An Energy Spectrometer for the International Linear Collider Bino Maiheu University College London [email protected] Bino Maiheu, HEP Seminar, University

An Energy Spectrometer for the An Energy Spectrometer for the International Linear ColliderInternational Linear Collider

Bino MaiheuBino MaiheuUniversity College LondonUniversity College [email protected]@hep.ucl.ac.uk

Bino Maiheu, HEP Seminar, University of Birmingham, Bino Maiheu, HEP Seminar, University of Birmingham, 16.05.200716.05.2007

BPMBPM

BPMBPM

BPMBPM

Reasons, challenges, test Reasons, challenges, test experiments and progressexperiments and progress


Seminar OutlineSeminar Outline

Why build the linear collider, and what is it actually ?Why build the linear collider, and what is it actually ?

How does such a linear collider look like ?How does such a linear collider look like ?

Importance of the beam energy measurement...Importance of the beam energy measurement...

Development of a magnetic chicane spectrometer Development of a magnetic chicane spectrometer based upon based upon high resolution Beam Position Monitors (high resolution Beam Position Monitors (BPMBPM))

Principles...Principles...High resolution cavity beam position monitors...High resolution cavity beam position monitors...

Test experiments, End Station A at SLAC...Test experiments, End Station A at SLAC...

Outlook for our project...Outlook for our project...


What is the ILC and why build it ?What is the ILC and why build it ?

ee++ee-- : colliding elementary particles : : colliding elementary particles : cleanclean !! Precision measurements from Precision measurements from

discoveries made at hadron machines discoveries made at hadron machines ( eg. LHC )( eg. LHC )

~10 ~10 kmkm

500 GeV – 1 TeV500 GeV – 1 TeVee-- ee++

Proposed ~30 km long Proposed ~30 km long linear linear ee++ee-- collider collider CM energy up to CM energy up to 1 TeV1 TeV InternationalInternational... obviously ... obviously targeted completion around 2020targeted completion around 2020

costs ~ Pcosts ~ PRFRF

ΔΔEEturnturn ~ E ~ E44 / / ρρ


Physics case for the ILCPhysics case for the ILC

Standard model physics Standard model physics Precision electroweak and QCD measurementsPrecision electroweak and QCD measurementsTop quark threshold, mass, width, yukawa couplingTop quark threshold, mass, width, yukawa couplingProperties of (a) Higgs particle(s)Properties of (a) Higgs particle(s)Giga Z, etc...Giga Z, etc...

Physics beyond the standard model.Physics beyond the standard model. What is awaiting us at the What is awaiting us at the TerascaleTerascale ? ? SUSY, GUT, extra dimensions, dark matter, etc...SUSY, GUT, extra dimensions, dark matter, etc...

The energy scale and the physics program The energy scale and the physics program push present day technology to the limit...push present day technology to the limit...

Lot of Lot of R&D programsR&D programs actively trying to make the ILC feasible both on the actively trying to make the ILC feasible both on the detectordetectorand acceleratorand accelerator side side


Proposed layout of the ILC... I hope :)Proposed layout of the ILC... I hope :)

ee-- source sourceee++ source source

main linacmain linacbeam delivery systembeam delivery system

damping ringsdamping rings

interaction regioninteraction region Particle sourcesParticle sources

electrons : pulsed laserelectrons : pulsed laser positrons : 150 GeV electrons through undulatorpositrons : 150 GeV electrons through undulator

Damping rings Damping rings reduce transverse beam size (emittance), establish bunch train structure, 2625/pulse reduce transverse beam size (emittance), establish bunch train structure, 2625/pulse

Main linac : Main linac : Accelerate beam from about 5 GeV to 500 GeV, super conducting RF cavitiesAccelerate beam from about 5 GeV to 500 GeV, super conducting RF cavities

Beam delivery system : beam diagnostics, focussing, collimationBeam delivery system : beam diagnostics, focussing, collimation Interaction region : final focussing and beams into collision. Interaction region : final focussing and beams into collision. Extraction line : safely dispose of heavily distorted beam + diagnosticsExtraction line : safely dispose of heavily distorted beam + diagnostics 1 Experimental hall, 2 detectors in push-pull and 14 mrad crossing angle1 Experimental hall, 2 detectors in push-pull and 14 mrad crossing angle


