E.C. AschenauerEIC INT Program, Seattle Week 81

Kinematics of elastic diffraction E.C. Aschenauer EIC INT Program, Seattle Week 82 4x250 4x100 4x50 no cuts: cuts: Q2 > 0.1 GeV && y 0.1 GeV && y < 0.9 GeV decay products of  & J/ ψ go more and more forward with increasing asymmetry in beam energies

Diffractive Physics: p’ kinematics E.C. Aschenauer EIC INT Program, Seattle Week 83 4 x 100 t=(p 4 -p 2 ) 2 = 2[(m p in.m p out )-(E in E out - p z in p z out )] 4 x 50 4 x 250 ? Diffraction: p’ need “roman pots” to detect the protons and a ZDC for neutrons t=(p 3 –p 1 ) 2 = m ρ 2 -Q 2 - 2(E γ* E ρ -p x γ* p x ρ -p y γ* p y ρ -p z γ* p z ρ )

How to detect exclusive protons  Detector concepts  Roman Pots for protons / charged particles  Zero Degree Calorimeters (ZDC) for neutrons  Preshower & ECal for photons, important for eA  e’A’   Challenges  angular emittance of the beam eRHIC: 0.1 mrad  how close to the beam can the roman pots go normally 10   1mrad  geometric acceptance of magnets  need thin exit windows for particles  need most likely more than one place to put roman pots E.C. Aschenauer EIC INT Program, Seattle Week 84

eRHIC Detector Concept E.C. Aschenauer EIC INT Program, Seattle Week 85 Forward / Backward Spectrometers: 2m 4m  central detector acceptance: very high coverage -5 <  < 5  Tracker and ECal coverage the same  crossing angle: 10 mrad;  y = 2cm and  x = 2/4cm (electron/proton direction)  Dipoles needed to have good forward momentum resolution and acceptance  DIRC, RICH hadron identification  , K, p  low radiation length extremely critical  low lepton energies  precise vertex reconstruction (< 10  m)  separate Beauty and Charmed Meson minimum angle for “elastic protons” to be detected in the main detector 10 mrad  p t = 1 GeV

IR-Design-Version-I 0.44 m Q5 D5 Q4 90 m 10 mrad m 3.67 mrad 60 m m 18.8 m 16.8 m 6.33 mrad 4 m Dipole © D.Trbojevic 30 GeV e GeV p 125 GeV/u ions eRHIC - Geometry high-lumi IR with β*=5 cm, l*=4.5 m and 10 mrad crossing angle Assume 50% operations efficiency  4fb -1 / week E.C. Aschenauer EIC INT Program, Seattle Week 86 Spinrotator

A detector integrated into IR – Version 1 E.C. Aschenauer EIC INT Program, Seattle Week 87 ZDC FPD  for ERL solution need not to measure electron polarization bunch by bunch  need still to integrate luminosity monitor  need still to integrate hadronic polarimeters, maybe at different IP FED space for e-polarimetry and luminosity measurements

Can we detect DVCS-protons and Au break up p E.C. Aschenauer EIC INT Program, Seattle Week 88  track the protons through solenoid, quads and dipole with hector  beam angular spread 0.1mrad at IR  Quads +/- 5mrad acceptance; geometric acceptance: 1.5cm  Proton-beam: p’ z > 0.9p z  100 GeV: p t max < 0.45 GeV  suboptimal as we loose intermediate p t (0.4 – 1.2 GeV)/ t range  solution could be to do the same as for the electrons swap the dipole and quads  lumi goes down  see next slides dipole and quads  lumi goes down  see next slides proton track  p=10% proton track  p=20% Equivalent to fragmenting protons from Au in Au optics (197/79:1 ~2.5:1) proton track  p=40%

m 3.5 m mm 5.75 m 16 IP Dipole: 2.5 m, 6 T  =18 mrad 4.5 m  =18 mrad  =10 mrad Estimated  * ≈ 8 cm  =44 mrad 6.3 cm ZDC p c / cm 6 mrad 11.2 cm 4.5 cm neutrons p c /2.5 IP configuration for eRHIC – Version-II E.C. Aschenauer 9EIC INT Program, Seattle Week 8 e Quad Gradient: 200 T/m

m Q5 D5 Q m 10 mrad m m m IP configuration for eRHIC – Version-II E.C. Aschenauer EIC INT Program, Seattle Week m 4.5  =18 mrad 5.75 m 5.75 cm 11.9 m m  = mrad

Can we detect “exclusive” protons E.C. Aschenauer EIC INT Program, Seattle Week 811  lets see acceptance now  beam angular spread 0.1mrad at IR  Dipole +/- 10 mrad; geometric acceptance: +/ cm  Quads +/- 3 mrad acceptance; geometric acceptance: < 1.5cm  Proton-beam: p’ z > 0.9p z  lets assume p z = p beam  maximal p t  100 GeV: p t max < 1 GeV  50 GeV: p t max < 0.8 GeV  minimal p t  assume 10  distance of roman pot to beam  100 GeV: p t min ~ 100 MeV  50 GeV: p t min ~ 50 MeV Looks much more promising than v-I, need to do full particle ray tracing

How to measure coherent diffraction in e+A ?  Beam angular divergence limits smallest outgoing  min for p/A that can be measured  Can measure the nucleus if it is separated from the beam in Si (Roman Pot) “beamline” detectors  p Tmin ~ p z A tanθ min For beam energies = 100 GeV/n and θ min = 0.1 mrad θ min = 0.1 mrad  Large momentum kicks, much larger than binding energy (~8 MeV) than binding energy (~8 MeV)  Therefore, for large A, coherently diffractive nucleus cannot be separated from beamline without breaking up E.C. Aschenauer EIC INT Program, Seattle Week 812 species (A) p Tmin (GeV/c) d (2)0.02 Si (28)0.22 Cu (64)0.51 In (115)0.92 Au (197)1.58 U (238)1.90

How to measure coherent diffraction in e+A ? E.C. Aschenauer EIC INT Program, Seattle Week 813  Rely on rapidity gap method  simulations look good  high eff. high purity possible with gap alone possible with gap alone ~1% contamination ~1% contamination ~80% efficiency ~80% efficiency  depends critical on detector hermeticity hermeticity  improve further by veto on breakup of nuclei (DIS) breakup of nuclei (DIS)  Very critical  mandatory to detect nuclear fragments from breakup fragments from breakupPurityEfficiencyrapidity

E.C. Aschenauer EIC INT Program, Seattle Week 814 BACKUP

6.5 T magnet, 2.5 m long 4.5 cm E.C. Aschenauer 15EIC INT Program, Seattle Week 8

E.C. Aschenauer EIC INT Program, Seattle Week 8 Quads for β*=5 cm © B.Parker 16