DESCRIPTION
STATUS
TECHNICAL SPECIFICATIONS
OPTICS
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The Materials Science and Powder Diffraction beamline BL04-MSPD is devoted to high anguler resolution Powder Diffraction, high pressure Powder Diffraction using Diamond Anvil Cells and Micro powder Diffraction at high energy. 

The beamline operates between 8 and 50 keV. This range adequately covers the desirable energy for almost any kind of powder diffraction experiments in transmission geometry. The high energy part makes posible total scattering experiments and high pressure diffraction using Diamond Anvil Cells. The easily tunable energy allows selecting adequate conditions for powder diffraction in transmission geometry : optimize absorption, avoid absorption edges.     

To accommodate the various experimental techniques, the BL04_MSPD beamline has two experimental end stations, one devoted to high angular resolution powder diffraction and the second one dedicated to high pressure and micro diffraction  experiments. 

Station of MSPD beamlineSample of MSPD beamline

 

BL04-MSPD is one of the seven first generation beamline of ALBA. The beamline was conceived in 2007 and conceptual design can be found in both documents ConceptualDesignReport.pdf and ConceptualDesignReportAddendum.pdf

The beamline is fully operational since mid 2012, giving service to public and proprietary research users.

The Front End was open for the first time end October 2011. The BL04-MSPD welcomed first academic users on the HP station in June 2012. The PD diffraction station ran academic experiments using the Position Sensitive Detector MYTHEN and the Multi Analyzer Detection setup in October 2012 and March 2013, respectively.    

 

Photon Energy Range    8 - 50 keV 
Flux at sample ~ 4·1012 ph/s 
Energy resolution 2·10-4

 

Beam size at sample
collimating
focus
KB

variable:
5 x 1.5 mm2
5 x 0.7 mm
2 
0.015 x 0.015 mm2
Beam divergence at sample  variable

 

High Pressure endstation

The High Pressure end station station consists of two stacks of linear and rotation stages from Huber (Germany). 

The first stack - sample tower - has from bottom up,
       2 crossed movement linear stages (XYdown +/- 25mm range)
       a vertical translation stage (Z 90mm range) 
       a rotation stage (Omega 360°)
       2 crossed movement linear stages (XYup +/- 25mm range)

The second stack - detector tower - has from bottom up
       2 long linear stages (400mm range Y along the beam, 350mm range X prependicular to the beam),
       a vertical translation (Z 90mm range)
       a rotation stage (+/- 90°)
       a tilt stage (+/- 5°)

In addition, a pin-hole prior to the sample and the beam stop can be remotely positioned along XYZ and XZ, repsectively.       

Sample environment and equipment available at ALBA for the High Pressure and Micro Diffraction station can be retrieved from SAMPLE ENVIRONMENTS page.

To integrate user supplied cells or equipment and to verify availability of the sample environments, please contact beamline staff.
To adapt mechanical pieces on the HP station, you can download the detailed drawing of the XY stage surface
The nominal distance from XY stage surface to the beam is 200 mm. Payload  must not exceed 30 kg.

 

 

High pressure endstation

 

Powder Diffraction endstation

The Powde Diffraction end station consists of a heavy duty 3 circles diffractometer manufactured by Huber (Germany). The outer and middle circles support respectively the high_angular resolution Multi Analyzer Detection (MAD) setup and the high-throughput Position Sensitive Detector (PSD) MYTHEN. The inner circle is equipped with an Eulerian Cradle (512.1 model from Huber) on which all sample environments are mounted. An ALBA designed 4 capillaries holder can be used with either cryostream and hot blower.     

Sample environment and equipment available at ALBA for Powder Diffraction station can be retrieved from SAMPLE ENVIRONMENTS page         

To integrate user supplied equipment and to verify availability of proposed sample environments, please contact beamline staff
To adapt mechanical pieces on the PD station, you can download the detailed drawing of the XYZ stage surface
Note the distance from XYZ stage surface to the beam can not exceed 60 mm 

 

 Powder diffraction endstation 


Detectors

Hardware descriptions are summarized below.
Data from both MYTHEN and MAD are processed inline using softwares developped/modified inhouse. Standard output file format is a 3 column ASCII file with 2Theta, Instensity, Estimated Standard Deviation, with up to 4 header lines starting with symbol #.

