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1. 28 2 3 ILLUSTRATED STEP BY STEP INSTRUCTIONS cccccccscocsccssscscscscsscssscesescsresssscssssasessstsscssstsvessavaressavsreaeaeisacereacavenee 29 QGnsto KOOKABURRA 1 TECHNICAL DESCRIPTION 1 1 INTRODUCTION This document provides a comprehensive technical description of the ultra small angle neutron scattering USANS instrument KOOKABURRA installed at the ANSTO OPAL reactor where a brief overview of USANS techniques and applications is followed by a general description of the layout and performance of KOOKABURRA 12 ABOUT USANS Modern materials science and engineering rely increasingly on a detailed knowledge of the interplay between structure and material properties and neutron scattering is a key tool for obtaining structural Modern materials science and information engineering rely increasingly on a In small angle neutron scattering SANS experiments detailed knowledge of the microstructure and interactions in neutrons are assumed to be elastically scattered by a soft and hard materials sample and the resulting scattering pattern can be analysed to provide information about the size shape orientation and number density of scattering entities within the sample SANS can provide a unique insight into the hierarchical structures of materials
2. Lj Recent Align Device Collect Data KKB Reduction HMM Tube Export Scripting Con Engine Engine V Lanauaade 3l Fill in all required KOOKABURRA information for your sample then click on Run Single Scan If you want to measure more samples one after the other the required information per sample needs to be saved under Save Single Scan Parameters the path for saving is V shared KKB Logbook Experiments External Users Configurations Then you need to click on Load Multiple Scan Parameters to create batch of scans The parameters of each loaded scan can be read via the dropdown menu Click on Multiple Scans to execute the batch of scans To check the status of your scan do the following Bn ot Plot Vi gt femmezea mws 1 Go to the window Analysis scripting Gumtree 2 Click on Window then New Window 3 Click the Load Script button 2 Click on Open file 3 Select KKB Plot py the path 1s V shared KKB Scripts KKB Plot py 4 Load the data file you want to look at by clicking on the green plus sign in the upper left corner Multiple files can 32 marked at once the path 1s W data current 5 Highlight the file you want to look at and click on Run 6 To export the file click on Export to CSV 7 Retrieve the exported data from V shared KKB Logbook T
3. close sample shutter go to instrument remove or change sample check samples for activation obtain sample clearance certifications O OU O0 O 0 O O O oO Illustrated step by step instructions for running experiments are provided in the next section At the end of the experiments all users will be provided with a complete data package including a copy of the relevant pages of the KOOKABURRA logbook 28 Qnsto KOOKABURRA 2 5 ILLUSTRATED STEP BY STEP INSTRUCTIONS 1 On the desktop of the instrument control computer double click the shortcut labelled Gumtree 1 10 5 normally this would already be open E 5 T Wb 0 nm fe 2 New windows will open on the screen Log on as follows For Role select Manager then type in the password ansto If Gumtree won t start click Cancel or try to close the Sap E TEE window Then do the following HM Sect dean you wart to amer i Host Name or IP address Port 22 E 1 On the desktop double click hu the shortcut labelled PuTTY Load save or delete stored session 2 Double click kookaburra ics pee 3 Use password kookaburra123 i Default Settings kookabura ics 4 Type runsics status 5 If SICS is running you should read sics listening on port 6 If SICS is not running type runsics start 7 If SICS is unresponsive type runsics stop then runsics start 9 If SICS is no
4. wavelengths as illustrated in Fig 4 HOPG Premonochromator at fixed 05 45 N Cold Neutron Guide CG3 Neutrons Arrangement of Si 111 and Si 311 Channel Cut Analyser Crystals Arrangement of s Si 111 and Si 311 lt Channel Cut Detector Monochromator Crystals Beam Detector Fig 4 Schematic layout of the KOOKABURRA double crystal USANS principle The perfect Si channel cut crystals of choice either Si 111 Si 311 are rotated into the neutron beam For details see text The incident neutron beams are reflected off a highly oriented pyrolytic graphite HOPG premonochromator crystal at a fixed angle of 45 either at A 4 74 using the HOPG 002 first order reflection or at A 2 37 A using the HOPG 004 second order reflection The expected performances of KOOKABURRA when operating at either wavelength are summarised in Table 1 KOOKABURRA HIGH INTENSITY MODE HIGH RESOLUTION MODE Weak Scattering Samples Strong Scattering Samples Wavelength A 24 74 2 37 Premonochromator HOPG 002 at 45 HOPG 004 at Osragg 45 Beryllium Filter In Out Channel Cut Crystals Si 111 at 49 2 Si 311 at Osragg 46 4 Full Darwin Width 2 21 urad 2A0p 5 4 urad Minimum Momentum Transfer 2 8 10 A Oi 1 4 10 Flux on Sample 190 000 n cm 5 23 000 n cm s Table 1 KOOKABURRA Instrument performances expected for operati
5. 2007 Workshop Report Pushing Small Angle Neutron Scattering at OPAL to Smaller Barker J G Glinka C J Moyer Kim Drews amp Agamalian M 2005 7 Appl Cryst 38 1004 1011 Boeuf A Gobert G amp Rustichelli F 1975 Nucl Instrum Methods 124 533 540 Bonse U amp Hart M 1965 Appl Phys Lett 7 238 Freund A K amp Rehm C 2011 Nucl Instrum Methods Phys Res Sect A 634 581 589 Herr H K nnecke M amp Maden D 1997 Physica B 241 243 124 126 James M Nelson A Brule A amp Schulz J C 2006 J Neutron Res 14 91 108 James M Nelson A Holt 5 Saerbeck T Hamilton W A amp Klose 2011 Nucl Instrum Methods Phys Res Sect A 632 112 123 Kennedy S J Robinson R A amp Hunter B A 2001 J Phys Soc Jpn 70 Suppl A 567 570 Kennedy S 2006 Physica B 385 386 949 954 Kline S R 2006 J Appl Cryst 39 895 900 Kroupa G Bruckner G Bolik O Zawisky M Hainbuchner M Badurek G Buchelt R J Schricker A amp Rauch H 2000 Nucl Instrum Methods Phys Res Sect A 440 604 608 Lam T Hauser N G tz A Hathaway P Franceschini F Rayner amp Zhang L 2006 Physics B 385 386 1330 1332 Rekveldt M T Plomp J Bouwman W G Kraan W H Grigoriev S amp Blaauw M 2005 Rev Sci Instrum 76 033901 Rehm C Barker J Bouwman W G a
