phenomenologyeaccelerator

arXiv:1110.
3042v1[physics.
acc-ph]13Oct2011August2,2018UpdatedReportAccelerationofPolarizedProtonsto120-150GeV/catFermilabSPIN@FERMICollaborationMichigan,Fermilab,JeersonLab,Virginia,Argonne,Bonn,TRIUMF,IHEP-Protvino,NovosibirskTheSPIN@FERMIcollaborationhasupdatedits1991-95ReportsontheaccelerationofpolarizedprotonsinFermilab'sMainInjector,whichwascommissionedbyFermilab.
ThisUpdatedReportsummarizessomeupdatedPhysicsGoalsfora120-150GeV/cpolarizedprotonbeam.
ItalsocontainsanupdateddiscussionoftheModicationsandHardwareneededforapolarizedbeamintheMainInjector,alongwithanupdatedScheduleandBudget.
Forreference,alsoattachedtothee-mailcontainingthisUpdatedReportarereprintsofthe1992and1995ReportsonPolarizedBeamsatFermilabbyourSPINcollaboration.
SomehighlightsoftheUpdateare:TwosuperconductingSiberiansnakesintheMainInjector,onesuperconducting60rotatorinthe120-150GeV/cextractionline,a4%partialwarmsolenoidalSiberiansnakeinthe8.
9GeV/cBooster(oscillatingwiththeBoosterfrequency)andsomeotherminorhardwareshouldallowabout75%polarizationtobemaintainedandmanipulatedintheRFQ,Linac,Booster,RecyclerRingandMainInjector,andthenextractedtotheexperiments(SeeFig.
1.
9).
Polarizedionsourcesnowhaveintensitiesof1.
0-1.
5mA.
WitheithertheformerIUCFAtomicBeam(ABS)typepolarizedionsource(whichisnowatDubna),orthereconstructedandimprovedZGS/AGSABS,weexpecttoobtainanintensityofabout1mA.
With10%ofthebeam-timepolarized,SeaQuest's50cmlongH2targetwouldhaveatime-averagedluminosityofabout2·1035cm2s1.
Theestimatedtotalcostoftheprojectisabout$4Million(2012dollars).
Theconstructiontimecouldbeabout2yearsafterapprovalandfunding.
1ContentsAbstract1Contents21UpdatedReportonPolarizedBeamsatFermilab31.
1SPIN@FERMIcollaborationlist31.
2ExperimentalOverview41.
3TheoreticalOverview71.
4Physicswith120-150GeV/cpolarizedbeams111.
5UpdatedSummaryofPolarizedBeamAcceleration161.
6SummaryofNeededPolarizedHardware191.
7HardwareInstalationandSchedule251.
8Commissioning261.
9EstimatedBudget281.
10Summary28References292Appendices(UnderseparateCover)2.
1UMHE92-05(1992)ReportonAccelerationofPolarizedProtonsto120and150GeVintheFermilabMainInjector.
2.
2UMHE95-09(1995)ReportonAccelerationofPolarizedProtonsto120GeVand1TeVatFermilab.
21UpdatedReportonPolarizedBeamsatFermilab1.
1SPIN@FERMIcollaborationlistAugust2,2018E.
D.
Couranta,A.
D.
Krisch,M.
A.
Leonova,A.
M.
T.
Lin,J.
Liu,W.
Lorenzon,D.
A.
Nees,R.
S.
Raymond,D.
W.
Siversb,V.
K.
WongUNIVERSITYOFMICHIGAN,ANNARBOR,U.
S.
A.
I.
KourbanisFERMILAB,BATAVIA,U.
S.
A.
Ya.
S.
Derbenev,V.
S.
MorozovJEFFERSONLAB,NEWPORTNEWS,U.
S.
A.
D.
G.
CrabbUNIVERSITYOFVIRGINIA,CHARLOTTESVILLE,U.
S.
A.
P.
E.
ReimerARGONNENATLAB,ARGONNE,U.
S.
A.
J.
R.
O'FallonDEPARTMENTOFENERGY,WASHINGTON,U.
S.
A.
G.
Fidecaro,M.
FidecaroCERN,GENEVA,SWITZERLAND.
F.
HinterbergerBONNUNIVERSITY,BONN,GERMANY.
S.
M.
Troshin,M.
N.
UkhanovINSTITUTEOFHIGHENERGYPHYSICS,PROTVINO,RUSSIAA.
M.
KondratenkoOOO"Zaryad",NOVOSIBIRSK,RUSSIAW.
T.
H.
vanOersTRIUMF,VANCOUVER,CANADAThespokespersonfortheSPIN@FERMICollaborationis:A.
D.
KrischTelephone:734-936-1027RandallLaboratoryofPhysicsTelefax:734-936-0794UniversityofMichiganE-mail:krisch@umich.
eduAnnArbor,Michigan48109-1040USAretiredPermanentaddress:aNYCbPortland31.
2ExperimentalOverviewM.
A.
Leonova,A.
D.
Krisch,Introduction.
Theinterestinspinphenomenahassignicantlyincreasedinrecentyears.
Itisnowclearthatspineectsinhighenergyinteractionsprovideessentialinformationabouttheelementaryparticles'propertiesandstructure.
Recently,therehasbeensignicantprogressinunderstandingthenucleon'slongitudinalandtransversespinstructureduetomanypolarizationexperimentsdoneatSLC,HERA,CERNandRHIC.
TheMainInjectorpolarizedprotonbeamwouldallowuniquestudiesofspinphenomenasuchasthe1-spinasymmetryinallinclusiveprocesses,includingDrell-Yanandhadronandhyperonproduction.
Itwouldalsoallowboth1-spinand2-spinasymmetrymeasurementsofexclusiveprocessessuchasproton-protonelasticscatteringatlargeP2⊥.
Thus,theMainInjector'sveryhighintensitycouldtestthevalidityofstronginteractiontheoriesatthefarlargerP2⊥valuespossibleat120-150GeV/c.
PolarizedDrell-YanExperiments.
TheE-866[1]andE-906(SeaQuest)collabora-tionshavehadalong-terminterestinstudyingDrell-Yanprocesseswitha120-150GeV/cpolarizedbeam.
DetailsaregiveninSection1.
4.
PolarizedlargeP2⊥elasticandinclusivescattering.
Transversespineectsappearexperimentallytoincreaseatlarge-P⊥.
AhighintensitypolarizedbeamcoulddetermineiftheseunexpectedspineectspersistatthelargerP⊥possibleatthe120-150GeV/cMainInjector.
TheSPIN@FERMICollaborationhopestocontinuestudyingtheproton'stransversespinstructurebyscatteringa120-150GeV/cextractedpolarizedprotonbeamfromasolidpolarizedprotontargetandaliquidhydrogentarget.
AsshowninFig.
1.
1,alargeleft-rightasymmetryANwasfoundinpolarizedproton-protonelasticscatteringatlargeP2⊥[2].
Currently,thenucleon'stransversespinstructureisunexploredexperimentallyaboveaboutP2⊥=7(GeV/c)2.
Figure1.
1:PlotofANagainstP2⊥forproton-protonelasticscattering(p↑+p→p+p)[2].
4Similarlargeasymmetrieswerefoundinlarge-XFinclusivepionproduction[3]fromPlab=12GeV/ctos=3900(GeV/c)2,asshowninFig.
1.
2.
Figure1.
2:Inclusive1-spinπ+andπAN(left-rightasymmetry)plottedagainstXF[3].
