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Number 28December 2005
Schweizerische Gesellschaft für Neutronenstreuung Société Suisse pour la Diffusion des Neutrons Swiss Neutron Scattering Society
Editorial:
Editor: Swiss Neutron Scattering Society
Board for the Period January 2004 – January 2007:
President: Dr. P. Allenspach [email protected] Board Members: Prof. Dr. S. Decurtins [email protected] Prof. Dr. B. Schönfeld [email protected]: Dr. S. Janssen [email protected]
Honorary Members: Prof. Dr. W. Hälg, ETH Zürich Prof. Dr. K.A. Müller, IBM Rüschlikon and Univ. Zürich Prof. Dr. A. Furrer, ETH Zürich and Paul Scherrer Institut
Revisers: Dr. W. Fischer, Paul Scherrer Institut Dr. K. Krämer, University of Berne
Address: Sekretariat SGN/SSDN Paul Scherrer Institut bldg. WLGA/002 5232 Villigen PSI, Switzerland phone: +41-(0)56 - 310 4666 fax: +41-(0)56 - 310 3294 www: http://sgn.web.psi.ch
Bank Account: 50-70723-6
Printing: Paul Scherrer Institut
Circulation: 1900, 2 numbers per year
Copyright: SGN/SSDN and the respective authors
On the cover:On October 14, 2005 the SINQ cold neutron radiography facility ‘ICON’ was inaugurated on the occasion of an international workshop on ‘Neutron Imaging Using Cold Neutrons’ at PSI. The new instrument is featured in detail by an article within this issue of Swiss Neutron News.The cover illustration shows a view into the ICON bunker: Nr. 1 shows the inner bunker, where a velocity selector, filters and other equipments can be inserted into the flight path of neutrons. Nr. 2 and 3 are the standard experimental positions. At the position Nr. 2 small and light probes can be examined (e.g. micro-tomography), where at position Nr. 3 bigger and heavier probes can be scanned through the neutron beam.
Contents
page
The President’s Page ...................................................................................... 2
Data Reduction on Time-of-Flight Instruments ......................................... 4
Dynamic Rotational Anion Disorder in Tetrahydroxoborate Sodalite Investigated by Quasielastic Neutron Scattering ....................... 13
ICON – The New Facility for Cold Neutron Imaging at the Swiss Spallation Neutron Source SINQ ..................................................... 20
Albert Furrer and Hans Ulrich Güdel received the 2005 ENSA Walter Hälg Prize .................................................................... 30
ENSA Press Release ..................................................................................... 33
Announcements ........................................................................................... 35
4th PSI Summer School in Zuoz 2005 ........................................................ 37
Day of Physics at PSI ................................................................................... 39
Conferences 2006 ......................................................................................... 40
SGN/SSDN – Registration Form ................................................................ 43
Dearmembers
Itisagreatpleasureformeandagreathonorforour society that two of its eminent members,AlbertFurrerandHansUlrichGüdel,havebeenawarded the „005Walter Hälg Prize“ of theEuropean Neutron Scattering Association(ENSA).FirstandforemostIwouldliketocon-gratulatethetwoprizewinnersinthenameofSGN/SNSSforthisprestigiousprizebutalsofortheir dedication to neutron scattering. Theirnames are intimately linked to the successfuldevelopmentofneutronscatteringanditsutiliza-tioninSwitzerlandandthepresent,verystrongstandingofSwissneutronscatteringonaninter-
nationalscale.AlbertandHansUeliwereco-foundersofSGN/SNSS,AlbertasitsfirstchairmanandHansUeliasaboardmember.YouwillfindalaudationbyJoëlMesotinthisissuelistingtheirscientificachievements.ItisamazingtoseeinhowmanyresearchfieldstheircollaborationhadandstillhasadecisiveimpactandIamlookingforwardtotheirfutureexperimentsandpublications.
TheinstallationoftheliquidmetaltargetMegapieintoSINQduringthefirsthalfof006willmarkamajor step in the targetdevelopment. It isaverycomplexanddemandingprojecttoassureasaveandsuccessfuloperationofthistarget.However,thepeopleinvolvedintheMegapiedevelopmenthavecarefullytriedtoexcludeanyeventualitiesbyputtingseverallayersofsecuritymeasuresinplaceandbytestingtheset-uponatestrig.Hence,everythingpossiblewasdonetoguaranteeasuccessfuloperation,butevenintheoptimumcaseitwillhaveasevereeffectfortheSINQusers:Theoperationoftheinstrumentsin006willbeseveralmonthsshorterthanusualandthereliabilityofthebeaminthesecondhalfoftheyearmightbeaproblem.Formoreinformationconcerningproposaldeadlinesandoperationschedule,pleaseconsultthe„announcementspage“inthisissue.
Inearlysummer006thefirstneutronsareplannedtobeproducedatthe3rdgenera-tionneutronsourceSNSinOakRidge,USA.Judgingfromtheexcellenttrackrecordofthisprojectasfarasbeingwithinthetimelimitandbeingwithinthebudgetareconcerned,Ihavenodoubtthatthisgoalwillbereached.Ofcourse,itwilltakesometimetorampthepoweruptothedesignvalueandtotransformtheinstrumentsinto
The President’s Page
3
reallyuserfriendlymachines,includingappropriatesampleenvironment,ancillaryfacilities and software,butnevertheless this eventwillmark theopeningofnewresearchopportunities.SNSwillnotreplacethesciencedonewithneutronssofaratexistingsourcesbutratheropensnewfieldsofscienceforneutrons.AfewyearsafterSNStheJapaneseJ-PARCwillstartoperation,fulfillingpartiallythedemandoftheOECD-MegascienceForumfrom1998:„prepare for provision for next generation sources in USA, Europe and Japan“.ItisencouragingtoseethattheEuropeanSpal-lationSource(ESS)regainedsomemomentum:TherearediscussionsgoingoninSwedenontheministeriallevel,UKisseriouslyconsideringitspolicyconcerningthefutureofneutronsourcesandthereisrenewedactivityinGermany(Sachsen/Sachsen-Anhalt)andinHungarytowardshostingESS.Forthevastmajorityofneutronusers,itwon‘tmatterwhereESSwillbelocatedaslongasitisassuredthatitwillbebuiltsomewhereinEurope.
PeterAllenspach
Data Reduction on Time-of-Flight Instruments
P. L.W. Tregenna-Piggott
Laboratory for Neutron Scattering, ETHZ and Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
1. IntroductionTheconversionofrawneutron-scatteringdataintophysicalfunctionsthatare,byandlarge,independentoftheinstrumentisaprocessknownasdatareduction.Giventhatneutronscatteringisamaturefield,onemightbeforgivenforthinkingthatthetheoryofdatareductioniswell-establishedandgenerallyaccepted.WhenjoiningtheLabora-toryforNeutronscatteringinAprilofthisyear,Iwasthereforesomewhatsurprisedtodiscoverthatnosuchconsensusexistsfordatareductionontheindirectgeometrytime-of-flight(TOF)instrument,MARS,forwhichIwastoassumeresponsibility.Coinci-dentwiththestartofmyappointment,thereemergedapublicationbyBrunoDorneronthisverytopic.1Iprofessmyselftoentertainaprofoundvenerationforthisworkandmuchofwhatfollowsconstitutesasummaryofhisdisquisition.Ibeginbyshow-inghoweasyitistofollowanerroneousmathematicalpaththatultimatelyleadstoasetofequationsrelatingrawTOFdatatothescatteringfunction,thatareintuitivelyincorrect,fortheyareasymmetricwithrespecttothetransformationbetweendirectandindirectgeometryTOF.IthenshowhowtheformalismofDorneraffordsarigorousprescriptionfordatareductionofTOFdatathatresolvesthediscrepancy,providinginvaluableinsightintothephysicalquantitiesthatareactuallybeingmeasured.
2. Determination of the Scattering Function from TOF Data
ThederivationofhowthescatteringfunctionmaybeextractedfromaTOFexperimentisusuallypresentedasfollows.TheprobabilitythattheinfinitesimalfluxofneutronsisscatteredintotheinfinitesimalsolidangledΩFandintheenergywindowdEFisrelatedtothescatteringfunctionby,
(1)
wherehwandhQaretheenergyandmomentumtransfer,andkIandkFaretheincom-ingandoutgoingwavevectorsrespectively.Inequation(1)andinallsubsequentequa-tions,allparametersthatdonotcontainspectralcomponentsareneglected.
1
Data Reduction on Time-of-Flight Instruments
Philip L.W. Tregenna-Piggott
Laboratory for Neutron Scattering, ETHZ and Paul-Scherrer Institute,
CH-5232 Villigen PSI, Switzerland.
1. Introduction
The conversion of raw neutron-scattering data into physical functions that are, by and large, independent of the instrument is a process known as data reduction. Given that neutron scattering is a mature field, one might be forgiven for thinking that the theory of data reduction is well-established and generally accepted. When joining the Laboratory for Neutron scattering in April of this year, I was therefore somewhat surprised to discover that no such consensus exists for data reduction on the indirect geometry time-of-flight (TOF) instrument, MARS, for which I was to assume responsibility. Coincident with the start of my appointment, there emerged a publication by Bruno Dorner on this very topic.1 I profess myself to entertain a profound veneration for this work and much of what follows constitutes a summary of his disquisition. I begin by showing how easy it is to follow an erroneous mathematical path that ultimately leads to a set of equations relating raw TOF data to the scattering function, that are intuitively incorrect, for they are asymmetric with respect to the transformation between direct and indirect geometry TOF. I then show how the formalism of Dorner affords a rigorous prescription for data reduction of TOF data that resolves the discrepancy, providing invaluable insight into the physical quantities that are actually being measured.
2. Determination of the Scattering Function from TOF Data
The derivation of how the scattering function may be extracted from a TOF experiment is usually presented as follows. The probability that the infinitesimal flux of neutrons is scattered into the infinitesimal solid angle Fd and in the energy window
FdE is related to the scattering function by,
2
( , )= F
F F I
kdS Q
d dE k (1)
where h and Qh are the energy and momentum transfer, and kI and kF are the incoming and outgoing wavevectors respectively. In equation (1) and in all subsequent equations, all parameters that do not contain spectral components are neglected.
1
Data Reduction on Time-of-Flight Instruments
Philip L.W. Tregenna-Piggott
Laboratory for Neutron Scattering, ETHZ and Paul-Scherrer Institute,
CH-5232 Villigen PSI, Switzerland.
