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Small and Wide Angle X-ray Scattering (SWAXS) beamline (BL-18)

1. Beamline Overview

A Small and Wide Angle X-ray Scattering (SWAXS) beamline (BL-18) is designed, developed, installed, operated and maintained by Solid State Physics Division of Bhabha Atomic Research Centre.

Small-angle X-ray scattering (SAXS) is a unique tool for analyzing structural correlation of condensed matter in mesoscopic length scale (1-100 nm), covering wide range of fields, including alloys, polymers, macromolecules, emulsions, porous materials, nanoparticles, soft-matter etc. This beamline aims to probe various complex issues including time dependent phenomena in these materials.

2. SWAXS Beamline parameters

Source 1.5 Tesla bending magnet based synchrotron X-ray
Operational mode Monochromatic X-ray (wavelength tunable by Double Crystal Monochromator)
Energy range 5 KeV – 20 KeV (Preferred 12 KeV for present experiments)
Angular acceptance of beam 2.0 mrad (Horizontal) X 0.13 mrad (Vertical)
Focusing optics Toroidal Mirror of size 1500 mm X 60 mm with 60 nm Pt and 5 nm Rh coating on Silicon substrate
Flux ~ 1011ph/cm2/s @12 KeV
Detectors 2-Dimension online image plate (For SAXS measurements)
Linear position sensitive gas detector (For WAXS measurements)
q-range 0.05 – 3.5 nm-1 (SAXS with 2-Dimension detector) and >2.0 nm-1 (WAXS with 1D detector)

3. Beamline description

The total length of the beamline from tangent point of bending magnet to end of detector stage is ~40 meters and consists of front-end, optical components and experimental station. The major optical components of the beamline, after the front-end are: i) Beam defining slit (slit-1), ii) Double Crystal Monochromator (DCM), iii) Baffle slit (slit-2), iv) Toroidal mirror (TM), v) Aperture slit (slit-3), vi) Beam shutter (BS). In addition, fluorescent screens are installed at different locations of the beamline to record and diagnose the beam profiles. All the optical components are in ultra-high vacuum (~10-8 mbar). The X-ray transparent diamond window has been used to isolate the optical components of the beamline from the experimental stage. The entire beamline is enclosed in radiation shielding hutches, consisting of three sections, namely, Optical, Intermediate and Experimental, with integrated personnel safety interlock system.

The schematic layout the SWAXS beamline (BL-18) showing the beamline components and the corresponding distances
The schematic layout the SWAXS beamline (BL-18) showing the beamline components and the corresponding distances


External view of Optical, Intermediate and Experimental hutches of the beamline
External view of Optical, Intermediate and Experimental hutches of the beamline
External view of Optical, Intermediate and Experimental hutches of the beamline


Internal view of Optical, Intermediate and Experimental hutches showing various components
Internal view of Optical, Intermediate and Experimental hutches showing various components
Internal view of Optical, Intermediate and Experimental hutches showing various components
Internal view of Optical, Intermediate and Experimental hutches showing various components


Double Crystal Monochromator (Left) and its crystal assembly (Right) inside the chamber

Mirror chamber installed on hexapod (Left) and the toroidal mirror (Right) installed inside the chamber
Double Crystal Monochromator (Left) and its crystal assembly (Right) inside the chamber

Mirror chamber installed on hexapod (Left) and the toroidal mirror (Right) installed inside the chamber
Double Crystal Monochromator (Left) and its crystal assembly (Right) inside the chamber

Mirror chamber installed on hexapod (Left) and the toroidal mirror (Right) installed inside the chamber


The DCM uses a pair of Si(111) crystal and selects monochromatic X-ray from white X-ray beam. The use of DCM offers the opportunity to tune the energy in the range of 5-20 KeV with a fixed height of beam exit. Another important optical component of the beamline is a 1.5 m long toroidal mirror with Rh and Pt coating on silicon substrate. This component focuses the X-ray beam onto the detector.

