DESCRIPTION

The Materials Science and Powder Diffraction Beamline is devoted to high-resolution powder diffraction and high pressure powder diffraction using diamond anvil cells.

The beamline operates between 8 and 50 keV. This energy range adequately covers the desirable range for almost any powder diffraction experiment, and at the same time it is possible to perform both total scattering experiments, and high pressure diffraction, for which it is not only desirable but sometimes necessary to have high-energy sources (E>30 KeV).

To accommodate the different experimental techniques there are two experimental end stations, one devoted to high resolution powder diffraction and the second one dedicated to high pressure experiments. 

Station of MSPD beamline   Sample of MSPD beamline

 

STATUS

BL04-MSPD is in fully operational since 2012 giving service to public and proprietary research users.

 

TECHNICAL SPECIFICATIONS

Photon Energy Range    8 - 50 keV 
Flux at sample ~ 4·1012 ph/s 
Energy resolution 2·10-4
Beam size at sample variable: 1.5 x 5 mm2 to 0.015 x 0.015 mm2
Beam divergence at sample  variable

 

High Pressure endstation

Sample environment and equipment available at ALBA:

  • on-line pressure calibration set-up (rubi luminescence method)

To integrate user cells or additional equipment and to verify availability of the sample environment equipment, please contact beamline staff

 

High pressure endstation

 

Powder Diffraction endstation

Sample environment and equipment available at ALBA:

  • Oxford cryostream 700 series (80-500 K) for samples in capillaries.
  • FMB Oxford hot air blower (RT-900 C) for samples in capillaries. Note that for T>700 C, quartz capillaries should be used.
  • The so called ICP-ITQ-ICIQ Capillary flow cell, for capillary samples: (RT-750 C) and Pressure (maximum pressure=15 bar). More details.

          capillary flow cell

  • Multipurpose cell. XAS/XRD in-situ cell for solid-gas reactions.

 

100 mL internal volume
Sample: Ø = 13 mm pressed pellet
T = RT-700 C
Angular aperture for XRD, 2θ ~ 22 deg
8 individual windows (four Ø = 25 mm and four Ø = 6 mm that allow for a multi-technique approach)
Note that the maximal gas pressure within the cell is limited, please contact staff for details.
Cell's Control System, ITQ-ALBA cabinet
Compact Control Table that allows to control: gas flow of up to 6 gases, sample P, T of the stabilization circuit and rough vacuum.
Mass flow controllers: 1x max. 1 L/min; 5 x 100 mL/min.
Can be adjusted to different cells available at ALBA.

 

To integrate user cells or additional equipment and to verify availability of this equipment, please contact beamline staff

 Powder diffraction endstation


Detectors

Powder Diffraction Station

            
 Mythen detector (PSI Detector group/Dectris) 6 Modules (Dectris/PSI Detectors group)
Strip-pitch 50 µm
Radius 550 mm
Covered Angular Range 40˚
Energy Range 8 - 30 keV
MAD26: High Resolution Detector 13 Channels with Si 111 and Si 220 crystals
Crystals can be changed via translation
Channel separation 1.5˚
Energy range 8 - 50 keV
Exchangeable slits

 

High Diffraction Station
CCD camera, SX165 (Rayonix)  Area: round, 165 mm diameter
Energy range:  20 - 50 keV
Dynamic range: 16 bit
PSF (Point Spread Function): 200 μm FWHM
Read Noise: 9 e-/pixel @ 3.5 sec. readout 
13 e-/pixel @ 2.5 sec. readout
Dark Current <0.01 e-/pixel/sec.

OPTICS

 

 MSPD Layout

 

The optical layout has to be flexible in order to allow for the variety of applications. Two main configurations can be distinguished as follows:

Mirrored mode  8 - 40 keV
Unmirrored mode > 40 keV 

 

The positions for the main components are: 

ID center  0 m
Gate valve of Front End FE 18.2 m
M1 collimating mirror  20 m
DCM Double Crystal Monochromator  23.5 m
KB-mirror (vertical)  30.9 m
KB-mirror (horizontal)  31.3 m
HP station 1  32 m
PD station 2  35 m

 

Mirror 1 collimates the beam in a vertical direction by a mechanical bender, thus increasing the energy resolution. It has three stripes each with different coatings (Pt, Rh, Si) to adapt reflectivity and harmonic suppression to be within the different energy ranges. Additionally, it serves to reduce the heat load on the monochromator and is, by necessity, externally water cooled. The glancing angle of the mirror is 2 mrad.

The crystal in the monochromator downstream M1 is a Si 111. To preserve energy resolution and flux at the sample under high heat load the crystals are externally cooled with liquid nitrogen. By doing this both thermal expansion is reduced as well as the conductivity of the silicon is increased, when compared to room-temperature values.        

For high-pressure and total-scattering experiments it is important to have access to considerably high levels of energy. For this setup the mirror can be moved to be out of the beam path. In its place a KB-mirror system using Multilayers can be inserted which serves to focus the beam on station 1. The KB-mirror is applicable in the energy range of about 20-50 keV and can also be used together with the collimating mirror M1. They are placed 1.1m and 0.7m upstream from station 1 on a granite table.

 

Monochromator

Type Si(111) Double Crystal with long 2nd crystal
Gap between crystals  10 mm (variable)
Absorbed power 670 W  (worst-case conditions)


KB mirrors

Vertical Focusing Mirror Horizontal Focusing mirror
Type Elliptically bent mirror Elliptically bent mirror
Substrate Si Si
Coating material Multilayer Multilayer
Angle of incidence 5 - 10 mrad 5 - 10 mrad
Mirror length  300 mm 300 mm

 

SOURCE

Source   Superconducting Wiggler SCW31
Insertion Device (ID) Superconducting wiggler with short period length. The actual K-value can be set with the current in the superconducting coils. At its maximum K = 6.08 the critical energy is Ec = 12.5 keV. The K-value can be reduced for experiments to be conducted at lower energies

 

Parameters

Material Superconducting coils
Period 31 mm 
Number of periods  60.5
K Max 6.08 
Photon source size (FWHM)  0.65 x 0.1 mm2 (HxV)
Photon source div. (FWHM) 1.4 x 0.18 mrad2 (HxV)