E.C. Aschenauer arXiv:

EIC User Meeting, Berkley, E.C. Aschenauer Does this saturation produce matter of universal properties in the nucleon and all nuclei viewed at nearly the speed of light? Where does the saturation of gluon densities set in? Is there a simple boundary that separates the region from the more dilute quark gluon matter? If so how do the distributions of quarks and gluons change as one crosses the boundary? How are sea quarks and gluons and their spin distributed in space and momentum inside the nucleon? How are these quark and gluon distributions correlated with the over all nucleon properties, such as spin direction? What is the role of the motion of sea quarks and gluons in building the nucleon spin? How does the nuclear environment affect the distribution of quarks and gluons and their interaction in nuclei? How does matter respond to fast moving color charge passing through it? Is this response different for light and heavy quarks? How does the transverse spatial distribution of gluons compare to that in the nucleon? q h **** e’e’e’e’ e

E.C. Aschenauer EIC User Meeting, Berkley, Requirements from Physics:  High Luminosity ~ cm -2 s -1 and higher  nucleon/nuclei imaging  Flexible center of mass energy  wide kinematic reach  Electrons and protons/light nuclei highly polarized  study spin  Wide range of nuclear beams (D to U)  high gluon densities  a wide acceptance detector with good PID (e/h and , K, p)  wide acceptance for protons from elastic reactions and neutrons from nuclear breakup neutrons from nuclear breakup

experimental program to address these questions: azimuthal asymmetries in DIS adds their transverse momentum dependence inclusive and semi-inclusive DIS longitudinal motion of spinning quarks and gluons machine & detector requirements prerequisites all need √s ep > 50 GeV to access x < where sea quarks and gluons dominate E.C. Aschenauer 4 multi-dimensional binning multi-dimensional binning  x, Q 2, z, p T (or t),   x, Q 2, z, p T (or t),  to reach p T > 1 GeV to reach p T > 1 GeV to reach |t| > 1 GeV 2 to reach |t| > 1 GeV 2 L ≃ 10 fb -1 L ≃ fb -1 exclusive processes adds their transverse position

E.C. Aschenauer EIC User Meeting, Berkley, EIChadron-hadron colliders fixed target experiments Kinematicsvery asymmetric beam energies  very boosted kinematics symmetric beam energies  most activity at mid rapidity totally asymmetric beam energies  all activity at very forward rapidities Backgroundssynchrotron radiation beam gas events some synchrotron radiation Moeller/Bhabha leptons Measurementsrun many “experiments: at once limited to single experiments at a time

E.C. Aschenauer EIC User Meeting, Berkley, Inclusive Reactions in ep/eA:  Physics: Structure Fcts.: g 1, F 2, F L  scattered lepton  kinematics of event (x,Q 2 )  identify scattered lepton  excellent electron id  Momentum/energy and angular resolution of e’ critical

E.C. Aschenauer EIC User Meeting, Berkley, 2016 HERAy> Measure of resolution power Measure of inelasticity Measure of momentum fraction of struck quark Kinematics: Possible limitations in kinematic coverage: low y-coverage: limited by E’ e resolution  y-coverage can be extended by beam energy scan  costly $ & beam time energy scan  costly $ & beam time or use hadronic final state to reconstruct event kinematics event kinematics  CC events require the hadron method high y limited by internal radiative corrections can be suppressed by requiring hadronic activity

E.C. Aschenauer 8 EIC User Meeting, Berkley, 2016 scattered lepton more and more at –  lepton beam energy scattered lepton:  main detector; -5 <  < 5   <-5 : scattered lepton needs to be detected in dedicated low-Q 2 tagger  kinematic coverage in Q 2 -x-  critical for physics low high hadron beam energy low high no influence on scattered lepton kinematics  hadron beam lepton beam

E.C. Aschenauer EIC User Meeting, Berkley, Lepton-PID:  suppression: the same  coverage for tracking & Ecal h - suppression through E/p  <-4: 1:1 -4<  <-1: 10:1 to 10 3 :1  <1: 10 4 :1