1. Introduction
The conversion of raw neutron-scattering data into physical functions that are, by and large, independent of the instrument is a process known as data reduction. Given that neutron scattering is a mature field, one might be forgiven for thinking that the theory of data reduction is well-established and generally accepted. When joining the Laboratory for Neutron scattering in April of this year, I was therefore somewhat surprised to discover that no such consensus exists for data reduction on the indirect geometry time-of-flight (TOF) instrument, MARS, for which I was to assume responsibility. Coincident with the start of my appointment, there emerged a publication by Bruno Dorner on this very topic.1 I profess myself to entertain a profound veneration for this work and much of what follows constitutes a summary of his disquisition. I begin by showing how easy it is to follow an erroneous mathematical path that ultimately leads to a set of equations relating raw TOF data to the scattering function, that are intuitively incorrect, for they are asymmetric with respect to the transformation between direct and indirect geometry TOF. I then show how the formalism of Dorner affords a rigorous prescription for data reduction of TOF data that resolves the discrepancy, providing invaluable insight into the physical quantities that are actually being measured.
2. Determination of the Scattering Function from TOF Data
The derivation of how the scattering function may be extracted from a TOF experiment is usually presented as follows. The probability that the infinitesimal flux of neutrons is scattered into the infinitesimal solid angle Fd and in the energy window
FdE is related to the scattering function by,
2
( , )= F
F F I
kdS Q
d dE k (1)
where h and Qh are the energy and momentum transfer, and kI and kF are the incoming and outgoing wavevectors respectively. In equation (1) and in all subsequent equations, all parameters that do not contain spectral components are neglected.
5
Themeasuredquantityistheintensityofneutronscollectedinagiventimechannelofwidth Δτ,confinedtothesolidangle,ΔΩF,whichisrelatedtothescatteringfunc-tionS(Q,w)by:
()
,
where II (tI, ΩI)istheincidentneutronflux,andp(kF)thedetectorefficiency.
mayberegardedasaJacobianneededforthenon-lineartransformationbetween
timeandenergy.InadirectTOFexperiment,amonochromaticbeamofknownenergyisscatteredbythesample;tFisthevariablewhilsttIisconstant.Equation()thenbecomes,
(3)
.
Thatthemeasuredintensity,inagiventimechannel,mustbemultipliedbyafactoroft 4F
toobtainthescatteringfunction,isaresultthatisgenerallyacceptedfordirectTOFgeometry.Butwhatisthecorrespondingprocedureforindirect(inverse)TOFgeom-etry?ThereaderwillforgivemeforaddressingthisquestioninconjunctionwithashortadvertisementfortheMARSspectrometer,aschematicforwhichisshownbelow:
Figure 1: Schematic of theMARSInstrument.Inprac-ticethereare1TOFdiffrac-tion detectors and 10 TOFINSdetectorswithinthesec-ondaryinstrumenthousing.
6
Asthenamesuggests,theexperimentisessentiallydirect-geometryTOFinreverse.Fivechopperslocatedintheprimaryinstrumentareusedtodefineapulseofquasi-whiteneutronsincidentuponthesample.ThescatteredneutronsthatreachtheTOFdiffractiondetectorsareemployedforthecalculationoftheBraggdiffractionpattern.Thescatteredneutronsthatreachdetectorsvia.themicaanalyzerbanksareemployedforthecalculationofthescatteringfunction.Theinstrumentmaybeconfiguredsothatonlythoseneutronsarisingfromadistinctmicareflection,forexamplethe00,reachthedetectorbanks.Thescatteringanglethendefinesthefinalenergyoftheneutronsthatmayreachthedetectors,viaBragg’slaw.
TheMARSspectrometerisuniqueinofferinghigh-resolutionoverawideenergy-transferrange,andpromisestobeapowerfulinstrumentforthestudyofawiderangeofphysicalphenomena,includingtranslationalandrotationaldiffusion;tunnellingspectroscopy;and,inparticular,magneticexcitations,asthedesignofthespectrom-eterfacilitatesthemeasurementofexcitationswithlargeenergytransferwithlowmomentumtransfer.
Returningtothetopicofdiscussion,forindirectgeometryTOF,tIisnowthevariablewhereastF isaconstantEquation()thenbecomes,
()
.
WehaveobtainedtheratherawkwardresultthatfordirectTOFthescatteringfunctionandmeasuredintensityareinter-relatedbyafactoroft 4
F,whereasforindirectTOFthe
factorist 2I.Whathaveweoverlooked?Sofarwehavesaidnothingabouttheincom-
ingflux, II (tI, ΩI). NeutronfluxTOFMonitor1,depicted inFigure1, isplacedupstreamfromthesampletomeasuretheintensityoftheincomingflux.Butwhatexactlydoesthemonitormeasure?Thequestionisfarfrombeingtrivial,andakeyachievementofDorneristoclarifythismatter.Thefollowingisasummaryofhisarticlewithalittlemoreexplanationandoneortwofiguresthrowninforgoodmeas-ure.
DornerbeginsbywritingtheinfinitesimalintensitydI(counts/sec)collectedinagivendetectoras:
(5) ,
wheredj(kI)istheinfinitesimalfluxofneutronsincidentuponthesampleinphasespace,
(6) .
Thefirsttermontheright-handsideofequation(6)isproportionaltothevelocityoftheneutron,andthesecondtermmaybeunderstoodasthedensityoftheneutronsinaninfinitesimalregionofreciprocalspace.p(kI)isdefinedbytheauthorasthespec-trumofthesource.Ittakesaccountofthevariationinwavelengthofthedensityoftheneutronsincidentuponthesample.SubstitutingEquations(1)and(6)intoequa-tion(5),weobtain,
()
Equation()maybesimplifiedbywriting,
(8) ,
and
(9) , wherethez-directioncoincideswiththedirectionofkF.
Equation(8)followsfromE = P 2 / 2m.Equation(9)maybereadilyunderstoodbyconsideringthefollowingschematic:
(10)
8
Insertingequations(8)and(9)intoequation()weobtainDorner’smasterformula:
(11) .
Equation(11)isbeautifulasitshowsthatwhenrelatingthemeasuredintensitytothescatteringfunction, theincomingbeamissymmetricwithrespect tothescatteredbeam.Sincek ~ 1/t,equation(11)maybereadilyconvertedfromphase-totime-space,
(1) ,
wherewehaveusedequation(10)and,
(13) .
Notethatthedensityofneutronsasdefinedby p(kI) dkI,x dkI,y dkI,zisequalto
.
Themeasuredintensityisobtainedbyintegratingequation(1).FollowingDornerwewrite:
(1) ,
whereS*(Q,w)isthescatteringfunctionconvolutedwiththenormalisedresolutionfunction.
Thevolumeelementsaregivenby,
(15)
9
FordirectTOFgeometry,VIisconstant,whilstVFisavariable.TheconverseholdsforindirectTOFgeometry.
Atthisjuncturewearenowinapositiontoresolvetheapparentdiscrepancybetweenequations(3)and().Inderivingequation(3),themeasuredintensityofneutronsscatteredfromthesampleisdefinedintermsofthefluxofneutronsscatteredinagiventimechannel,confinedtothesolidangleΔΩF.Inorderfortheincomingfluxofneu-tronstobedefinedidentically,thecomponentsofthemomentaoftheincomingbeamperpendiculartokI,mustbewrittenintermsofthesolidanglevia.equation(10).Bymakingthefollowingsubstitution,
(16) ,
equations(3)and()arethen:
(1) ,
(18) .
fordirectandindirectTOFgeometryrespectively,inaccordancewithequations(1)and(15).
ThecorrectionforVImaybeswallowedupinthecountsmeasuredbyamonitorposi-tionedbeforethesample.Theintensitymeasuredbythemonitormaybewritteninthegeneralform:
(19) ,
wherej(kI)istheincomingneutronflux,
(0)
andE(kI) isthemonitorefficiency.
j(kI) isobtainedbydividingthemeasuredmonitorcountsbyE(kI):
(1) .
10
I black det.isequivalenttomeasuringtheincomingfluxwiththehelpofablackdetec-toratthesampleposition.Inpracticethismaybeachievedbymeasuringthevana-diumspectrumwithnoanalyserbanks,i.e.usingthediffractiondetectorsdepictedinFigure1.
DividingthemeasuredintensitybyI black det.yields:
()
Inshort:
(3)
Equation(3)statesthatifthemeasuredintensityisnormalisedtotheincidentneutronflux, thenthescatteringfunctionisobtainedbymakingthefurthercorrectionofdivid-ingImeas,corbytI.Themonitorefficiency,E(kI),maybewritteninthegeneralform,
() ,
wherebisconstant,characteristicofthemonitor.
Intheinstancewhenbλ<<1,equation()simplifiesto,
(5) .
Thus,whenthemonitorisaweakabsorber,weobtain:
(6)
HenceVIisobtaineddirectly,
() .
Equation()thensimplifiesto:
(8) .
11
Themica00reflectioncorresondstoλF≈0Åinbackscatteringgeometry.Inprin-cipleitshouldbepossibletocomparetherelativeintensitiesofexcitationswithλ Iintherangeof1to0Å,althoughitisnotpossibletocoversuchalargeenergywindowinoneexperiment.Fortheneutronfluxmonitor1,ontheMARSspectrometer,theconstantbhasthevalue0.015,andhenceequation(5)isbutafairapproximationtothedetectorefficiencyinthe1to0Åwavelengthrange.Thus,thedatareductionwillbeperformeddirectlyfromequations(1),(3)and().
TheIRISinstrument,locatedatISIS,isanindirectgeometryTOFspectrometer,sim-ilarindesignandconcepttoMARS,thoughlessversatile.Measurementsfromthisinstrument,whichhasbeeninoperationanumberofyears,shouldassistintheexper-imentalverificationofthecorrectdatareductionprocedure.Frominformationreceivedfromtheinstrumentresponsible,theconversionofthecountscollectedwithin a given time channeltothescatteringfunctionproceedsinaccordancewithequation(3).However,itnotcleareithertomeortoDornerwhethertheintensityisfurthermulti-pliedbythefactor,
(9) ,
where ΔtandΔw arethewidthsofthetimechannelsandthecorrespondingenergychannelsrespectively. ThereasoningforincludingthisJacobianisthenon-linearconversionbetweentimeandenergy.However,asthisfactorhasalreadybeenincor-poratedintotheoperationofdividingthemeasuredintensitybythemonitorcounts,thefurtheroperationofmultiplyingtheintensitybythefactorinequation(9)wouldnotbevalid.IfthedatareductiononIRISdoesindeedincorporatethisfactor,thenIbelievethedatareductionofIRISdata,aspresentlyundertaken,tobeincorrect.Com-paredtoamodelcalculation,experimentaldatapointsontheneutron-energy-gainsideofthespectrumwouldbetoohighinintensity,anddataontheneutronenergy-losssidetoolowinintensity.
