Ingrid-Maria Gregor Der Silizium Recoil Detektor für HERMES Technisches Seminar DESY Zeuthen 8. April 2003 m Introduction m HERMES at DESY Hamburg m What

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


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


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


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


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


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


Inclusive... semi-inclusive .... exclusiveInclusive... semi-inclusive .... exclusive

inclusive

semi-inclusive

exclusive want to take a closer look here

recoiling protonlow momentum


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


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


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


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


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


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


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


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


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


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


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 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


Charge InjectionCharge Injection

in

inin C

VQ

240001


Readout Conceptual DesignReadout Conceptual Design

22

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


First PrototypeFirst Prototype

ZEUS hybrid sensor

23

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


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


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


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


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, 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


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


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


Present Status of Mechanical DesignPresent Status of Mechanical Design

SciFi Connector Holding Structure

Scattering Chamber

TargetCell

HERABeamline

TIGRESensors

Hybrid

CoolingCollimator


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


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 !!

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Ingrid-Maria Gregor Der Silizium Recoil Detektor für HERMES Technisches Seminar DESY Zeuthen 8. April 2003 m Introduction m HERMES at DESY Hamburg m What