6. Both the QUOKKA and the KOOKABURRA cells can be inserted into the sample holder compartments of the five position sample changer using appropriate adapter plates Note that the sample changer moves in vertical direction 21 Qnsto KOOKABURRA 2 1 4 Sample environment There is a range of sample environment SE equipment which may be used on KOOKABURRA for in situ measurements of the sample within a controlled environment Users must refer to the relevant instruction manual for the equipment being used A dedicated support structure for SE equipment is available on the instrument When SE equipment is used the standard five position sample changer can not be available at the same time If users plan to bring their own equipment it needs to be checked by the ANSTO Bragg sample environment team prior to the experiment 2 2 OPERATION OF KOOKABURRA Prior to the experiments users will be given an induction to the correct use of the KOOKABURRA instrument This will enable them to independently mount and remove samples KOOKABURRA e leave experiment area and lock the access door open and close the sample shutter e operate the instrument control equipment within allowed limits e run experiments by following the procedure given below o start GUMTREE SICS input information about user and sample start scans control experiment periodically using GUI repeat scans according to the experiment program stop pause experiment
7. Guide Translation Fig 9 Schematic layout of the KOOKABURRA upstream optics with main components indicated 1 3 4 2 Premonochromator assembly About 30 m away from the cold source a premonochromator crystal has been installed in the white neutron beam exiting the cold neutron guide CG3 of effective dimensions 170 mm high x 50 mm wide Its function is to select a monochromatic neutron beam and to focus it onto the sample position which is located between the channel cut monochromator and the channel cut analyser crystal at a nominal distance of 1600 mm from the premonochromator The schematic layout of the premonochromator assembly comprising of the premonochromator crystal and tilt and rotation stages for its alignment is shown in Fig 10 Premonochromator Crystal Mounting Fig 10 Left Schematic layout of the KOOKABURRA premonochromator assembly with main components indicated Right Premonochromator crystal mounting 14 Qnsto KOOKABURRA The premonochromator crystal material is highly oriented pyrolytic graphite HOPG with dimensions 82 5 mm horizontal x 168 mm vertical x 1 8 mm thick Since the premonochromator is doubly focusing i e it is curved both horizontally and vertically it consists of a composite of five vertical arrays of 17 HOPG pieces each piece with dimensions 16 5 mm horizontal x 10 mm vertical The pieces were mounted on a silicon support plate SESO http www seso com approaching th
8. a Sydney Weather Forec Status Config Stream Read SoftVeto View Log Clients BM1 0 000 counts sec Controlled by SICS ics1 kookaburra nbi ansto gov au 8080 All DAQ 3749 04 20 70 BM2 0 000 counts sec 0 counts BM3 0 000 counts sec Server Up 4293 03 27 19 counts Mesytec MPSD8 MCPD8 Ethernet DAE Disable auto refresh Total x y histogram Questions and Comments to Mark Lesha ANSTO Original version Gerd Theidel SINQ Mark Koennecke SINQ ANSTO OPAL NBI Histogram Server Version 2 12 2 0 built Sep 5 2014 12 41 12 gcc 4 3 0 20071129 experimental trunk revision 130511 File Edit View History Bookmarks Tools Help Cameras x caml kookaburra nbi ansto gov au index html all feeds amp video mode 2 Searc 1 KKB Histogram Server _ Beam Monitor x Bragg JIRA NBI Com Bragg Institute NBI Por kJ Google Scholar LEO S Startpage 2 KKB Cameras a Sydney Weather Forec cam kookaburra nbi ansto gov au 80 proxy ANSTO OPAL NBI Kookaburra All Instrument Video Feeds 34
9. analyser stage and the main detector Its opening is 0 mm 70 mm in both the horizontal and vertical directions The openings of both slit systems are adjustable through four separate blades in the up down left right directions each controlled by motors and encoders The material of the slit blades is sintered B4C of 5 mm thickness Fig 15 KOOKABURRA Slit systems the slit shown on the left has been installed between the channel cut monochromator crystal and the sample position the slit shown on the right has been installed between channel cut analyser crystal and the main detector for details see text During operation the maximum opening of the slit systems corresponds to the maximum beam size transmitted through the channel cut monochromator and channel cut analyser crystal of 50 mm x 50 mm This value also determines the maximum sample size 1 3 4 7 Sample stage For routine experiments a multi position sample changer is used to successively position various samples in the neutron beam centre using a linear translation stage To this end the distance between channel cut monochromator and analyser stage is at its minimum of 600 mm see Fig 13 For experiments requiring any sample environment equipment the distance between the two stages can be increased variably up to a maximum of 1 100 mm by moving the channel cut analyser 20 Qnsto KOOKABURRA stage away from the sample position as illustrated in Fig 16 In the latter c