2. Data Reduction and Analysis Software
Recently,aconcertedefforthasbeeninstigatedbetweenneutron-scatteringinstitutionstocollaborateonasoftwarepackagefortheinterpretationofneutron-scatteringdata,andIamproudthatthePSIisapartofthiscollaboration.DAVEstandsforDataAnalysisandVisualisationEnvironment,andisaseriesofprogramswrittenbyRobDimeo andhis colleagues at theNational Institute ofStandards andTechnology(NIST),WashingtonD.C.,forthereductionandanalysisofneutronscatteringdata.NotonlydotheNISTteamdistributetheirsoftwarefreely,theyprovideintroductorycoursesinInteractiveDataLanguage(IDL)andaremorethanwillingtoofferadviceandencouragementtoscientistsfromotherinstitutions,wishingtowritedatareduc-
1
tionprogramswithintheDAVEenvironment.FOCUSDataReduction(FDR)issuchaprogram,andwaswrittenbytheauthorofthisarticle,inconstantconsultationwithFanniJuranyi,presentlythepersonresponsibleforFOCUS,thedirectgeometryTOFinstrument,hereatthePSI.Wewantedtoconceiveaprogramsuitableforthenoviceaswellastheseasoneduser,andIbelieveweachievedthisgoal.Themaininterfaceisshownbelow.
Figure 2:MainInterfaceoftheFocusReductionProgram
Aminimalamountofinputisrequiredtoreducearawdataset;theprogramchoosessensibledefaultsforyou.Ontheotherhandasophisticated,user-specificworkupofthedatamaybeaccomplishedusingtheAdvancedOptions.Perhapsthemostattrac-tiveaspectoftheprogramisthatsubsequenttoreduction,thedatamaybeanalysedwithanyoneoftheexcellentprogramsintheDAVEprogramsuite.Weshallnowproceed towrite thedata reductionprogramforMARS,alongwithaprogramtochangethevariablesoftheinstrument(chopperphases,analyserbankpositionsetc.)accordingtoscientificspecifications,assetoutbytheuser.Themotivationforwritinggoodsoftwareisclear:thebetterthesoftware,thelessworkforthelocalcontact.
References
[1] B.Dorner,Journal of Neutron Research,vol13/2005.[] FelixFernandez-Alonso,INS_Reduction,privatecommunication.
13
Dynamic Rotational Anion Disorder in Tetrahydroxoborate Sodalite Investigated by
Quasielastic Neutron Scattering
D. Wilmer, F. Juranyi*, M. Kalwei, H. Koller
University of Münster, Institute of Physical Chemistry and Sonderforschungsbereich 458 Corrensstr. 30/36, 48149 Münster, Germany
*Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
Abstract
Thedynamicrotationaldisorderoftetrahydroxoborateanions,B(OH)–,intetrahydrox-
oboratesodalite,Na8[AlSiO]6[B(OH)],hasbeeninvestigatedinseveralquasielasticneutronscatteringexperimentsusingthetime-of-flightspectrometerFOCUS.Aboveaphasetransitionatabout303K,thecompleteanionunitreorients,probablybyjumpdiffusion,withresidencetimesbetween100ps(310K)and3ps(0K),thereorienta-tionratesbeingactivatedwith0.1eV.ThereisevidenceforanadditionalfasterprotonmotionrestrictedtoacirclearoundaB-Obond.Accompanyingmeasurementsoftheionicconductivityshowthatthesodiumions,althoughidentifiedaslocallymobileinanearlierNMRinvestigation,exhibitmoderatelong-rangetransportpropertiesonly.Possibledynamiccorrelationsbetweenthelocalizedmotionsofhydroxoborateanionsandsodiumcationsobviouslydonotleadtoanenhancedsodiumionconductivity.
Introduction
Zeolitesarecrystallineporousaluminosilicateswhichcontainchargebalancingcati-onsintheirextra-frameworkvoids.Thecationconcentrationdependsonthechargedensityofthealuminosilicateframework,i.e.,thenumberofAlatomsintetrahedralpositionperunitcell.
Inspiteofthehighconcentrationofextra-frameworkcations,theionicconductivitiesofzeolitesystemsreportedsofararerelativelypoor,evidentlyduetothelowcationmobility.Inthispaper,wereportonourinvestigationsoftetrahydroxoboratesodalite,amaterialwhichwasregardedasapotentialsodiumconductor.
Thesodaliteframeworkconsistsofspace-filling668(sodalite)cageswithalternatingAlO/
–andSiO/tetrahedra.Figure1showsawiremodelofthesodalitecagewherethecornersrepresentSiandAlcentresandtheframeworkoxygenatomsareomitted.
1
In tetrahydroxoboratesodalite,eachcagecontainsfoursodiumatomsatpositionsclosetothesodalitecagesix-ringsinatetrahedralarrangementandanorientationallydisorderedB(OH)
–anion [1]. Inastaticpicture,sodiumatomsinneighboringsodalitecagesarelocatedattheoppositesideofthosesix-rings which are not “blocked” by sodium atomsinsidethecage. At303K,thematerialexhibitsaphasetransitioninducedbytheonsetofdynamicalprocesses[].Thehigh-temperaturephaseiscubicwitha= 9.015Å,thespacegroupisP3n.Abovethephasetransitiontemperature,3Na-NMR-MASspec-trashowconsiderable linenarrowingandasinglesodiumposition,indicatinganenhancedsodiumionmobility[3].Thedetailedanalysisof11B1Hand11B3NaNMR-REDORmeasurementsperformedat30KsuggeststhatontheNMRtimescale,theB(OH)
– anions undergo isotropic reorientationswhilethesodiumionsexhibitarestricted,non-iso-
tropicdynamics[3].Akeyquestionhereiswhetherandtowhatextentthereorienta-tionofthehydroxoborateanionsenhancesthecationmobilityinthesenseofwhathasbecomefamousunderthetermpaddle-wheel mechanism[].
At60K,i.e.,belowthephasetransitiontemperature,theNMRresultsagreedwellwiththepredictionsofamodelwhichconsidersarotationofprotonsaroundallB-ObondsaswellasarotationofthewholeB(OH)unitaroundoneB-Obond,cf.Fig..
TheNMRresultscouldneithergivetheanionreorientationratesnorcouldtheychar-acterisethelongrangecationtransport.We,therefore,decidedtoperformaquasie-lasticneutron scattering study to reveal furtherdetails of the anion reorientationmotion,accompaniedbyconductivitymeasurementstoinvestigatethecationconduc-
Figure 1:Sodalitecagewithfourtetrahedrally arranged sodium ionsinsideandoutsidethecageoftetrahydroxoborate sodalite. TheB(OH)
– anion resides close to the center of the cage; the representationinthefigureempha-sisesitsorientationaldisorder.
Figure 2:Sketchofthehydroxoborateanion,B(OH)–.
TheBOunit formsa regular tetrahedronwithaB-Obondlengthof1.Å.TheO-Hbondlengthisassumedtobe0.91Å, theB-O-Hbondangleclose to161°, inanalogytoboratehydrates[5].Thesketchshowsacon-ceivabletypeofanionreorientation,i.e.,acombinationofprotonrotationonacirclearoundafixedB-Oaxisandrotation of the whole unit, here shown to take placearoundoneofthetetrahedralC3axis.ThepredictionsofthisdynamicmodelprovedtobeingoodagreementwiththeNMR-REDORdatameasuredat60K,i.e.,inthelow-temperaturephase.
15
tivity.SinceprotonsaremovingduringreorientationoftheB(OH)–unitsandthe
dynamicneutronscatteringbehaviourisdominatedbytheprotons’largeincoherentscatteringcrosssection,quasielasticneutronspectroscopyisideallysuitedtoinvesti-gatehydroxoboratereorientationinoursystem.
Experimental
Samplesof11B-enrichedtetrahydroxoboratesodalitewerepreparedbyhydrothermalsynthesis.Detailsonthesynthesismaybefoundelsewhere[3].Theuseof11B-enrichedsamplesreducesneutronlossduetothehighneutronabsorptioncrosssectionof10B.Thepowdersamplesareneitherhygroscopicnorotherwisesensitiveandthuseasytohandle.Fortheneutronscatteringexperiments,sampleswerefilledintoindium-sealed,cylindricalthin-walled(0.5mm)aluminiumcans(10mmdiameter,50mmlength)availableatthespectrometer.Samplemassesforthetwosetsofneutronscatteringexperimentswere.gand3.3g.
Quasi-elasticneutronscatteringspectrawerecollectedonthetime-of-flightspectrom-eterFOCUS,locatedatthePaul-Scherrer-Institute,Villigen,Switzerland.Datawerecollectedatfourtemperaturesabovethe303Kphasetransitionbutwellbelowdecom-positionwhichcommencesabove50Kwithalossofwaterandendsinacollapsinglatticeatevenhighertemperatures.
Inafirstsetofexperiments,FOCUSwasoperatedinthetime-focussingmodeusingthePG00monochromator.Usingtwodifferenttake-offanglesofferedtheopportu-nitytoselecttwoincidentneutronwavelengthsandelasticenergyresolutions.Inasecondsetofexperiments,weused therelativelynewmicamonochromator(00reflexion)toobtainevenbetterresolution(µeVFWHM)attheexpenseofneutronfluxandscatteringvectorrange.Table1summarisestheparametersoftheneutronscatteringexperimentsonFOCUS.
Wavelength/Å .3 5. 11.8
Qmax/Å-1 . .0 0.99
Resolution/µeVFWHM 10 5
Thetime-of-flightdatawerenormalizedandcorrectedfordetectorsensitivityusingscatteringdataofavanadiumsample,regroupedandconvertedtotheenergytransferscaleusingtheFOCUSstandardpackageforrawdatatreatment,NATHAN.