Thereare2independent1-spinANasymmetriesinlargeP2⊥elasticscattering(polar-izedbeamandpolarizedtarget),p↑+p→p+pandp+p↑→p+p.
(1.
1)Foridenticalparticles,suchas2protons,the2independentANasymmetriesmustbeequal.
Thesewouldbemeasuredsimultaneouslywiththe2-spinANNasymmetry,p↑+p↑→p+p.
(1.
2)Figure1.
3:Spin-spineectsin2-spinproton-protonelasticscatteringatlargeP2⊥[4].
AsshowninFig.
1.
3,alargeandunexpected2-spinasymmetrywasfoundatlargeP2⊥near12GeV/c.
OnecoulddetermineifthelargeandstillunexplainedANNdisappearsorpersistsatthelargeP2⊥availableatthehigh-intensity120-150GeV/cMainInjector.
5Moreover,withthehighintensityMainInjector,onecouldsimultaneouslymeasuretheunpolarizedproton-protonelasticcrosssectionatlargeP2⊥withmuchbetterprecisionthannowexists.
Figures1.
1,1.
3,1.
4(and1.
6)showcompilationsofallexistingdataontheproton-protonelasticscattering'scrosssectionanditsANandANNasymmetriesaboveafewGeV/c.
Figure1.
4:Allunpolarizedelasticproton-protoncrosssectiondataabove3GeV/cplottedagainstthescaledP2⊥variable[5].
61.
3TheoreticalOverviewD.
W.
Sivers,M.
A.
Leonova,A.
D.
KrischSpinhasbeenthequantumnumberthathasmystiedphysicistssinceitspublicationbyUhlenbeckandGoudsmitin1925[6].
Indeed,atthe1982SPINSymposium,C.
N.
Yangstated"Iforonesuspectthatthespinandgeneralrelativityaredeeplyentangledinasub-tlewaythatwedonotunderstand"[7].
ThemodernspinerabeganwithWolfenstein's[8]eortstodevelopaformalismtodescribespinexperiments,followedbythediscoverybyOxleyetal.
oflargespineectsat200MeV[9].
Fermi'slastpaper[10]focusedonhisamazementthattheproton'sspin,whichhadsolittleenergy,wassoimportantat200MeV.
Thispaperresultedinhisex-studentChamberlainandothersstartingaseriesofdoubleandtriplescatteringexperimentsanddevelopingpolarizedprotontargetsandusingthemwithunpolarizedbeams.
Next,thedevelopmentofthe12GeV/cZGSpolar-izedprotonbeamallowedmanyprecisespinexperiments,suchasproton-protonelasticscatteringexperiments[4,11],whichfoundunexpectedlylargeANandANNasymmetriesathighP2⊥.
ThisstartedtheeraofGeVpolarizedbeamsandpolarizedtargetsatmanyhighenergyandnuclearacceleratorsandcollidersandmanytheoreticaleortstotrytounderstandtheresultingdata.
Therewasabeliefthatquantumchromodynamics(QCD)predictedthatalltransversesinglespinasymmetrieswouldvanishatlargetransversemomentum.
ThismisconceptioncanbetracedtostatementsfoundinthepaperofKane,PumplinandRepko[12].
Itcorrectlypointedoutthatlargetransversesinglespinasymmetriesarenotgeneratedinperturbativeprocessesinvolvinglightquarks,ANdσ(qq↑→qq)/dσ(qq→qq)=αs(Q2)Qmqf(θCM).
(1.
3)Buttheymistakenlyneglectedotherpossibletwist-3mechanismsinacollinearfactor-izationformulationofahardscatteringmodel,andusedthistosuggestthevanishingof1-spinobservables,suchasAN.
During1978-1988thisconclusionwaswidelyaccepted.
Thecorrectinterpretation[13]oftheirresultwasthat,sinceperturbativeprocessesin-volvinglightquarksdonotthemselvesgenerate1-spinasymmetries,theycouldbeusedtoprobetheasymmetriescausedbythesoftnonperturbativedynamicsofQCDduetotheinterplayofconnementanddynamicchiralsymmetrybreaking.
Theasymmetriesgeneratedbysuchspin-orbitdynamicscanbeparameterizedintokT-dependentdistribu-tionfunctions(Siversfunctions[13]orBoer-Muldersdistributions[14])orintokT-dependentfragmentationfunctions(Collinsfunctions[15]orpolarizingfragmentationfunctions[13,16]).
Theycanalsobeparameterizedintospecictwist-3operatorsinacollinearfactoriza-tionapproach.
Muldersandhiscollaborators[16]classiedtheappropriateoperatorsfor1-spinasymmetriesbut,mistakenly,calledthemT-oddsuggestingthattheyviolatedtimereversalinvariance.
Intruth,thesymmetrytheyviolatedinvolvesatransformationrelatedtotheHodgedualoperatorofdierentialgeometry[17].
TheTrentoConventionsfortransversespinasymmetriesaredescribedinRef[18].
ThesubjectreceivedaboostwhenHeppelmann,CollinsandLadinsky[19]notedthatthequarktransversitydistribu-tions,δTq(x),denedbyRalstonandSoper[20]andrenamedbyJaeandJi[21],couldbemeasuredinsemi-inclusivedeepinelasticscattering(SIDIS),ANdσ(lp↑→l′πX)∝δTq(x)H1(z).
(1.
4)HereH1(z)istheCollinsfunction[15]thatdenesanasymmetryinthefragmentationofatransverselypolarizedquark.
Asymmetriesinvolvingfragmentationfunctionscan7beseparatedfromthoseinvolvingdistributionsinSIDISandintheDrellYan[22]pro-cess.
Inhadron-hadroncollisionstheycanalsobeseparatedattheleveloftwo-particlecorrelationsinthenalstate.
Acomprehensivephenomenologicalttoasymmetriesine++e→hadrons,semi-inclusiveDISandinclusiveproductioninpolarizedhadron-hadronscattering,hasbeenpublishedbytheTuringroup[23].
Theytthetransversitydistributionsforupanddownquarks,favoredanddisfavoredCollinsfunctions,andorbitaldistributionsforupanddownquarks.
ThisphenomenologyiscurrentlybeingextendedtoNLOinQCDperturbationtheory.
Animportantfeatureof"T-odd"dis-tributionfunctionsisthattheyarerequiredtodisplayadramaticprocessdependenceinordertobeconsistentwithagaugeformulationofQCD.
ThisresultcanbecalledCollinsconjugation[24].
Itneedstobetested.
Onecomparisoninvolvesthemeasurementoforbitaldistributions(whicharecalledSiversfunctions)inDISandintheDYprocess,f⊥q1T(DIS)=f⊥q1T(DY).
(1.
5)However,otherscanalsobeconsidered.
Inparticular,theBoer-Muldersdistributionsexhibitthesameprocessdependenceasorbitaldistributions.
Relatedprocessesinvolvingassociatedbaryonproductioncanalsobestudied.
.
ExclusiveprocessesinQCDinvolvelocaldescriptionsintermsof,socalled,gener-alizedpartondistributions(GPD's)andeectiveeldtheoriesincorporatingconstraintsgeneratedbycrossingandanalyticity.
Quantumchromodynamicspredictsthatelastictransversespinasymmetriesforhadron-hadronscatteringatlargetransversemomentainvolveacombinationoftheChou-Yang[25]mechanisminvolvingorbitalangularmomen-tumandtheBrodsky-Lepage[26]eectiveeldtheorywhichinvolvestruncationoftheFockstatescombinedwithpower-lawapproximationstoeectiveformfactors.
However,thedatashowninFigs.
1.