E.C. Aschenauer EIC User Meeting, Berkley, Inclusive Reactions in ep/eA:  Physics: Structure Fcts.: g 1, F 2, F L  scattered lepton  kinematics of event (x,Q 2 )  identify scattered lepton  excellent electron id  Momentum/energy and angular resolution of e’ critical Semi-inclusive Reactions in ep/eA:  Physics: spin of the proton, FF, TMDs  flavor tagging through hadron type  Kaon asymmetries, cross sections  strangness PDFs  Kaon asymmetries, cross sections  strangness PDFs   ±,K ±,p ± separation over a wide range |  <3  covers entire kinematic region in p t & z  covers entire kinematic region in p t & z   Excellent particle ID   Excellent particle ID  excellent p resolution at forward rapidities  excellent p resolution at forward rapidities  TMDs: full  -coverage around  *, wide p t coverage  Excellent vertex resolution  Charm, Bottom separation

E.C. Aschenauer 11 Cuts: Q 2 >1 GeV,  no difference between  , K ±, p ± EIC User Meeting, Berkley, 2016 hadrons are boosted more and more to –  lepton beam energy low high hadron beam energy low high hadron momentum at fixed  increases Impact on hadron PID

E.C. Aschenauer EIC User Meeting, Berkley, Hadron-PID: technique dE/dx and RICH  /K ratio 3-4 K/p ~ 1 -5  < 2: 0.1 GeV < p < 10 GeV 0.1 GeV < p < 10 GeV 2 <  < 5: 2 <  < 5: 0.1 GeV < p < 100 GeV 0.1 GeV < p < 100 GeV  impact on RICH technology

E.C. Aschenauer EIC User Meeting, Berkley, Cuts: Q 2 >1 GeV 2, GeV -3<  <3 covers entire kinematic region in p t & z important for physics no difference between  , K ±, p ± no difference between  , K ±, p ±

E.C. Aschenauer EIC User Meeting, Berkley, Inclusive Reactions in ep/eA:  Physics: Structure Fcts.: g 1, F 2, F L  scattered lepton  kinematics of event (x,Q 2 )  identify scattered lepton  excellent electron id  Momentum/energy and angular resolution of e’ critical Semi-inclusive Reactions in ep/eA:  Physics: spin of the proton, FF, TMDs  flavor tagging through hadron type  Kaon asymmetries, cross sections  strangness PDFs  Kaon asymmetries, cross sections  strangness PDFs   ±,K ±,p ± separation over a wide range |  <3  covers entire kinematic region in p t & z  covers entire kinematic region in p t & z   Excellent particle ID   Excellent particle ID  excellent p resolution at forward rapidities  excellent p resolution at forward rapidities  TMDs: full  -coverage around  *, wide p t coverage  Excellent vertex resolution  Charm, Bottom separation Exclusive Reactions in ep/eA:  Physics: GPDs, parton imaging in b T through DVCS, excl. VM/PS prod.  Exclusivity  large rapidity coverage  rapidity gap events ↘ reconstruction of all particles in event ↘ reconstruction of all particles in event  high resolution, wide coverage in t  b t  Roman pots  eA:  acceptance for neutrons in Zero Degree Calorimeter  veto nucleus breakup  determine impact parameter of collision

E.C. Aschenauer EIC User Meeting, Berkley, Cuts: Q 2 >1 GeV, GeV, 0.01<y<0.85 DVCS – photon kinematics: increasing Hadron Beam Energy: influences max. photon energy at fixed  photons are boosted to negative rapidities (lepton direction) e  ECal granularity: needs to be able to distinguish clusters down to  =1 o

16 two methods: to select events E.C. Aschenauer EIC User Meeting, Berkley, 2016 proton/neutron tag method o Measurement of t o Free of p-diss background o Higher M X range o to have high acceptance for Roman Pots / ZDC challenging Roman Pots / ZDC challenging  IR design  IR design Need for Roman Pots (RP) and Zero Degree Calorimeter (ZDC) detector acceptance:  >4.5  t (~p t 2 ) reach influences b T uncertainty t min ~ GeV 2  300 GeV 2  F/F > 50% t min ~ GeV 2  300 GeV 2  F/F > 50% p’ acceptance critical: Large Rapidiy Gap method o M X system and e’ measured o Proton dissociation background o High acceptance in  for detector Need for HCal in the forward region

17  Identify Most Forward Going Particle (MFP)  Works at HERA but at higher √s  EIC smaller beam rapidities Hermeticity requirement: needs just detector to be present  -4 <  < 2 needs just detector to be present  -4 <  < 2 does not need momentum or PID does not need momentum or PID simulations: no show stopper for EIC √s simulations: no show stopper for EIC √s (can achieve <10% contamination, 90% efficiency ) (can achieve <10% contamination, 90% efficiency ) E.C. Aschenauer EIC User Meeting, Berkley, 2016  dis /  diff = 90:10 DIS Diffractive Diffractive ρ 0 production at EIC:  of MFP