Additionalconductivitymeasurementstoinvestigatesodiumiontransportpropertiesin our sodalite system used uniaxially pressed (10 kbar) cylindrical samples of
Table 1:FOCUSinstrumentparametersforthemeasurementsontetrahydroxoboratesodalite.Theexperimentsat.3Åand5.ÅusedthePG00monochromator;MICA00offeredthehighestresolutionsetup.
16
Na8[AlSiO]6[B(OH)]whosecircularfacesweresputter-coatedbythingoldlayerswhichservedaselectrodes.MeasurementsusedaNovocontrolAlphahighresolutiondielectricanalyserinafrequencyrangefrom0.1Hzto3MHz.
Results and Discussion
Thefirstmeasurements(PG00monochromator)withelasticenergyresolutionsof5µeVand10µeVFWHMrevealedquasielasticbroadeningatalltemperatures(310Kto0K)abovethephase transition.Inafirstphenomenologicaldataanalysis,asimplemodelfeaturingasingleLorentzianplusanelasticcontribution,bothconvo-lutedwiththeinstrumentresolutionfunction,wasfittedtoallspectra.Theresultingelastic-incoherentstructurefactor(EISF)stronglydependedontemperatureandreso-lution.Atconstanttemperature,thelinewidthstonotdependmuchonthescatteringvectormodulusQ,indicatingthat,inaccordancewithourexpectations,wearemoni-toringaratherlocalizedtypeofmotion.ThedetectedEISFtendencytodecreasewithincreasingresolutionandincreasingtemperatureindicatedthatthereorientationoftheanionswastooslowtobefullyresolvedatthegiveninstrumentalsetups.Asimplesolutiontothisproblem,i.e.,anincreaseintemperaturetoacceleratethereorientation,wouldfailduetothedecompositionofthesample.We,therefore,decidedtousetherelativelynewMICAmonochromatoroption[6]onFOCUStoobtainhigherresolvedquasielasticspectra.AnexamplespectrumwitharesolutionofµeVFWHMisgiveninFigure3.
ThespectraobtainedfromtheMICAsetupcouldeasilybefittedusingasingleLorentz-ianplusandelasticcontribution,bothbroadenedwiththeelasticenergyresolutionfunction,cf.Figure3.Simultaneousfittingofallspectra(fivedifferentQvalues)measuredatthesametemperatureyielded,forthefirsttime,characteristicresidence
Figure 3:Examplespectrumoftetrahydroxoborate sodalite,Na8[AlSiO]6[B(OH)], meas-uredonFOCUSusingtheMICAmonochromator [6]. Error barssymbolise measured data. Thinsolid line: fit using an elasticcomponent(thicksolidline)anda quasielastically broadenedLorentzian (dashed line), bothbroadenedbytheelasticresolu-tionfunction.
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timesfortheanionreorientationwhichrangefrom3ps(0K)toabout100ps(310K)andexhibitanArrhenius-typetemperaturedependence,cf.Figure.Theactivationenergyis0.1eV.Moreover,wenowobtainanEISFwhichnolongerdependsontemperature,i.e.,wenowseemtofullyresolvethequasielasticbroadeningduetothehydroxoboratereorientation.
Unfortunately,thehigh-resolutionMICAsetupcausedanincidentneutronwavelengthof11.8Å,resultinginaratherlimitedQrangewithamaximumofabout1Å-1.AnanalysisofthespatialdetailsoftheanionreorientationbasedontheEISFisthusnotfeasible,i.e.,itishardlypossibletodecidewhetherweobserveisotropicrotationaldiffusionorwhethertheprotonsperformamorerestrictedtypeofmotion,e.g.,jumpdiffusionaroundoneofthetetrahedralsymmetryaxes.
TheobservedEISFindicates,however,areorientationofthewholeB(OH)-unit–
rotationoftheprotonaroundasingleB-OaxiswouldonlyleadtoaslightdecreaseoftheEISFinthegivenQrange.
Furtherspatialdetailswillbeobtainedfromarecentlyperformedquasielasticexperi-menton thebackscatteringspectrometer IRIS (ISIS,Didcot,UK)whichoffersauniquecombinationofhighresolutionandlargeQrange.Detailswillbereportedelsewhere,assoonasthedataarefullyanalyzed.
OnthebasisofthespectraobtainedusingtheMICAsetup,itispossibletoimprovethedataanalysisofourinitialPG00measurements:wenowperformasimultaneousfittoallspectraobtainedatagiventemperaturewithamodelwhichusestwoquasie-lasticcomponentsplusanelasticpart.Inthesefits,weconstraintheLorentzianlinewidthsforallQvaluestoasinglevaluebutlettheirweightsvary.Inaddition,wefixthelinewidthofthesmallercomponenttothevalueobtainedfromtheanalysisoftheMICAmeasurements.Undertheseconditions,weobtainthequasielasticintensities(at0K)showninFigure5.Forcomparisonwepresenttheresultsofacalculation
Figure 4: Characteristic residencetimesandelastic-incoherentstructurefactorof tetrahydroxoboratesodalite,Na8[AlSiO]6[B(OH)], measured atµeVresolution(MICAsetup).
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basedonamodelwhichconsidersbothjumpdiffusionofthewholeanionunitaroundthespatiallyfixedC2andC3axisandjumpdiffusionoftheprotonsaroundthe(mobile)B-Oaxes[].
Itisobviousthatthegeneralcharacteristicsofthemeasuredquasielasticintensitiesarereasonablywellrepresentedbythemodelcurves.Thenarrowerquasielasticcom-ponentwhichessentiallyreflectsthe(slower)reorientationofthewholeB(OH)
-unitexhibitsitsintensitymaximumatQ≈1.Å-1;duetoitsreducedradius,thefasterpro-tonrotationaroundtheB-OaxescausesaquasielasticintensitywithsmallerslopewhenplottedagainstthescatteringvectorQ.Itisinterestingtonotethatthescenariofoundherebyquasielasticneutronscatteringfor the high-temperature phaseagreeswellwiththeresultoftheNMRmeasurementsfor the low-temperature phase.Noreasonablefitstothequasielastichigh-temperaturephasespectracouldbeobtainedusingtheisotropicdiffusionmodel[8]althoughtheNMRinvestigationsgaveaclear
Figure 5:Quasielasticintensities(filledsymbols)ofNa8[AlSiO]6[B(OH)],ex-tractedfromthe5.Ådata(PG00setup,5 µeV FWHM elastic energy resolu-tion).Solidanddashedlinesareresultsofourmodelcalculation.
Figure 6:TotalelectricalconductivityofNa8[AlSiO]6[B(OH)]asafunctionof temperature (Arrhenius representa-tion).
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indicationfortheisotropicreorientationofthehydroxoborateanion[3].Thisisprob-ablyduetothefactthatneutrontime-of-flightspectroscopyissensitivetoamuchshortertimescalethanNMRmeasurements.
OurconductivitymeasurementsontetrahydroxoboratesodaliteshowthatthehighsodiumionmobilitydetectedintheNMRmeasurements[3]isindeedoflocalizednature.TheArrheniusrepresentationofourdcconductivitydata(cf.Figure6)showsthattetrahydroxoboratesodalite,inspiteofitslocalcationmobility,isonlyamoder-atesodiumionconductor,i.e.,itslocalmobilitydoesnottransformintoaconsiderablelong-rangeiontransport.Activationenergiesfoundherearesignificantlyhigher(0.3eVand0.eVaboveandbelowthephasetransitiontemperature,respectively)thanfortheanionreorientation,andthereishardlyanychangeofslopeatthephasetransi-tiontemperature.
We,therefore,havetoconcludethatintetrahydroxoboratesodalite,wecannotdetectadynamiccorrelationbetweenthedynamicrotationaldisorderoftheanionsandthelongrangetransportofthecations.Nevertheless,theremightwellbeaclosecorrela-tionbetweentheB(OH)
-reorientationandthelocalsodiummotioninsidethesodal-itecage.
Acknowledgement
ExperimentsreportedinthisworkwerepartiallyperformedatthespallationneutronsourceSINQ,Paul-Scherrer-Institut,Villigen,Switzerland.FinancialsupportbytheGermanFederalMinistryofEducationandResearchandby theGermanScienceFoundation(DFG,SFB58)isgratefullyacknowledged.
References
[1] J.C.Buhl,C.Mundus,J.Löns,W.Hoffmann,Z.Naturforsch.9a(199)111.[] G.Engelhardt,P.Sieger,J.Felsche,AnalyticaChimicaActa83(1993)96.[3] H.Koller,M.Kalwei,J.Phys.Chem.B.108(00)58.[] A.Lundén,SolidStateIonics8-30(1988)163;SolidStateComm.65
(1988)13.[5] C.C.Freyhardt,in„BildungundCharakterisierungkristallinerPhasenin
Systemen(NR)O-BO3-HO“,Hartung-Gorre-Verlag,Konstanz1996.[6] F.Juranyi,S.Janssen,J.Mesot,L.Holitzner,C.Kägi,R.Tuth,R.Bürge,
M.Christensen,D.Wilmer,R.Hempelmann,Chem. Phys.9(003)95.[] M.Bée,QuasielasticNeutronScattering,AdamHilger,Bristol1988.[8] V.F.Sears,Can.J.Phys.5(196)3.
0
ICON – The New Facility for Cold Neutron Imaging at the Swiss Spallation Neutron Source SINQ
G. Kühne 1, G. Frei 1, E. Lehmann 1, P.Vontobel 1, A. Bollhalder 2, U. Filges 2, M. Schild 2
1 Neutron Imaging and Activation Group (NIAG), ASQ Division 2 Laboratory for Developments and Methods (LDM) Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
Abstract
Basedontheverygoodexperienceandknowledgegainedwiththermalneutronradi-ographyatNEUTRA,novelcapabilitiescanbepredictedforthenewbeam-linewithcoldneutrons:Microtomography,neutronphasecontrastimaging,contrastenhancedradiography,improvedquantificationoftracerelementsandenergyselectiveneutronimaging.
Thetwomainconditionsforhighqualityneutronimaging–radiography,tomographyandespeciallyforneutronphasecontrastimaging–areahighbeamcollimationandasufficientlyhighneutronflux.Itwasexaminedwhetherneutronguidesintheacces-siblepartsofthebeamchannelforICONcouldenhancetheperformanceoftheinstru-ment.Thefollowingfindingsresulted:1)theenhanceddivergenceprovidedbytheguideisnotmatchedtothecollimation(L/Dratio)plannedfortheinstrumentand)theextendedimagesizeprovidedbytheguideisnothomogeneouslyilluminated.Ithasthereforebeendecidednottouseguidesinsidethetargetblock.
