Post on 28-Dec-2015
Study of Study of response response
uniformity of uniformity of LHCb ECALLHCb ECAL
Mikhail Prokudin, ITEPMikhail Prokudin, ITEP
OutlineOutline
►MotivationMotivation►Geometry of modulesGeometry of modules►Experimental setupExperimental setup►ProcedureProcedure►MC modelingMC modeling►ResultsResults
light yieldlight yield►ConclusionConclusion
MotivationMotivation► ““Shashlik” technologyShashlik” technology
cheapcheap fast enoughfast enough
► triggertrigger radiation hardradiation hard easy to segmenteasy to segment
► ResolutionResolution
a – stochastic terma – stochastic term ~8%/sqrt(E)~8%/sqrt(E) b – constant termb – constant term
► stochasticstochastic termterm decrease thickness of decrease thickness of
absorberabsorber► increased volume ratioincreased volume ratio
increased Morier radiusincreased Morier radius► more shower overlapsmore shower overlaps
►keep volume ratiokeep volume ratio constantconstant photostatisticsphotostatistics
► constant termconstant term increase the volume ratioincrease the volume ratio technologytechnology
►die-mold price ~10k $die-mold price ~10k $►MC model of light MC model of light
propagation in scintillator propagation in scintillator tiletile
bE
a
E
dE
7%
RD36 data
Modules geometryModules geometry
► LHCbLHCb► inner: 4x4cminner: 4x4cm22 cells cells►middle: 6x6cmmiddle: 6x6cm22 cells cells►outer: 12x12cmouter: 12x12cm22 cells cells
6767xx44mm layers of mm layers of scintillatorscintillator
6666x2mmx2mm layers of leadlayers of lead
► PrototypePrototype 4x4cm4x4cm22 cells cells 280280x0.5mm layers of x0.5mm layers of
scintillatorscintillator 280280x0.5mm layers of x0.5mm layers of
leadlead
Experimental setupExperimental setup
Beame, μ
Beam plug
Calorimeter
25.111m 10.97m 2.935
new chamber
old chambers
Calorimeter assembly8 modules (12x12cm2x1) for leakage
control
testing module
LED1
LED2
PIN
LED monitoring system scheme
Coordinate determinationCoordinate determination► Beam size: 3x3cmBeam size: 3x3cm22
► Energy cut: 60-65% Energy cut: 60-65% MPV positionMPV position
►Details of Details of calorimeter calorimeter construction are construction are visiblevisible
Shifts corrected for each positionSame procedure for electrons
Muons
Muons. ProcedureMuons. Procedure
► energy only in energy only in central cellcentral cell
► 1x1 mm1x1 mm22 regions regions► fit with Landau fit with Landau
distributiondistribution first fit to estimate first fit to estimate
ranges ranges second fit withsecond fit with
► f(xf(xstartstart)=0.4*Max)=0.4*Max► f(xf(xendend)=0.05*Max)=0.05*Max
no Landau Gauss no Landau Gauss convolutionconvolution►much more statisticsmuch more statistics
Electrons. procedureElectrons. procedure
► Collect energy in Collect energy in 3x3+4 cells3x3+4 cells wider signals with if wider signals with if
other 4 cells other 4 cells includedincluded
► 1x1 mm1x1 mm22 regions regions► Iterative fit Iterative fit
procedureprocedure [-1.2[-1.2δδ, +2, +2δδ] region] region
MC modelingMC modeling
►Signal nonuniformitySignal nonuniformity Light collection nonuniformityLight collection nonuniformity
►Special ray tracer programSpecial ray tracer program
Scintillator tile thickness variationsScintillator tile thickness variations►Measured directlyMeasured directly
Convolution with particle energy Convolution with particle energy depositiondeposition
““natural” smearingnatural” smearing energy deposition nonuniformityenergy deposition nonuniformity dead materialdead material
►GEANTGEANT
Ray tracer programRay tracer program► OpticsOptics
refractionrefraction► Fresnel formulasFresnel formulas
reflectionreflection► mirrormirror► diffusediffuse
attenuationattenuation► in mediumin medium► on surfaceon surface
all processes could all processes could depend on wavelengthdepend on wavelength
► GeometryGeometry geometrical primitivesgeometrical primitives
► cylindercylinder► boxbox
Boolean operationsBoolean operations voxelizationvoxelization
► Main optical parametersMain optical parameters quality of scintillator surfacequality of scintillator surface whiteness of paintwhiteness of paint size of “edging”size of “edging”
Example of ray tracer testExample of ray tracer test
► Edge effect in Edge effect in light collectionlight collection compensate dead compensate dead
material between material between tilestiles
not trivialnot trivial LHCb innovationLHCb innovation
LHCb inner moduleLHCb inner module
Electrons Muons
Scale!
