Der Silizium Recoil Detektor für HERMES · 2007. 1. 29. · SciFi Connector Holding Structure Scattering Chamber Target Cell HERA Beamline TIGRE Sensors Hybrid Cooling Collimator

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Ingrid-Maria Gregor

Der Silizium Recoil Detektor Der Silizium Recoil Detektor für HERMESfür HERMES

Technisches SeminarTechnisches SeminarDESY ZeuthenDESY Zeuthen8. April 20038. April 2003

IntroductionIntroduction

HERMES at DESY HamburgHERMES at DESY Hamburg

What do we want to measure ?What do we want to measure ?

RecoilRecoil Detector OverviewDetector Overview

Silicon Silicon Recoil DetectorRecoil Detector

PrinciplePrinciple

First measurementsFirst measurements

Zeuthen activitiesZeuthen activities

Summary and OutlookSummary and Outlook

8. April, 2003Ingrid-Maria Gregor

HERA at DESY HamburgHERA at DESY Hamburg

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HERA with polarised beamHERA with polarised beam

spin of electrons are “all” parallel to one axisspin of electrons are “all” parallel to one axisHERMES is target experiment, but beam is HERMES is target experiment, but beam is notnot stopped in its region stopped in its region


The HERMES SpectrometerThe HERMES Spectrometer

yellowyellow: gas target: gas targetredred: tracking detectors: tracking detectors

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green: particle identificationblue: calorimeter

HERA Measurement of Spin

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The Polarised Internal Gas TargetThe Polarised Internal Gas Target

years 1996years 1996--2000 longitudinal polarised2000 longitudinal polarisedsince 2002 transversal polarisedsince 2002 transversal polarised


But what do we do there?But what do we do there?

nucleons consist of quarks and nucleons consist of quarks and gluons gluons spin of the nucleon: known to spin of the nucleon: known to be 1/2be 1/2how contribute the different how contribute the different constituents to the spin? constituents to the spin?

NUCLEON

from quark parton model: from quark parton model: quarks should carry largest quarks should carry largest part (0.6)part (0.6)EMC 1988: quark contribution EMC 1988: quark contribution only 0.12only 0.12

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And how do we measure ?And how do we measure ?

deep inelastic scattering (DIS)deep inelastic scattering (DIS)polarised electron interacts only with quark of oposit polarised electron interacts only with quark of oposit spinspinby switching the polarisation asymmetries can be by switching the polarisation asymmetries can be measuredmeasured


Inclusive... semiInclusive... semi--inclusive .... exclusiveinclusive .... exclusive

inclusive

semi-inclusive

exclusive want to take a closer look here

recoiling protonlow momentum

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Generalised Parton DistributionsGeneralised Parton Distributions

exclusive exclusive reactions,e.g.reactions,e.g.

sdfrlskdfjlskdfslkdfjslkdfjsfareare becoming a promising and powerful becoming a promising and powerful experimental tool to investigate the spin structure experimental tool to investigate the spin structure of the nucleonof the nucleon

a unifieda unified theoretical framework describing theoretical framework describing inclusive and exclusive inclusive and exclusive reactionsreactions at the same time at the same time has been obtainedhas been obtained

Generalised Parton DistributionsGeneralised Parton Distributions

γepep →


The Recoil DetectorThe Recoil Detector

Position ofRecoil Detector

problem: with the acceptance of HERMESproblem: with the acceptance of HERMES we can not we can not measure the recoiling protonmeasure the recoiling proton

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3D Model of the Recoil Detector3D Model of the Recoil Detector


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Silicon DetectorSilicon Detector

to detect protons from to detect protons from DVCS and to reject DVCS and to reject events with intermediate events with intermediate ΔΔ resonanceresonanceuses energy deposition to uses energy deposition to determine momentumdetermine momentum22 layers of siliconlayers of silicon16 double sided16 double sided Si Si sensors (TIGRE)sensors (TIGRE)300 300 μμm thicknessm thickness758 758 μμm strip pitchm strip pitchppminmin 135 MeV/c135 MeV/cθθ acceptance:0.4 acceptance:0.4 -- 1.35 1.35 radrad


Principle of Silicon DetectorsPrinciple of Silicon Detectors

+

−

Δt~10ns++ +

+ ++ +

−− −

−−−−

fully depleted pn junction for particle detectionfully depleted pn junction for particle detectionsignal size is depending on particle energysignal size is depending on particle energy