ThenewradiographybeamlineICONforimagingwithcoldneutronsisinstalledatchannel5ofthespallationneutronsourceSINQ.Ithasadirectviewontotheliquiddeuteriumcoldsource.Therearetwostandardexperimentpositionsatdifferentdis-tancesLfromthebeamportexitandfivedifferentaperturesizesDinthediaphragmsystemcanbechosen.
Differentbeamcharacterisationmeasurementshavebeendone.TheneutronspectrumwasacquiredwiththeTOF-technique.Theaccordancewiththecalculationwasquitegoodforwavelengthsgreaterthan1Ångstrom.Themaximumfluxdensityatthebeamportexitwithanaperturesizeof8cmwasdeterminedwithGoldfoilactivation.Beamsizesandprofilesat thetwomainexperimentpositionshavebeenanalyzedusingimagingplates.Theneutronandgammadosemeasurementshavebeenperformedincollaborationwiththeradiationprotectiongroup.
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TheinaugurationofICONwascelebratedduringtheInternationalWorkshopon“Neu-tronImagingusingColdNeutrons”heldonOctober13thand1th005atPSI.
Thefirstfourlong-termexperiments(durationmorethanoneweek)willbefinisheduntilendofthisyear.
1. Introduction
ThefirststepsinneutronradiographyatthePaulScherrerInstitute(PSI)weremadeinthelate80’softhelastcenturyattheswimmingpoolresearchreactorSAPHIR.Thefinalshutdownofthereactorattheendof1993imposedatemporarystoptoneutronradiographyatPSI.Anewneutronradiographyfacility(NEUTRA)[1]wasdesignedforthespallationsourceSINQ.TogetherwiththeoperationalstartofSINQattheendof1996,thefirsttestsconcerningbeampropertiesandnewdetectorsystemscouldbeperformed.ThelastsevenyearsofNEUTRAshowasuccessfulstoryofdevelopment.Theprogressistwo-fold:Oneinimagingtechniques,detectorandcamerasystemsandtheotherinanincreasingnumberofinternalandexternalusersfromuniversitiesandindustries[,3,].
ICON–thenewneutronimagingfacilitywithcoldneutronsisnowanidealextensiontoNEUTRA.
2. Background
Theadvantageofcoldneutronsforimagingpurposesistheirhighercontrastsformostofthesamplematerialsandthehigherdetectionprobability.Therefore,thinnerdetec-torscanbeutilizedandhigherspatialresolutionachievedasaconsequence.Tomog-raphy investigations (so called micro-tomography) are planned with the goal toapproachthe30µmresolutionrangeneverreachedbeforefordigitalneutrontomog-raphy.
Equippedwithanenergy-selectingdevice,narrowenergybandscanbecutoutfromthecoldspectruminthoseregionswheretheBraggedgesarelocated.Thiswillenabletheenhancementofcontrastsforspecificmaterials.
Twoapproachesinphasecontrastimagingareunderconsideration:phasecontrastimagingwiththepinholegeometryforedgeenhancementiswellsuitedforcoldneu-trons,sincethephaseshiftisproportionaltotheneutronwavelength.Andsecondly:Firstexperimentsondifferentialphasecontrastimagingusingagratinginterferometergavealreadysomepromisingresults.
Themainprerequisitesforhighqualityneutronimaginginradiography,tomographyandespeciallyinneutronphasecontrastimagingarehighbeamcollimation,highflux,
andlowbackground.Thecomplianceoftheseconditionsrequiresacompromisetobemadebetweenresolutionandintensity.Inordertoextractasmanyneutronsaspos-siblefromthegivencoldsource,theuseofaneutronguideisoftenessential.Theneutronguidetransportsneutronsoflongwavelengths(sloworcoldneutrons)bytotalreflectionuptoanangleof0.1°perÅngstromofneutronwavelength.Forradiography,thisinherentdivergenceoftheneutronbeammakesitdifficulttoobtainsharpimages,forwhichaparallelbeamisneeded.ThesharpnessofanimageisdirectlydependentontheL/Dratio.DisthediaphragmdiameterandListheflightpathlength,i.e.,thedistancefromthediaphragmtothedetector.AnincreaseoftheL/Dratio,inordertoobtainasharperimagebyclosingthediaphragm(decreasingD)orbyincreasingthedistancetothedetectorL,hastheconsequenceofadecreaseinneutronfluxandthere-forealongerexposuretime.TheeffectofaneutronguideintheinnerpartofthebeamplughasbeeninvestigatedbyMonteCarlosimulation.Forthesimulationoftherel-evantneutrondata(wavelengthdistribution,neutronflux,twodimensionalspatialdistributionoftheneutronsatdifferentpositionsofthebeampath),thesoftwarepack-ageMcStasversion1.[5]wasused.Themuchbetterhomogeneityofthetwo-dimen-sional neutron distribution for the layout without neutron guide was – despite adecreaseofneutronfluxbyafactorthree–thereasontokeepawayfromneutronguidesinthedesign.
ThecomfortablespaceandinfrastructurewillenablecomplementaryexperimentalconditionstothealreadyexistingthermalneutronradiographystationNEUTRA.
3. Experimental setup
3.1 Experimental area
Theexperimentalarea(fig.1)isaconcreteconstruction(bunker),whichcontainsthewholeexperimentsetup.Itiscontrolledbyanadmissionsafetysystem,theLocalAccessControl(LAC)system.
Thefirsttwometersup-beaminthebunker(Nr.1infig.1)areseparatedfromtherestbyconcreteshieldingblocksandacloseddoor,alsocontrolledbythesafetyinterlocksystemLAC.Inthisinnerbunker,activatedcomponentslikethefail-safeshutter,theexperimentshutter,thevelocityselector,thetime-of-flightchopperandtheBerylliumfilterandotherequipmentcanbeplaced.Inexperimentswherenoadditionalcompo-nentsarenecessary,anevacuatedflighttubeismounted.
Ahorizontallymovablefail-safe shutter isplaceddirectlyatthebeamportexit.Itisasandwichconstructionconsistingof10cmthickborated(5%)Polyethylene,0.5mmGadoliniumand1cmLead.Theclosingtimeislessthantwoseconds.Apressurestoragetank,whosenominalvalueiscontrolled,guaranteesthefail-safecondition.
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Behindthefail-safeshutter,afastexperiment shutter(closingtime:100ms;composi-tion:mm6LiFand5.5mmBC)ispositioned.
ThedesignoftheICONfacilityisversatile:Twomeasuringpositionsforexperimentsandenoughspaceforadditionaluserequipmentsareavailable.Thepositionissuitedforsmallerobjectsandcanbeequippedwiththemicro-tomographyandscanningtable,whereasattheposition3largeandheavy(upto500kg)objectswithhighcol-limationcanbeimaged.
Twobeam limiters (motorizeddiaphragms)areavailable:oneinafixedpositioninsidetheinnerbunkerandtheotherinfrontoftherespectivelyprobepositionor3.
Behindposition3,aneutronandgammaabsorbingbeam dumpisplaced.Theγ-andn-dosemeasurementshaveshown,thattheshieldingisn’tsufficientforthetwolargeapertureopenings.Duringthenextshut-downperiodtheshieldingbackplanehastobeimproved.
Figure 1:InsidetheICONbunker:Nr.1showstheinnerbunker,whereavelocityselector,filtersandotherequipmentscanbeinsertedintotheflightpathofneutrons.Nr.and3arethestandardexperimentalposi-tions.AtthepositionNr.smallandlightprobescanbeexamined(e.g.micro-tomography),whereatpositionNr.3biggerandheavierprobescanbescannedthroughtheneutronbeam.
3.2 The inner collimator
Thetargetblockinsertsplacedinthebeamchannelcontaintheinnercollimator(fig.).Intheheliumgasfilledinsertthecoldneutronsareextractedfromthecoldsourcetothefrontendofthecollimatorwhichhasasquareopeningof8cmx8cm.Thiscollimatoropeningissurroundedbyironshieldingthroughoutthewholelengthoftheinnercollimator(totallength.m).
Thecentralpartofthecollimatorisequippedwithsixrevolvingdrums,whichareusedasashuttertoswitchoffthebeam.Thefirstandthelasthalfdrumarefilledwithboroncarbidetoincreasetheshieldingperformanceoftheshutteragainstlowenergyneu-trons(thermalandcoldneutrons).Theotherfourdrumsaremadeofsteelinordertoshieldhigh-energyneutronsandgammarays.
Inthelastpartoftheinnercollimator(justaftertherevolvingdrums),aturnabledia-phragmsystem(Fig.3)issituated.Thediaphragmsystemismadeofsteelandhasalengthof30cm.Theneutronentrancesideiscoveredwith1mmthickGadoliniumplatesinwhichtheapertureshavebeenmachined.Thesixapertures(D=8cm,cm,cm,1cm,0.1cmand0.05cm)canbechosendependingontherequiredL/Dratio(rangeseetablesand3)orforphasecontrastimaging.
Allfreespacearoundthecomponentsinsidethetargetisfilledwithaheliumatmos-pheretoavoidtheactivationofair.Attheexitofthetargetblock,thereisahelium-tightAluminiumwindow,whichcanbepenetratedeasilybythecollimatedneutronbeam.
Main shuttersystem
Diaphragmsystem
Fail-safe and experimentshutter
Spallationtarget
Cold source
Moderatortank
Figure 2:SimplifiedcrosssectionofSINQwiththespallationtarget,thecoldsourceandtheinnercol-limatorcontainingthemainshuttersystemandthediaphragmsystem.
Figure 3: Turnablediaphragmsystemwithsixdif-ferentapertures(8cm,cm,cm,1cm,0.1cmand0.05cm)seenfromtheneutronentranceside.Thelengthofthediaphragmsystemis30cm.
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4. Beam Characterisation – Results
4.1 Beam sizes
Themeasuredvaluesofthehomogenousflatregion(plateausize)inthebeamprofilesinhorizontalandverticaldirectionforallaperturesaregiveninthefollowingtablesforthetwoexperimentpositions[6].
