Detector & Interaction Region Concepts for DES and SIDIS Pawel Nadel-Turonski Jefferson Lab, Newport News, VA EICC meeting, January 10–12, 2010, Stony Brook, NY

12 January Outline 1. Deep Exclusive Reactions 2. Detector and Interaction Region Concepts 3. SIDIS Kinematics at various proton energies Acceptance and PID Only brief discussion Taking advantage of crossing angle and symmetric kinematics Detector implementation

12 January Exclusive meson kinematics – p Meson kinematics integrated over all Q 2 –Vertical lines at 30° (possibly up to 40°) indicate transition from central barrel to endcaps –Horizontal line indicates maximum meson momentum for π/K separation with a DIRC Problem: cross section falls rapidly with Q 2 –Higher Q 2 is needed due to factorization requirements for GPD determination, but plots shown are dominated by photoproduction. Tanja Horn ep → e'π + n 4 on 12 GeV4 on 30 GeV4 on 250 GeV

12 January Exclusive meson kinematics – Q 2 Tanja Horn ep → e'π + n 4 on 12 GeV4 on 250 GeV4 on 60 GeV “Asymmetric” kinematics: 250 GeV protons –high Q 2 mesons are detected in ion side endcap May suggests slightly different optimizations, but no major differences “Symmetric” kinematics: GeV protons –high Q 2 mesons are detected in the central barrel

12 January Exclusive meson kinematics – p at higher Q 2 Tanja Horn 4 on 250 GeV4 on 30 GeV no Q 2 cut Q 2 > 10 GeV 2 The meson momentum distribution has a strong Q 2 -dependence DIRC not useful at 250 GeV. Large bore angle (RICH acceptance) helpful? No mesons at small angles where solenoid resolution is poor (both kinematics). Momentum resolution (dp/p ~ p from tracking), a challenge at 250 GeV?

12 January “Symmetric” kinematics – 4 on 30 GeV Tanja Horn ep → e'π + n recoil baryonsscattered electronsmesons no Q 2 cut Q 2 > 10 GeV 2 t-distribution unaffected forward mesons: low Q 2, high p low-Q 2 electrons in electron endcap high-Q 2 electrons in central barrel: 1-2 < p < 4 GeV mesons in central barrel: 2 < p < 4 GeV

12 January For Q 2 > 10 GeV 2, 4 on 30 or 250 GeV is quite different Tanja Horn recoil baryonsscattered electronsmesons 4 on 250 GeV 4 on 30 GeV  t/t ~ t/E p  lower E p better DIRC not useful very high momenta electrons in central barrel, but p different 2.5° 0.5°

Exclusive electron kinematics – Q 2 Tanja Horn ep → e'π + n 4 on 250 GeV4 on 12 GeV4 on 60 GeV Q 2 -distribution similar for all proton energies –Electron momenta are very different on ion side! Electrons with Q 2 > 5 GeV 2 will generally be detected in the central barrel Higher electron energies shift distribution to the left electrons with beam energy

12 January (Crab) crossing angle and symmetric kinematics 2. Detector Challenges 3. Accelerator benefits Allow a compact forward ion detector Can be used to eliminate synchrotron radiation Produce electron and meson momenta comparable to CLAS – Good momentum resolution – Good particle identification Reduced chromaticity (f/ β *) Optimization of forward ion detection PID at higher electron enegies (5-10 GeV) DES detector and Interaction Region concepts

12 January Dipole coils Forward detection with crossing angle Electrons on solenoid axis, ions cross at 3° (50 mrad) –Improves hadron tracking at small angles, also in solenoid (v x B = 0 on axis) –Outer radius of electron FFQs about 10 cm if 4-6 m from IP Common forward dipole has some disadvantages –Produces synchrotron radiation (field exclusion plates?) –Field settings according to electron energy, not ion energy –Requires downstream steering for ions before FFQs –Introduces a large amount of dead material close to bore –Even a 1 m diameter aperture offers only 9° incoming acceptance ions solenoid electron FFQs ion FFQs 3°3° 0°0° dipole (approximately to scale) Scattered positive and incoming negative particles bent “down” additional ion dipole(s) detectors electrons 5 m 3.5 m3 m IP Alternative dipole geometry

12 January Forward detection optimized for DES Downstream dipole on ion beam line has several advantages –No synchrotron radiation –Positive particles are bent away from the electron beam –Long recoil baryon flight path gives access to low -t –Does not interfere with RICH and forward calorimeters Used as veto for DES in symmetric kinematics Improved hermeticity and lower backgrounds? exclusive mesons 2.5° recoil baryons solenoid electron FFQs 3°3° 0°0° ion dipole w/ detectors (approximately to scale) ions electrons IP detectors ion FFQs -t coverage for neutrons –9 m flight path from IP to ion FFQ sufficient at 30 GeV