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Bethe Bloch (1)Bethe Bloch (1)

energy deposition can be parametrised with Bethe-Bloch formalism

for low momentum: dE/dx falls like 1/1/ββ22

minimum = minimal ionising particle = MIPrises very slowly for larger momenta


Punch Through PointsPunch Through Points

dependence of dependence of ΔΔEE11 on on ΔΔEE22which is characteristic for each which is characteristic for each particle type => PIDparticle type => PIDlow initial energy: particle low initial energy: particle stopped in first layerstopped in first layerpunchpunch--through point 1: gets through point 1: gets stuck in layer 2stuck in layer 2punchpunch--through 2:both layers through 2:both layers are passed are passed --> total energy > total energy deposition decreasesdeposition decreases

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Bethe Bloch (2)Bethe Bloch (2)

huge dynamic huge dynamic range to be range to be detecteddetectedup to about up to about 100MeV : proton 100MeV : proton stuck in Sistuck in Si>130 MeV: Si >130 MeV: Si passes both layerspasses both layers

to get energy to get energy information: information: analog readout analog readout chipchip

1/1/ββ22 regionregion


Helix128 Helix128 -- 3.03.0

0.8 0.8 μμm CMOS processm CMOS process10 MHz sampling frequency10 MHz sampling frequency128 input channels128 input channelsAnalog pipeline 141 cells deepAnalog pipeline 141 cells deep

PreampPreamp--Shaper good noise char. Shaper good noise char. Radiation tolerant 220 krad. Radiation tolerant 220 krad. Dynamic range Dynamic range

+/+/-- 40 fC or +/40 fC or +/-- 10 MIP10 MIPrequired: +/required: +/-- 280fC280fC

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Memory PipelineMemory Pipeline

channelnumber

cell

1 2 3 4 .................... (128+trailer)

12345

.

.

.

.

.

128

read


Readout Conceptual DesignReadout Conceptual Design

analogue frontend readout chip with large dynamic range analogue frontend readout chip with large dynamic range necessarynecessaryHELIX dynamic range is “only” 10 MIPHELIX dynamic range is “only” 10 MIPchargecharge division by capacitive coupling division by capacitive coupling readoutreadout“poor man’s solution” “poor man’s solution” --> much better than new design> much better than new design

tested with charge directly injected intotested with charge directly injected intoone minimal ionising particle (MIP) creates 24000 one minimal ionising particle (MIP) creates 24000 electron/hole pairs in 300 electron/hole pairs in 300 μμm siliconm silicon

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Charge InjectionCharge Injection

in

inin C

VQ24000

1=


Readout Conceptual DesignReadout Conceptual Design

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dynamic rangedynamic rangeof low gain Helix: ~10MIPof low gain Helix: ~10MIPof high gain Helix: ~40MIP (10 pF)of high gain Helix: ~40MIP (10 pF)

~70MIP (5 pF)~70MIP (5 pF)

10 pF

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First PrototypeFirst Prototype

ZEUS hybrid sensor

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sensor: TIGRE, 99 x 99 mm2, double sided300 μm silicon thicknessstrip pitch: 758 μmreadout pitch: 758 μmreadout: HELIX chips, 0.8 μm CMOS128 channels

sensor: TIGRE, 99 x 99 mmsensor: TIGRE, 99 x 99 mm22, double sided, double sided300 300 μμm silicon thicknessm silicon thicknessstrip pitch: 758 strip pitch: 758 μμmmreadout pitch: 758 readout pitch: 758 μμmmreadout: HELIX chips, 0.8 readout: HELIX chips, 0.8 μμm CMOSm CMOS128 channels128 channels


Testbeam at DESYIITestbeam at DESYII

carbon fibre generates Bremsstrahlungs carbon fibre generates Bremsstrahlungs beambeammetal plate metal plate ----> converts into > converts into electron/positron beamelectron/positron beamdipol magnet spreads beam outdipol magnet spreads beam outmagnet used to select energy (1magnet used to select energy (1--6GeV)6GeV)

to check if charge sharing results in reasonable values to check if charge sharing results in reasonable values when tested under realistic conditionswhen tested under realistic conditionsto scale previous charge injection studies to “real” MiPsto scale previous charge injection studies to “real” MiPs