ThecalculatedL/D–expressionindicatesthecollimationofthebeam,whichisameas-urefortheneutronimagequality(e.g.sharpness).ThesharpnessoftheimageincreaseswiththeL/Dvalue,whiletheneutronflux(numberofneutronswhicharrivetheprobeandthedetector)decreases.Thereforeacompromisebetweenimagequalityandmeas-uringtime(andpossibleprobeactivation)hastobefoundforeachexperiment.
Aneutronimageoftheopenbeamatpositionwithanapertureofcmisshowninfigureandthecorrespondingprofilesinfigure5.
Table 1:Beamsizesatposition Table 2:Beamsizesatposition3
4 6 8 10 12 14 16 18 200
100
200
horizontal profile [cm]
gray
leve
ls
4 8 12 16 20 240
100
200
vertical profile [cm]
gray
leve
ls
4 6 8 10 12 14 16 18 200
100
200
horizontal profile [cm]
gray
leve
ls
4 8 12 16 20 240
100
200
vertical profile [cm]
gray
leve
ls
Figure 4: Open beam image atpositionandaperturesizecm.
Figure 5:Horizontal(left)andvertical(right)profileoftheimageinfigure.
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4.2 Neutron spectrum and flux
TheneutronspectrumwasmeasuredusingtheTime-Of-FlighttechniquewithaBC-steelchopper(Jülich-Chopper).Thecomparisonwiththecalculatedspectrum(seefig.6)showsadiscrepancyforwavelengthsshorterthanabout1Å.ThecoldneutronsourceusedintheMcStassimulationisathreetemperatureMaxwelldistribution,whichisacorrectassumptionforbeamlineswithneutronguideswhichcutofftheshorterwavelengthsof thenon-moderatedhigh-energyspallationneutrons.In theICONbeamline this isnot thecase; theshort-wavelengthneutronsappear in thebeam.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160
1.105
2.105
3.105
lambda [Å]
BG
cor
r
ICON spectrum: 13. Juli 2005 / Guido Kühne, Gabriel Frei
BG corr: measured and background corrected [counts per mAh]
Intensity_norm: calculated and normalized to the measured maximum
Figure 6:Compari-sonofthemeasured(blacksquares)andthecalculated(line)wave-length spec-trum.
Figure 7: Energyspectrum and thecross sections ofGoldandCadmium.
Theneutronfluxwasdeterminedbythegoldfoilactivationtechnique.DifferentGoldfoilswithandwithoutaCadmiumshieldinghavebeenactivatedatthebeamportexitwithanaperturesizeof8cm.FortheevaluationtheTOFmeasurements,cross-sec-tionsofAuandCd(seefig.)havebeenusedfortheenergyweighingofthecrosssections[6].Thecorrespondingresultsaresummarizedintable3.
4.3 Neutron dosimetry and shielding
Theneutrondosemeasurements[]behindthebackplaneresultedinatohighvalueforthetwolargeaperturesizes(8cmandcm).Thereforetheseopeningscannotbeuseduntiltheshieldingofthebackplaneisoptimized.ThecorrespondingMonte-Carlocalculationsareontheway.Thefirstresultshavebeenvalidatedwithrepeatedneutrondosemeasurements.Thereasonfortheinsufficientshieldingeffectivenessoftheexistingbackplanewasanunderestimationofthefractionofhigh-energyspalla-tionneutronsintheICONcoldbeam.TheneutrondosemeasurementshavebeenperformedwiththestandardPSIneutrondoseratemeters(ICRU-spheres),whichcanindicatedoseratesforneutronswithenergiesbelow0MeV.Todeterminethefluxofveryhigh-energyneutrons(E>0MeV),theso-calledC-11measurementwasreal-ized[8].Theirradiationofa1Ccontainingcrystalsamplewithhigh-energyneutronscanbedescribedwiththefollowingreactionequation:1C+nfast→13C→ 11C+n.Withthepositron-decayof11Ctheveryhigh-energyneutronfluxwasdeterminedto1.1·105cm-·s-1.AccordingtothealreadymentionedMonte-Carlocalculationstheveryhigh-energyneutronsgiveanon-negligiblecontribution to theneutrondose rate,whichcannotbeindicatedbythestandardPSIneutrondoseratemeters.Thereforeandbecauseoftheplannedboostoftheprotoncurrentinthefuture,theconstructionofthenewshieldinghastobeconservative.
5. Detectors and camera systems
Neutronradiographyimageswillberecordedbyahighperformance08x08pixelCCDcamerasystemAndorDV36fromAndorTechnology,lookingontoa6Libasedneutronscintillatorscreen,whichhasbeenoptimizedinperformanceandpriceinourgroup.Thecameraandacustom-madelensopticsystem(1:1optic)willbemounted
Table 3:Measuredneutronfluxdensityatbeamportexitandaperture8cm
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onacommonbench.Oneofourgoalsistheimprovementofthespatialresolution.Withthiscamerawehaveanominalpixelsizeof13.5µm(CCDchipsize:.6cmx.6cmand08x08pixels).Iftheproducerofthe1:1opticcanfulfilthespeci-ficationsasofferedwebelievetoreachatleastaresolutionof30µm.
Fordynamicneutronradiography,imagingwitheitheranintensifiedCCDcamerasystemoranamorphousSiliconbasedflatpanelwillbeused.Staticradiographywiththeinherentlyhighestpossibleresolutionwillbeperformedwiththeimagingplatetechnique(BAS-500:0cmx0cm/pixelsize:50µmandVistaScan:10cmx10cm/pixelsize:1.5µm).SomepromisingotherimagingtechniquesbasedonCMOStechnologyorpixeldetectors(e.g.PILATUS–N,aPSIdevelopment)areundercon-siderationtoo.
Inthisway,ahighflexibilityandoptimalperformanceisguaranteedforcoldneutronimaginginasmanyapplicationsaspossible.
6. Outlook
Besidetheusualexternalandinternaluserprogramthemaintopicsforfurtherinves-tigationsareenergyselectiveimagingeitherusinganeutronchopperandatriggeredcameraorusingavelocityselectorandphasecontrastimagingwitheitherapinholegeometryoragratinginterferometertechnique.
Acknowledgments
WewouldliketothankallthePSIstaffthathasbeeninvolvedinthisprojectforpro-fessionalexcellenceandenthusiasm,inparticularthosefromthePSIworkshop,theNeutronSpallationSourcedivisionASQandlastbutnotleasttoKurtClausen,theheadofourdepartmentforcriticalandhelpfuldiscussion.
References
[1] E.Lehmannetal.,Nucl.Instr.andMeth.inPhys.Res.A3(1996)11–15[] B.Winkler,K.Knorr,A.Kahle,P.Vontobel,E.Lehmann,B.Hennion,G.Bayon:
Neutronimaginganneutrontomographyasnondestructivetoolstostudybulk-rocksamples,EuropeanJournalofMineralogy,Vol1,00
[3] E.Lehmann,P.Vontobel,A.Herrmann:Non-destructiveanalysisofnuclearfuelbymeansofthermalandcoldneutrons,Nucl.Instr.andMeth.inPhys.Res.A515(003)5–59
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[] D.Goers,M.Holzapfel,W.Scheifele,E.Lehmann,P.Vontobel,P.Novak:Insituneutronradiographyoflithiumionbatteries:thegasevolutionongraphiteelec-trodesduringthecharging,JournalofPowerSources,130(00)1–6
[5] P.Willendrup,E.Farhi,K.Lefmann,P.-O.Åstrand,M.HagenandK.Nielsen:UserandProgrammersGuidetotheNeutronRay-TracingPackageMcStas,Ver-sion1.,Risø-R-116(EN),RisøNationalLaboratory,Roskilde,Denmark,May003
[6] E.Meier,R.Hassanein:Characterizationofthespatialneutrondistributionofthenew beam line for cold neutron imaging ICON, PSI Project-Report P050(005)
[] N.Frei:DosisleistungsmessungenWNHA/ICON,PSIStrahlenschutz–Mitteilung(Juli005)
[8] N.Frei:C-11MessungmitundohneWolframharz,PSIStrahlenschutz–Mitteilung(November005)
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Two Eminent Members of the Swiss Neutron Society Receive the Walter Hälg Prize of
the European Neutron Scattering Association
J. MesotLaboratory for Neutron Scattering, PSI & ETH Zurich
5232 Villigen PSI, Switzerland
AtthelastICNSconferenceinSydney,twomembersoftheSwissNeutronSociety,AlbertFurrerandHans-UlrichGüdelhavebeenawardedthe5thWalterHälg(*)PrizeoftheEuropeanNeutronScatteringAssociation(ENSA)inrecognitionoftheirmanyimportantcontributionstoourunderstandingofawidevarietyofinterestingmagneticmaterials.Beforedescribinginsomedetailstheirlife-longjointancoherentactivitiesandachievements,itisimportanttoemphasizethatthroughtheirrespectiveuniversi-ties(ETHZurich)and(Univ.Bern)andtheiroutstandingqualitiesasteachers,bothFurrerandGüdelhavebeenabletoconstantlyrecruitandmaintainverycompetitiveresearchteams,ascanbeseenfromanimpressivelistofhigh-levelpublications.
Thescientificco-operationbetweenthegroupsofFurrerandGüdelcanbeconsideredasatrulyinterdisciplinaryventure,becauseFurrerandGüdelreceivedtheiruniversitydegreesinsolidstatephysicsandinorganicchemistry,respectively.Nevertheless,theyachievedtocombineandjointhecultureofthetwodisciplinesincommonprojectswithgreatsuccess.Theirco-operationstartedinthemid-seventieswithstudiesofmagneticclustercompounds.Theycoulddirectlymeasuretheenergysplittingsofmagneticdimersandhigherclustersbyinelasticneutronscattering.Subsequentlythisworkhas servedas akey reference in similarmeasurementsperformedbyothergroups,sinceitdidnotonlydemonstratethefeasibilityofsuchexperiments,butpro-videdthetheoreticalbasisforthedatainterpretation,asincreasinglyusedtodayinthefieldofspinclustersincludingsupramolecularnanomagnets.