Some of many challenges...Some of many challenges... Average Average accelerating gradientaccelerating gradient ~ 31.5 MeV/m ~ 31.5 MeV/m Final Final focussingfocussing needed to get 2x10 needed to get 2x103434/cm/cm22/s/s

Lumi ~ fLumi ~ freprep / / σσxxσσyy

ffreprep = 40 kHz (LEP), = 5 Hz (ILC) = 40 kHz (LEP), = 5 Hz (ILC)

Need vertical beam size of 5 nm + measure it !!Need vertical beam size of 5 nm + measure it !! ( compare to 0.0003x10( compare to 0.0003x103434/cm/cm22/s and 500 nm /s and 500 nm beam size for SLC )beam size for SLC )

Infrastructure :Infrastructure :31 km main tunnel + 6.7 km damping ring31 km main tunnel + 6.7 km damping ring230 MW power consumption230 MW power consumption

Beam dump.. dispose of 18MW of beam powerBeam dump.. dispose of 18MW of beam power ( compare to 0.04 MW for SLC )( compare to 0.04 MW for SLC )

Beam Delivery System ( e.g. energy measurement): Beam Delivery System ( e.g. energy measurement): you you only get 1 goonly get 1 go, no averaging ( LEP ), no averaging ( LEP )

The ILC physics program requires an The ILC physics program requires an energy measurement uncertainty of dE/E = 10energy measurement uncertainty of dE/E = 10-4-4

Let's have a look at the top quark to understand why...Let's have a look at the top quark to understand why...


Top quark : large decay width -> Top quark : large decay width -> pQCD !!pQCD !! ILC = top quark factory, ILC = top quark factory, QCD precision testsQCD precision tests Better precision on the top mass constrains Higgs & SUSY parameters betterBetter precision on the top mass constrains Higgs & SUSY parameters better

Physics case for good energy Physics case for good energy measurementmeasurementCase study : the top quarkCase study : the top quark

Beam energy determination is largest contribution of systematics...Beam energy determination is largest contribution of systematics...


Influence of energy spread on top Influence of energy spread on top threshold...threshold...Luminosity spectrum dL/dELuminosity spectrum dL/dE

Top quark mass scanTop quark mass scan

Uncertainty on Uncertainty on beam energy measurementbeam energy measurementcontributes directly to the contributes directly to the uncertainty on theuncertainty on theILC physicsILC physics output... output...

Energy at collision is Energy at collision is not delta functionnot delta function !! !! Inherent energy spreadInherent energy spread Beamstrahlung Beamstrahlung Initial state radiationInitial state radiation

Magnetic chicane with high resolution BPMsMagnetic chicane with high resolution BPMs


Study & design Study & design magnetic chicanemagnetic chicane for for beam energy measurement beam energy measurement using using Beam Position Monitors (BPMs) : Beam Position Monitors (BPMs) :

so... reduce energy measurement to beam position measurementso... reduce energy measurement to beam position measurementRoyal Holloway University LondonRoyal Holloway University London: S. Boogert: S. BoogertCambridgeCambridge : M. Slater, M. Thomson and D. Ward : M. Slater, M. Thomson and D. WardUniversity College LondonUniversity College London: F. Gournaris, A. Lyapin, B. Maiheu, S. Malton, D. Miller and : F. Gournaris, A. Lyapin, B. Maiheu, S. Malton, D. Miller and M. WingM. Wing

(putting the I in ILC :)(putting the I in ILC :)

EE ~ ~ ∫∫B.dl/B.dl/ΘΘBPM SpectrometryBPM Spectrometry

BPMBPM

BPMBPM

BPMBPM

δE/E ~ 10-4

Move beam by 5 mm at center(dispersion)

At least δx~ 500 nm needed

NanoBPM@ATF (KEK) (KEK) : test : test resolutionresolution, try different , try different analysis analysis methodsmethods, BPM stability tests, , BPM stability tests, multi bunchmulti bunch operation, advanced operation, advanced electronics techniques, electronics techniques, inclinationinclination of beam in BPMs. of beam in BPMs.