1,1.
2and1.
3aretoosmallasetofdatatoconclusivelylterthevarioustheoreticalapproaches.
Itsrangeneedstobeincreased.
Highintensity120-150GeV/cpolarizedprotonbeamsfromtheMainInjectorcouldallowacomprehensiveexperimentalprogramoftransversesingle-spinanddouble-spinexperiments.
Single-SpinAsymmetriesThesestudiestakeadvantageofthehighluminositypossiblewithapolarizedbeamscatteringonanunpolarizedtarget,togetherwiththeexibilityofincorporatinghigh-resolutionmeasurementsofmomentumwithparticleidenticationinxed-targetexper-iments.
Alistofimportantexperimentswouldinclude:1.
PolarizedDrellYanasymmetriesANdσ(p↑+p→+++anything)(1.
6)ThisisafundamentalmeasurementthatcanbeusedtotestthevalidityofthegaugeformulationofQCDinregionswherethefundamentaldegreesoffreedomcannotbeclearlyisolated.
Inthissense,CollinsconjugationcanbeformulatedinanalogytotheBohm-AharanovtestofthegaugeformulationofQED.
82.
SpinasymmetriesinBaryonproductionANdσ(p↑+p→B+anything)(1.
7)Theseasymmetriesinvolvemechanismscloselyrelatedtothoseresponsibleforthepro-ductionofbaryonswithpolarization(P)fromunpolarizedscatteringprocesses.
Pdσ(p+p→B↑+anything)(1.
8)Inclusivehyperonpolarization[Eq.
(1.
8)]wasstudiedexperimentallyinthelate1970satFermilab[27].
3.
ElasticScatteringSingleSpinAsymmetriesANdσel(p↑+p→p+p)(1.
9)ThiscouldtestthecombinationoftheBrodsky-Lepage[26]eectiveeldtheorywiththeChou-Yang[25]formulationofelasticscatteringinvolvingorbitingconstituents.
Itprovidesanindependentmeasurementofthemeanorbitalangularmomentumoftherotatingcharges.
4.
SpinasymmetriesininclusivepseudoscalarandvectormesonproductionANdσ(p↑+p→M+anything),(1.
10)whereM=π,K,η,η′,ρ,K,ω,φ.
Theseprocesseswerestudiedexperimentallyinthelate1980satFermilab[28].
MuchhigherintensitystudiescouldprovideamorepreciseunderstandingofCollinsfunctionsandprecisionmeasurementsoforbitaldistributions.
5.
Two-particlecorrelationsANdσ(p↑+p→φ++φ+anything)(1.
11)Non-resonanttwo-particlecorrelationscanbeusedtodistinguishbetweenasymmetriesthatoccurinthefragmentationprocess(Collinsfunctions)fromthosethatoccurintheproton'sdistributionorbitaldistributions(Siversfunctions).
Theseexperimentstakeadvantageoftheabilitytocombineaccuratemomentummeasurementswithparticleidenticationinxedtargetexperiments.
6.
SpinasymmetriesininclusiveJ/ψ,ψ′andCharmproductionANdσ(p↑+p→J/ψ+anything);ANdσ(p↑+p→ψ′+anything)(1.
12)LiketheDrellYanprocess,theseprocessesarefreefromimportantfragmentationasym-metriesandcanbeusedtomeasuregluonorbitaldistributionfunctionsand,hence,gluonorbitalangularmomentum.
Again,theaccesstoforwardkinematicsisanimmensead-vantageofxedtargetkinematics.
9Double-SpinAsymmetriesCombiningapolarizedbeamwithapolarizedtargetprovidesaccesstotwospinasymme-tries.
HereweonlymentionafewtransverseANNasymmetries,whichcouldbestudiedexperimentallyusingaMainInjectorpolarizedbeam:1.
Drell-Yan2-SpinExperimentANNdσ(p↑+p↑→+++anything)(1.
13)Thereisastrongprejudicethatantiquarktransversitiesareverysmall,butthisbeliefneedstobeconfrontedwithexperiment.
Inaddition,therearemanyotherasymmetriesinvolvingdierentangulardistributionsthatappearwiththeextradegreeoffreedom.
2.
High-P2⊥2-Spinproton-protonelasticExperimentANNdσelastic(p↑+p↑→p+p)(1.
14)Extendingtheseexperiments[4,11]totheP2⊥availableattheMainInjectorwouldprovideatremendousexpansionoftherangeinwhichtheBrodsky-Lepage[26]approachtoexclusiveprocesseshasbeenmeasured.
101.
4Physicswith120-150GeV/cpolarizedbeamsW.
Lorenzon,A.
D.
KrischA120-150GeVpolarizedbeamattheFermilabMainInjectorandaliquidhydrogentargetand/orasolidpolarizedprotontarget(PPT)couldallowawiderangeof1-spinand2-spinasymmetrymeasurements.
Particularlyinterestingwouldbe:Drell-Yan[22]scatteringexperimentswithatransverselypolarizedprotonsbeamonunpolarizedliquidhydrogentargets;andlarge-P2⊥elasticscatteringinviewofthestillunexplainedhugetransversespin-eectsat12to28GeV/cfoundattheZGS[29]andAGS[30].
Sometransverselypolarizedhadronmeasurementsinclude:theSiversasymmetriesinhighprecisionpolarizedDrell-Yanexperiments;the1-spinANand2-spinANNinlarge-P2⊥proton-protonelasticscattering;the2-spinproton-protontotalcrosssectionσtotANN;the2-spinDNNofΛ-hyperonpolarizationviaitsself-analyzingdecay;theleft-rightasymmetryinΣ0-productionorρ-production;theleft-rightasymmetriesininclusivepionandkaonproduction.
1.
PolarizedDrell-Yanscatteringhasbecomeamajormilestoneinthehadronicphysicscommunity,motivatedbyafundamentalpredictionofQCDthatpostulatesasignchangeintheSiversfunction[13]measuredinDrell-Yanscatteringascomparedtosemi-inclusivedeepinelasticscattering(SIDIS)[24,31].
EachquarkandantiquarkavorhasitsownSiversfunctiondescribedbyatransverse-momentumdependentdistributionfunctionthatcapturesnon-perturbativespin-orbiteectsinsideapolarizedproton.
TheexperimentalvericationofthesignchangegoestotheheartofthegaugeformulationofQCDandwouldfundamentallytestthefactorizationapproachtothedescriptionofprocessessensitivetotransversepartonmomenta.
Itwouldbecrucialtoconrmthevalidityofourpresentconceptualframeworkforanalyzinghardhadronicreactions.
13Figure1.
5:SchematiclayoutofthepolarizedDrell-Yanspectrometer.
Thepolarizedbeamentersfromtheleftandhitsa50-cmlongunpolarizedtargetbeforeitisstoppedinthe5-mlongsolid-ironmagnet.
11TheHERMES[32]andCOMPASS[33]experimentshavemeasuredsingletransversespinasymmetriesandperformedglobaltstotheSiversasymmetrieswithhighprecision.
Inordertomakeameaningfulcomparisonofshapeandsign,comparablemeasurementsareneededforsinglespinasymmetriesintheDrell-Yanprocess.
WhilemanyexperimentsaroundtheglobeaimtomeasurepolarizedDrell-Yaneitherwithapolarizedbeamorapolarizedtarget,noneofthemisoptimizedforDrell-YanexceptfortheSeaQuestdi-muonspectrometerattheFermilabMainInjector.
SeaQuestwilluse5-slongspillsof2·1012protons/seachminute(Iav=1.
