| Sıra | DOSYA ADI | Format | Bağlantı |
|---|---|---|---|
| 01. | Backgrounds Designs Energies Polarization | pptx | Sunumu İndir |
Transkript
IR Design Considerations and Machine Detector Interface for Electron Ion Colliders Brett Parker April 11, 20198th Workshop of the APS Topical Group on Hadronic Physics from Wednesday, 10 April to Friday, 12 April 2019, Denver, Colorado, USA
EIC Machine Detector Interface (MDI) Introduction•Experimental Goals•Accelerator Operations•IR Magnet Performancei l ll i2*This presentation ruthlessly borrows slides from other presentations... please wait for a list of sources when the end credits roll by.i r t ti r t l l rr li fr t r r t ti ... l it f r li t f r t r it r ll .*
What is needed to address EIC Physics?3polarized electron and hadron (p,d,He-3) beams: access to spin structure of nucleons and nuclei Spin vehicle to access the spatial and momentum structure of the nucleon in 3d Full specification of initial and final states to probe q-g structure of NN and NNN interaction in light nucleinuclear beams: D to Pb accessing the highest gluon densities saturation quark and gluon interact with a nuclear mediumhigh luminosity 1033-34 cm-2s-1: mapping the spatial and momentum structure of nucleons and nuclei in 3d access to rare probes, i.e. Wslarge kinematic coverage: access to x and Q2 over a wide range center-of-mass energy √s: 20 – 140 GeV
Current EIC General Purpose Detector ConceptsJefferson lab concept: JLEICsPHENIX → EIC Argonne concept: TOPSiDEBrookhaven concept: BEAST4
April 1-3, 2019Ideal is to measure everything, everywhere. ~100% acceptance for the whole event!l i il5Ion beamlineElectron beamlineCentral Detector/SolenoidDipoleDipoleForward (Ion) DetectorScattered ElectronParticles Associated with Initial IonParticles Associated with struck partonWhat does an idealized EIC detector have?
EIC IR Design Optimization Logic6All OK Forward Charged Acceptance Forward Neutral Acceptance Rear Acceptance (Polarization & Luminosity Measurements) Detector / IR Magnet Overlap Coil Stress Limit Beam Pipe Design (Lose Aperture) Field Strength Coil End Fields (e-beam)Experimental GoalsAccelerator OperationsIR Magnet Performance Magnet Strength (Peak Beta) Field Leakage (e-Beam Synrad) Field Quality (Harmonic errors, Local Correction Coils) Magnet Apertures (e-beam & hadron injection)The IR designer’s challenge is to prove that the valid solution space is not of measure zero. I i r’ ll i t r t t t li l ti i t f r r .
EICs are unique colliders.7EIC LHC /RHICcollide different beam species: ep & eA consequences for beam backgrounds hadron beam backgrounds, i.e. beam gas events synchrotron radiationasymmetric beam energies boosted kinematics high activity at high |h|High repetition rateJLEIC: 2.1ns eRHIC 8.7ns between bunchescrossing angle eRHIC 25mrad JLEIC: 50mrad wide range in center of mass energies factor 7both beams are polarized stat uncertainty: ~ 1/(P1P2 (L dt )1/2) collide the same beam species: pp, pA, AA beam backgrounds hadron beam backgrounds, i.e. beam gas events, high pile upsymmetric beam energies kinematics is not boosted most activity at midrapiditymoderate repetition rate25 ns between bunchesno crossing angle yetlimited range in center of mass energies LHC: factor 2 RHIC: factor 26 in AA and 8 in ppno beam polarization stat uncertainty: ~1/(L dt )1/2Differences impact detector acceptance and possible detector technologies
8IR Design Overview and Conventions (Outgoing Hadrons)(Incoming Electrons)(Incoming Hadrons)(Outgoing Electrons)eRHIC Example lCrossing Angle?i l
For our EIC, why use a crossing angle?9LHeC Example lColliding ProtonsColliding ProtonsElectronsElectronsNon-colliding Protonson-colliding ProtonsSynradSynradWe learn from HERA-II experience that synrad driven background needs careful study.Both dipole and solenoid fields are hereForward Side Rear SideDoes not have RICHLHeC
For our EIC, why use a crossing angle?109.0mhadronselectronshadronic calorimetersTPCe/m calorimeters silicon trackersGEM trackersRICH detectors3T solenoid coilsBNL concept: BEASTThe HERA and LHeC concepts use separation dipoles to get the beams apart...and dipoles generatesynrad which can lead tobackgrounds to avoid.But a crossing angle geometry needs CrabCavities so not to lose too much luminosity... The answer is PID.
11EIC PID needsare more demandingthen yournormalcollider detectorEICneeds absoluteparticle numbers athigh purity and lowcontaminationEFor our EIC, why use a crossing angle?