Neutronexperimentsonmagneticclustersprovidedirectinformationontheexchangeinteractionbetweenthemagneticions.Uptothepresent,theHeisenbergmodelhasbeenwidelyusedtodescribeexchangeinteractionsinmagneticsystems,althoughitinherentlyrepresentsjustafirstapproximationofthetruesituation.FurrerandGüdelstartedtosearchforhigher-ordertermsandfoundindeeddirectspectroscopicevidenceforanappreciablecontributionofbiquadraticexchangeinneutronexperimentsonMnpairsinthedilutedone-dimensionalmagnetCs(Mn,Mg)Br3.Thenatureofbiquadraticexchangedoesnotonlyinvolvepairinteractions,butalsothree-body,four-body,etc…
31
interactionsifextendedtohigherclusters.FurtherneutronexperimentsonMntrimerchainsegmentsinCs(Mn,Mg)Br3provedtheexistenceofatruethree-spinexchangetermsimilarinmagnitudetothecorrespondingbiquadratictwo-spinterm.Thiswasaresultoffundamentalimportance,sincen-bodyinteractions(n>)havesofaronlybeenverifiedinsolid3He,nuclearmatter,anddisorderedbinaryalloys.
InthelateeightiesGüdel’sgroupwassearchingforsuitablematerialstobeusedinthedesignofefficientup-conversionlasers.CompoundsofcompositionCs3RBr9(R=rareearth)werefoundtobeparticularlywellsuitedforthispurpose.TheelectronicpropertiesofthesecompoundsaregovernedbythedimersofRionsbuiltintothemolecularunit,thusitwasobvioustostudythecorrespondingexcitationstogetherwithFurrer’sgroupwhichhadbeenactiveinRmagnetismforalongtime.TheneutronexperimentsperformedforalmostthewholeRseriesprovidedcompletelyunexpectedresults.Theusualphenomenologicalmodels(Heisenberg,Ising,xy)failedtorepro-ducetheobservedenergyspectra.However,anexchange-tensorformalismwhichtakesintoaccounttheinitialandfinalelectronicstatesoftheinteractingions,turnedouttoprovideanexcellentdescription.
AparticularlyinterestingsystemstudiedbyFurrer’sandGüdel’sgroupswasthespin-dimercompoundCs3CrBr9,becauseitexhibitsfield-inducedmagneticorderingwhenthesinglet-tripletenergygapcloses,thusBose-Einsteincondensation(BEC)ofthetripletstateswithagaplessGoldstonemodecouldbeexpectedtooccur.However,detailedfield-dependentneutronscatteringexperimentsshowedthatthelowestsin-glet-tripletexcitationbranchdoesnotsoftencompletelyduetosomeinherentanisot-ropy.Nevertheless,theseexperimentsservedasanexcellentbasisforthelaterobser-vationofBECinTlCuCl3.
IntheninetiesFurrer’sgroupstartedsystematicinvestigationsoftheinhomogeneousmaterialspropertiesofhigh-temperaturesuperconductors.Motivatedbythefactthat
AlbertFurrer HansUlrichGüdel
3
suitablydopedspin-laddercompoundssuchasCa@Sr1CuO1becomesupercon-ducting(underpressure),aco-operationwasinitiatedforthenovelS=1/spin-laddercompoundsACuCl3 (A=K,Tl,NH)withGüdel’sgroupwhichhas thenecessaryexpertiseinthesynthesisandgrowthofsinglecrystals.InafirststepthedispersionofthemagneticexcitationswasestablishedforKCuCl3byinelasticneutronscattering.Surprisingly,themagneticexcitationsturnedouttobedispersiveinalldirectionsofreciprocalspace(i.e.,notonlyalongtheladderdirectionasanticipated)withstructurefactorsimagingthenearest-neighbourCupairdistance,therebyprovingthatthiscom-poundserieshasthepropertiesofanS=1/spin-dimerratherthanaspin-laddercom-pound.Theexperimentswerethenextendedtoinvestigatethemagneticfielddepend-enceofthesinglet-tripletexcitationincludingtheisostructuralcompoundTlCuCl3.BasedontheseexperimentsFurrer,Güdelet al.realisedthatthefield-drivenquantumcriticalitycanindeedbereachedinthesesystemsasdemonstratedearly003.
Toconclude,Furrer’sandGüdel’sjointworkoveraperiodofthreedecadesisexem-plary.Itdemonstratesthevirtuesofinter-disciplinarityandcontinuity,andassuchshouldbetakenasamodelfortheyoungergenerationofscientists.
(*) Prof. Walter Hälg:
ThedonatoroftheENSAprizeisProf.WalterHälg,thefounderofneutronscatteringinSwitzerland.BorninBaselin191,heisoneofthepioneersofneutronscattering.From193to196heworkedinparticlephysicsat thePhysicalInstituteof theUniversityofBaselandontheconstructionofa1MeVCock-roft-Waltonaccelerator.Hespenttheyears196-1960attheAGBrownBoveriCoBaden(BBC),andwaspromotedheadofthephysicsdepartment1955.DuringhistimeatBBC,heworkedonthedevelopmentoftheSwissheavywaterreactorDIORITatWürenlingen,whichwentcriticalon6August1960.
Alsoin1960,hewasnamedfullProfessorforNuclearReactorTechnologyattheSwissFederalInstituteZürichandwasinvolvedintheconstructionoftheneutronspectrometersatthereactorDIORIT.Hecarriedoutthefirstcalculationsforaspalla-tionsourceusingthesurplusprotonsofthe500MeVringofthenearinstituteforneutronproduction,SIN,afterdecommissioningofthereactorDIORITinAugust19.
During10years,hewasmemberandpresidentofthe“Forschungskommission”oftheSwissFederalInstituteZürich.Currently,heisanhonorarymemberof theSwissNeutronScatteringSocietyandofthedistinguishedPhysicalSocietyofZürich.
WalterHälgretiredinautumn198.
WalterHälg
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2005 Walter Hälg Prize of the European Neutron Scattering Association (ENSA)
AlbertFurrer HansUlrichGüdel
EverytwoyearstheEuropeanNeutronScatteringAssociation,ENSA,awardstheprestigiousWalterHälgPrizetoEuropeanscientistsforanoutstandingprogrammeofresearchinneutronscatteringwithalongtermimpactonscientificand/ortechnicalneutronscatteringapplications.ThePrizeof10’000SwissFrancsisdonatedbyPro-fessorWalterHälg,thefounderofneutronscatteringscienceinSwitzerland.In005theHälgPrizeistobepresentedataspecialsessionoftheInternationalConferenceonNeutronScattering,tobeheldinSydney,Australia,betweenNovemberandDecember.
Thenominationsreceivedforthe005HälgPrizewereexaminedbyaninternationalselectioncommitteeconsistingofauthoritiesrepresentingthemajorscientificdisci-plines,bothwithinandbeyondthefieldofneutronscattering.Theselectioncommitteeisdelightedtoannouncethatthe005HälgPrizewillbeawardedexceptionallytoboth
Professor Albert Furrer (ETH Zürich and Paul Scherrer Institute)and
Professor Hans Ulrich Güdel (University of Bern)
inrecognitionoftheimportantroletheircontinuingcollaborationhasplayedindevel-opingnewandinterestingmagneticmaterialsandstudyingthemtoobtainunique
3
insightsintotheirmagneticproperties.Thecollaborationbeganinthe190‘swithstudiesofmagneticclustercompoundsthatshowedthedetailednatureoftheexchangeinteractions.Thelaserrare-earthmaterialswerethenstudiedandshowedthat theexchangeinteractionsweremorecomplexthanexpected,butcouldbeunderstoodbytakingaccountofboththeinitialandfinalrareearthstates.Mostrecentlytheyhaveperformedelegantexperimentsonspindimersandhavemeasuredthetripletexcita-tionsandshownbyapplyingamagneticfieldthattheycouldinduceaBose-Einsteincondensationtoamagneticallyorderedstate.Alloftheseexperimentsshowtheimpor-tanceofthecollaborationbetweenthechemistwhogrowsthenewmaterialsandtheneutronscattererwhostudiesthedetailednatureoftheexcitations.
AlbertFurrerobtainedhisdoctorateatETH,Zürichin190andheldpost-doctoralpositionsinDenmarkandtheUSAbeforereturningtoETH,ZürichwherehebecameHeadoftheLaboratoryforNeutronScatteringfrom198-00.HebecameChairmanofENSAin199andhasheldmanyimportantadministrativeposts.
HansUlrichGüdelobtainedhisdoctoratefromtheUniversityofBernin190.HethenwenttoDenmarkandfollowedthatbyatimeinAustraliabeforereturningtotheUniversityofBern.Hewasco-founderandboardmemberoftheSwissNeutronScat-teringAssociationandhassinceheldmanyimportantadministrativerolesinNeutronScattering.
35
Announcements
SGN/SSDN Members
TheSwissNeutronScatteringSocietywelcomesthefollowingnewmembers:
• H.Sitepu,DepartmentofGeosciences,VirginiaTech,Blacksburg,USA• M.Janoschek,LaboratoryforNeutronScattering,PSIÐZurich• M.Salakhitdinova,SamarkandStateUniversity,Uzbekistan
PresentlytheSGNhas19members.
News from SINQ
DuringtheannualacceleratorshutdownofPSIinwinterandspring006theliquidleadbismuthtargetMEGAPIEwillbeinstalledatSINQ.SincetheinstallationwillcauseanextendedshutdownofthePSIneutronfacilityuptotheendofJuneitwasdecidedtocancelthefall005callforproposals(deadlineNov15).Thewaitingtimebetweenthesubmissionofproposalsandthescheduleofbeamtimewouldhavebeennotacceptablefortheusers.
FortheremainingoperationcycleI/06(July/August06)theSINQusersareencour-agedtomakeuseoffastaccessprocedures,forwhichanextendedshareofurgentbeamtimewillbereserved.Thenextregularcallforproposalswillbelaunchedinspring006askingforbeamtimerequestsfortheperiodSeptember-December006.Theuserswillbeinformedaboutimportantdatesbyanemailnewsletter.
More information:http://sinq.web.psi.ch/sinq/news.htmlhttp://sinq.web.psi.ch/sinq/access.htmlhttp://megapie.web.psi.ch
PSI Digital User Office also available for the SμS facility at PSI
RecentlythePSIUserWebinterface‘DigitalUserOffice,DUO’hasbeenextendedtohostalsotheuseroperationoftheSwissMuonSourceSµSatPSI.InadditiontoSINQandSLS,theSµSisthethirdPSIuserfacilityintegratedintoDUO.Withasingle
36
accounttheusersnowcansubmitproposalstotheindividualfacilities,applyforPSIbadgesanddosimetersandmanagetheirexperimentsatPSI.