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Reference TelescopeReference Telescope

Zeus testbeam was usedZeus testbeam was usedsystem with three different reference system with three different reference detectorsdetectorsdevice under test (DUT) movable in all device under test (DUT) movable in all three directionsthree directionsscintillators for triggerscintillators for triggerdata is stored as digitalised ADC countsdata is stored as digitalised ADC counts


Reference TelescopeReference Telescope

sensor: 32 x 32 mmsensor: 32 x 32 mm22, single sided, p, single sided, p--side side stripsstrips300 300 μμm silicon thicknessm silicon thicknessstrip pitch: 25 strip pitch: 25 μμmmreadout pitch: 50 readout pitch: 50 μμmmreadout: VA2 chips, 1.2 readout: VA2 chips, 1.2 μμm CMOSm CMOS128 channels128 channels

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Testbeam PictureTestbeam Picture


Energy Loss DistributionEnergy Loss Distribution

high gain channel:no Gaussian noise, Landau fit

S/N:6.5

energy loss distribution for energy loss distribution for 1GeV electrons in 300 um 1GeV electrons in 300 um silicon (one strip, 10pF silicon (one strip, 10pF coupling, ncoupling, n--side)side)Gaussian distributed noise is Gaussian distributed noise is cut (threshold = 3 x noise)cut (threshold = 3 x noise)Landau fit Landau fit ----> signal size = > signal size = most probable peakmost probable peaksignal to noise ratio S/N = 6.5signal to noise ratio S/N = 6.5

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Comparison pComparison p--Side and nSide and n--SideSide

both sides were tested with 1 GeV electronssame channels were addressedsignals size of both sides are within +/- 5%p-side ~100ADC counts, S/N = 7.8 (1MIP)n-side ~ 80ADC counts, S/N = 6.5 (1MIP) small S/N -> due to large capacitance of strips20% difference -> due to large difference in total capacitance of strips


Difference pDifference p--Side and nSide and n--SideSide

can be explained by the difference in the strip capacitance

Cvirt: total capacitance of readout (high gain Helix, low gain Helix, fanout)calculating this network, a difference of 17% in the signal size is expected

p-side n-side

strip capacitance CSTR 34 pF 54 pF

interstrip capacitance Cint 9 pF 7 pF

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Present Status of Mechanical DesignPresent Status of Mechanical Design

SciFi Connector Holding Structure

ScatteringChamber

TargetCell

HERABeamline

TIGRESensors

Hybrid

CoolingCollimator


Summary SiSummary Si--DetectorDetector

HELIX 3.0 chosen for readout.HELIX 3.0 chosen for readout.First prototypes have been constructed and tested First prototypes have been constructed and tested in test beam.in test beam.Readout using charge divisionReadout using charge division has been shown to has been shown to work.work.

50% charge collection due to large sensor 50% charge collection due to large sensor capacitance.capacitance.S/N for 1 MIP is 6.S/N for 1 MIP is 6.5 (n5 (n--side)side)With a 5 pF coupling capacitor, particles With a 5 pF coupling capacitor, particles depositing 140 times the energy of a 1 MIP depositing 140 times the energy of a 1 MIP particle can be measuredparticle can be measured!!

first “real hybrid” is in productionfirst “real hybrid” is in productiontest stand in Zeuthen for laser tests and electrical test stand in Zeuthen for laser tests and electrical teststests

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Zeuthen ActivitiesZeuthen Activities

coordination of projecttestbeamlaser testschip acceptance testparameter tuninghybrid testingACC.....

coordination of projectcoordination of projecttestbeamtestbeamlaser testslaser testschip acceptance testchip acceptance testparameter tuningparameter tuninghybrid testinghybrid testingACCACC..........

WolfWolf--Dieter NowakDieter NowakJames StewartJames StewartWolfgang LangeWolfgang LangeArne VandenbrouckeArne VandenbrouckeMikhail KopytinMikhail KopytinIvana HristovaIvana Hristovameme

with lots of help from with lots of help from the technical staff !!!the technical staff !!!

THANK YOU !!THANK YOU !!

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Der Silizium Recoil Detektor für HERMES · 2007. 1. 29. · SciFi Connector Holding Structure Scattering Chamber Target Cell HERA Beamline TIGRE Sensors Hybrid Cooling Collimator