overview - Thomas Jefferson National Accelerator …A magnet chicane directs the CEBAF electron beam...

HPSOverviewS.Stepanyan(JLAB)HPSUpgradeERR

June12,2017,JeffersonLab

EXPERIMENT AT JLAB

Outline• Introduction• HPSperformanceduring2015and2016engineeringruns

• Statusofdataanalysis• Whyupgrades(#1)• HPSsetupfor2018run(#1,#2)• BeamlinewithCLAS12(#2)• Expectedradiationlevels(5)• Documentation(#6)• Summary

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S.Stepanyan,HPSUpgradeERRJune12,2017,JeffersonLab

CosmologicalEvidencesforDarkMatter


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rotationalspeedofspiralgalaxies

gravitationallensing

Allobservationscan[only]beexplainedinacoherentmannerifthegravitationaleffectofahugeamountofnon-baryonicmatter[darkmatter(DM)]isassumed

CMB

TheVectorPortaltoHiddenSector4

S. Stepanyan, HPS Upgrade ERR June 12, 2017, Jefferson Lab

ε 2 =!αα

a isthefine-structureconstant

Thesimplestcase,aheavyparticlethatischargedunderbothEMandDMcharges,andcouplestotheStandardModelphotonthroughthekineticmixing.

!A

B.Holdom,Phys.Lett.B166,196(1986).


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Fixedtargetexperiments:kinematics

J.D.Bjorken,R.Essig,P.Schuster,andN.Toro,Phys.Rev.D80,2009,075018

HPS in Hall B SiVertexTrackerInstalledFeb23,2015

PbWO4Ecal InstalledSeptember,2014

AmagnetchicanedirectstheCEBAFelectronbeamontoaWfoil.Producede+e- pairsaretriggeredbyPbWO4 Ecal andmomentumanalyzedbythe Sivertextrackerinsidetheanalyzingmagnet.

e-


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HPSExperiment


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0.001 0.01 0.1 110-11

10-10

10-9

10-8

10-7

10-6

10-5

10-40.001 0.01 0.1 1

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

mA' HGeVL

a'êa

APEXêMAMITest Runs

U70

E141

E774

am, 5s

am,±2s favored

ae

BaBar

KLOE

Orsay

Bumphuntregion

Displaceddecayvertexsearch

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Beam’sEyeViewoftheSVTinsidethevacuumchamber

SiLayerIisonly10cmfromWtargetandhasonly1mmgapbetweentopandbottommodulesfor~1012/secelectronsgothrough

HPSEngineeringruns,spring2015and2016


HPSEngineeringRuns


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Twosuccessfulruns:• Spring2015:50nA,1.056GeVelectronbeam(nightandweekendrunning)-SVTintwoconfigurations,edgeat1.5mmand0.5mm-10mC accumulatedchargeateachSVTposition(1.7PACdays)

• Spring2016:200nA,2.3GeVelectronbeam(weekendrunning)-92.5mC accumulatedchargewithSVTat0.5mm(5.4PACdays)

BeamlinePerformance


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• Highqualitybeamwasdeliveredwiththeverticalbeamsizeof14µm

• Thebeamhalowasassmallas10-5

• Theverticalbeampositionwasmaintainedwithin20µmthroughouttherunbythebeamfeedbacksystem

• Nochangesinthebeamcontrolormonitoringisexpectedforthenextrun

ECal Performance


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• Lead-tungstatecalorimeterwith44216cmlongcrystals(1.3x.1.3cm2 crosssection)withAPDreadout(HamamatsuS8664-1010)

• Allchannelsworked,maxratearoundtheelectronbeamexit~1MHz• Initialcalibrationswithcosmicmuons wassufficientforthetriggersetup• Goodenergy/time

resolution• 2-clustertimecoincidence

leaves<1%accidentals• efficiencymeasured

~100%• ProvidedtriggerforDAQ,

with>95%efficiency(includesclusterreconstructionandpositionandenergyanalysis)

• NochangestoEcal willbemadeforthenextrun

SVTPerformance


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• TheedgeofL1isat0.5mmfromthebeam• L1occupancy≤1%,hitefficiency>95%• Momentumresolution~7%at1GeV• Themassresolutionwithin10%ofsimulation

-MollerM(e-e-)usedasbenchmark• Vertexresolutionasexpected

StatusofDataAnalysis

• 2015datahavebeenfullycalibratedandprocessed• Issueswitheventgeneratorshavebeenfixed:

– replacedMG4 withMG5,normalizationimprovedand– fixedtargetFFissueanduseofwronga value– movewide-anglebrem.generationtoMG4becauseofwrongtreatmentofthescatteredelectronin

EGS5

• Radiative tridentfractioniscorrectlyextracted


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• Detectorefficiencies wellunderstood,goodagreementbetweenMCanddata