10. because the range of accessible real space length scales D is relatively large ranging between 10 and few 1 000 with the corresponding scattering vector magnitudes 27 D ranging between 1 and 10 Q 0 4 sin 0 2 where is the scattering angle A is the wavelength of the incident neutrons In many experimental cases it is desirable to extend this experimentally The USANS technique measurable range to length scales up to D 10 10 um allows determination of corresponding to Q 10 A the ultra low Q region accessible EEO SECIS size through ultra small angle neutron scattering USANS shape orientation etc of complex systems covering length scales in the range of 100 nm to 10 USANS is useful for studies of pores and cracks in rocks cement engineering materials very large biological or polymer molecules or macromolecular assemblies and mesoscopic magnetic particles The range of interest includes bacteria blood cements clays clusters in metals coals colloids complex fluids emulsions foams food gels granular materials hydrogels membranes micellar systems minerals and mineral processing nanocomposites nanotechnology phase transitions polymer blends polymers porous materials powders precipitates proteins rocks thin metallic or organic films viruses etc KOOKABURRA Grain Structures Membrane Biophysics Drug Delivery Syst
11. done via tilt rotation and linear translation stages ADC beneath the granite base plate When swapping between channel cut monochromator crystals i e between the two wavelengths both shielded boxes will be rotated by 180 The same arrangement as described above for the channel cut monochromator stage is valid for the channel cut analyser stage located after the sample position Both channel cut monochromator and analyser stages are mounted on a single optical table made from granite ADC The total weight of the loaded granite table is about 1 3 tons this reduces the impact of external vibrations on the relative angle of the monochromator and analyser channel cut crystals which determines the angular resolution of the instrument 19 Qnsto 1 3 4 6 Slit systems On KOOKABURRA two motorised slit systems ADC are used to define the dimensions of the neutron beam before and after the sample see Fig 15 for their schematic layout The first slit system is placed between the channel cut monochromator stage and the sample stage Its opening is mm 115 mm in horizontal direction and 0 mm 70 mm in vertical direction The wider opening in the horizontal direction takes into account the two different Bragg angles of the channel cut crystals or two different neutron beam paths required when operating the instrument at two different wavelengths see Fig 13 A second slit system is placed between the channel cut
12. monitor required to record the intensity of the incident neutron beam two transmission detectors required to monitor the intensity of the neutron beam transmitted through the sample and a main detector array required to measure the intensity of the neutron beam transmitted past the channel cut analyser crystal The beam monitor is installed immediately behind the sample shutter as a neutron counter ORDELA http www ordela com It operates at low He pressure with a neutron detection 22 Qnsto KOOKABURRA efficiency of 5x10 at 15 meV 2 3 Both transmission and main detectors consist of He filled 5 inch 1 inch 25 4 mm long position sensitive detector tubes GE http www ge energy com The operation of KOOKABURRA at two different wavelengths requires a set of two individual detectors to measure the transmitted beam with efficiencies of 196 for A 4 74 A and 1096 for 2 37 The two transmission detector tubes diameter 2 5 inch are mounted next to each other on a shielded support structure The main detector consists of a hexagonal array of five detector tubes diameter lt 1 inch with two tubes in the front and three tubes in the back inside a shielding box made from Cd lined borated polyethylene to protect the detector tubes from stray neutrons Given that the distance between channel cut monochromator and channel cut analyser stages is variable the main detector shielding box is mounted on a lin
13. 40 x 40 90 35 x 35 85 30 x 30 75 25x25 55 20 x 20 40 15x15 25 10 x 10 15 5x5 5 Table 1 Expected neutron beam intensities as a function of the utilised beam cross section Neutron Beam Intensity 30 40 Pre Sample Slit Opening mm Fig 1 Expected beam intensities as a function of the utilised neutron beam cross section 26 Qnsto KOOKABURRA 2 1 3 Sample mounting Samples that don t require a container like e g rock slabs or other solid specimens can directly be mounted on a holding frame For any other sample material like liquids gels powders etc demountable KOOKABURRA sample cells are available with variable path lengths of 0 1 2 5 and 10 mm and variable cross sections of 10 x 10 20 x 20 30 x 30 40 x 40 and 50 x 50 in units of mm see Fig 2 e g 50x50 mm e g 10x10 mm Fig 2 Top photos Components of KOOKABURRA demountable sample cells Sketch Exemplary KOOKABURRA cell inserts defining the sample size Lower right photo QUOKKA and KOOKABURRA demountable sample cells side by side window sizes 19 mm diameter and 50 mm x 50 mm respectively Note that the standard QUOKKA demountable sample cells and QUOKKA banjo cell holders both with a maximum neutron beam cross section of 19 mm in diameter can also be easily accommodated on the KOOKABURRA instrument which utilises a standard five position sample changer although increased sample areas usually result in superior data
14. 74 A The neutron beam shown in red enters and leaves the Si 111 monochromator crystal shown in green at 49 2 relative to the beam coming off the premonochromator before entering and 18 Qnsto KOOKABURRA leaving the Si 111 analyser crystal also shown in green The paths of the neutron beams transmitted towards the transmission detector and beam stop respectively are indicated in blue The minimum distance between the channel cut monochromator CC M and the channel cut analyser CC A of 600 mm can be variably increased to up to 1 100 mm for accommodation of any sample environment equipment note that in Fig 13 the position of the channel cut analyser stage for the maximum distance of 1 100 mm is labelled CC A The bottom layout in Fig 13 shows the setup used when operating KOOKABURRA at A 2 37 The Si 311 crystals shown in pink are rotated into the neutron beam at an angle of 46 4 relative to the beam coming off the premonochromator The channel cut monochromator and analyser crystals are housed in two separate shielded monochromator analyser boxes made from aluminium lined with boron plastic and furnished with beam entrance and exit cut outs see Fig 14 Si 311 Analyser Si 111 Monochromator Si 111 Analyser 5 311 Monochromator Fig 14 Arrangement of two sets of channel cut monochromator and analyser crystals as indicated by the arrows Alignment of the channel cut monochromator crystal in use can be