-> -> spectrometer aspects of BPMs can be testedspectrometer aspects of BPMs can be testedESA@SLAC : test : test stabilitystability and and operational issuesoperational issues with a full with a full implementation of implementation of 4 magnet chicane4 magnet chicane and 3 BPM stations and 3 BPM stations

-> -> test of real chicane prototypetest of real chicane prototypewill talk about ESA later on...will talk about ESA later on...

Different aspects of the project...Different aspects of the project...


What kind of BPMs to use ?What kind of BPMs to use ? Beam position monitors essential diagnostic for Beam position monitors essential diagnostic for

acceleratorsacceleratorsBeam orbit in accelerator : steering, alignment, Beam orbit in accelerator : steering, alignment, energyenergySpecialist applications such as energy Specialist applications such as energy spectrometerspectrometer

Many different varieties existMany different varieties existOperate via electromagnetic interaction with Operate via electromagnetic interaction with structure placed around the beamstructure placed around the beamButton (1 mm – 10 um)Button (1 mm – 10 um)Stripline (100 um - 1 um)Stripline (100 um - 1 um)Resonant cavity (1 um - 20 nm)Resonant cavity (1 um - 20 nm)......


Introducing resonant cavity beam position Introducing resonant cavity beam position monitors...monitors...

Solution of the EM wave equations taking into account Solution of the EM wave equations taking into account the boundary conditions of the conducting walls leads to the boundary conditions of the conducting walls leads to certain eigenmodes of cavity excitation by the beam...certain eigenmodes of cavity excitation by the beam...

Configuration of first dipole mode : TM110Configuration of first dipole mode : TM110

Excitation voltage for TM110 mode :Excitation voltage for TM110 mode :

For the interested :) :For the interested :) :

VVex ex = = EE00 T Ttrtr L L rr / a / a OffsetOffset w.r.t. electrical center w.r.t. electrical center

Total electrical field ( Total electrical field ( bunch chargebunch charge ) )


Of course in real life...Of course in real life...... it's a little bit more complicated... as usual :)... it's a little bit more complicated... as usual :)

Accurate Accurate geometrical designgeometrical design of cavity and manufacturing of cavity is critical of cavity and manufacturing of cavity is critical Cavity size determines frequencyCavity size determines frequency Positioning of antennae to couple out the RF power ( typically couple of GHz )Positioning of antennae to couple out the RF power ( typically couple of GHz )

Dipole mode depends on :Dipole mode depends on :bunch chargebunch chargebeam offsetbeam offsetbut but also beam tiltalso beam tilt

need reference cavity :need reference cavity :monopole mode TM010monopole mode TM010sensitive to charge onlysensitive to charge only

Prototype reference cavity, Prototype reference cavity, designed by A. Lyapin (UCL)designed by A. Lyapin (UCL)


Handling RF signals from a resonant cavity Handling RF signals from a resonant cavity BPM...BPM...

LO

RF

LO

Filters,Amplifier

sADC

Filters,Amplifier

s

Dipole (TMDipole (TM110110) : charge + offset + tilt) : charge + offset + tilt

Monopole (TMMonopole (TM010010) : charge) : charge

1.1. Normalize Normalize signal to Ref (Q) Cavity signal to Ref (Q) Cavity2.2. IQ IQ rotationrotation ( (ππ/2 tilt phase difference)/2 tilt phase difference)3.3. Calibrate Calibrate

Tilt axisTilt axis

Pos. axisPos. axis

IQ phaseIQ phase

Determine Determine AmplitudeAmplitude & & PhasePhase Fit waveform : V = VFit waveform : V = V

00 + + AA e e--Г(t-t0)Г(t-t0) sin[ω(t-t sin[ω(t-t00) + ) + φφ]]

Digital Down Conversion (DDC) :Digital Down Conversion (DDC) : Multiply waveform with eMultiply waveform with eiωtiωt

Filter out 2ω componentFilter out 2ω component Sample waveform at fixed point for linearity Sample waveform at fixed point for linearity

-> -> AA, , φφDisentangleDisentangle charge, offset and tilt : charge, offset and tilt :

Complex planeComplex plane

++

++

++

++

Typically GHzTypically GHzthink of mobile phones...think of mobile phones...