6·1011protons/s)ona50-cmlongliquidhydrogen(ordeuterium)target(Np=2.
1·1024cm2).
Thisresultsinanaverageluminosityof3.
4·1035cm2s1andatotalintegratedbeamof3.
4·1018protonsontargetoveraperiodof2to3yearsofrunning.
ThebigattractionforapolarizedDrell-YanprogramattheFermilabMainInjectorisaspectrometerandhydrogentargetthatarewell-understood,fullyfunctioning,andoptimizedforDrell-YanattheendofdatacollectionfortheSeaQuestexperiment,showninFig.
1.
5.
Basedonthestudypresentedinthisreportandexperiencefromcurrentpolarizedionsources,itisexpectedthatanionsourcethatproduces1mAatthesourcecandeliverupto150nA(about1·1012p/s)totheexperimentbyusing30two-secondcyclesandslipstackingintotheMainInjector.
Assumingthat50%ofthetotalbeamtimeisallocatedtotheexperiment,aluminosityof1·1036cm2s1canbeobtained.
Itisimportanttonotethatevenifonly10%oftheavailablebeamtimewasallocatedtotheexperiment,aluminosityof2.
0·1035cm2s1isstillverycompetitive.
Inaddition,theSeaQuestspectrometeraccommodatesalargecoverageinx,i.
e.
,x1=0.
30.
9coveringthevalencequarkregion,andx2=0.
10.
5coveringtheseaquarkregion.
WhiletheSiversfunctioncanbemeasuredforboththevalencequarksortheseaquarks,seaquarkeectsmightbesmallduetocompetingprocesses,whilevalencequarkeectsaregenerallyexpectedtobelarge[34].
Thus,usingapolarizedbeammighthaveasubstantialadvantageoverapolarizedtarget.
Thecombinationofhighluminosity,largex-coverageandahigh-intensitypolarizedbeammakesFermilabarguablythebestplacetomeasureDrell-Yanscatteringwithhighprecision.
2.
Polarizedelasticscatteringcouldshednewlightonthenatureofthestrongin-teraction.
AsdiscussedintheattachedMarch1992PolarizedMainInjectorReport,onecoulddomanyxed-targetelasticpolarizedbeamexperimentswithveryhighluminosity.
These120-150GeV/cexperimentscouldusetheexistingMichigansolidPolarizedProtonTarget(PPT)whichoperatedattheAGSwithatime-averagedbeamintensityofover1011protons/sandpolarizationofabout85%.
Witha10%timeshareavailableforpolar-izedbeam,theexpected120-150GeV/cpolarizedbeamintensityof1·1012protonsperMainInjectorcycle,wouldgiveanaveragebeamintensityof1·1011protons/sscat-teringfromthissolidpolarizedtarget(Np=2·1023cm2);theproton-protonluminositywouldbeaboutL=2·1034cm2s1.
(1.
15)AhighqualityrecoilprotonspectrometercouldsimultaneouslyextendtherangeofAN,ANNandtheelasticcrosssectionintheunexploredlarge-P2⊥regionshowninFigs.
1.
1,1.
3and1.
6,andFig.
1.
4,respectively.
ApossibleplacementforthesolidPPTandalarge-P2⊥elasticrecoilspectrometerintheMesonHallisshowninFig.
1.
7.
Moreover,theexperimentwasoriginallyproposedforthe400GeV/cUNKwherethenon-elastic12backgroundwasconsiderablylarger;thus,therecoilspectrometermightbesignicantlyshortenedtotbetterintotheMesonHall,aswasdoneintheU-70Hall,afterUNKwassuspended.
TheseexperimentscouldrunsimultaneouslywiththeMainInjectorrunninginthepolarizedandunpolarizedmodeoninterspersedpulses.
These120-150GeV/cxed-targetspinexperimentsmayprovidefurtherjusticationfordevelopingpolarizationcapabilityatFermilab.
TheSPIN@FERMIcollaborationhasbeenveryinterestedin120-150GeV/clarge-P2⊥elasticproton-protonspinexperimentssincethe1980s.
Theluminosityof2·1034cm2s1shouldbeadequateforelasticscatteringouttoP2⊥of12(GeV/c)2.
Theexpectedpolarizedelasticeventratesperdayareabout:200000atP2⊥=2(GeV/c)2;40000atP2⊥=4(GeV/c)2;4100atP2⊥=6(GeV/c)2;480atP2⊥=8(GeV/c)2;80atP2⊥=10(GeV/c)2;20atP2⊥=12(GeV/c)2.
Wemightlaterincreasetheseeventratesby:increasingthepolarizedionsourceintensityabove1.
5mA;furtherimprovingthePPTforrunningwithhighbeamintensity.
3.
PolarizedLarge-P⊥inclusiveprocesses.
Measuringinclusivespineectsatthehigh-intensityMainInjectorcouldprovideaprecisenewprobeofthestronginteractionatverylargeP⊥.
Onecouldpreciselymeasure,atverylargeP⊥,the1-spintransverseasymmetries(AN)ininclusiveprocessessuchas:p↑+p→π±+anything,(1.
16)p↑+p→K±+anything.
(1.
17)Fig.
1.
8showstheunpolarizedinclusivejetdatafromtheD0andCDFdetectors[35].
Thesedataindicatethatjetsandthusprobablypions,kaonsandantiprotonscouldbepreciselymeasured,withhighaccuracy,atthemaximumP2⊥of54(GeV/c)2availableat120GeV/cand67(GeV/c)2at150GeV/c.
Unfortunately,itisverydiculttomeasurethe2-spininclusiveANNfromasolidpolarizedprotontarget(PPT)duetotheunpolarizedprotonsandneutronsintheNH3target'sbeads,andinthePPT'sheliumcoolantandbeadcontainer.
However,itisstraightforwardtomeasure1-spininclusiveasymmetries(AN)fromaliquidhydrogentarget.
NotethatbyaddingtwosimplethresholdCherenkovcounterstotheelasticrecoilspectrometershowninFig.
1.
7,onecouldpreciselymeasureinclusivecrosssections,aswasdonein1967-69attheZGS[36]andin1971attheISR[37].
Sincetheinclusivepion,kaonandantiprotonproductioncrosssectionsatlargeP2⊥arefarlargerthantheelasticcrosssectionsonecouldmakeratherpreciseANmeasurements,evenatP2⊥of50-70(GeV/c)2.
Then,thepredictionthatforinclusiveprocessesAN=0atlargeP2⊥couldbedenitivelytestedwithhighprecision.
13Figure1.
6:CompilationofallelasticANdataabove2GeV/cshowingrangeofpossibleSPIN@FERMIexperiment.
Figure1.
7:PossibleSPIN@FERMIexperimentlayoutintheMesonHall.
14Figure1.
8:Inclusivejetcross-sectionplottedagainsttransverseenergy[35].
4.
PolarizedTotalCrossSections.
TheMainInjectorpolarizedbeamcouldallowextendingthe2-spintransverseproton-protontotalcrosssectionσtotANNmeasurementsto120-150GeV/c.
Onecouldusethetraditionalbeamabsorbtiontechniquewithcircularscintillatorsofdecreasingradiusfollowedbyextrapolationoftheirmeasuredratesbacktozeroradius.
Thissimplemeasurement[38]wastherstpolarizedbeamexperimentwhenthepolarizedZGSbeamrstoperatedin1973.
Measuringσtotisfareasierinxedtargetexperimentsthanincolliderexperiments.
151.
5UpdatedSummaryofPolarizedBeamAccelerationM.
A.