15. KOOKABURRA Qnsto The Ultra Small Angle Neutron Scattering USANS Instrument KOOKABURRA USER MANUAL Qnsto KOOKABURRA Table of Contents 1 TECHNICAL DESCRIPTION BARN 3 1 1 INTRODUCTION ARM 3 1 2 ABOUT UYAN 3 1 2 1 USANS TECHNIQUES vecccscscsscscsccssscssssssessssescerssessssssessesssssssessssesssrssestsrsststsrsavsssrsisassrsisavsrsissversatsrsitevereaseveseees 4 12 2 HOW WE DECIDED WHAT TYPE OF LOW Q INSTRUMENT TO BUILD eee 4 1 3 THE KOOKABURRA USANS INSTRUMENT eerte na k a k aL Ma retener repetere terere an aa 5 1 3 1 INSTRUMENT CONCEPT vecccscscsccscscsscssscssssesssssscssesesessesssessssesssrssessssestsrsseavsrsissvesisassrssesvsrsisstsrsasersiesvereaversseees 6 1 3 2 INSTRUMENT PERFORMANCE cccccscsscscscssscsscssscssssesssssesessesesssssssssssessssesesrssestsrsstsvsvsiestersssstsrsisatsresssvsseessseaes 10 1 333 INSTRUMENT LAYOUT tette eter tette ttt AADI EA EDA DE EE EEE Ea naaa 11 1 3 4 INSTRUMENT COMPONENTS eee 13 1 3 4 1 COLDSNEUTRON GUIDE C33 tipa axo RE UU AS edP RUP Rc xu Pw n ovn Pra Re 13 1 3 4 2 PREMONOCHROMATOR ASSEMBLY Vo pex E IUEN e EEVSa pes ve eo Pace 14 1 3 4 3 BERYLLIUM FILTER ccc eee ecececececcececcccececeacececececcececeaencecececeacececeaesececeececeaeaceceaeaseceesasececececeacecececeaseceeeaeee
16. Si 311 channel cut monochromator crystal are mounted on a granite base plate back to back with a sidewise offset so that the beam centre is aligned on first reflection for both crystals with respect to the premonochromator crystal The Bragg angle for the Si 111 crystals is 49 2 for 4 74 A while the Bragg angle for the Si 311 crystals is 46 4 for 2 37 Therefore the respective neutron beam paths between monochromator and analyser crystals differ by a few degrees The schematic layout of the channel cut crystals is shown in Fig 13 Fig 12 KOOKABURRA Beam stop 17 KOOKABURRA Premonochromator 1 1 JC Circular 39 55 Shielding Box 00 gt Containing Two Quintuple Bounce Channel Cut Crystals Q lt Transmission Detectors l 4 74 P d Slit Systems Optical Table Be 1100 46 4 amp 00 lt Transmission Detectors 22 37 CU Out For Vertical Sample Main Detector Beam Stop Assembly Fig 13 Schematic layout of two sets of channel cut crystals mounted inside circular shielding boxes on top of the optical granite table CC M channel cut monochromator CC A channel cut analyser positioned 600 mm away from CC M channel cut analyser positioned 1 100 mm away from CC M Top Using Si 111 at 49 2 Bottom Using Si 311 at 46 4 For details see text The top layout in Fig 13 depicts the setup used when operating KOOKABURRA at A 4
17. ally such decision is based on a reasonable comparison to similar previous experiments or simulated data The proper choice of wavelength will be verified by quick scans performed prior to full USANS scans 2 1 2 Sample requirements The Q range accessible on KOOKABURRA starts from 1 8 10 A for the short and 3 10 for the long wavelength and goes up to about Q 1 10 depending on the sample morphology which determines at which Q the background will be reached Details of preliminary measurements and or simulation calculations provided help determine the Q range of interest for individual experiments As a rough guide an absolute intensity of 10 100 cm is required for the long wavelength and about 10 000 100 000 for the short wavelength to detect a USANS signal The maximum neutron beam cross section to be used on KOOKABURRA is 50 mm x 50 mm Therefore wherever feasible enough sample material should be provided by the users to ensure an adequate use of the beam Table 1 lists the neutron beam intensity as a function of the beam size cross section the data are also plotted in Fig 1 According to the figures presented a sample size of about 30 mm x 30 mm and above is preferred Large beam areas will not only speed up experiments but also result in improved data better signal to noise ratio at high Q 23 KOOKABURRA Neutron Beam Cross Section Neutron Beam Intensity 50 x 50 100 45x45 98
18. and the SESANS instrument at Delft Rekveldt et al 2005 respectively to experimentally determine the advantages and disadvantages of both techniques The standard samples consisted of polystyrene microspheres featuring different particle diameters and various scattering powers e Instrument Performance Estimations Monte Carlo and analytical calculations helped estimate the performances of either instrument type double crystal USANS and SESANS being installed at OPAL Although both techniques are applicable for studying large scale objects they have different strengths and it follows that different science will be done on these two instruments which are complementary rather than competitive A survey of the Australian large scale structures science community revealed that a rather large range of scientific problems needs to be covered by the new instrument According to the experts double crystal USANS is better suited for investigating the widest possible range of sample properties and the widest range of sample scattering powers A paper titled DCD USANS and SESANS a comparison of two neutron scattering techniques applicable for the study of large scale structures has been published Rehm et al 2013 1 33 THEKOOKABURRA USANS INSTRUMENT The KOOKABURRA USANS instrument is based on the classical Bonse Hart Bonse amp Hart 1965 method which consists of using two multiple reflection crystal systems arranged in a non dispersive geom