• Twostudentsgraduatedusing10%unblinded sample

• Full2015bumphuntunblinded andapproved

• FirstbumphuntresultshavebeenpresentedatJLABseminar

2015BumpHuntResults


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2s limit

Finalmassspectrum,0.5MeVbins

ε2 =Smax ⋅ δmf ⋅ ΔB ⋅m %A

&

'((

)

*++×

2Neffα

3π

&

'((

)

*++

Smax −powerconstrainedupper limit

f − radiative tridentfractionα − fine structure constantNeff = 1 −decay fraction to the SM model particles

ΔB − background/MeVδm −mass resolutionm %A − %A mass

Analysisnoteisinpreparationsforthereview.ExpecttosubmitthefirstHPSphysicspublicationthisfall.

WhyUpgrades(#1)


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• Analysis of the HPS engineering run data showed worse than expected reach in both the bump hunt and the vertexing searches.

• These reach discrepancies between what we had projected in our proposal and what we measured experimentally were traced to two mistakes : 1.we did not account for the ”electron hole” in the ECAL acceptance. Nine

modules were removed from the crystal rows nearest to the beam for each of the top and bottom ECAL halves because they suffered very high rates from scattered beam electrons. As it turns out, almost half of the pairs in our rough acceptance have the electron ending up in that hole, so they have been missing in our nominal trigger. Our pairs-1 trigger requires a coincidence of two clusters, one in each of the top and bottom ECAL.

2.In the proposal for vertexing reach we had assumed constant acceptance for decay lengths out to 10 cm for electron-positron pair detection. The fall-off in efficiency for decays that occur more than 3 cm downstream of the target had not been properly accounted for.

ProposedUpgrades(#1)


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• In order to mitigate these losses in our reach, two modest upgrades to the existing HPS setup are proposed:

1. Move Layers 2 and 3 closer to the beam and add a new layer, Layer-0, 5 cm downstream of the target. L0 will improve vertex resolution by x2 so the vertex cut will be closer to the target§. The L2 and 3 move will improve efficiency of reconstruction for decays far downstream of the target.

2. Add scintillation counter in front of the ECal on the “positron” side to be used in the trigger to triggering on positrons only. The single arm trigger will allow to recover electrons lost the ECal hole.

Proposed upgrades will not change beamline or beam delivery procedures, nor radiological conditions in the Hall and around the HPS setup in downstream alcove. Upgrade will not affect Ecal, DAQ, slow controls.

§Layer-0wasproposedandbeingplannedbeforeweknewwehadlostreachfromthemistakesintheproposal.

HPSconfigurationfor2018run(#1)


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ECal

L0

SVT Hodoscope

HPSBeamline


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Faraday&cup&

Beam&viewer&

Photon&beam&dump&

Beam&blocker&

BPM&2H02&Harp&2H02A&

SVT&collimator&

Chicane&D1&

Chicane&D2&Spectrometer&&

Halo&monitors&

HPS&setup&dipole&

Halo&monitors&

• TogofromtheCLAS12operationstoHPSthefollowinghastobedone:– removebeampipeinthealcove,moveHPSmagnetstotherunningposition– connectvacuumchamberstothebeampipes– install2H02BPMandtheHPSSVTcollimator– movecleanupcollimatorand2H01harptotheHPSlocation(willbecome2H02Aharp)

BeamlinewithCLAS12(#2)


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• CLAS12usesthesystems(beamtransport,monitoringandcontrols)usedbyHPSfortheengineeringrun.

• BeamlinechangesforCLAS12aremainlyinaddingmoreshieldingandcollimators:– ashieldingontopofthetaggerdipoleyoke– tungstenshielddownstreamoftheCLAS12target,andthroughthetorusbore– poly.blocksforneutronshieldingdownstreamofthecollimatorbox– additionalcollimatorshavebeenaddedinthecollimatorbox

• Theonlychangeinbeamopticscontrolsisthepositionofthe2H00girderonthespaceframe.Itwillbe3metersupstreamfromitsoriginalposition(10%increaseofthedistancetotheHPStarget)thatwillnothaveimpactonbeamfocusingattheHPStarget.

• ThebeamfastshutdownsystemforCLAS12usesthenewFSDmodules,withmuchimprovedhardwareandfirmware.Thenewsystemworksthesameway,acceptssignalsfromhalocounterandwillallowtochoseshortertriptimes(<1ms)thantheoldone.

• Thenewbeampipethroughthetaggermagneteliminatestheneedtopumpdownthetaggervacuumchamberthatwillprovidebetterbeamvacuuminthatregion.