Leonova,R.
S.
Raymond,A.
D.
KrischToacceleratepolarizedprotonsintheMainInjector,changesareneededinmostFermilabacceleratorstagesasshowninFig.
1.
9.
Someofthesechangeswerediscussedintheattached1992PolarizedMainInjectorReport[39];however,muchoftheinformationisnowoutofdate.
The"searchable"attached1995Report[40],whoserelevantsectionsarelistedbelow,containsmanymoredetails,whichcouldhelponetofollowthisbriefUpdatedReport.
Section3p.
49PolarizedBeamIntensitySection4p.
53PolarizedProtonAccumulationinRecyclerRingSection5p.
55HighIntensityPolarizedHSourceSection6p.
67RFQforpolarizedHSection7p.
85LowEnergyBeamTransportSection8p.
91BoosterResonanceCorrectionSection9p.
107MainInjectorSiberianSnakesSection12p.
147PolarimetersSection14p.
181SpinRotationinTransportLinesSection15p.
187ComputerControlsandInterfacesThemajornewitemsorchangesneededareshownbelowandsummarizedinthisUpdatedReport,wherewediscusspolarizedbeamaccelerationinthecurrentMainInjector.
Figure1.
9:MajoritemsneededforpolarizedbeamatFermilab.
16AcceleratorModications1.
PolarizedIonSource:Polarizedionsourcesnowhaveintensitiesof1.
0-1.
5mA[41,42].
EithertheformerIUCFAtomicBeamtype(ABS)polarizedionsource(whichisnowatDubna),orthereconstructedandimprovedZGS/AGSABS,couldprovide1mA.
2.
BeamTransportLinefrom35keVPolarizedSourcetoRFQ:PolarizedsourcecouldshareFermilab'snewRFQwithunpolarizedsourcesbyusingnewbendingmagnetstoswitchbetweensourceseachcycle.
Nodepolarizationifallbendsarehorizontal.
3.
RFQ:NodepolarizationinanRFQ;nochangesareneeded.
4.
BeamTransportLinefrom750keVRFQtoLINAC:Nochangesareneeded.
5.
35keV&400MeVPolarimeters:A35keVRHIC-typepolarimetercouldmonitorthesourcepolarizationduringunpolarizedcycles.
A400MeVbeam-linepolarimeterwitha0.
5mmcarbontargetcouldmonitorpolarizedcycleswith1%beamloss.
6.
BeamStackingandIntensity:Nochangesareneeded.
7.
400MeVLINAC:ThereisnodepolarizationinLINACs;nochangesareneeded.
8.
400MeVTransportLine:Depolarizationisonly0.
2%;nochangesneeded.
9.
8.
9GeV/cBoosterPartialSiberianSnake:Awarm4%partialsolenoidalsnake,usingtheBoosterpowersupplytooscillateat15HzwithaMaxB·dl1.
33T·mat8.
9GeV/c,shouldovercomeall15imperfectionresonances(Seep.
22).
Onecouldcompensatesmallbetatron-tuneshiftbyproperlyrampingringquadrupoles.
[TheAGSmayhaveausedsimilarmagnet.
][WeakcorrectordipolesmightinsteadovercometheratherweakimperfectionresonanceswhileimprovingtheBoosterbeamalignment.
]10.
8.
9GeV/cBoosterPulsedQuadrupoles:Twopulsedquadrupoles(3-10srisetime)shouldovercometheonefairlyweakintrinsicresonance.
11.
8.
9GeV/cTransportLinePolarimeters:FastrelativeandCNIcalibratedpolarimeters,sharingaCarbonorshlinetarget,couldmeasuretherelativepolarizationaftereachpolarized67msBoostercycle.
12.
8.
9GeV/cTransportLines:TheBooster-RRlinehasintermingledhorizontalandverticalbends;rotatorNEEDSMORESTUDY.
NodepolarizationinRR-MIline.
13.
8.
9GeV/cRecyclerRing:Operatingpointfarfromanyresonance(Seep.
22).
14.
120-150GeV/cMainInjectorSiberianSnakes:TwosuperconductingSiberiansnakesinMainInjectorshouldmaintain95%ofinjectedpolarization.
ThesnakesmustbeonoppositesidesofMIwithorthogonalspinrotationaxes.
Thesnakeorbitexcursionsmusttinsidethesnakemagnets'IDat8.
9GeV/cinjection.
15.
120-150GeV/cPolarimeters:RelativeandCNIpolarimetersinthe120-150GeV/ctransportlinesharinga0.
3mmcarbonorshlinetargetcouldmeasurethebeampolarizationduringpolarizedcycleswith3%beamloss.
ThefastpolarimetercouldbecalibratedagainsttheCNIpolarimeter,and/orthePolarizedProtonTargetbymeasuringsimultaneouslyelasticANfromthebeamandtarget(Eq.
1.
1).
[Internalpolarimetersmaybepossiblewithavery-fast-pulsed-valvehydrogenjettarget.
]16.
120-150GeV/cTransportLineSpinRotators:Asuperconducting60spinrotatormaybeneededtocorrectforthespinrotationduetotheintermingledhorizontalandverticalbendsinthetransferline.
NEEDSMORESTUDY.
17.
ComputerControlsandInterfaces:Controlsforallpolarizedbeamhardwaremustbeinterfacedwithmainacceleratorcontrolcomputer.
17ProcedureforacceleratingpolarizedprotonsSeaQuestmightprefertwo3-secondorthree2-secondpolarizedcyclesperminute.
How-ever,itmightbemostpracticaltoswitchfromunpolarizedtopolarizedcyclesforoneminuteonceeverytenminutes.
Thiswouldalsogivethepolarizedbeam10%ofthebeam-timeandtheunpolarizedbeam90%.
Itsmostimportantadvantageoverswitchingonceperminute,isthatitwouldreducetheswitchingfrequencytenfoldandallowfarslowerswitchingtimesfortheswitchingmagnetsbeforetheRFQandmostimportantlymuchslowertimeforswitchingthepolarimetertargetsinandoutofthebeams.
Goingfrom50mstoperhaps1swouldsignicantlyincreasetheswitchinghardware'slifetimeandreduceitscost.
Itwouldalsoreducethetargets'oscillationsaftereachswitch,whichwasasignicantprobleminrecentexperimentsatCOSY[43].
The2secondsofswitchingtimecouldbechargedtothepolarizedbeamtime.
Thefollowingshouldbedonetotunethepolarizedbeam(onceaftereachshut-down):a.
TurnonthepolarizedHionsourceandmeasurethepolarizationatthe35keVLamb-ShiftPolarimeter.
Tunethepolarizedsourcetomaximizethepolarization.
b.
AdjusttheswitchingmagnettoinjectpolarizedratherthanunpolarizedHionsintothemainlowenergybeamtransport(LEBT)linetotheRFQandLINAC.
c.
Measurethepolarizationat400MeVwithacarbon-targetpolarimeter.
d.
TurnontheBoosterpartialsnakeandadjustitsrampandthetimingofthepulsedquadrupolestomaximizethepolarizationmeasuredbythe8.
9GeV/ctransportlinepolarimeters.
e.
TurnonthetwoMainInjectorsnakesandmeasurethepolarizationinthetwoMainInjectorinternal(orpossiblyextractedbeam)polarimeters.
Adjustthesnakecurrentstogethertomaximizethepolarization.
[ThetwocoldsuperconductingMainInjectorSnakesstayONduringbothpolarizedandunpolarizedcycles.
]f.