2-dimensional data from the HP station are binary European Data Format (EDF). Visualization and processing from 2D to 1D can be perfomed through most standard (Fit2D, Dioptas, DAWN) or inhouse developped (D2Dplot) softwares. 

        

Powder Diffraction Station

            
High-throughput 
Position Sensitive Detector MYTHEN

Energy Range 8 - 30 keV / / Typical angualr resolution 0.02° FWHM

6 Modules (Dectris/PSI Detectors group)
300 µm thick silicon sensors with 1280 strips with 50 µm pitch 
Sample-Sensor distance of 550 mm
Total covered angular range ~40˚ in 0.006° binned steps
ms time resolution 

Full pattern acquisition :
              ms : 1 position / trigger mode
       1-5 sec : 1 position, ~40° range
    1-10 min : 6 positons, ~60° range
     ~40 min : 72 positions, ~130° range (PDF)  

High-angular resolution
Multi Anayzer Detection setup MAD

Energy Range 8 - 50 keV / Typical angualr resolution 0.005° FWHM

13 channels with either Si111/Si220 analyzer crystal
and YAP scintillator coupled to PhotoMultiplier
Channel separation 1.5˚
Analayzer crystals changed by manual  translation, Si220 used at high energy

Full pattern acquisition :
        typical scanning speed 1°/min with binned steps of 0.003° 

 

High Pressure 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.

The overall layout of BL04-MSPD components is displayed above and positions of main components given below.
Physical separation between machine and beamline vacuum is achived by a 150 micron thick CVD window. An additional 320 micron thick CVD window is positioned ~20 cm upstream to reduce heat load. At the end of the OPTICS hutch, 254 micron Be windows are positioned as beamline UHV-air interface. 

ID center  0 m
FE fix aperture mask 10.6 m (14.4 x 3.9 mm2 H x V)
FE variable aperture slits 14 m (max 19 x 4.9 mm2 H x V)
Gate valve of Front End FE 18.2 m
CVD window 18.9 m (Front End-Beamline Optics interface)
Collimating/Focusing Mirror 21 m
White Beam Slits 22.9 m
White Beam Fluorescence screen 23.6 m
Double Crystal Monochromator  24.8 m
Monochromatic Beam Slits 25.6 m
Be windows 28.3 m (Beamline Optics UHV-air interface) 
Pre KB slits ~29 m
KB-mirror (vertical)  29.9 m
KB-mirror (horizontal)  30.3 m
HP station 1  31 m
Pre PD slits ~34 m
PD station 2  35 m
 


Collimating/focusing mirror

The white beam Mirror either collimates or focus the beam in vertical direction. Collimating the beam reduces the white beam divergence down to ~15 microradians  (the residual divergence is essentially induced by slope errors of the mirror surface), thus improving the energy resolution after the monochromator. The mirror bending mechanism allows focusing the beam on the Powder Diffraction station, which is necessary when operating with the Position Sensitive Detector. Highest angular resolution over a wide 2Theta range is obtained with the Multi Analyzer Detection Setup and collimated beam. The radius of curvature for focus on PD and collimated modes are 10 km and 21 km , respectively.         

The mirror is a 1200 long, 95 mm wide and 70mm thick single crystal block of silicon. It has three eeffctive stripes (uncoated Si, coated Rh and Pt) to adapt reflectivity and harmonic suppression within specific energy ranges. The working angle is fixed to 2 mrad grazing incidence.

Additionally, the mirror serves to reduce the heat load on the monochromator. It is indirectly cooled by two independent water circuits. Heat load is evacuted through water circulating pipes brazed to copper blocks partially immersed into grooves containing a liquid  mixture of Ga-In-Sn. 

Above 40keV, where reflectivity dropps down, the mirror must be removed and the white beam from the source directly impinges the monochormator. Vertical aperture is adjusted to mate the length of first crystal of monochormator and to reduce heat load. All mirror downstream components can be adjusted in height for either mirror or unmirror mode.     

