Characteristics

Electron Energy: 1.7 GeV
Magnetic Field: 1.3 T
Power: 50 W (0.3A, 3 x 0.41 mrad2)
Critical Energy: 2.5 keV
Source Size:

σx 0.158

σy 0.040

mm

mm

Source Divergence

σx 388

σy  21

µrad

µrad

The Beamline is designed for x-ray diffraction and for Extended X-ray Absorption Fine Structure spectroscopy and X-ray Absorption Near Edge Spectroscopy (EXAFS, XANES) experiments. In combination with an ultrafast laser, a temporal resolution of the duration of the x-ray probe pulse (~100 ps in hybrid mode, ~ 10ps in low-α mode) can be achieved. The beamline is equipped with a collimating parabolic mirror M1 and a refocusing parabolic mirror M2. Both mirrors are fabricated from Silicon substrate. Further mirror parameters are:

Mirror coating Rh 50 Å + Pt 600 Å, surface roughness < 3Å, grazing incidence angle 0.3 deg

M1 M2
Size: 1200 x 60 mm 1200 x 60 mm
Distance to Source: 16890 mm 7000 mm (to focal point)

 

The Beamline provides two operational modes: monochromatic beam (option 1) and white beam (option 2).

Option 1

The white collimated beam passes a double crystal monochromator DCM, which covers an energy range from 2.1 keV to 18 keV. It consist of two Si(111) crystals and provides an energy resolution of 1/1000 up to 1/5000.

Option 2

By taking the monochromator crystals of the beam path the focussed white beam can enter the experimental hutch. In this configuration the focal point is 25 mm lower compared to option 1.

Detectors

  • For time-resolved experiments we employ a fast photomultipliers (PMT, Hamamatsu) in combination with fast plastic scintillators (rise time < 0.5 ns).
    The electrical output of the PMT is optionally amplified with a low-noise current amplifier (FEMTO) and fed into a time-correlated single-photon-counting module (TCSPC, PicoHarp 300, Fa. PicoQuant).
    In combination with ultrafast detecors, the TCSPC-module has a temporal resolution of 4 ps. Typically we choose a channel width of 20 ps and cover a temporal interval of 4.6 µs.
  • Several energy dispersive detectors (Amptek, Roentec) are available. They were successfully used for energy resolving white beam diffraction techniques or reflectometry.

Diffractometer

A θ-2θ diffractometer (Fa. Huber) is presently available. (resolution Dq min= 0.001 deg). In near future a new 4-circle diffractometer will be installed . It allows time-resolved diffraction experiments in symmetric and asymmetric Bragg geometries.

Cryostat

The future setup will additionally allow to perform diffraction experiments at low temperature. It provides a cryostat that enables sample cooling down to approximately 20 K.

Beamline Layout
Layout of the KMC3/XPP beamline

BeamlineFlux
Total flux in the focus at 100 mA ring current.

Rev. Sci. Instrum., 83:6(063303)

Laser System

Laser Type: Fiber Laser
Model: CLARK Impulse
Repetition Rate: User adjustable: from  200
 to    25
kHz
MHz
Pulse Energy: User adjustable: 0.8
10
µJ @  25 MHz
µJ @ < 2 MHz
Average Output Power:

User adjustable: < 20

typically:      2

W @ 2 MHz

W @ 0.2 MHz

Pulse Duration: < 250 fs
Transverse Mode: TEM00, M2 < 1.2 - 1.5 depending on pulse energy
Noise: < 1 % RMS

 

Center Wavelength: 1030 nm

NOPA Setup

BessyNOPA

A high repetition-rate NOPA setup allows for the generation of wavelength-tunable pulses in the range of 440 nm to 990 nm. The pulses can be compressed from the initial duration of ~250 fs down to 20 fs - 30 fs. The NOPA is pumped with frequency tripled pulses from the CLARK-Impulse laser system. A fraction of the laser output is employed to generate a white-light continuum which is used as a seed for the NOPA.
In our setup, the residual of the fundamental beam is used as a pump beam for ultrafast optical pump-probe measurements. The frequency-converted output of the NOPA is employed as the probe beam.

High Repetition-Rate THz Setup

The installation of a setup for linear time-resolved THz spectroscopy at high repetition rates is envisioned in the near future. Typical applications for such setups are electrical conductivity measurements in metals and semiconductors and FIR spectroscopy.