(10s of MHz)(10s of MHz)


Some examples of resonant RF cavities...Some examples of resonant RF cavities...

Rectangular cavity, Rectangular cavity, separate X and Yseparate X and Y

Pillbox cavity, with X and Y in same physical cavityPillbox cavity, with X and Y in same physical cavityoptimised for short ILC bunch spacing ( 300 ns ) and cleaning for use in cold LINACoptimised for short ILC bunch spacing ( 300 ns ) and cleaning for use in cold LINAC

Z. Li and C.Adolfson et al.Z. Li and C.Adolfson et al.

ILC cold linac prototypes, 2.9 ILC cold linac prototypes, 2.9 GHzGHz

SLAC linac cavity BPMs, 2.9 GHzSLAC linac cavity BPMs, 2.9 GHz

KEK Cavities, 6.4 GHzKEK Cavities, 6.4 GHz

Coupling slot ( antenna )Coupling slot ( antenna )


What precision can we reach with these What precision can we reach with these BPMs ?BPMs ?

15.6 nm position resolution15.6 nm position resolution2.1 urad tilt resolution2.1 urad tilt resolution

NanoBPM Collaboration: NanoBPM Collaboration: LBNL, LLNL, SLAC, KEK, BINPLBNL, LLNL, SLAC, KEK, BINP BINP BPMs in LLNL/SLACBINP BPMs in LLNL/SLACspaceframe on hexapodsspaceframe on hexapods


However, current BPM designs not optimal for However, current BPM designs not optimal for ILC purposes...ILC purposes...So far a good ILC spectrometer BPM prototype in itself hasn't been built yet...So far a good ILC spectrometer BPM prototype in itself hasn't been built yet... apertureaperture ( machine protection, resolution ) ( machine protection, resolution ) resolutionresolution, stability, stability monopole rejection : monopole rejection : distortion of decaying waveformdistortion of decaying waveform coupling -> coupling -> decay timedecay time (multi bunch studies) (multi bunch studies)

Our collaboration is developing a new prototype together with processing Our collaboration is developing a new prototype together with processing electronics exactly for this purpose... beam test underway at ESA in SLAC. electronics exactly for this purpose... beam test underway at ESA in SLAC.

Dipole cavity, 2878 MHzDipole cavity, 2878 MHz

Reference cavityReference cavity

Processor electronicsProcessor electronics


Putting it all together : T474 at ESA (SLAC)Putting it all together : T474 at ESA (SLAC)

2 mile LINAC2 mile LINAC

End Station AEnd Station A


End Station A at SLAC as ILC testfacilityEnd Station A at SLAC as ILC testfacility ESA is well suited for ILC test experiments, among others : ESA is well suited for ILC test experiments, among others :

collimator wakefields (N. Watson, S. Molloy et al.) collimator wakefields (N. Watson, S. Molloy et al.) bunch length diagnostics, bunch length diagnostics, synchrotron light detectorsynchrotron light detectormagnetic chicane spectrometer ( magnetic chicane spectrometer ( T-474T-474 ) )

Possibility to vary energy, bunch chargePossibility to vary energy, bunch chargebunch length etc.. systematic studies !bunch length etc.. systematic studies !


T474 at ESA (SLAC)T474 at ESA (SLAC)Collaboration with LBNL (Collaboration with LBNL (Y. Kolomensky et al.Y. Kolomensky et al.), SLAC (), SLAC (M. Woods et al.M. Woods et al.), ), Notre Dame (Notre Dame (M. Hildreth et al.M. Hildreth et al.), DESY Zeuthen, JINR Dubna, ...), DESY Zeuthen, JINR Dubna, ...