18 Measure spatial gluon distribution in nuclei How: Diffractive vector meson production:  Momentum transfer t = |p Au -p Au  | 2 conjugate to b T e + Au → e  + Au  + J/   PRC 87 (2013) Fourier Transform E.C. Aschenauer EIC User Meeting, Berkley, 2016 suppress by detect break-up neutrons Reconstruct the eA collision geometry: for details see L. Zheng, ECA, J-H. Lee arXiv: Eur. Phys. J. A (2014) 50: 189 arXiv: Eur. Phys. J. A (2014) 50: 189arXiv: Eur. Phys. J. A (2014) 50: 189

E.C. Aschenauer EIC User Meeting, Berkley, Au: 100 GeV  < 4 mrad Excitation Energy # Neutrons Au: 50 GeV  < 4 mrad Excitation Energy # Neutrons Need a 4 mrad beam element free cone before the zero degree calorimeter to detect the breakup neutrons

E.C. Aschenauer EIC User Meeting, Berkley, Rapidity Coverage: tracking: -4 <  < 4 calorimetry: -5 <  < 5 ,K,p identification: -3 <  < 3 PID Requirements: lepton / hadron separation strongly rapidity dependent 1:1 at  < -1 10:1 to 10 3 :1 at -4<  < :1 at -1  <1 ,K,p Identification:  /(K,p) ratio ~3-4  need high K efficiency and purity  positive ID K/p ratio ~1 momentum-coverage: -5  < 2: 0.1 GeV < p < 10 GeV 2 <  < 5: 0.1 GeV < p < 100 GeV 2 <  < 5: 0.1 GeV < p < 100 GeV Momentum / Energy resolution: RICH in f/b rapidity:  p/p < 1% p < 10 GeV 1<|  |<3 Combined Calorimeter and Momentum resolution: in x-Q 2 bins > 60% for % for 0.01<y<0.95 Dual radiator RICH for 1<|  |<3

E.C. Aschenauer EIC User Meeting, Berkley, An EIC Detector integrating all requirements

22 low Q 2 taggerandluminositydetector Hadron PID: -1<  <1: proximity focusing RICH + TPC: dE/dx 1<|  |<3: Dual-radiator RICH Lepton-ID: -3 <  < 3: e/p 1<|  |<3: in addition Hcal response &  suppression via tracking 1<|  |<3: in addition Hcal response &  suppression via tracking |  |>3: ECal+Hcal response &  suppression via tracking -4<  <4: Tracking (TPC+GEM+MAPS) MAPS: CMOS Monolithic Active Pixel Sensors   E.C. Aschenauer EIC User Meeting, Berkley, 2016 To Roman Pots & Zero Degree Calorimeter hadron beam lepton beam fully model in Geant Hcal  -vertex Ecal GEM RICH TPC

E.C. Aschenauer 23  {PYTHIA 20x250 GeV, NO bremsstrahlung} -> {GEANT} -> {Kalman filter track fit}  same procedure; simulation WITH bremsstrahlung  looks good despite poor resolution at low y and long bremsstrahlung tails Resolutions in electron method: diverges for y e  0 depends on E’ e diverges for  ’ e  180 o depends on E’ e and  ’ ezz E’ e and  ’ ezz EIC User Meeting, Berkley, 2016

E.C. Aschenauer 24  Describes migration between kinematic bins  Important to keep it close to 1.0 for successful unfolding bremsstrahlung OFF bremsstrahlung ON  Bremsstrahlung matters even for detector with ~5% X/X 0 “Straightforward” tracking can hardly help at y<0.1 “Straightforward” tracking can hardly help at y<0.1 Migration from bin to bin influences  bin size  statistical precision:  N: given by events which are generated and reside  N: given by events which are generated and reside in the same bin in the same bin EIC User Meeting, Berkley, 2016 How can we improve further:  Try to account for bremsstrahlung photon  Combine Ecal and tracking info for lepton  Change Method: use hadronic final state information

E.C. Aschenauer EIC User Meeting, Berkley, 2016 Measure of resolution power Measure of inelasticity Measure of momentum fraction of struck quark Hadron method: e-p/A 0 o 180 o +  ---- high important to unfold measured quantities to Born level electron method hadron method: DA method: all plots for 15 GeV on 250 GeV 25