Adjustforslowextractionintothespinexperimentalarearatherthanfastextrac-tionintotheneutrinoproductionline.
g.
Adjustthespinrotatorinthe120-150GeVtransportlinetogivetheproperspindirectioninthespinexperimentalarea.
Measuretheextractedpolarizationusingabeamlinepolarimeter.
h.
Recordthemagnets'settingsintoaseparateleforapolarizedbeamcycle.
.
Thefollowingwouldbedoneduringoperationforswitchingbetweenpolarizedandun-polarizedcycles:a.
AdjusttheswitchingmagnettoinjectpolarizedionsintothemainLEBTlinetotheRFQ.
b.
Loadthecyclesettingsforapolarizedbeam(withasnakerampandquadrupolepulseintheBooster,andaat-topintheMainInjectorwithslowextractionintothespinexperimentalarea).
c.
Set400MeVand8.
9GeVpolarimetertargetstoswitchintobeamonlyonpolarizedcycles,ifneeded.
d.
AdjusttheswitchingmagnettoinjectunpolarizedionsintothemainLEBTlinetotheRFQ.
e.
Loadthecyclesettingsforanunpolarizedbeam.
181.
6SummaryofNeededPolarizedHardware1.
PolarizedIonSourceThesourceshouldproduceahighintensityH↑ionbeamusingBelov-type[41]Deu-teriumchargeexchangefromagroundstatetypeH↑atomicbeamstage.
Intensity:1.
0mAPulseLength:40100sPolarization:morethan75%Emittance:1.
5πmm-mradOutputEnergy:35keVPulseFrequency:15HzProductionTime:1224monthsRemarks:Thisisaspecializedhighmaintenancedevice;FermilabstashouldbeintegratedearlyintotheH↑sourceprogram.
EstimatedCost:$600,0002.
BeamTransportlinefrom35keVpolarizedsourcetotheRFQ.
NormalizedEmittance:0.
3πmm-mradVacuum:107TorrHardware:VacuumPipeandVacuumPumpsFocusingQuadrupolesandEinzellensesBunchers(1or2)SwitchingMagnet(1-3HzbetweenH↑lineandunpolarizedlines)BuildingModicationTime:3months;EstimatedCost:$100,000ProductionTime:12monthsEstimatedCost:$100,0003.
RFQTheradiofrequencyquadrupolepreaccelerator(withpowersupply)shouldaccel-erate35keVionstotheLINACacceptanceenergy.
Energy:35keVto750keVFrequency:201.
25MHzIonType:polarizedHTransmissionEciency:98%MaximumCurrent:50mACavitylength:163cmMinimumradius:2.
6mmNormalizedEmmittance:0.
3πmm-mradIntervaneRFVoltage:67kVRFPower:100kWProductionTime:12or0monthsEstimatedCost:$400,000or$04.
BeamTransportlinefrom750keVRFQtoLINAC.
ProductionTime:Nochangeneeded.
EstimatedCost:$0195.
35keVand400MeVPolarimetersThesepolarimeterscouldmeasurethetransport-linepolarizationbeforetheRFQandaftertheLINAC.
EnergyandType:35keV:Lamb-shift(killsbeam;useduringunpolarizedcycles);400MeV:p+C→p+C(kills1%ofbeam)Detectors:35keV:QuenchinstrongE-eld;measureLyman-αphotons;400MeV:ScintillatorsPolarizationMeasurementAccuracy:35keV:2%in10sec;400MeV:2%in1minProductionTime:12monthsEstimatedCosts:35keV:$100,000;400MeV:$100,0006.
BeamStackingandIntensityOnecouldusesomethingliketheunpolarizedstackingprocedureforpolarizedions:40spulsesat15HzrepetitionrategoingintotheLINACandinjectedintotheBoosterfor12turns;then6BoosterpulsesinjectedintotheRecyclerRingfollowedby6morepulsesusing"slip-stacking";theninjectionintotheMainInjectorring.
Energy:400MeVinjectionintoBooster;8.
9GeV/cstackinginRRandMI.
PolarizedBoosterPulseIntensityEstimate:(46-turn-injection)1.
0mA*100s*6.
24·1018protons/C=6.
2·1011protons;(18-turn-injection)1.
0mA*40s*6.
24·1018protons/C=2.
5·1011protons;(12-turn-injection)1.
0mA*26s*6.
24·1018protons/C=1.
66·1011protons.
MIPulseIntensityEstimate(2*6=12BoosterPulsesand95%transf.
ec.
):with100ssourcepulse:7·1012protons;with40ssourcepulse:2.
8·1012protons;with26ssourcepulse:1.
9·1012protons.
With10%polarized-beam-time,onecouldoptimizetheinstantaneousandaverageintensitiesbyvaryingthepolarizedpulses'duration,frequency,andsequencing:a.
with100ssourcepulse:nineteen3-secpulsesevery10thminutewithat-topof31.
5=1.
5secandslowextractiontimeof1.
5secgivinginstantaneousintensityof4.
7·1012p/secandaverageintensity13·1012p/min.
b.
with26ssourcepulse:two3-secpulseseveryminutewithat-topof31.
334=1.
666secandslowextractiontimeof1.
66secgivinginstantaneousintensityof1.
1·1012p/secandaverageintensity3.
8·1012p/min.
c.
with26ssourcepulse:three2-secpulseseveryminutewithat-topof21.
334=0.
666secandslowextractiontimeof0.
66secgivinginstantaneousintensityof2.
9·1012p/secandaverageintensity5.
7·1012p/min.
Nochangesneeded.
EstimatedCost:$07.
400MeVLINACThereisnodepolarizationinLINACs;nochangesneeded.
EstimatedCost:$08.
400MeVTransportLineDepolarizationisonly0.
2%;nochangesneeded.
EstimatedCost:$0209.
8.
9GeV/cBoosterPartialSiberianSnakeArampedwarmsolenoid4%partialsnakeshouldovercomeall15imperfectiondepolarizingresonancesatGγ=3to17(Seep.
22).
Trytorunatνy=6.
7.
Energy/Momentum:400MeVto8.
9GeV/cMagneticFieldIntegral:sinewavewithamplitudeincreasingfrom0.
14to1.
33T·mAmpereTurns:106maximumMaximumCurrentDensity:823A/cm2CoilDimensions:InnerRad:4.
6cm;OuterRad:16.
3cm;Length:156cmWireDimensions:12mm*12mmwith5mmdiamwaterpath1080turns(9layers*20turns)SolenoidParameters:L20mH;R110mPowerSupply:BoosterPowersupplyprovidescurrentrampedat15HzintoaspecialsolenoidcircuitwithC8.
5mF;PeakVoltage1kV;AveragePower45kWProductionTime:12months[TheAGSmayhaveausedsimilarmagnet.
]EstimatedCost:$200,00010.
8.
9GeV/cBoosterPulsedQuadrupolesTwopulsedquadrupoles(withceramicvacuumchambersandapowersupply)couldjumptheBooster'sintrinsicdepolarizingresonance(Gγ=0+νy)nearγ=3.
79.
Onecoulduseormodify2ofthe15AGSPulsedQuadrupoles(builtbyMichigan)andpossibly1or2oftheirpowersupplies(builtbyBrookhaven).
Energy:T=2.
56GeV(P=3.
36GeV/c)Risetime:3s(300sfalltime)Tuneshift:νy=0.
2FieldGradient:1.
38T·m1Geometry:3.
5cminsideradius*50cmlongInductance:5HPowerSupply:4.
3kV,1.
3kAforbothquadrupolesProductionTime:12monthsEstimatedCost:$100,00011.