Dipole magnetsDipole magnets

April run 2006 ( 2 weeks ) April run 2006 ( 2 weeks ) :: Commissioning of new cold linac prototype triplet (BPM 3,4,5), where BPM4 on x,y mover systemCommissioning of new cold linac prototype triplet (BPM 3,4,5), where BPM4 on x,y mover system Commissioning of old SLAC BPMs (9,10,11)Commissioning of old SLAC BPMs (9,10,11) Digitisation/signal processing optimization Digitisation/signal processing optimization

July run 2006 (2 weeks )July run 2006 (2 weeks ) : : Commissioning of interferometer system (BPMs 3,4,5) + energy BPM24 upstreamCommissioning of interferometer system (BPMs 3,4,5) + energy BPM24 upstream Stability data taking with 10 BPMs, frequent calibrationsStability data taking with 10 BPMs, frequent calibrations

March 2007 ( 2 weeks )March 2007 ( 2 weeks ) : : Commissioning of calibration tone system and new UK BPM processor hardwareCommissioning of calibration tone system and new UK BPM processor hardware Commissioning of 4 chicane magnets and first full spectrometer dataCommissioning of 4 chicane magnets and first full spectrometer data

BPM stationsBPM stations

feedbackfeedback

SPEAR GIRDERS SPEAR GIRDERS


BPM Calibration at ESA...BPM Calibration at ESA... Calibrate the measured BPM position against a well known beam offset.Calibrate the measured BPM position against a well known beam offset. Important to Important to minimize impact for this on physics data takingminimize impact for this on physics data taking...... At ESA :At ESA :

feedback setpoint calibrations : do we trust the setpoint calibration ?feedback setpoint calibrations : do we trust the setpoint calibration ?corrector calibrations : feedback off, drifts !corrector calibrations : feedback off, drifts !mover calibrations : mover calibrations : correctcorrect with interferometer, correction factor, with interferometer, correction factor,

however be careful for fake interferometer driftshowever be careful for fake interferometer drifts ! !helmholtz coil calibrations helmholtz coil calibrations : fast, averaging slopes ( march 2007 run ): fast, averaging slopes ( march 2007 run )

Automation of the process is an important operational issue for the ILCAutomation of the process is an important operational issue for the ILC


Stability issues : degradation of resolution Stability issues : degradation of resolution over timeover time

~6

0kH

z

~8 hours

Mainly temperature difts cause Mainly temperature difts cause degradation degradation of the systemof the system

gain driftsgain driftscavity shape changes : frequency cavity shape changes : frequency changeschanges

Constant Constant calibration tone calibration tone !!!!ATF resultATF result

First of all... let's define resolution :)First of all... let's define resolution :)


Drift of residual means...Drift of residual means... Monitors the Monitors the relative gain drifts between the stationsrelative gain drifts between the stations

in terms of position measurementin terms of position measurement Direct impact on the stability of the energy measurementDirect impact on the stability of the energy measurement

How stable is ourHow stable is ourmeasurement of the measurement of the entire orbit ?entire orbit ?

To be correlated with temperatureTo be correlated with temperature

How stable is our position How stable is our position measurement in 1 BPM stationmeasurement in 1 BPM station


Magnetic measurements...Magnetic measurements...

4 Magnets were mapped during4 Magnets were mapped during summer 2006 in SLAC measurement summer 2006 in SLAC measurement lablab(SLAC, DESY, JINR)(SLAC, DESY, JINR) Operating current of 150 AOperating current of 150 A Integrated Bdl of 1.1 kG.mIntegrated Bdl of 1.1 kG.m Long term stability analysis in Long term stability analysis in

progressprogress

4.43851 mm4.43851 mm

Small inhomogeneity in magnetsSmall inhomogeneity in magnets

Important to understand for future ILC Important to understand for future ILC operation : beam disruption after chicaneoperation : beam disruption after chicane


Chicane results, first beam energy Chicane results, first beam energy measurementsmeasurements Taking into account integral B.dl and deflection at center of chicane, canTaking into account integral B.dl and deflection at center of chicane, can

compute correct beam energycompute correct beam energy Have to Have to subtract incoming orbitsubtract incoming orbit in each event in each event Total error in energy calculation 2.5e-4 ( ~7 MeV ) (preliminary!)Total error in energy calculation 2.5e-4 ( ~7 MeV ) (preliminary!) Further detailed analysis stability studies underway...Further detailed analysis stability studies underway... More and better data to come in July...More and better data to come in July...