Two types of beam position monitors (BPM-1 & 2) to view the X-ray beam spot
Two types of beam position monitors (BPM-1 & 2) to view the X-ray beam spot
Two types of beam position monitors (BPM-1 & 2) to view the X-ray beam spot


Two types of slits (slit-1 & 2 with four blade mechanism) and (slit-3 with four bar mechanism) to collimate the X-ray beam
Two types of slits (slit-1 & 2 with four blade mechanism) and (slit-3 with four bar mechanism) to collimate the X-ray beam
Two types of slits (slit-1 & 2 with four blade mechanism) and (slit-3 with four bar mechanism) to collimate the X-ray beam


Three UHV compatible slits are installed in the beamline. The slit-1 and 2 uses the four blades, driven by four linear motors to control the beam size, whereas slit-3 uses four bar mechanism to control the precise opening of the slit. The first slit of the beamline (slit-1) defines both the horizontal and vertical acceptance angle of the beam from bending magnet source whereas the other slits are used for sacrificial collimation of the beam to increase the resolution. The fourth slit is installed just before the sample mounting stage to reduce background scattering.

X-ray beam spot at different optical components and beam size with intensity profile at sample position
X-ray beam spot at different optical components and beam size with intensity profile at sample position
X-ray beam spot at different optical components and beam size with intensity profile at sample position
X-ray beam spot at different optical components and beam size with intensity profile at sample position
X-ray beam spot at different optical components and beam size with intensity profile at sample position
X-ray beam spot at different optical components and beam size with intensity profile at sample position
X-ray beam spot at different optical components and beam size with intensity profile at sample position


The monochromatic beam at sample position is obtained after fine alignment of the DCM, TM and other optical components. A portable single crystal based beam position monitor was used to record the beam profile at the sample position in air.

Diamond window is used to isolate ultra-high vacuum from ambient condition. Linear position sensitive detector is aligned to collect the scattering data from sample
Diamond window is used to isolate ultra-high vacuum from ambient condition. Linear position sensitive detector is aligned to collect the scattering data from sample
Diamond window is used to isolate ultra-high vacuum from ambient condition. Linear position sensitive detector is aligned to collect the scattering data from sample


Various components of experimental station are shown. The 2-D online image plate detector is installed at the end of the experimental station
Various components of experimental station are shown. The 2-D online image plate detector is installed at the end of the experimental station
Various components of experimental station are shown. The 2-D online image plate detector is installed at the end of the experimental station


Diamond window is used to isolate the ultra-high vacuum from the ambient condition at sample stage where the X-ray beam comes to air. One small rotatable shutter is installed just after the diamond window to control the incident beam time on sample to perform time-resolved study. A 1-D gas detector was installed at 1 meter distance from sample for WAXS measurements. A 2-D online image plate detector is installed at the end of the movable detector stage for SAXS measurements. The detector is isolated from the vacuum (~10-3 mbar) of the experimental station by a kapton film window of 150 µm thickness and 250 mm diameter. The sample to image plate detector distance can be changed from ~3m to ~6m to tune the q range. The scattering signal from standard Silver Behenate sample was obtained at 16 KeV energy keeping sample to detector distance at 3015 mm. The scattering profile was used to calibrate the q scale.

(a) Kapton window to isolate the vacuum of experimental station from the 2-D detector (b) shows the 2-D SAXS profile of Silver Behenate sample used for calibration of q scale
(a) Kapton window to isolate the vacuum of experimental station from the 2-D detector (b) shows the 2-D SAXS profile of Silver Behenate sample used for calibration of q scale
(a) Kapton window to isolate the vacuum of experimental station from the 2-D detector (b) shows the 2-D SAXS profile of Silver Behenate sample used for calibration of q scale


2D SAXS profiles collected for various samples are shown below. By tuning the sample to detector distance (SDD) and X-ray energy, we can access wide wave vector range.

2D SAXS profiles at 12 KeV X-ray (a) Ordered porous silica @ SDD: 5350 mm (b) Ordered porous silica @SDD 3139 mm (c) Spray-dried silica micro-granules @ SDD 3015 mm  and (d) Anisotropic scattering from mice bone@ SDD 5350 mm
2D SAXS profiles at 12 KeV X-ray (a) Ordered porous silica @ SDD: 5350 mm (b) Ordered porous silica @SDD 3139 mm (c) Spray-dried silica micro-granules @ SDD 3015 mm  and (d) Anisotropic scattering from mice bone@ SDD 5350 mm
2D SAXS profiles at 12 KeV X-ray (a) Ordered porous silica @ SDD: 5350 mm (b) Ordered porous silica @SDD 3139 mm (c) Spray-dried silica micro-granules @ SDD 3015 mm  and (d) Anisotropic scattering from mice bone@ SDD 5350 mm
2D SAXS profiles at 12 KeV X-ray (a) Ordered porous silica @ SDD: 5350 mm (b) Ordered porous silica @SDD 3139 mm (c) Spray-dried silica micro-granules @ SDD 3015 mm  and (d) Anisotropic scattering from mice bone@ SDD 5350 mm
2D SAXS profiles at 12 KeV X-ray (a) Ordered porous silica @ SDD: 5350 mm (b) Ordered porous silica @SDD 3139 mm (c) Spray-dried silica micro-granules @ SDD 3015 mm and (d) Anisotropic scattering from mice bone@ SDD 5350 mm