19. ase the beam intensity will be reduced by a factor of 0 7 from the effect of defocusing Sample 2 Shutter Channel Cut Motion Stage Beam Stop Main Detector Sample LP Shutter Channel Cut Monochromator Motion Stage Beam Stop Detector Fig 16 Top Location of channel cut analyser CC A stage during routine experiments using a multi position sample changer not shown for clarity Bottom Moving the CC A stage further downstream allows accommodation of sample environment equipment between the monochromator and analyser crystals The sample changer as well as any sample environment equipment is independently supported by an appropriate table which is not in contact with the optical table in order not to transfer vibrations to the highly sensitive arrangement of the channel cut crystals For a schematic layout of such table see Fig 17 21 KOOKABURRA 12 T Magnet Fig 17 Schematic layout of a self supporting sample environment equipment table for KOOKABURRA As an example of the use of sample environment equipment Fig 18 shows a rheometer placed in the KOOKABURRA sample position Fig 18 Example for the use of sample environment equipment a rheometer has been placed in the sample position between the monochromator and analyser crystals of KOOKABURRA 1 3 4 8 Detector system and data treatment management The detector system consists of a beam
20. at 2 37 the 4 74 neutrons will not be further transported through the Si 311 channel cut crystal set up Qnsto KOOKABURRA 1 3 2 Instrument performance Fig 5 shows the very sharp rocking curve profiles obtained by using the two different wavelengths available at KOOKABURRA For the long wavelength option using Si 111 channel cut crystals with a resulting wavelength of 4 74 A the full width half maximum value is 0 0015 for the short wavelength option using Si 311 channel cut crystals with a resulting wavelength of A 2 37 A the full width half maximum value is 0 0003 both values are in very good agreement to theoretically expected figures e Si 111 2 4 74 A FWHM 0 0015 Si 311 2 2 37 A FWHM 0 0003 Normalised Neutron Intensity 0 006 0 004 0 002 0 000 0 002 0 004 0 006 Channel Cut Analyser Deviation Angle deg Fig 5 Very sharp rocking curve profiles obtained by using either Si 111 or Si 311 channel cut crystals on KOOKABURRA The two different wavelengths and the full width half maximum values of the curves are indicated 10 Qnsto KOOKABURRA 1 3 3 Instrument layout KOOKABURRA has been installed at the ANSTO OPAL Kennedy et al 2001 Robinson amp Kennedy 2002 Kennedy 2006 cold neutron guide CG3 downstream of the EMU backscattering instrument and upstream of the PLATYPUS reflectometer James et al 2006 2011 see Fig 6 Fig 6 Neutron scatter
21. closed cycle refrigerator air cooled and an associated vacuum system are also required 16 Qnsto 1 3 4 4 Sample shutter and beam stop KOOKABURRA A sample shutter or beam shutter allows the opening and closing of the neutron beam The premonochromator shielding bunker which houses the premonochromator crystal assembly and the beryllium filter features 200 mm thick lead walls lined with 5 mm thick borated rubber in order to achieve radiological doses outside the bunker below the design limit of 3 uSv h The sample shutter is mounted to the outside of that bunker A re entrant fixed beam stop stops the diffracted beam past the channel cut monochromator crystal Its opening is 155 mm horizontal x 275 mm vertical with a depth of 200 mm The lead thickness is 50 mm with its inside lined with 5 mm thick borated rubber see Fig 12 1 3 4 5 Channel cut monochromator analyser stages All four channel cut crystals used on KOOKABURRA i e two Si 111 channel cut crystals and two Si 311 channel cut crystals manufactured by Holm http www holm silicon de were satisfactorily characterised on the neutron optics instrument S18 at the ILL Kroupa et al 2000 which was configured as a high resolution Bonse Hart camera using the Si 333 reflection at a Bragg angle of 45 with a corresponding wavelength of 1 48 A At the KOOKABURRA channel cut monochromator CC M stage before the sample position both a Si 111 and a
22. e nominal curvatures with a sagittal vertical radius of curvature of 2 27 m and a meridional horizontal radius of curvature of 4 54 m using indium metal as bonding material The Bragg angle of the assembled premonochromator crystal is fixed at 45 The crystal assembly was characterised on the double crystal test instrument T13C of the Institute Laue Langevin ILL in Grenoble France Boeuf et al 1975 using the HOPG 004 reflection at a Bragg angle of 45 with a corresponding wavelength of 2 37 The neutron mosaic spread was measured to be 0 6 at FWHM in both the horizontal and vertical directions while the average peak reflectivities were determined as 44 796 5 596 in the sagittal and 44 096 2 696 in the meridional direction respectively These figures show that the HOPG material is of excellent quality and that the mosaic spread is isotropic The use of such a doubly focusing premonochromator leads the significantly enhanced neutron intensity at the sample position Freund amp Rehm 2011 The premonochromator crystal is mounted on tilt and rotation stages to allow position control ADC Advanced Design Consulting http www adc9001 com 15 Qnsto KOOKABURRA 1 3 4 3 Beryllium filter Since KOOKABURRA enables individual operation at either A 4 74 A or A 2 37 a beryllium Be filter is required to absorb higher order wavelengths when operating the instrument A 4 74 A The Be filter is moved out of the ne
23. ear stage ADC which follows the position of the channel cut analyser crystal see Fig 16 Besides the main detector shielding box and the linear stage the detector support structure also holds the second slit system as well as a beam attenuator kit comprising plexiglass plates of different thicknesses on a small linear stage HIWIN http www hiwin com Instrument control data acquisition experimental planning and data analysis of the KOOKABURRA USANS instrument is carried out by a computerised system consisting of the following i a data acquisition computer directly interfaced with the USANS detector electronics complete with histogram memory software ii SICS SINQ Instrument Control System computer server software Herr et al 1997 and iii GumTree user application software Lam et al 2006 Reduced USANS data can be analysed using model independent methods or non linear fitting to one of a large and growing catalogue of structural models which has been developed at the NIST Center for Neutron Research Kline 2006 25 Qnsto KOOKABURRA 1 4 REFERENCES Agamalian M Wignall G D amp Triolo R 1997 J Appl Cryst 30 345 352 Agamalian M Carpenter J M amp Treimer W 2010 J Appl Cryst 43 900 906 Agamalian M 2011 Bonse Hart USANS Instrument ch 1 1 3 1 in Neutrons Soft Matter edited by T Imae T Kanaya M Furusaka amp N Torikai pp 73 93 Hoboken John Wiley and Sons ANSTO