E.C. Aschenauer EIC User Meeting, Berkley, EIC: Interaction Region and ancillary detector systems: hadron and lepton polarimeters luminosity detector low Q 2 tagger ZDC and Roman Pot systems all needed from the beginning

E.C. Aschenauer 27 Summarized at: Hadron Beam: 1.the detection of neutrons of nuclear break up in the outgoing hadron beam direction  location/acceptance of ZDC  location/acceptance of ZDC 2.the detection of the scattered protons from exclusive and diffractive reaction in the outgoing proton beam direction the detection of the spectator protons from 3 He and Deuterium the detection of the spectator protons from 3 He and Deuterium  location/acceptance of RP; 3.space for hadron and local polarimetry Lepton Beam: 1.minimize impact of detector magnetic field on lepton beam  synchrotron radiation 2.space for low Q 2 scattered lepton detection 3.space for the luminosity monitor in the outgoing lepton beam direction 4.space for lepton polarimetry Important EIC is a high luminosity machine cm -2 s -1 such controlling systematics becomes crucial  luminosity measurement  lepton and hadron polarization measurement EIC User Meeting, Berkley, 2016

E.C. Aschenauer 28 5 x 250 starts here 5 x 100 starts here hep-ph: (M.Stratmann, R. Sassot, ECA) cross section: pQCD scaling violations world data current data w/ EIC data

E.C. Aschenauer EIC User Meeting, Berkley, Need systematics ≤ 2% arXiv: Dominant systematics: Luminosity Measurement  Relative Luminosity  R needs to be controlled better then A LL ~10 -4 at low x ~10 -4 at low x Absolut polarization measurements: electron P e and hadron P p Need also an excellent Luminosity measurement relativeluminosity

Polarized hydrogen Jet Polarimeter (HJet) Source of absolute polarization (normalization for other polarimeters) Slow (low rates  needs looong time to get precise measurements) Proton-Carbon Polarimeter RHIC and AGS Very fast  main polarization monitoring tool Measures polarization bunch profile and lifetime Needs to be normalized to HJet Local Polarimeters at Experiments sits between spin rotators Critical to define spin direction at experiments  can use the concept of pC  asymmetry vanishes for longitudinal polarisation All of these systems are necessary for the hadron beam polarization measurements and monitoring E.C. Aschenauer 30 EIC User Meeting, Berkley, 2016 All the equipment is used at RHIC to measure polarization since many years

31 Account for beam polarization decay through fill  P(t)=P 0 exp(-t/  p ) growth of beam polarization profile R through fill pCarbonpolarimeter x=x0x=x0x=x0x=x0 ColliderExperiments correlation of dP/dt to dR/dt for all 2012 fills at 250 GeV Polarization lifetime has consequences for physics analysis  different physics triggers mix over fill  different  different Result: Have achieved 6.5% uncertainty for DSA and 3.4 for SSA  will be challenging to reduce to 1-2% polarised Deuterium and He-3 polarimetry will be challenging  to use CNI you need to make sure D and He-3 does not break up E.C. Aschenauer EIC User Meeting, Berkley, 2016

572 nm pulsed laser 572 nm pulsed laser laser transport system laser transport system laser light polarization laser light polarization measured continuously measured continuously Considerations:  Measure Polarization as close to IP as possible  location should have bremsstrahlungs and synchrotron radiation contamination minimized  Polarimeter needs to measure both longitudinal and transverse component  important for systematics  Polarimeter technology needs to allow to have precise polarisation measurements as function of all depolarizing effects, as function of all depolarizing effects,  feedback to collider  requires to integrate electron polarimeter fully into machine lattice E.C. Aschenauer EIC User Meeting, Berkley,  Method: Compton backscattering longitudinal polarization  Energy asymmetry longitudinal polarization  Energy asymmetry transverse polarization  position asymmetry transverse polarization  position asymmetry  segmented Calorimeter  to measure both components HERA LPol: achieved systematic uncertainty 1.4%

E.C. Aschenauer EIC User Meeting, Berkley,  Compton events produced by shining a laser on the electron beam while flipping the helicity state and measuring the resulting asymmetry  Can measure either the scattered photon or electron or best both  Most probable energy of scattered photon is at the Compton edge  Scattered photons highly collimated in electron beam direction  Fairly large analyzing power at the Compton edge Cross section Cross section 5 GeV e beam 5 GeV e beam 15 GeV e beam 15 GeV e beam 20 GeV e beam 20 GeV e beam 2.33 eV laser for all cases max photon energy = GeV max photon energy = GeV max photon energy = 5.23 GeV max photon energy = 5.23 GeV max photon energy = 8.33 GeV max photon energy = 8.33 GeV Longitudinal asymmetry (analyzing power)