LHCb inner module.LHCb inner module.
Between fibers
Near fibers Near fibers
Between fibers
Electrons Muons
Gray – MC. Black – data. Scale!
Prototype modulePrototype module
Prototype. 0.5мм
LHCb. 4мм
Scale!
Prototype module and inner Prototype module and inner LHCb module LHCb module
Gray – MC. Black – data. Scale!
Between fibers
Near fibers
Between fibers
Near fibers
LHCb inner Prototype
LHCb outer moduleLHCb outer module► 12x12cm12x12cm22
►Distance between Distance between fibers 15mmfibers 15mm 10mm in inner 10mm in inner
modulemodule►Only 2 delay wire Only 2 delay wire
chamberschambers worse position worse position
resolutionresolution►One set of optical One set of optical
parameters to parameters to describe all data!describe all data!
Between fibers
Near fibers
Gray – MC. Black – data.
Light yieldLight yield
ExperimentExperiment► Use monitoring Use monitoring
system system
MCMC►Generate photons Generate photons
uniformly inside uniformly inside tile volumetile volume
► Inner module for Inner module for normalizationnormalization
TestbeaTestbeamm
Cosmic Cosmic setupsetup MCMC
innerinner 30003000 31003100 30003000
middlemiddle 36003600 35003500 36003600
outerouter 25002500 26002600 25702570
prototypprototypee
700700 -- 600600
ConclusionsConclusions
►Measurements of Measurements of uniformity of LHCb uniformity of LHCb calorimeter response calorimeter response presentedpresented different probesdifferent probes
►electronselectrons►muonsmuons
different modulesdifferent modules► innerinner►outerouter►prototypeprototype
absorber and absorber and scintillator thickness scintillator thickness 0.5mm0.5mm
► Calorimeter response Calorimeter response uniformity modeleduniformity modeled thickness thickness
measurementsmeasurements light collectionlight collection
► ray tracer code developedray tracer code developed► tile model createdtile model created
GeantGeant►dead material simulationdead material simulation
►Model parameters Model parameters extractedextracted and checked for various and checked for various
geometriesgeometries
Coordinate determinationCoordinate determination
►Modify coefficientsModify coefficients residualsresiduals
►keep mean at 0keep mean at 0►narrownarrow
► Cut Cut χχ22<4<4 denominator from denominator from
“Delay wire “Delay wire chambers...” by chambers...” by J.Spanggaard.J.Spanggaard.
LacingLacing
Ray tracer testingRay tracer testing► Visualize Visualize
trajectoriestrajectories individual individual
photonsphotons using ROOT using ROOT
for drawingfor drawing
Geant modelGeant model
► Geant3Geant3► Gorynych Gorynych
frameworkframework for ITEP FLINT for ITEP FLINT
experimentexperiment► Tile model with Tile model with
holes and fibersholes and fibers same as for ray-same as for ray-
tracingtracing► 67x4mm 67x4mm
scintillator layersscintillator layers 66x2mm layers of 66x2mm layers of
leadlead► Dead materialDead material
steel tape, 0.2mm steel tape, 0.2mm thickthick
white paint, 0.15mm white paint, 0.15mm at edge of tileat edge of tile
Steel tape, 0.2 mm
White paint, 0.15 mm
Fiber in each hole