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 ? Recoil Detector OverviewRecoil Detector Overview Silicon Recoil DetectorSilicon Recoil Detector
PrinciplePrinciple First measurementsFirst measurements Zeuthen activitiesZeuthen activities
Summary and OutlookSummary and Outlook
IntroductionIntroduction HERMES at DESY HamburgHERMES at DESY Hamburg What do we want to measure ?What do we want to measure ? Recoil Detector OverviewRecoil Detector Overview Silicon Recoil DetectorSilicon Recoil 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
8. April, 2003Ingrid-Maria Gregor
HERA with polarised beamHERA with polarised beam
spin of electrons are “all” parallel to one axisspin of electrons are “all” parallel to one axis HERMES is target experiment, but beam is HERMES is target experiment, but beam is
notnot stopped in its region stopped in its region
8. April, 2003Ingrid-Maria Gregor
The HERMES SpectrometerThe HERMES Spectrometer
yellowyellow: gas target: gas target redred: tracking detectors: tracking detectors
4
green: particle identification blue: calorimeter
HERA Measurement of Spin
8. April, 2003Ingrid-Maria Gregor
The Polarised Internal Gas TargetThe Polarised Internal Gas Target
years 1996-2000 longitudinal polarisedyears 1996-2000 longitudinal polarised since 2002 transversal polarisedsince 2002 transversal polarised
8. April, 2003Ingrid-Maria Gregor
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 1/2
how 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
8. April, 2003Ingrid-Maria Gregor
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 spinpolarised electron interacts only with quark of oposit spin by switching the polarisation asymmetries can be by switching the polarisation asymmetries can be
measuredmeasured
8. April, 2003Ingrid-Maria Gregor
Inclusive... semi-inclusive .... exclusiveInclusive... semi-inclusive .... exclusive
inclusive
semi-inclusive
exclusive want to take a closer look here
recoiling protonlow momentum
8. April, 2003Ingrid-Maria Gregor
Generalised Parton DistributionsGeneralised Parton Distributions
exclusive reactions,e.g.exclusive reactions,e.g.
sdfrlskdfjlskdfslkdfjslkdfjsf are becoming a promising and are becoming a promising and powerful experimental tool to investigate the spin powerful experimental tool to investigate the spin structure of the nucleonstructure of the nucleon
a unified theoretical framework describing a unified theoretical framework describing inclusive and exclusive reactions at the same time inclusive and exclusive reactions at the same time has been obtainedhas been obtained
Generalised Parton DistributionsGeneralised Parton Distributions
epep
8. April, 2003Ingrid-Maria Gregor
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
8. April, 2003Ingrid-Maria Gregor
3D Model of the Recoil Detector3D Model of the Recoil Detector
8. April, 2003Ingrid-Maria Gregor
50<p<1400 MeV/c50<p<1400 MeV/c0.1<0.1<<1.35 rad<1.35 rad
The Recoil Proton SpectrumThe Recoil Proton Spectrum
MC simulationsMC simulations kinematic distribution: kinematic distribution:
recoil proton momentum recoil proton momentum versus polar angleversus polar angle
silicon detects low silicon detects low momentum recoil momentum recoil protonsprotons
SciFi is more suited for SciFi is more suited for higher momentum higher momentum protonsprotons
pro
ton
mom
en
tum
polar angle
8. April, 2003Ingrid-Maria Gregor
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 resonance resonance
uses energy deposition to uses energy deposition to determine momentumdetermine momentum
2 layers of silicon2 layers of silicon 16 double sided Si 16 double sided Si
sensors (TIGRE)sensors (TIGRE) 300 300 m thicknessm thickness 758 758 m strip pitchm strip pitch ppminmin 135 MeV/c 135 MeV/c
acceptance:0.4 - 1.35 acceptance:0.4 - 1.35 radrad
8. April, 2003Ingrid-Maria Gregor
Principle of Silicon DetectorsPrinciple of Silicon Detectors