EIC User Meeting, Berkley, 2016 Concept: Use Bremsstrahlung ep  ep  as reference cross section  different methods: o Bethe Heitler, QED Compton, Pair Production  Hera: reached 1-2% systematic uncertainty Goals for Luminosity Measurement:  Integrated luminosity with precision δL< 1%  Measurement of relative luminosity: physics-asymmetry/10 EIC challenges:  with cm -2 s -1 one gets on average 23 bremsstrahlungs photons/bunch for proton beam  A-beam Z 2 -dependence  this will challenge single photon measurement under 0 o E.C. Aschenauer 34 zero degree photon calorimeter high rate  measured energy proportional to # photons  subject to synchrotron radiation additional pair spectrometer low rate   The calorimeters are outside of the primary synchrotron radiation fan   The spectrometer geometry  low energy cutoff in the photon spectrum,  depends on dipole field and calorimeter transverse location

35  The expected angular distribution of Bremsstrahlung photons  Bethe-Heitler calculation  typical angle emission less than 0.03 mrad  what is the beam divergence contribution   = angular beam divergence  = (normalized) emittance  = lorentz factor  * = beam optics parameter at IP Large contribution: critical to be considered in the design E.C. Aschenauer EIC User Meeting, Berkley, 2016

E.C. Aschenauer EIC User Meeting, Berkley, 2016  Requirements for detector and IR clearly defined and documented in different documents and actively maintained web-pages  To capitalize on the EIC physics potential as well as on its high luminosity a new uncompromised detector is needed from day one  Working hand-in-hand with machine groups to integrate the detector and its auxilliary ones into the machine and IR-design is mandatory 36 Detector and IR design will need to be adapted to new physics measurements Happy New Year to everybody to everybody and the EIC and the EIC

E.C. Aschenauer EIC User Meeting, Berkley, BACKUP

 Inclusive cross section   tot =  ela +  qela +  inel +  v o for all parts photons can be radiated from the incoming and outgoing lepton, high Z-material Compton peak. radiation is proportional to Z 2 of target, for elastic scattering like bremsstrahlung radiation is proportional to 1/m 2 of radiating particle  elastic:  quasi-elastic: scattering on proton in nuclei o proton stays intact o nuclei breaks up  two photon exchange? Interference terms? E.C. Aschenauer EIC User Meeting, Berkley, initial final vacuum loops

 Modify kinematics  Q 2 :  initial state: E’ beam = E beam – E  o photon goes along the beam line  final state: E’ out = E out – E  o photon goes somewhere in Calo  RadCor and detector smearing don’t factorize  need to have RadCor implemented in MC to unfold effects on kinematics  unfolding in bins o N true =N meas -N bckg  Migration from bin to bin influences bin size  increased  N E.C. Aschenauer EIC User Meeting, Berkley, events smeared into acceptance

Cross section: Pythia  ep : 0.30 mb – 0.55 mb Luminosity: cm -2 s -1 = 10 6 mb -1 s -1 E.C. Aschenauer EIC User Meeting, Berkley, Interaction rate: 0.3 MHz – 0.5 MHz EIC 15 GeV x 250 GeV low ∫multiplicity; 4-10 √s = GeV N ch (ep)~N ch (eA) < N ch (pA)

E.C. Aschenauer EIC User Meeting, Berkley, Extended IR region and by pass modeled in Geant low Q 2 -tagger RP gain acceptance with a gain acceptance with a station very far down (>40m) station very far down (>40m) still need to model this still need to model this seems to be lost in magnet yoke seems to be lost in magnet yoke can work with CAD to improve can work with CAD to improve -6 < θ < -5 mrad -5 < θ < -4 mrad -4 < θ < -3 mrad -3 < θ < -2 mrad -2 < θ < -1 mrad -1 < θ < 0 mrad 0 < θ < 1 mrad 0 < θ < 1 mrad e-polarimeter and luminosity detector are next to be integrated in IR and modeled in Geant

E.C. Aschenauer 42  Assume e/m calorimeter with energy resolution ~5%/√E is used in addition to tracking  Consider no-bremstrahlung case for simplicity tracking only tracking + EmCal How can we improve further:  Try to account for bremsstrahlung photon  Procedure: use hadronic final state information  a good EmCal clearly helps to extend useful y-range EIC User Meeting, Berkley, 2016