For our EIC, why use a crossing angle?129.0mhadronselectronshadronic calorimetersTPCe/m calorimeters silicon trackersGEM trackersRICH detectors3T solenoid coilsBNL concept: BEASTPlacing small radius dipoles inside the detector blocks acceptance.l i ll i i l i i l .So integrate dipole with solenoid, but then cannot use a RICH!“Projective” field for a RICH not compatible with a large diameter dipole.j ti fi l f I ti l i l i i l .RICHNo dipoles here! il s r !Dipole here?il rDipole here?il rJLab concept: JLEICRICHFor RICH want tracks aligned with magnetic field
April 1-3, 2019Roman PotsJLEIC IR Design Layout Schematic13Forward SideRear SideForward Sidee-TaggerLumi MonitorPolarimeter Chicane(Triple function on rear side)(Charged and neutral particle acceptance)Roman PotsJLEIC Example ZDCJLEICSpectrometer Dipole
eRHIC IR Design Aperture Schematic14B0Q1Q2B1C1XB2AB2BQ0Q1Q1AQ1BQ2Q1Q2B2Lumi Monitor e-TaggerZDCRoman PotsForward SideRear SideProtonsElectrons±4.5 m Detector SpaceeRHIC Example
Detector Requirements15Exclusive Reactions in ep/eA: Exclusivity criteria: eA: large rapidity coverage rapidity gap events HCal for 1<h<4.5 ep: reconstruction of all particles in event wide coverage in t (=pt2) Roman pots eA: large acceptance for neutrons from nucleus break-up Zero Degree Calorimeter veto nucleus breakup determine impact parameter of collision Poses stringent requirements on IR designkk'p'pqgapMxt=pt2proton momentum [GeV/c]0 50 100 150 200 250proton scattering angle [mrad]05101520253011021031041015 GeV on 50 GeV15 GeV on 100 GeV15 GeV on 250 GeV-4.5<h<4.5scattered protonsbreak-up neutrons15 GeV on 50 GeV 15 GeV on 100 GeV11021031015 GeV on 250 GeVh-5-4-3-2-1012345Energy (GeV)-110 1 10Energy (GeV)-110 1 10Energy (GeV)-110 1 10 210Cuts: Q2>1 GeV, 0.01<y<0.85 DVCS – photon kinematics:
16Forward Scattered NeutronsDiffractive physics in eA Measure spatial gluon distribution in nuclei Reaction: Momentum transfer t = |pAu-pAu′|2 suppress by detecting break-upneutronsPhysics requires forward scattered nucleus needs to stay intact Veto breakup through neutron detectionRequirement: Need at +/- 4 mrad beam element free cone before the zero degree calorimeter to detect the breakup neutrons No nuclear dependence for heavy A there neutrons are also critical to reconstruct collisions geometry L. Zheng, ECA, J-H. Lee arXiv:1407.8055 precision neutron energy reconstruction transv. size of ZDCAu
eRHIC Forward Magnet Apertures17B0PFQ1PFC1XPFQ2PFB1PFB2APFB2BPFQ0EFQ1EFZDCForward SideeRHIC Example lSpectrometer DipoleRoman Pot RegionClosest Large Aperture, High Field Quadrupole
Compact Forward Magnet Example18Direct Wind, NbTi, Actively Shielded eRHIC Q1PFX (mm)BY (T)Main CoilShield CoilZero Field RegionQ1PF By FieldRapt = 55 mmEfficiency Factor = 90%Gnet @ 275 GeV = 80.8 T/mBudget for outer structure was set to accommodate the electron beam pipe.g t f r t r str ct re as s t t acc ate t e electr ea i e.• Forward magnets must have large apertures to accommodate neutrons and forward charged particles.• But combination of large aperture and large gradient mean a large B-field at the coil....• However, the electron beam must be shielded from any large external fields.“Pole Tip Field” = 4.4 TQuad FieldReturn Flux
19Very forward scattered particlesproton momentum [GeV/c]0 50 100 150 200 250proton scattering angle [mrad]05101520253011021031041015 GeV on 50 GeV15 GeV on 100 GeV15 GeV on 250 GeVThe very forward scattered particles are critical to detect for elastic/diffractive physics and not detectable in main detector. ProtonNote:Main detector acceptance starts at 35 mradFull pT coverage of proton critical for physicspT = p’L sin(Q) p’L > 97% of pBeam 0.65 < Q (mrad) < 10 0.2 GeV < pt < 1.3 GeV small pT-acceptance limited by beam divergence, emittance and beta-function rule of thumb keep 10s between Roman Pot and beam large pT-acceptance limited by magnet apertureseRHICJLEIC
Shielding e-Beam Inside Spectrometer Dipole20B0 Magnetic YokeSuperconducting Coilse-BeamMagnet is aligned with the e-beam, so p-beam enters at 25 mrad angle.agnet is aligned ith the e-bea , so p-bea enters at 25 rad angle.ExperimentalDetector Hereri t lt r r1.3 T Cancel Coil DetailQ0EFeRHIC B0PF/Q0EF• Both eRHIC and JLEIC need to pass an e-beam through main aperture of first hadron spectrometer dipole (B0PF).• eRHIC even places a quad (Q0EF) inside.• This slide shows how, with a combination of a bucking dipole and passive shielding, this can be accomplished.• There are also other options for doing this with various tradeoffs possible.