t~10ns
fully depleted pn junction for particle detectionfully depleted pn junction for particle detection signal size is depending on particle energysignal size is depending on particle energy
8. April, 2003Ingrid-Maria Gregor
Bethe Bloch (1)Bethe Bloch (1)
energy deposition can be parametrised with Bethe-Bloch formalism
for low momentum: dE/dx falls like 1/1/22 minimum = minimal ionising particle =
MIP rises very slowly for larger momenta
8. April, 2003Ingrid-Maria Gregor
Punch Through PointsPunch Through Points
dependence of dependence of EE11 on on EE22 which is characteristic for each which is characteristic for each particle type => PIDparticle type => PID
low initial energy: particle low initial energy: particle stopped in first layerstopped in first layer
punch-through point 1: gets punch-through point 1: gets stuck in layer 2stuck in layer 2
punch-through 2:both layers punch-through 2:both layers are passed -> total energy are passed -> total energy deposition decreasesdeposition decreases
8. April, 2003Ingrid-Maria Gregor
Bethe Bloch (2)Bethe Bloch (2)
huge dynamic range to be huge dynamic range to be detecteddetected
up to about 100MeV : up to about 100MeV : proton stuck in Siproton stuck in Si
>130 MeV: Si passes both >130 MeV: Si passes both layerslayers
to get energy information: to get energy information: analog readout chipanalog readout chip
1/1/22 region region
8. April, 2003Ingrid-Maria Gregor
Helix128 - 3.0Helix128 - 3.0
0.8 0.8 m CMOS processm CMOS process 10 MHz sampling frequency10 MHz sampling frequency 128 input channels128 input channels Analog pipeline 141 cells deepAnalog pipeline 141 cells deep
Preamp-Shaper good noise char. Preamp-Shaper good noise char. Radiation tolerant 220 krad. Radiation tolerant 220 krad. Dynamic range Dynamic range
+/- 40 fC or +/- 10 MIP+/- 40 fC or +/- 10 MIP required: +/- 280fCrequired: +/- 280fC
8. April, 2003Ingrid-Maria Gregor
Memory PipelineMemory Pipeline
channelnumber
cell
1 2 3 4 .................... (128+trailer)
12345
.
.
.
.
.
128
read
8. April, 2003Ingrid-Maria Gregor
Readout Conceptual DesignReadout Conceptual Design
analogue frontend readout chip with large dynamic range analogue frontend readout chip with large dynamic range necessarynecessary
HELIX dynamic range is “only” 10 MIPHELIX dynamic range is “only” 10 MIP charge division by capacitive coupling readoutcharge division by capacitive coupling readout ““poor man’s solution” -> much better than new designpoor man’s solution” -> much better than new design
tested with charge directly injected intotested with charge directly injected into one minimal ionising particle (MIP) creates 24000 electron/hole one minimal ionising particle (MIP) creates 24000 electron/hole
pairs in 300 pairs in 300 m siliconm silicon
8. April, 2003Ingrid-Maria Gregor
Charge InjectionCharge Injection
in
inin C
VQ
240001
8. April, 2003Ingrid-Maria Gregor
Readout Conceptual DesignReadout Conceptual Design
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dynamic rangedynamic range of low gain Helix: ~10MIPof low gain Helix: ~10MIP of high gain Helix: ~40MIP (10 pF)of high gain Helix: ~40MIP (10 pF) ~70MIP (5 pF)~70MIP (5 pF)
10 pF
8. April, 2003Ingrid-Maria Gregor
First PrototypeFirst Prototype
ZEUS hybrid sensor
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sensor: TIGRE, 99 x 99 mmsensor: TIGRE, 99 x 99 mm22, double sided, double sided 300 300 m silicon thicknessm silicon thickness strip pitch: 758 strip pitch: 758 mm readout pitch: 758 readout pitch: 758 mm readout: HELIX chips, 0.8 readout: HELIX chips, 0.8 m CMOSm CMOS 128 channels128 channels
sensor: TIGRE, 99 x 99 mmsensor: TIGRE, 99 x 99 mm22, double sided, double sided 300 300 m silicon thicknessm silicon thickness strip pitch: 758 strip pitch: 758 mm readout pitch: 758 readout pitch: 758 mm readout: HELIX chips, 0.8 readout: HELIX chips, 0.8 m CMOSm CMOS 128 channels128 channels
