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 peter.allenspach@psi.ch Board Members: Prof. Dr. S. Decurtins silvio.decurtins@iac.unibe.ch Prof. Dr. B. Schönfeld schoenfeld@iap.phys.ethz.chSecretary: Dr. S. Janssen stefan.janssen@psi.ch

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) .

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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.

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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).

19

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

33

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,PSI&ETHZurich• 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

3

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