Hall-BBeamlineUpstreamoftheTarget

Hall-BDownstreamBeamline

Shielding

2H00Quadrupolesandcorrectors

Collimator

BPM2H01 Harp

2H01A

Beamviewer

Beamblocker

Faradaycup

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Collimator

AllbeamlinedeviceshavebeenusedduringHPSandPRad

Hall-B beamline: 2H-line

Thisconfigurationisfortheengineeringrun.ForHPS,2H01Aharpwillbere-locatedinfrontofthefirstchicanedipole

Theonlynewelement,willbeinstalledbymidDecember


Poly.blocks

HPStoCLAS12(#2)


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• TogofromtheCLAS12operationstoHPSthefollowinghastobedone:– removebeampipeinthealcove,moveHPSmagnetstotherunningposition– connectvacuumchamberstothebeampipes– install2H02BPMandtheHPScollimator– removeCLAS12cryo-target– movecleanupcollimatorand2H01harptotheHPSlocation(willbecome2H02Aharp)– installthebeampipethroughthetorusandtheCLAS12CD– connectbeampipesandpumpdown

• DuringtheCLAS12operationsHPSwillbemovedout:- 2H02Aharpandthecleanupcollimatorwillbeinstalledonthespaceframe(2H01harp)- Upstreamchicanedipoleand2H02girderwillberemoved- Analyzingmagnetwillbemovedtobeam-right- Downstreamchicanedipolewillbeloweredtothefloor- 6”beampipethenconnectsupstreamanddownstreambeamlineforCLAS12

RadiationLevels(#5)• Estimatesoftheradiologicalconditionhavebeendoneinitiallyin2014andinclude

allrunningconditionsproposedintheoriginalHPSproposal• TheHPSRSADhasbeenupdatedin2016andwillbeupdatedbeforethenextrun• Nochangestothetargetsorbeamcurrentrequestareanticipatedfortheupcoming

run.TheonlyexpectedchangeintermsofradiationcontrolisthepossibilityofhavingarapidaccessforHall-B(wedidnothaditduringtheengineeringrunduetoinsufficientnumberofmonitors)

• ProposedupgradeswillnotchangeradiologicalconditionsintheHalloraroundtheHPSsetupindownstreamalcove.

• ForCLAS12operationsmoreshieldinghasbeenaddedtothebeamline,rightdownstreamofthetaggermagnet.ThisnewshieldwillinfactimproveradiationbackgroundonHPS.

• Thebeamtransportandbeamdumpstaysunchangedfromwhatwaspresentduringtheengineeringruns.CLAS12usesthesamebeamtransportsystemsandthesamebeamdump.


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Documentation(#6)

• Therun-pageexists(thesamepagewillbeused)• Thedocumentationfromtheengineeringrunwillbeupdatedasneeded:

– COOwillonlyneedanupdateforPDL(anewPDLmaybeassigned)– ESADhasbeenupdatedtoincludethenewscintillationhodoscope– RSADisthesame,willbereviewedonesmorebeforetherun(ashadbeendonefor2016run)

• Detectoroperationsmanualsandprocedureswillbeupdatedasneeded• Willneedanoperationsmanualforhodoscope (expectedtohavebyendof2017)• Hot-checkoutsystemwillbeusedasbefore(nowitincludesalsofullCLAS12and

hasbeenusedforCLAS12KPP)


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TentativeRunPlanfor2018


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• AnewreachestimateincludesupgradedSVTandthetriggersetupwiththenewhodoscope

• HPSengineeringrunswererunat1.05GeVand2.3GeVwithverylimitedbeamtime

• Forthenextrunweplantouse4.4GeVbeam.Datatakingmustbeatleast4PACweekslong

• Withminorchangestothebeamlineandanewenergyregime,~5daysofcommissioningwillbeneeded,aswellas~5daysforcalibrationrunswillbeneeded(0-field,emptytarget,carbontarget,differenttriggerruns)

Totalof40PACdaysat4.4GeVwillberequestedforthenextrun

Summary• HPShassuccessfullycompletedengineeringrunsin2015and2016,at1.05GeV

and2.3GeV,respectively.• BasedontheHPSperformance,JLABmanagementgrantedthefullapprovalto

HPS.• Thebumphuntresultfrom2015runhasbeenreleased(May3seminaratJLAB).• Theactualreachturnedouttobesmallerthanwhatweoriginallyestimatedin

ourproposal.• Thisdiscrepancywastracedtothemistakesinthedetectorefficiencyestimates

duetheelectron“hole”inECal andthevertexdependentacceptanceforlongliveddecays.

• Proposedupgradestothetracker,andthetriggersystemwillmitigatetheseissues.

• TheHPSbeamlinewillhaveminorchangesnecessaryforCLAS12operation.Thetarget,Ecal,slow-controlsandDAQwillremainunchanged.

• TransitionfromCLAS12toHPSrequiresonlyminorconfigurationchange.


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overview - Thomas Jefferson National Accelerator …A magnet chicane directs the CEBAF electron beam...

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