The mirror vessel and moving mechanism was manufactured by CINEL (Italy), the mirror block and bending mechanism by Winlight (France) 

 

OpenMirror

 

Fix exit Double Crystal Monochromator (DCM)

Energy selection is achieved through two successive Bragg reflexion of silicon (111, d-spacing 3.135 Angstroem). To preserve energy resolution and flux under high heat load, the crystals are externally cooled with liquid nitrogen.
Energy resolution is ΔE/E ~2 10-4, taking into account white beam divergence and Darwin Width. The length and the shadowing of the 2nd crystal limit the energy to 50keV and 7keV, respectively. The pitch of the second crystal is finely tuned by a piezo actuator. Outcoming versus Incoming beam ratio is continuously maintained through an electronic module, so called MOCO for MOnochromator COntroller.  

The DCM was manufactured by BRUKER (Germany)

Type Si(111) DCM with long 2nd crystal
Fix Exit Gap Offset   20 mm 
Absorbed power 670 W  (worst-case conditions)

DCM inside


KB mirrors

For High-Pressure experiments, both a small beam spot and a high energy are required. The former triggers the maximal pressure achievable in Diamond Anvil Cells, the latter warrants enough transmission through the massive diamonds exerting the pressure on the sample. Focusing the beam down to a dozen micron beam size is obtained using Kirkpatrick-Baez (KB) mirror system. On BL04-MSPD, the KB system parameters have been optimally selected for 30keV operation, but ensures proper beam focus in the 20-50 keV energy range.

The small beam size offered by KB system is used as well for Micro Diffraction experiments in transmission geometry.

The KB system has been manucaftured by Irelec (France)
 

Vertical Focusing Mirror Horizontal Focusing mirror
Type Elliptically bent mirror Elliptically bent mirror
Substrate Si Si
Coating material Multilayer Multilayer
d-spacing 2.97 nm 2.56 nm
Number of W/Si layers 110 150
Angle of incidence 5 - 10 mrad 5 - 10 mrad
Mirror length  300 mm 300 mm
Reflectivity 20 keV 75% 75%
50 keV 90% 90%
Mean resolution ΔE/E (20–50 keV) 2.5% 1.8%

 

Beam size at HP station

The beam spot at the HP station is surveyed every time we configure the beamline with KB mirrors. It is achieved using a camera looking at a direct beam illuminated fluorescence screen. Optimization of the beam spot is perfomed by tuning the pitch angle and the bending radius of the vertical and horizontal focusing KB mirrors.
Refinement of the projections clearly reveals the Lorentzian character of the beam profile in horizontal and vertical directions causing the beam spot to extend up to 75 microns at 10% maximum. The tails are supressed by inserting a pinhole of variable diameter before the sample.     

 

HP beam spot 

 Horizontal Projection Vertical Projection

 

Source   Superconducting Wiggler SCW30
Insertion Device (ID) Superconducting wiggler with short period length manufactured by Budker Institute of Nuclear Physics (Novosibirsk, Russia). 
The actual K-value can be set adjusting the current in the superconducting coils. At maximum magnetic field of 2.15 Tesla,  K = 6.08 and critical energy Ec = 12.5 keV.
The K-value can principally be lowered by reducing the magnetic field, hence reducing beam size and divergence, or reducing maximum power. The SCW is however presently permanently operated at its maximul magnetic field value.

 

Parameters

Material Superconducting coils made of NbTi wires
Magnetic gap 12.6 mm
Period length 30.16 mm 
Number of periods  58.5
K max / B max 6.08 / 2.15 Tesla

Photon flux (Iring=250 mA) through FE fix aperture
@15 keV
@30keV


1.10·1015(ph/s/0.1% bandwith)
4.52·1014 (ph/s/0.1% bandwith)

Photon source size (FWHM) 
@15 keV
@30keV


0.65 x 0.11 mm2 (HxV)
0.59 x 0.08 mm2 (HxV)

Photon source divergence (FWHM)
@15keV
@30keV


1.15 x 0.23 mrad2 (HxV)
1.00 x 0.16 mrad2 (HxV)

Picture taken during Jan2019 intervention 

SCWopen Picture taken during Jan2019 intervention