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Small and Wide Angle X-ray Scattering (SWAXS) beamline (BL-18) [an error occurred while processing this directive]

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, 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
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
Focal spot at farthest detector position 0.70 mm (Horizontal) X 0.20 mm (Vertical) (~8 m from sample @8 KeV)0.70 mm (Horizontal) X 0.20 mm (Vertical) (~8 m from sample @8 KeV)
Flux ~ 1011ph/cm2/s @8 KeV
Q-range @8 KeV 0.25 - 6.0 nm-1 (with presently installed linear gas detector)

0.05 - 2.0 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.
Double Crystal Monochromator (Left) and its crystal assembly (Right) 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.
Mirror chamber installed on hexapod (Left) and the toroidal mirror (Right) installed 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 spot
Two types of beam position monitors (BPM-1 & 2) to view the X-ray spot
Two types of beam position monitors (BPM-1 & 2) to view the X-ray spot


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

Profile of X-ray beam at different optical components and at sample position.
Profile of X-ray beam at different optical components and at sample position.
Profile of X-ray beam at different optical components and at sample position.
Profile of X-ray beam at different optical components and at sample position.
Profile of X-ray beam at different optical components and 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.

Various components at experimental station are shown. Diamond window is used to isolate ultra-high vacuum with ambient condition. Linear position sensitive detector is aligned to collect the scattering data from sample.
Various components at experimental station are shown. Diamond window is used to isolate ultra-high vacuum with ambient condition. Linear position sensitive detector is aligned to collect the scattering data from sample.
Various components at experimental station are shown. Diamond window is used to isolate ultra-high vacuum with ambient condition. Linear position sensitive detector is aligned to collect the scattering data from sample.
Various components at experimental station are shown. Diamond window is used to isolate ultra-high vacuum with ambient condition. Linear position sensitive detector is aligned to collect the scattering data from sample.
Various components at experimental station are shown. Diamond window is used to isolate ultra-high vacuum with ambient condition. Linear position sensitive detector is aligned to collect the scattering data from sample.


4. Test results

SAXS profiles of mesoporous silica with varying pore correlation depending on its method of synthesis. Silica–I and II corresponds to 2D hexagonal ordering and partially ordered pores, respectively. Silica-II corresponds to disordered porous system.
SAXS profiles of mesoporous silica with varying pore correlation depending on its method of synthesis. Silica–I and II corresponds to 2D hexagonal ordering and partially ordered pores, respectively. Silica-II corresponds to disordered porous system.

SAXS profiles of (a) metal oxide framework and (b) Zeolites, showing the correlation peak due to ordered pore structure.
SAXS profiles of (a) metal oxide framework and (b) Zeolites, showing the correlation peak due to ordered pore structure.
SAXS profiles of (a) metal oxide framework and (b) Zeolites, showing the correlation peak due to ordered pore structure.


Evolution of SAXS profiles as function of time of Sodium Dodecyl Sulfate-Water during evaporation process. The SAXS profiles were collected at an interval of ~5 min. The evaporation induced crystallization of the SDS-Water phase is evident.
Evolution of SAXS profiles as function of time of Sodium Dodecyl Sulfate-Water during evaporation process. The SAXS profiles were collected at an interval of ~5 min. The evaporation induced crystallization of the SDS-Water phase is evident.


Evolution of crystalline phase in hydrated Sodium Dodecyl Sulfate (SDS) at different stage of drying. The multi-lamellar phases are evident from the SAXS data.
Evolution of crystalline phase in hydrated Sodium Dodecyl Sulfate (SDS) at different stage of drying. The multi-lamellar phases are evident from the SAXS data.

5. Present status

The SWAXS beamline is operational after successful installation and alignment of the various components and inaugurated on 27th March, 2019. The trial experiments on several samples of different kinds have been performed and the beamline parameters are being optimized. The beamline will be available to users soon.

Inauguration of SWAXS beamline on 27th March, 2019
Inauguration of SWAXS beamline on 27th March, 2019
Inauguration of SWAXS beamline on 27th March, 2019

Tentative date of next modifications:

Installation of 2-Dimension online image plate detector in movable detector stage during April-May 2019.

Tentative date for starting of user operation: June 2019

6. Contact Information

Dr. S.M. Yusuf
Head, Solid State Physics Division,
Bhabha Atomic Research Centre,
Mumbai-400085,
Phone: 022-2559-5608,
Email:smyusuf@barc.gov.in
Dr. Debasis Sen       022-2559-4608  debasis@barc.gov.in
Dr. Jitendra Bahadur 022-2559-6281  jbahadur@barc.gov.in
Mr. Avik Das              022-2559-4606  avikd@barc.gov.in
Beamline phone number: 0731-244-2518
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