8.
9GeV/cTransportLinePolarimeterFastrelativeandcalibratedCNIpolarimeterscouldmeasurethebeampolarizationaftereach67msBoosteraccelerationcycleusingp-Carbonandp-pelasticandquasielasticasymmetriesandCNIasymmetries,respectively(seeItem15).
Energy/Momentum:8.
9GeV/cTarget:ProbablymovingCH2shlineorcarbonberDetector:ScintillatorsPolarizationMeasurementAccuracy:3%in4minsProductionTime:12monthsEstimatedCost:$200,00012.
8.
9GeV/cTransportLinesNEEDSMORESTUDYNodepolarizationinRR-MainInjectorline.
Booster-RRlinehasintermingledhorizontalandverticalbends;needsspinRotator.
EstimatedCost:$100,0002113.
8.
9GeV/cRecyclerRingNohardwarechangesareneeded,butoneshouldchangetheRR'sνytobetteravoidtheGγ=24νyintrinsicresonance,whichisneartheRR'sxedγof9.
536.
ThenearbyGγ=17imperfectionresonanceatγ=9.
483maybeaproblemthatNEEDSMORESTUDY.
EstimatedCost:$0Table1.
1:FermilabBoosterdepolarizingresonances.
[40]νsγT(GeV)31.
6730.
6310.
0001042.
2311.
1550.
0001452.
7891.
6780.
0002663.
3472.
2010.
0011073.
9052.
7250.
0018084.
4623.
2470.
0004895.
0203.
7710.
00005105.
5784.
2940.
00013116.
1364.
8180.
00027126.
6945.
3410.
00022137.
2515.
8630.
00040147.
8096.
3870.
00042158.
3676.
9100.
00030168.
9257.
4340.
00206179.
4837.
9570.
01010K=0+νy3.
7812.
5490.
0132K=24-νy9.
6118.
0640.
0474Figure1.
10:Boosterimperfectiondepolarizingresonancestrengthsand1%depolarizationline.
[40]2214.
120-150GeV/cMainInjectorSuperconductingSiberianSnakesTwoSiberiansnakes[44,45,46]eachcontaining4superconductingtransverseDCheli-caldipolemagnetscouldovercomealldepolarizingresonancesintheMainInjectorbyrotatingthespinby180aboutahorizontal45axis.
ThetwosnakesmustbeplacedonexactlyoppositesidesoftheMainInjectorring,probablyintheMI-30andMI-60straightsections.
Moreover,toovercomestrongdepolarizingresonancesthespinrotationaxesofthetwosnakesmustbeorthogonal;forexample,theiraxescouldbe+45and45fromlongitudinal.
Notethatsincetheyaresuper-conducting,onemustcertifytheMainInjectortunnelforcryogenicliquids.
Wehavecomeupwith2dierentsnakedesignswhicharedescribedbelow.
BotharebasedonthecleverandecientRHIC4-helicaldipoledesign[47,48],whereall4helicesareofequallengths,withtheinnerpairofhelicesatequalhighB-eldsandtheouterpairatequallowerB-elds.
Moreover,eachofthe4dipoleshasthesame360helicalrotation.
Ournewdesign[49]isbasedonmodifyingtheRHICdesignbymakingtheinnerpairshorterthantheouterpair,sothattheupanddownverticalbeamexcursionsareexactlyequal.
Thisminimizestheinsidediameterofthesnakesandthussignicantlyreducestheircost.
Thesetwonewsnakedesignsseemquiteinteresting.
Thesnakesarefairlyshortwithrathersmallorbitexcursions,asdiscussedbelow.
The6"ID/Bmax=5TsnakeswouldrequirelesstimeandR&D;theyhavethesameIDastheMainInjector;thus,theyseembestfromsomepointsofview.
However,the4"ID/Bmax=8Tsnakeswouldbeshorter,andspaceforasnakeinMI-60maybeanissue.
Moreover,itcouldserveasaninexpensivepilotprojectforusingsuperconductingNiSnmagnetsinhighenergyacceleratorswithafactorof2000lessNiSncablethanthe27kmLHC.
Figure1.
11:Snakeswith(LEFT)4"IDandBmax=8Tand(RIGHT)6"IDandBmax=5T.
23TwoPossibleSiberianSnakeDesignsDescription6"IDandBmax=5T4"IDandBmax=8TSpinRotationAxis4545NumberofHelicalDipoles44HelicalDipole'sLengths3.
108m(2)&1.
934m(2)1.
943m(2)&1.
548m(2)TotalSnakeLength11.
6m7.
8mBmax5T8TMaxHorExcursion31.
7mm19.
8mmMaxVertExcursion49.
8mm31.
2mmMagnetAperture6"ID(152mmID)4"ID(100mmID)Momentum:8.
9GeV/cto120-150GeV/cProductionTime:24monthsEstimatedCost:$600,000(basedonRHICsnakecost)15.
120-150GeV/cTransport-Line&PossiblyInternalPolarimetersTwotransport-linepolarimeterspointedatonetargetcouldmeasurethebeampo-larizationaftereachpolarizedMIaccelerationcycle.
Onepolarimetershouldbefastbutonlyrelativelycalibratedforbeamtuning.
Theotherpolarimetercouldbeslowbutshouldbeabsolutelycalibrated.
AfastrelativeandaCNIpolarimeterinthe120-150GeV/ctransportlinesharinga0.
2mmcarbonorshlinetargetcouldmeasurethebeampolarizationaftereachpolarizedcyclewith2%beamloss.
ThefastpolarimetercouldbecalibratedagainsttheCNIpolarimeter,[and/orthePolar-izedProtonTargetbymeasuringsimultaneouslytheelasticANfromthebeamandtarget(SeeEq.
1.
1)].
TheCoulombNuclearInterference(CNI)polarimeterwouldmeasuretheleft-rightasymmetryinproton-protonelasticscatteringintheCNIregion[50][P2⊥0.
003(GeV/c)2]usingverysmallrecoilhodoscopesverynear90lab.
TheFastpolarimetercoulduse2smallscintillatorarmstodetectp-Carbonandp-pelasticandquasielasticscattering.
[InternalfastandCNIpolarimetersmaybepossiblewithvery-fast-valve-pulsedhydrogenjettarget.
]ProductionTime:12monthsEstimatedCost:$200,000transportline+$200,000internal16.
120-150GeV/cTransportLineSpinRotatorNEEDSMORESTUDYThereissignicantspinrotation(perhaps60)intheMItoexperimentalareastransferlines.
Thiscouldbecompensatedbyacoldhelicalspinrotatorinthe120-150GeV/ctransferline.
Therotatorwouldbesomewhatsimilartotheeight90rotatorsinRHIC.
ProductionTime:24monthsEstimatedCost:$300,000(basedonRHICrotatorcost)17.
ComputerControlsandInterfacesControlsforallpolarizedbeamhardwaremustbeconvenientlyandreliablyinter-facedwiththemainacceleratorcontrolcomputer.
ProductionTime:12monthsEstimatedCost:$200,000241.
7HardwareInstalationandScheduleThebelowscheduleassumesthat:1.
thefundingdecisionforthispolarizedbeamprojectismadebyDecember2011;2.
theIUCFpolarizedsourcenowatDubnawillbeavailable;3.
Brookhavenwillhelptobuildthesuperconductingsnakesandrotator;4.
theswitchingmagnetsandvacuumpipesforthepolarizedsourcewillbeinstalledalongwiththeRFQ;5.
theusedAGSpartialsnakeandpulsedquadrupoleareavailable;6.
theionsourcearea(orsomenearbyarea)isaccessibleduringMIrunning.