8. April, 2003Ingrid-Maria Gregor
Testbeam at DESYIITestbeam at DESYII
carbon fibre generates Bremsstrahlungs carbon fibre generates Bremsstrahlungs beambeam
metal plate --> converts into metal plate --> converts into electron/positron beamelectron/positron beam
dipol magnet spreads beam outdipol magnet spreads beam out magnet used to select energy (1-6GeV)magnet used to select energy (1-6GeV)
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 conditions
to scale previous charge injection studies to “real” MiPsto scale previous charge injection studies to “real” MiPs
8. April, 2003Ingrid-Maria Gregor
Reference TelescopeReference Telescope
Zeus testbeam was usedZeus testbeam was used system with three different reference system with three different reference
detectorsdetectors device under test (DUT) movable in all device under test (DUT) movable in all
three directionsthree directions scintillators for triggerscintillators for trigger data is stored as digitalised ADC countsdata is stored as digitalised ADC counts
8. April, 2003Ingrid-Maria Gregor
Reference TelescopeReference Telescope
sensor: 32 x 32 mmsensor: 32 x 32 mm22, single sided, p-side , single sided, p-side stripsstrips
300 300 m silicon thicknessm silicon thickness strip pitch: 25 strip pitch: 25 mm readout pitch: 50 readout pitch: 50 mm readout: VA2 chips, 1.2 readout: VA2 chips, 1.2 m CMOSm CMOS 128 channels128 channels
8. April, 2003Ingrid-Maria Gregor
Testbeam PictureTestbeam Picture
8. April, 2003Ingrid-Maria Gregor
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, n-side)coupling, n-side)
Gaussian distributed noise is Gaussian distributed noise is cut (threshold = 3 x noise)cut (threshold = 3 x noise)
Landau fit --> signal size = Landau fit --> signal size = most probable peakmost probable peak
signal to noise ratio S/N = 6.5signal to noise ratio S/N = 6.5
8. April, 2003Ingrid-Maria Gregor
Comparison p-Side and n-SideComparison p-Side and n-Side
both sides were tested with 1 GeV electrons
same channels were addressed
signals 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 strips
20% difference -> due to large difference in total capacitance of strips
8. April, 2003Ingrid-Maria Gregor
Difference p-Side and n-SideDifference p-Side and n-Side
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
8. April, 2003Ingrid-Maria Gregor
Present Status of Mechanical DesignPresent Status of Mechanical Design
SciFi Connector Holding Structure
Scattering Chamber
TargetCell
HERABeamline
TIGRESensors
Hybrid
CoolingCollimator
8. April, 2003Ingrid-Maria Gregor
Summary Si-DetectorSummary Si-Detector
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 division has been shown to Readout using charge division 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 6.5 (n-side)S/N for 1 MIP is 6.5 (n-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 measured!particle can be measured!
first “real hybrid” is in productionfirst “real hybrid” is in production test stand in Zeuthen for laser tests and electrical test stand in Zeuthen for laser tests and electrical
teststests
8. April, 2003Ingrid-Maria Gregor
Zeuthen ActivitiesZeuthen Activities
coordination of projectcoordination of project testbeamtestbeam laser testslaser tests chip acceptance testchip acceptance test parameter tuningparameter tuning hybrid testinghybrid testing ACCACC ..........
coordination of projectcoordination of project testbeamtestbeam laser testslaser tests chip acceptance testchip acceptance test parameter tuningparameter tuning hybrid testinghybrid testing ACCACC ..........
Wolf-Dieter NowakWolf-Dieter Nowak James StewartJames Stewart Wolfgang LangeWolfgang Lange Arne VandenbrouckeArne Vandenbroucke Mikhail KopytinMikhail Kopytin Ivana HristovaIvana Hristova meme
with lots of help from with lots of help from the technical staff !!!the technical staff !!!
THANK YOU !!THANK YOU !!