JLEIC Magnets and Component Integration21~2.6 mion beame beam eQUS1 eQUS2iBDS1Detector SolenoidJLEIC iQUS1a(Magnet yoke not shown)IR designs require production of many new challenging magnets (fortunately NbTi seems to be ok and Nb3Sn may not be needed).JLEIC Example lBut there are still quite significant engineering challenges in order to fit everything in veryrestricted availablespace!
eRHIC Rear Side Magnet Apertures22Rear SideLumi Monitore-TaggereRHIC Example ProtonsrotsElectronsElectronsTapered aperture magnetsDipole bend to separate e-beam from lumi photons and quad synrad fan and analyze rear going electrons from physics events.SynradSy raBethe-Heitler set e- eitler sFor eRHIC, the e-polarimetry chicane is located elsewhere.
E.C. Aschenauer23Requirements for Lepton BeamLuminosity DetectorConcept: Use Bremsstrahlung ep epg as reference cross section•different methods: •Bethe Heitler, QED Compton, Pair Production•Hera: reached 1-2% systematic uncertaintyGoals for Luminosity Measurement:•Integrated luminosity with precision δL/L< 1%•Measurement of relative luminosity: physics-asymmetry/10 ~10-4 – 10-5EIC challenges:•with 1033 cm-2s-1 one gets on average 23 bremsstrahlungs photons/bunch for proton beam A-beam Z2-dependence•Need more sophisticated solution•BH photon cone < 0.03 mrad acceptance completely dominated by lepton beam sizezero degree photon calorimeterhigh rate Fast feedback for machine tuningmeasured energy proportional to # photons subject to synchrotron radiationpair spectrometerlow rateHigh precision measurement for physics analysis The calorimeters are outside of the primary synchrotron radiation fanWorkgroup explores common issues Lumi Monitor Schematic
B-Factories put our challenges in perspective.Managing Synrad Backgrounds at an EIC24• Look to have only soft bends, well upstream of the IR region.• And use upstream masks to control upstream synrad that is unavoidably generated.• Look to limit the maximum synrad critical en rgy to be less than 40 keV (k-edge of W).• Look to let residual synrad fan pass completely though central detector region on to absorbers and masks far from IP.• Look to block as much synrad backscatter albedo as possible with downstream masks.• For eRHIC rear side design the rear side apertures are tapered to allow passage of synrad cone generated by upstream quads.In addition to using existing synrad codes to estimate and mitigate the anticipated backgrounds, we also collaborate with B-factory experts who have a lot of experience dealing with such backgrounds. I iti t i i ti r t ti t iti t t ti i t r , l ll r t it -f t r rt l t f ri li it r . B-Factory designs must take into account complex synrad masking- t i t t i t t l i
Detector Beam Pipes for an EIC25JLEIC Central Beam Pipe eRHIC Central Beam Pipe i• Small diameter, thin walled Be in center region.• Smooth tapers and transitions to limit energy deposited by beam in trapped modes (wakes).• Need to provide beam tube cooling and for any Higher Order Mode (HOM) damping absorbers.• Need to provide adequate vacuum pumping.• eRHIC / Beast plans include in situ bakeout.
... and there is still plenty more work that needs be done to realize an EIC26EICUG IR / Luminosity Working Group interface between accelerator / IR design and thephysics requirements proper implementation of the physics program in particular for forward / backward detectionConveners: • Accelerator / IR: C. Montag (BNL), V. Morozov (JLab)• Physics: C. Hyde (ODU), A, Kiselev (BNL)EICUG Working Group on Polarimetry plan / develop the optimal methods and techniques formeasuring the electron and ion beam polarization with highprecisionConveners E.-C. Aschenauer (BNL), D. Gaskell (JLab)
...and I would like to thank many people27Elke-Caroline Aschenauer Roman MartinTim Michalski Vasiliy MorozovRobert PalmerRenuka Rajput-GhoshalDmitry RomanovMichael SullivanMark WisemanHolger Witte...for much of the material presented today.
Backgrounds Designs Energies Polarization
Yıl : 2020
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