Future plans for ESAFuture plans for ESA Had 3 successful runs so farHad 3 successful runs so far

Upcoming run in July 9Upcoming run in July 9thth until the 22 until the 22th th 2007.2007.

Install and commission the new spectrometer BPM prototype complete with Install and commission the new spectrometer BPM prototype complete with

mover systemmover systemcavities are currently being measured on UCL and RHUL testbenchescavities are currently being measured on UCL and RHUL testbenchesmover system is being commissionedmover system is being commissioned

vertical elevation stage and horizontal stages with stepper motors vertical elevation stage and horizontal stages with stepper motors and linear encoders ( 0.5 and 0.1 um resp )and linear encoders ( 0.5 and 0.1 um resp )

Improve processor electronics in long run...Improve processor electronics in long run... Continue taking data with chicane, need to Continue taking data with chicane, need to

understand better systematics and stabilityunderstand better systematics and stability Couple of papers underway : commissioning, Couple of papers underway : commissioning,

Spectrometer BPM prototype and Spectrometer BPM prototype and full T-474 ESA paperfull T-474 ESA paper


Simulation....Simulation....Of course.. one final issue... It's all fine to study stability and operational Of course.. one final issue... It's all fine to study stability and operational issues at 28.5 GeV, but we really need it at issues at 28.5 GeV, but we really need it at 500 GeV500 GeV : simulation ! : simulation !

Currently developing :Currently developing : GEANT4 simulation of simple spectrometer chicaneGEANT4 simulation of simple spectrometer chicane

beam distortion, track halo, synchrotron radiationbeam distortion, track halo, synchrotron radiationinterface with core BPM processing library and simulation library to have a interface with core BPM processing library and simulation library to have a

full simulation of the entire systemfull simulation of the entire system Transport beam down to IPTransport beam down to IP through rest of BDS through rest of BDS Make studies for optimal Make studies for optimal chicane designchicane design, , updateupdate

baseline document eventuallybaseline document eventually


SummarySummary

Physics case for an a 1 TeV linear e+e- collider is clear !Physics case for an a 1 TeV linear e+e- collider is clear !

Importance of the Importance of the energy measurementenergy measurement, direct contribution to , direct contribution to systematicssystematics on on threshold studies ( e.g. Top quark )threshold studies ( e.g. Top quark )

Proposed magnetic chicane for Proposed magnetic chicane for single pass energy measurementsingle pass energy measurement Based upon high resolution Based upon high resolution resonant cavity beam position monitorsresonant cavity beam position monitors

Operational principles of these devicesOperational principles of these devices

Full chicane prototype test experiment is commissioned at Full chicane prototype test experiment is commissioned at ESA in SLACESA in SLAC

First results, data analysis ongoing + next run planned for this summer...First results, data analysis ongoing + next run planned for this summer...

Simulation studies...Simulation studies...


Thanks for listening...Thanks for listening...

Some links at UCLSome links at UCLhttp://www.hep.ucl.ac.uk/lc/http://www.hep.ucl.ac.uk/~bino/T474//http://www.hep.ucl.ac.uk/~liapine/http://www.hep.ucl.ac.uk/~sboogert/

SLAC ILC page SLAC ILC page http://www-project.slac.stanford.edu/ilc/default.htmhttp://www-project.slac.stanford.edu/ilc/default.htm

SLAC ESA pageSLAC ESA pagehttp://www-project.slac.stanford.edu/ilc/testfac/ESA/esa.htmlhttp://www-project.slac.stanford.edu/ilc/testfac/ESA/esa.html

Central ILC pageCentral ILC pagehttp://www.linearcollider.orghttp://www.linearcollider.org

...and for the ...and for the interested :interested :

Documents

An Energy Spectrometer for the International Linear Collider Bino Maiheu University College London [email protected] Bino Maiheu, HEP Seminar, University