24. eass 16 1 3 4 4 SAMPLE SHUTTER AND BEAM STOP vEVEN Slat aud Eua uxo dedu nata te EXE EX ou 17 1 3 4 5 CHANNEL CUT MONOCHROMATOR ANALYSER 17 1 3 4 6 B SYSTEMS easiest vote ac censors oe tatiaado gana escanaceenenuctoesuavacseesuscacacaseaagatovscaunccavactewnauesovacaracateacdsuuacstanagesnassavsucauactta ds 20 1 3 4 7 SAM a Tal ze 20 1 3 4 8 DETECTOR SYSTEM AND DATA TREATMENT MANAGEMENT 0eececceececcecceceecececeecececceceececeesecauececaueeecaes 22 1 4 REFERENCES RM 24 2 USER GUIDE FOR INSTRUMENT OPERATION csccesececesececececececscscscececescscscscscacacacscscscscscscscscscsceesesescssacatacacacass 25 2 1 PRELIMINARIES cccccccccececcscocsccscscsscscsccucscscsscssaccssscavessssasessasesssvarcssavaressavesesssvascisavsuessavsrsavascisaveisavaveisavaeisavavereseaee 25 211 WAVELENGTH OPTIONS eee tette teret AD LAA AA AED L DL entente p 25 2 1 2 SAMPLE REQUIREMENTS vesesccscscsscssscsssscsessesssscsssessesesessssesesrssesssessresesverssssvssesvstsrsisstsseassvsseatsrsisstsieavereaceee 25 2 13 SAMPLE MOUNTING eene tette ADA AD L D A EA AA LEDS terrestre ters p 27 214 SAMPLE ENVIRONMENT ccccsccscscoscscscsscscscssesesscssscsscsssessssesssrssessssessesssesssestesicavsvsssassvsseatsvsreatsrsisstsasavereaceees 28 2 2 OPERATION OF KOOKABURRA
25. emp Plot Data Repository to plot them using the software of your choice NOTE Details of the samples neutron wavelength and environmental conditions are recorded in the KOOKABURRA electronic log HDF files Details of personnel proposal number instrument configuration sample environment used and any other special features must be recorded in the KOOKABURRA manual logbook Generation of the electronic log is automatic upon running a sample KOOKABURRA t 6 52 KKB0002892 Sample G9 foils off Path for electronic log HDF files W data current 33 monitor detector intensities do the following 1 On the desktop double click the shortcut labelled Mozilla Firefox 2 Click on the bookmark labelled KKB Histogram Server 3 Use the following credentials to log on User Name manager Password ansto To check the instrument cameras do the following 1 On the desktop double click the shortcut labelled Mozilla Firefox 2 Click on the bookmark labelled KKB Cameras KOOKABURRA I File Edit View History Bookmarks Tools Help x j View Data x dasl kookaburra nbi ansto gov au 8081 admin viewdata egi C Q Search 3 KKB Histogram Server _ Beam Monitor Bragg JIRA NBI Com NBI Bragg Institute NBI Por Google Scholar LEO ma Startpage _ KKB Cameras
26. ems Pharmacology Dental and Medical Composites Biology amp 1 Agglomeration and Water Transport Cements Oil Bearing Rocks Paint Pigments Biomaterials Fillings Life amp Particle Size y Implants Sciences Precipitates Complex Fluids Food Cosmetic Personal Care Pharmaceuticals Drug Delivery Mining Industries Structure and Dynamics of the Opal Silica Water System Viruses Bacteria Shape Changes in Red Blood Cells Fig 1 Example of three high level research areas that benefit from applying the USANS technique see three blue circles Listed next to them are associated areas of interest It follows that there is a broad range of materials that may be studied by USANS 1 2 1 USANS techniques In recent years two types of ultra low Q neutron scattering techniques have been developed namely the double crystal USANS method which uses perfect silicon Si crystals in Bragg reflection and spin echo SANS SESANS in which the spin precessions of a polarised beam of neutrons are used to encode the scattering angle to very high precision Both techniques are only sensitive to scattering in one direction while in the perpendicular direction the measurements are averaged over the possible wavevector transfers i e they measure scattered intensity from the sample with excellent angular resolution in one direction of a few arc seconds b
27. etry to achieve a steep decrease in the tails of the perfect crystal diffraction curves This technique permits the detection of very small angular deviations of the neutron beam after scattering from a sample placed between two channel cut crystals Agamalian et 1997 In the following we discuss the concept and layout of the KOOKABURRA double crystal USANS instrument followed by detailed descriptions of the instrument components Rehm et al 2013 Qnsto KOOKABURRA 1 3 1 Instrument concept The central parts of KOOKABURRA are two identical multi bounce channel cut perfect Si single crystals Schwahn et al 1985 labelled monochromator and analyser see Fig 2 mounted on a single optical bench When the monochromator and analyser crystals are perfectly aligned to each other analyser rotation angle 0 the incident neutron beam is totally reflected into the main detector Premonochromator lt Neutrons Channel Cut Channel Cut Analyser rysta Crystal N N Transmission AA Detector Stop Perfect Si Channel Cut Crystal Main Detector Fig 2 Schematic layout of the double crystal USANS principle The main instrument components are two identical perfect silicon Si channel cut crystals placed in front labelled monochromator and after the sample labelled analyser respectively During the experiment the analyser crystal is rotated and thus a very sharp rocking curve prof