4. Selected results

SAXS profiles of mesoporous silica with varying pore correlation depending on its method of synthesis. Silica–I has bi-continuous cubic structure whereasSilica-2 has 2D hexagonal ordered porous channels. Silica-3 is disordered porous system. Silica-4 has correlated randomly jammed spray dried porous micro-granules (using online image plate detector)
SAXS profiles of mesoporous silica with varying pore correlation depending on its method of synthesis. Silica–I has bi-continuous cubic structure whereasSilica-2 has 2D hexagonal ordered porous channels. Silica-3 is disordered porous system. Silica-4 has correlated randomly jammed spray dried porous micro-granules (using online image plate detector)


WAXS profiles of (a) metal oxide framework and (b) Zeolites, showing the correlation peak due to ordered pore structure. (using 1d gas detector)
WAXS profiles of (a) metal oxide framework and (b) Zeolites, showing the correlation peak due to ordered pore structure. (using 1d gas detector)
WAXS profiles of (a) metal oxide framework and (b) Zeolites, showing the correlation peak due to ordered pore structure. (using 1d gas detector)


Evolution of SAXS profiles as function of time of Sodium Dodecyl Sulfate-Water gel during evaporation process. The SAXS profiles were collected at an interval of ~5 min. The evaporation induced restructuring of the lamellar phase in SDS-Water is evident [1].
Evolution of SAXS profiles as function of time of Sodium Dodecyl Sulfate-Water gel during evaporation process. The SAXS profiles were collected at an interval of ~5 min. The evaporation induced restructuring of the lamellar phase in SDS-Water is evident [1].
Evolution of SAXS profiles as function of time of Sodium Dodecyl Sulfate-Water gel during evaporation process. The SAXS profiles were collected at an interval of ~5 min. The evaporation induced restructuring of the lamellar phase in SDS-Water is evident [1].


Evaporation induced evolution of lamellar structure at different stage of drying.  The SAXS profiles of the powder and SDS gel after completion of drying process sample are shown for comparison. The swelling of SDS gel appears to be reversible process [1].
Evaporation induced evolution of lamellar structure at different stage of drying.  The SAXS profiles of the powder and SDS gel after completion of drying process sample are shown for comparison. The swelling of SDS gel appears to be reversible process [1].
Evaporation induced evolution of lamellar structure at different stage of drying. The SAXS profiles of the powder and SDS gel after completion of drying process sample are shown for comparison. The swelling of SDS gel appears to be reversible process [1].

5. Present Status

The SWAXS beamline is operational after successful installation and alignment of the various optical components and inaugurated on 27th March, 2019. The trial experiments on several samples have been performed and the beamline parameters are optimized.

Inauguration of SWAXS beamline on 27<sup>th</sup> March, 2019
Inauguration of SWAXS beamline on 27<sup>th</sup> March, 2019
Inauguration of SWAXS beamline on 27th March, 2019


Tentative date of next modifications:

Installation of an adapter, for simultaneous SAXS and WAXS measurements, will be carried out during November-December 2019. Different sample environments are under design and development phase.

Published results:

[1] Evaporation-induced structural evolution of the lamellar mesophase: a time-resolved small-angle X-ray scattering study, Jitendra Bahadur, Avik Das, Debasis Sen, J. Appl. Cryst. 2019, 52, 1169-1175

6. Contact Information

Dr. S.M. Yusuf
Head, Solid State Physics Division
Bhabha Atomic Research Centre
Mumbai-400085
Phone: 022-2559-5608 Email: smyusuf(at)barc.gov.in

For experimental feasibility and beam-time related enquiry:

Name Phone Email
Dr. Debasis Sen 022-2559-4608 debasis(at)barc.gov.in
Dr. Jitendra Bahadur 022-2559-6281 jbahadur(at)barc.gov.in
Mr. Avik Das 0731-244-2518/74 avikd(at)barc.gov.in


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