More information:http://user.web.psi.ch/http://sls.web.psi.ch/goto.php/duo/
Open Positions at ILL
TochecktheopenpositionsatILLpleasehavealookattheILL-homepage:http://www.ill.frfollowingthelink‘JobOffers’.
3
4th Summer School on Condensed Matter Research, Zuoz, Switzerland
F. van der Veen and H.J. Weyer Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
ThePaulScherrerInstitutoffersworld-classsynchrotron,neutron,andmuonfacilities.Forthe005ZuozSummerSchool,therefore,“Spectroscopy/Microscopy”wascho-senasmaintopic.Followingtheconceptoftheschool,alsonotedintheannounce-ment,nospecialknowledgeofthefieldwasrequired.
Accordingly,theprogramstartedwithbasicintroductionstothegenerationofsyn-chrotronradiation(LeonidRivkin)andneutrons(KurtClausen)andscientificques-tionsaddressedatthesefacilities(FrisovanderVeen,JoelMesot).Thisconceptoftandemtalks(onetalkemphasizingthetechnique,theotherscientificapplications)wasfollowedthroughouttheprogram.PhilippAebipresentedthebasicsofangle-resolvedphotoemissionork-spacemicroscopyandMarkGoldenelucidateditsappli-cationsinthefieldofhigh-TCsuperconductors.
ResonantinelasticX-rayscatteringwascoveredbyMarcoGrioniandGiacomoGhir-inghelli,withadescriptionofthetechnique,instrumentation,andselectedexperimen-talresultsusingsoftandhardX-rays.Applicationsofthistechniquetostronglycor-relatedmaterialsunderhighpressurewerediscussedbyClaudiaDallera.Neutron
Zuozvillagetour duringanafternoonbreak.
38
spectroscopy as a probeof structural andmagnetic dynamicswas introducedbyAndrewBoothroyd.DesMcMorrowdiscussedexcitationsincondensedmatterprobedwithneutrons.
Asthereisalsoapowerfulmuon-spin-rotation(µSR)facilityatPSI,ChristofNieder-mayerdiscussedwhatmuonscantellusaboutcondensedmatter,bypointingtotheirstrongsensitivitytolocalmagneticfieldsandtheirtemporalfluctuations.
Astrongandever-increasingcommunityatsynchrotronfacilitiesusesthetechniqueofX-rayAbsorptionFineStructure(XAFS).Itswideapplicabilityinmaterialsandenvironmentalsciencesanditssensitivitytoshort-rangeorderingwasdiscussedbyRoelPrinsandDonaldSparks.
InfraredspectroscopywithitsdifferentfacetswaspresentedbyLeoDegiorgiandMarkTobin,whileMichaelMartinintroducedtheaudiencetothepossibilityofusingTerahertzradiationatsynchrotronfacilities.TheuseofinfraredellipsometryforthecharacterizationofsuperconductorswaselucidatedbyDirkvanderMarel.TheoptionsofX-raymicroscopywithitselementalandchemicalsensitivitywerediscussedbyHaraldAde.RainerFinkdiscussedapplicationsofzone-platebasedx-raytransmissionmicrospectroscopy.
PhotoelectronemissionmicroscopyusedasaprobeofmagnetismonthenanoscalewasdescribedbyFrithjofNolting.MayaKiskinovadescribedtheapproachtochemi-cal and electronic properties of surfaces and interfaces.Thomas Greber gave animpressiveinsightintothepotentialapplicationsofphotoelectrondiffractionandUrsStaubtooktheaudienceontheroadfromorderedchargetoorderedorbitals.Hedem-onstratedthatbyresonantscattering,i.e.,bycombiningspectroscopywithdiffraction,theorientationoftheorbitalscanbeprobed.
Accordingtothestyleofthemeetingasaschool,basicissuesshouldnotbeforgotten.ClausAscherongaveinhistalkanintroductiontoscientificpresentationanddiscussedthoseissuesessentialforgivingagoodscientifictalk.Althoughdirectedmainlytowardtheyoungerparticipants,thetalkwasdefinitelyalsoofinterestforthemoreseniorattendees.ThemeetingconcludedwithadiscussionofmagneticexcitationsinstronglycorrelatedsystemsbyStephenHayden.
Theschoolwasattendedbyoveronehundredparticipants,amongthemabouteightystudentsonthepost-graduateorpost-doctorallevel.Themajorityofthesestudentscamefromwestern-andeasternEuropeancountries.Transparanciesofthepresenta-tionsweremadeavailabletotheparticipantsduringtheschool.PDFversionsofthetalkshavebeendepositedontheschoolwebsite(http://sls.web.psi.ch/view.php/sci-ence/events/Conferences/Zuoz005/Program.html).
WethankMrsChristineKunzforallthearrangementsshemadethatturnedtheschoolinasuccess.ThesupportoftheschoolbytheEUFP6I3InitiativesIA-SFSandNMI3andbytheSwissNationalScienceFoundationisgratefullyacknowledged.
39
‘Day of Physics’ at PSI on October 30
S. JanssenNUM department, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
OnOctober30,005thePaulScher-rerInstitutopeneditsdoorsforanothervisitors’dayandfacedanoverwhelm-inginterestofthepublic:Morethan9000peopletooktheopportunitytohaveacloserlookatthePSIfacilitiesand research laboratoriesduring the‘DayofPhysics’.
Ontheirwayoverthecampusthevis-itorspassedbyfour‘Einstein-Presen-tations’ entitled ‘Light’, ‘Space andTime’,‘Energy’and‘Atoms’.Inmul-timediashowsthepeoplewereintro-
ducedtotopicslike‘speedoflight,E=mc,photoeffect’or‘diffusion’.
InadditionthePSIUserLaboratoriesSLS,SINQ,SµS,andtheparticlephysicspre-sentedtheirmethodsandhotresearchtopicsinapublicmanner.AtSINQthepresen-tationshowedhowneutronsmighthelptoexplaintheeffectofHigh-TemperatureSuperconductivity.Aspecialhighlightduringthe‘show’wasthesuperconducting‘MANEPmodelrailway’,whichwaskindlymadeavailablebytheInstituteofPhysics,UniversityofGeneva.
ThePSI/Michelinfuelcellcar‘HY-LIGHT’,thePSIprotontherapyfacility,severalinformationboothsonenergyresearch and environment aswellasaspecial‘physicslabo-ratoryforchildren’completedaveryinteresting,colorfulandlively‘OpenDay’atPSI,whichwill definitely not be the lastone.
Morethan9000visitorsattendedthe‘PSIDayofPhysics005’.
Even ‘Einstein’ showed up toexamineifhistheoriesarereallyunderstood…
0
Conferences and Workshops 2006
(an updated list with online links can be found here: http://sinq.web.psi.ch/sinq/links.html)
January
InnovativeNanoscaleApproachtoDynamicStudiesofMaterialsJanuary 9-14, 2006, Okinawa, Japan
GordonResearchConference(GRC)onSuperconductivityJanuary 22-27, 2006, Santa Ynez Valley Marriott Buellton, CA, USA
HighPressurePSIWorkshop:µSRTechniquesandApplicationsJanuary 25, 2006, Paul Scherrer Institute, Villigen, Switzerland
SµSUsers‘MeetingJanuary 25-26, 2006, PSI Villigen, Switzerland
February
006SwissPhysicalSociety-MaNEPSymposiumFebruary 13-14, 2006, EPFL Lausanne, Switzerland
Workshopon‚PresentStatusandFutureofVeryColdNeutronApplications‘February 13-14, 2006, Paul Scherrer Institut, Switzerland
SymposiumfortheInaugurationofthe‚JuelichCentreforNeutronScienceJCNS‘andEuropeanUsersMeetingFebruary 16-17, 2006, Forschungszentrum Jülich, Germany
March
Swiss-RussianWorkshopon‚QuantumMagnetismandPolarisedNeutrons‘March 1-4, 2006, PSI Villigen, Switzerland
10thLaboratoryCourseonNeutronScatteringMarch 13-24, 2006, FZ Jülich, Germany
Confit006–3rdInternationalWorkshoponDynamicsinConfinementMarch 23-26, 2006, Grenoble, France
1
SpringMeeting(SolidStatePhysics)oftheGermanPhysicalSocietyandEPSCondensedMatterDivisionMarch 27-31, 2006, Dresden, Germany
April
1thAnnualMeetingoftheGermanCristallographicSocietyApril 3-6, 2006, Freiburg, Germany
ILLMilleniumSymposiumandEuropeanUsersMeetingApril 27-29, 2006, ILL Grenoble, France
May
8thSINQUsers‘MeetingMay 10, 2006, PSI Villigen, Switzerland
ICCS006:InternationalConferenceonComputationalScienceMay 28-31, 2006, University of Reading, UK
June
11thInternationalCeramicCongressandthForumonNewMaterialsJune 4-9, 2006, Acireale, Sicily, Italy
EuropeanSchoolon‚ScatteringMethodsappliedtoSoftCondensedMatter‘June 10-17, 2006, Bombannes, Gironde, France
IFAMST5:5thInternationalForumonAdvancedMaterialScienceandTechnologyJune 11-17, 2006, Xiangtan and Zhangjiajie, Hunan Province, China
006AmericanConferenceonNeutronScatteringJune 18-22, 2006, St. Charles, IL, USA
July
StronglycorrelatedsystemsinlowdimensionJuly 2-8, 2006, Ascona, Switzerland
XIIIInternationalConferenceonSmallAngleScatteringJuly 9-13, 2006, Kyoto, Japan
MS-HTSC-VIII, 8th International Conference on Materials and Mechanisms ofSuperconductivityandHighTemperatureSuperconductorsJuly 9-14, 2006, Dresden, Germany
ACA006,AnnualMeetingoftheAmericanCrystallographicAssociation006July 22-27, 2006, Honolulu, Hawaii, USA
August
5thPSISummerSchoolonCondensedMatterResearchAugust 19-26, 2006, Zuoz, Switzerland
September
10thEuropeanPowderDiffractionConferenceSeptember 1-4, 2006, Geneva, Switzerland
ICfe006:6thInternationalConferenceonf-elementsSeptember 4-9, 2006, Wroclaw, Poland
thEuropeanConferenceonResidualStressesSeptember 13-15, 2006, Berlin, Germany
PolarisedNeutronSchoolSeptember 19-22, 2006, Berlin, Germany
PNCMI006,PolarisedNeutronsinCondensedMatterInvestigationsSeptember 25-28, 2006, Berlin, Germany
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