28. ile recorded During the experiment neutron scattering intensities are measured as a function of the momentum transfer Q scattering angle 0 at a time i e only small angle scattering corresponding to the same angle 0 is reflected Minute deviations in the neutron beam direction after scattering by the sample are observed as a broadening of the double crystal analyser rocking curve see Fig 3 Experimental Rocking Curve Without Sample With Sample Neutron Intensity a u 0 00 0 01 0 02 0 03 Channel Cut Analyser Deviation Angle deg Fig 3 In a typical double crystal USANS experiment rocking curves are measured with and without a sample material being present Small angle scattering caused by the sample material results in a broadening of the initially sharp rocking curve profile and the difference between these two rocking curves will be analysed Because the channel cut crystals are perfect Bragg reflection of a particular wavelength is restricted to a very narrow angular range of neutron trajectories that fall within the so called Darwin width which is typically a few arc seconds Agamalian et al 1997 Barker et al 2005 Within this uncertainty neutron trajectories are completely correlated with neutron wavelength The Bonse Hart USANS technique can use a relatively wide range of wavelength divergence angle combinations simultaneously which enhances the flux on
29. ing instruments installed at the cold neutron guide CG3 at the ANSTO OPAL reactor The general assembly of KOOKABURRA is schematically shown in Fig 7 while Fig 8 shows a photo of the instrument during the installation phase 11 KOOKABURRA Guide CG3 Premonochromator Platypus Assembly Chopper Premonochromator Shielding Bunker Beryllium Ry m Filter EH 0 P b ucc Sample Shutter amp Flight Tube Neutron Beam Channel Cut Analyser Stage Detector Monochromator Stage 4 y Channel Cut Optical Table Beam Stop Main Detector Fig 7 General assembly of the KOOKABURRA USANS instrument at the ANSTO OPAL cold neutron guide CG3 with main components indicated A doubly focusing highly oriented pyrolytic graphite HOPG premonochromator device extracts a monochromatic neutron beam A beryllium filter can be used to remove by scattering neutrons with wavelengths below 4 A if required A sample shutter allows opening and closing of the neutron beam The sample position is surrounded by the channel cut monochromator and analyser stages The distance between these two stages is variable in order to be able to accommodate any sample environment equipment like cryostats magnets etc It follows that the location of the main detector which needs to be in line with the channel cut analyser crystal is variable too For detailed descriptions of the main instrument components see secti
30. mp Pynn R 2013 J Appl Cryst 46 354 364 Rehm C Brule A Freund A K amp Kennedy S J 2013 J Appl Cryst 46 1699 1704 Robinson amp Kennedy 5 J 2002 Physica B 311 44 49 Schwahn D Miksovsky A Rauch H Seidel E amp Zugarek G 1985 Nucl Instrum Methods Phys Res Sect A 239 229 234 24 Qnsto KOOKABURRA 2 USER GUIDE FOR INSTRUMENT OPERATION The purpose of this section is to provide instructions for the use of the ultra small angle neutron scattering USANS instrument KOOKABURRA A comprehensive technical description of the instrument concept layout components and performance is provided in the previous chapter 2 1 PRELIMINARIES 2 1 1 Wavelength options KOOKABURRA can individually be operated at two different wavelengths to optimally accommodate weakly and strongly scattering samples in one sample position Depending on the specific scattering powers of sample material provided by the users a wavelength of either A 4 74 A or A 2 37 A neutrons is selected as follows The 4 74 A wavelength high intensity operation mode is most appropriate for weakly scattering samples The 2 37 A wavelength high resolution operation mode is most appropriate for strongly scattering samples For meaningful USANS data collection it needs to be thought through which wavelength option can be considered the most appropriate one for the sample material to be investigated Ide
31. on at two different wavelengths Note that the precise values for the full width at half height depend on whether the Darwin or the Ewald solution applies see e g Agamalian et al 2010 When operating the instrument with 4 74 neutrons two Si 111 channel cut crystals will be used at a Bragg angle of 49 2 Also a beryllium filter will be moved into the beam to remove by scattering neutrons with wavelengths below 4 i e to suppress higher order wavelengths emerging from the premonochromator When operating the instrument with 2 37 neutrons two Si 311 channel cut crystals will be used at a Bragg angle of 46 4 and the beryllium filter will be moved out of the beam The 4 74 wavelength high intensity operation mode is most appropriate for weakly scattering samples but it should be noted that the four times larger full Darwin width for the 4 74 A operation of 2A05 21 urad compared to a value of 2 0 5 4 urad for the 2 37 A operation results in a poorer resolution at small values of Q Qmin for 4 74 is a factor of two larger than Qmin for 2 37 A see Table 1 Note that Qmin is estimated as Qmin 4NAQp A Agamalian 2011 Concerns about multiple scattering for strongly scattering samples can be addressed by switching to the A 2 37 A mode when necessary Although both the first and second order neutrons will reach the channel cut monochromator crystal when the beryllium filter is moved out of the beam when operating KOOKABURRA
32. ons below 12 KOOKABURRA Sample Position Pre Sample Slit Channel Cut N Sample Shutter Channel curNMonochromator E N Transmission Detectors Analyser Stage A Stage 4 2 Beam Monitor aaar 7 mej Fig 8 The KOOKABURRA USANS instrument during the installation phase 1 3 4 Instrument components 1 3 4 1 Cold neutron guide CG3 KOOKABURRA utilises neutrons delivered by the OPAL cold neutron guide CG3 This guide is fed by a hydrogen cold neutron source 363 mm high x 108 mm wide with a total flux of 1 8x10 2 cm s at 25 K Kennedy 2006 CG3 includes straight neutron guide sections with curved neutron guide sections in between with a radius of curvature of 1 3 km supermirror coatings of m 3 at the top and bottom of the neutron guides and m 2 5 on the sides a cut off wavelength of about A 0 8 A and a beam cross section 200 mm high x 50 mm wide The upper 20 mm of CG3 are exclusively used to provide neutrons to the PLATYPUS neutron reflectometer installed downstream of KOOKABURRA Therefore the remaining effective beam cross section for KOOKABURRA is 170 mm high x 50 mm wide Fig 9 shows the schematic layout of the KOOKABURRA upstream optics CG3 neutron guide premonochromator assembly beryllium Be filter on a translation stage and the sample shutter 13 KOOKABURRA KOOKABURRA Premonochromater Assembly Neutron