ThenonecouldinstallsomeofthenecessaryhardwareduringthepresentlyplannedFY2012MainInjectorupgradeperiod.
AsshowninFig.
1.
12,about2yearsseemsanappropriatetimeforthepolarizedbeamengineeringdesignandfabrication.
Apossiblecommissioningsequenceis:a.
Thepolarizedionsourceisacriticalpathitem.
ItshouldbeobtainedpromptlyifDubnaagreestosellorleasetheformerIUCFsource.
Thenitcouldbeinstalledandcommissionedduringthelongshutdown.
[Ifnot,thereconstructedZGS/AGSpolarizedsourcemightbereadybylate2013.
Thenitcouldbeinstalledandcom-missionedduringthe2014summershutdown.
]b.
Thepolarizedsource's35keVtransportlines,andthesourceswitchingmagnetsshouldbefabricatedandinstalledalongwiththeRFQ.
c.
The35keVpolarimetercouldthenbeinstalledandcommissionedalongwiththepolarizedsource.
d.
The400MeV,8.
9GeV/candhopefullytwo120-150GeV/cpolarimeterscouldbefabricatedbyearly2013.
Thentheycouldbeinstalledandcommissionedduringthe2013Summershutdown.
e.
TheBooster'spartialsnakeandfasttune-jumpingquadrupolesshouldbeobtainedpromptly.
Theycouldthenbeinstalledduringthelongshutdown.
ThentherecouldbeBoosterpolarizedbeamstudies,involvinginjection,acceleration,andextractionduringthe2013Summershutdown.
f.
ThesuperconductingSiberiansnakesand60rotatorarethesecondcriticalpathitem.
TheyshouldbeobtainedpromptlyifBrookhavenagreestofabricatethem.
Thentheycouldbeinstalledandcommissionedduringthe2014Summershutdown.
g.
Duringlate2014polarizedprotonscouldbeinjectedintotheMainInjectorforcommissioninginthe10%ofbeam-timemode.
251.
8CommissioningTheFermilabpolarizedbeamcommissioningmightbesomewhatsimilartotheAGSpolarizedbeamcommissioning[30],wherethepolarizedprotonsource,the750keVRFQandthe200MeVLINACwerersttunedusinga200MeVpolarimeter.
Thepolarized200MeVLINACbeamwasthentransportedtotheAGSandaccelerated.
IntheFermilabBooster,thepartialsnakeshouldpreventdepolarizationbytheimperfectionresonancesandthefasttuneshiftingquadsshouldovercometheintrinsicdepolarizingresonances.
Weexpecttomaintainthefullsourcepolarizationof75%-80%duringaccelerationintheBoosterandtransporttotheMainInjector.
WewouldthenmeasuretheMainInjectorpolarizationduringandafteraccelerationandmaytuneitsSiberiansnakesifnecessary.
WemayalsoadjusttheMainInjectororbits,tunes,andchromaticitytomaintaingoodemittance,intensity,andpolarization.
Polarizedbeamwouldthenbeextractedandtransportedtotheexperimentalareas;thebeamtransportlinerotatorswouldthenbetuned.
ThisitemNEEDSMORESTUDY.
26NeedsMoreStudy25August2011A.
D.
Krisch/D.
A.
Nees/M.
A.
Leonova91011121234567891011121234568910111212345689101112123456789101112FermilabShut-DownSchedule1.
PolarizedIonSource2.
35keVTransportLine:PIS-RFQ3.
RFQnomodificationsneeded4.
750keVTransportLine:RFQ-LINACnomodificationsneeded5.
35keVPolarimeter400MeVPolarimeter6.
BeamStackingnomodificationsneeded7.
400MeVLINACnomodificationsneeded8.
400MeVTransportLine:LINAC-Boosternomodificationsneeded9.
8.
9GeV/cBoosterSiberianSnake10.
8.
9GeV/cBoosterPulsedQuads11.
8.
9GeV/cPolarimeter12.
8.
9GeV/cTransportLines:Booster-RRNeedsMoreStudy8.
9GeV/cTransportLines:RR-MInomodificationsneeded13.
8.
9GeV/cRecyclerRingoperateatslightlydifferentverticalbetatrontune14.
120-150GeV/cMainInjectorSiberianSnakes15.
120-150GeV/cPolarimeters16.
120-150GeV/cTransportLineSpinRotatorNeedsMoreStudy17.
ComputerControlsFermilabShut-DownsObtainorFabricateDecisionInstallFinalDesignCommissionPOSSIBLEPOLARIZEDBEAMPROJECTCHART7CalendarYears720152011201220132014Figure1.
12:PossibleProjectChart.
271.
9EstimatedBudgetPreaccelerator$0.
9MPolarizedHionsource$0.
6M35keVpolarimeter$0.
1MRFQandpowersupply(35keVto750keV)$0.
0MBeamlines,switchingmagnets&vacuumsystem$0.
1MBuildingModication$0.
1M400MeVLINAC$0.
1M400MeVpolarimeter$0.
1M8.
9GeV/cBooster$0.
6MSolenoidpartialSiberiansnake(rampedwarm)$0.
2MTwo3secpulsedquadrupoleswithpowersupplies$0.
1M8.
9GeV/cpolarimeter$0.
2M8.
9GeV/ctransferlinespinrotator$0.
1MMainInjector$0.
9MTwoHelicalSiberiansnakes$0.
6MPowersuppliesforsnakes$0.
1M120-150GeV/cpolarimeters(CNI&Inclusive)$0.
2M120-150GeV/cTransferLine$0.
5M120-150GeV/cpolarimeters(CNI&Inclusive)$0.
2M120-150GeV/ctransferlinespinrotator$0.
3MMiscellaneous$0.
2MComputers,controlmodules,cables,andinterface$0.
2MMainInjectorsubtotal$3.
2MContingency(25%)$0.
8MMAININJECTORTOTAL$4MTheestimateforthetotalcostofobtaining120-150GeV/cpolarizedprotonbeamcapabilityatFermilabisgivenin2012Dollars.
1.
10SummaryWitha50cmlongliquidhydrogentargetand10%ofthebeamtime,thetime-averagedpolarizedbeamluminosityfortheMainInjectorcouldprobablybeabout2·1035cm2s1orhigher.
Thispolarizedluminosityshouldallowprecisemeasurementsofspin-asym-metriesouttoP2⊥of50-70(GeV/c)2forinclusivehadronproduction.
Theworld'shighestintensitypolarizedprotonbeamwitha50cmhydrogentargetwouldalsoallowprecisestudiesofpolarizedDrell-Yanprocesses.
Withasolidpolarizedprotontarget,itcouldalsoallowhigh-precision1-spin,2-spinandspin-averagedstudiesofviolentelasticproton-protoncollisionsouttoP2⊥ofatleast12(GeV/c)2-afundamentalprobeofthestronginteraction.
Thetotalcostofprovidinga120-150GeV/cpolarizedprotonbeamcouldbeabout$4Millionandthetimeneededforproducingtheneededhardwarecouldbeabout24monthsfromthetimeofapprovalandfunding.
28References[1]J.
M.
Mossetal.
,DraftLetterofIntent,10May1995.
[2]P.
R.
Cameronetal.
,Phys.
Rev.
RapidComm.
D32,3070(1985);D.
G.
Crabbetal.
,Phys.
Rev.
Lett.
64,2627(1990).
[3]C.
A.
Aidala,Proc.
of18thInt.
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