Designation:E2426−10StandardPracticeforPulseCountingSystemDeadTimeDeterminationbyMeasuringIsotopicRatioswithSIMS1ThisstandardisissuedunderthefixeddesignationE2426;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1ThispracticeprovidestheSecondaryIonMassSpec-trometry(SIMS)analystwithamethodfordeterminingthedeadtimeofthepulse-countingdetectionsystemsontheinstrument.Thispracticealsoallowstheanalysttodeterminewhethertheapparentdeadtimeisindependentofcountrate.1.2Thispracticeisapplicabletomosttypesofmassspectrometersthathavepulse-countingdetectors.1.3Thispracticedoesnotdescribemethodsforpreciseoraccurateisotopicratiomeasurements.1.4Thispracticedoesnotdescribemethodsfortheproperoperationofpulsecountingsystemsanddetectorsformassspectrometry.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2E673TerminologyRelatingtoSurfaceAnalysis(Withdrawn2012)32.2ISOStandards:4ISO21270SurfaceChemicalAnalysis—X-rayphotoelec-tronandAugerelectronspectrometers—Linearityofin-tensityscale;andreferences1,2,10,13and14therein.3.Terminology3.1Definitions:3.1.1SeeTerminologyE673fordefinitionsoftermsusedinSIMS.3.1.2SeeTerminologyISO21270fordefinitionsoftermsrelatedtocountingsystemmeasurements.3.1.3isotopicratio,n—writtenasm2X/m1X,foranelementXwithisotopesm1andm2,referstotheratiosoftheiratomicabundances.Whenitisavaluemeasuredinamassspectrom-eteritreferstotheratioofthesignalintensitiesforthetwospecies.3.1.3.1Discussion—Thenotation∆m2Xorδm2Xreferstothefractionaldeviationofthemeasuredisotopicratiofromthestandardratioorreference.Inthispractice,∆m2Xwillrefe...