33. sample without sacrificing the Q resolution The high angular resolution required for double crystal USANS experiments is enhanced through multiple reflections of the neutron beam before and after the sample KOOKABURRA utilises quintuple bounces inside the perfect Si channel cut crystals Optimisation of the instrument with regards to determining the most efficient type of premonochromator crystal channel cut crystals and scattering geometry has been discussed elsewhere Freund amp Rehm 2011 Note that in a traditional SANS experiment the optimal sample scatters between 596 and 2096 of the incident neutron beam For the case of less than 596 scattering the signal to noise ratio might be poor note that the lower limit depends somewhat on the shape of the scattering curve For scattering of more than 2096 of the beam the SANS intensity would be strong enough to create noticeable multiple scattering resulting in a shape distorted scattering curve For the strongly scattering samples an adequate sample optimisation i e a reduction of the scattering can often be achieved by manipulating the sample via for example dilution reduction in sample thickness or contrast matching Note that the scattering power of a sample is also proportional to A Qnsto KOOKABURRA In order to optimally accommodate samples which differ in scattering powers the versatile KOOKABURRA USANS instrument is designed to allow individual operation at two different
34. ut with a large acceptance in the perpendicular direction of a few degrees which is described as slit smearing 1 2 2 How we decided what type of low q instrument to build At the ANSTO workshop Pushing Small Angle Neutron Scattering at OPAL to Smaller held in November 2007 ANSTO 2007 it was concluded that there is a strong scientific case with broad scientific application and a pre existing low Q user community in Australia Two options for a new low Q instrument to be built at OPAL were defined Qnsto KOOKABURRA e Classical Double Crystal USANS This method also known as Bonse Hart method Bonse amp Hart 1965 uses two perfect Si crystals in Bragg reflection as collimators Spin Echo SANS SESANS This recently developed method uses spin precessions of a polarised neutron beam to encode the scattering angle to very high precision To help decide on the most appropriate type of instrument for the Australian community we have carried out a detailed comparison of the capabilities of both methods Based on experimental round robin test measurements as well as analytical calculations we analysed the strengths weaknesses and experimental limitations and investigated possible performance gains for both set ups at OPAL Round Robin Neutron Scattering Measurements Round robin test measurements have been performed on a set of standard samples using the BT 5 double crystal USANS instrument at NIST Barker et al 2005
35. utron beam when KOOKABURRA operates at A 2 37 via a linear stage Huber http www xhuber com Details of the Be filter and its location inside the premonochromator shielding bunker are shown in Fig 11 Sample Shutter Cold Head of Closed Cycle Refrigerator Beam Port M 5 Vacuum Shroud E 1 iila Stage Fig 11 Left Schematic layout of the KOOKABURRA Be filter assembly with main components indicated Right Locations of premonochromator stage and Be filter inside the shielding bunker The beryllium material is made of the highly pure and isotropic S 200 F standard grade which contains very low amounts of hydrogen Materion http www materion com formerly Brush Wellman company One block of polycrystalline beryllium where the average grain size is 8 6 um and theoretical density is 99 99 with dimensions 60 mm horizontal x 170 mm vertical x 150 mm thick along the neutron path is surrounded on four sides by 2 3 mm thick BORTEC Al B4C metal matrix composite with 1696 B4C sheets plus an additional outer layer of 0 5 mm thick cadmium Cd Placed inside a vacuum shroud made from aluminium Janis http www janis com the Be BORTEC Cd assembly is mounted to a 10 mm thick copper frame Since cooling of the filter has a large effect on the transmission of the Be the transmission of 4 neutrons through Be is increased by 125 596 on cooling from 300 K to 80 K a cooling system
36. w running close the PuTTY window and start Gumtree Two new windows should now open SICS Experiment SICS Gumtree and Analysis Scripting Gumtree First window SICS Experiment SICS Gumtree The dark grey panel on the right side of this window provides an overview of the current status of KOOKABURRA the reactor source and the current motor positions of KOOKABURRA instrument components Premonochromator Beryllium Filter Channel Cut Monochromator Pre Sample Slit System 1 Sample Positioner Channel Cut Analyser Post Sample Slit System 2 Beam Attenuator Main Detector Environment Controllers For normal user operation the only important features in the window SICS Experiment SICS Gumtree are FZ SERVER STATUS lt PAUSE COUNTING Click to Pause Counting the option to pause resume counting by clicking the pause button pmchi pmom a PREMONOCHROMATOR lt BERYLLIUM FILTER bex 30 KOOKABURRA the option to fully stop the current experiment by clicking the big red stop button 17M of 443M nd pis LS Second window Analysis Scripting Gumtree In this window we will load a script for setting up and running an experiment 1 Click the Load Script button 2 Click on Open file 3 Select KKB Scan py the path is V shared KKB Initialised ScriptsKKB Scan py Open file Reload New script

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