12 January m Forward ion (proton) detection at 250 GeV If luminosity is only high at max ion energy, asymmetric kinematics may be unavoidable recoil baryons 0.5° Achieving low-t coverage comparable to symmetric kinematics will require long unobstructed flight paths –45 m vs. 9 m (for neutrons; for protons only taking geometry into account)

14 December Solenoid yoke integrated with a hadronic calorimeter and a muon detector EM calorimeter Conceptual sketch of main detector layout EM calorimeter RICH (DIRC?) Tracking RICH Hadronic calorimeterMuon Detector? HTCC EM calorimeter ions electrons (not to scale) Time-of-flight detectors shown in green IP is shown at the center, but can be shifted (left) –Determined by desired bore angle and forward tracking DIRC would have thin bars arranged in a cylinder with mirrors and readout after the EM calorimeter on the left

12 January DES (and SIDIS) at higher energies – DIRC or RICH? With 12 GeV CEBAF, has the option of using higher electron energies – DIRC no longer sufficient for π/K separation RICH would extend diameter of solenoid from approximately 3 to 4 m –Main constraint since bore angle is not an issue in JLab kinematics 4 on 30 GeV s = 480 GeV 2 5 on 50 GeV s = 1000 GeV 2 (10 on 50 GeV) s = 2000 GeV 2 RICH based on ALICE design might push the limit from 4 to 7 GeV –Requires a more detailed study Q 2 > 10 GeV 2

12 November C. Weiss Luminosity [cm -2 s -1 ] s [GeV 2 ] COMPASS JLAB6&12 HERMES (M)EIC MeRHIC DIFF DIS EW DES JETS SIDIS Nucleon structure beyond the valence region MEIC optimized for s of GeV 2 (see talks by T. Horn and C. Weiss)

12 January T solenoid with 3-4 m diameter Hadronic calorimeter and muon detector integrated with the return yoke (c.f. CMS) TOF for low momenta π/K separation options –DIRC (BaBar) up to 4 GeV –RICH (ALICE) up to 7 GeV? e/π separation options –Lead-tungsten Very good resolution –Tungsten powder / scintillating fiber Very compact, 6% resolution Tracking Solenoid Yoke, Hadron Calorimeter, Muons Particle Identification Central Tracker –Radius: at least 80 cm assumed –Microchannel or silicon detectors? CLAS12: Micromegas –Integrated vertex tracker Central detector

12 January Bore angle: ~45° (line-of-sight from IP) High-Threshold Cerenkov Time-of-Flight Detectors Electromagnetic Calorimeter Bore angle: 30-40° (line-of-sight from IP) Ring-Imaging Cerenkov (RICH) Time-of-Flight Detectors Electromagnetic Calorimeter Hadronic Calorimeter Muon detector (at least small angles) –Important for J/Ψ photoproduction Tracking Electron side (left) Ion side (right) Forward / Backward –IP may be shifted to electron side Lower momenta –3 regions of drift chambers g Detector endcaps

12 January Synchrotron radiation is not an issue for outgoing electrons –Can use strong dipole to cover small scattering angles Still need steering dipole on either the electron or ion beam line to compensate for independently adjustable beam energies Ion quads can be placed closer on electron side. Low-Q 2 tagging? – very conceptual! 3°3° 0°0° “tagger” detector (not to scale) steering dipolesion FFQs electron FFQs dipole ions electrons

12 November Diffractive and SIDIS (TMDs) 4 on 250 GeV4 on 50 GeV diffractive DIS Diffractive kinematics for 4 on 50 are still quite symmetric Both reactions produce high-momentum mesons only at small angles DIRC and forward RICH seem sufficient With 3° crossing angle, solenoid and ion-only dipole (5 m from IP) also seem adequate To do: study SIDIS kinematics in many bins to see actual coverage!

12 November Summary Deep exclusive reactions (GPDs) and Semi-Inclusive DIS (TMDs) are essential for studying nucleon/nuclear structure Symmetric kinematics are ideal for probing gluons and sea quarks, but require high luminosities (10 34 ) at medium energy A 3° crossing angle allows optimization of the forward detection

12 November Backup

The central detector geometry is currently being implemented in GEANT4 –CLAS12 simulation engine (GEMC) is used –Detector elements modeled down to digitization level –Standard CLAS tools can be used for analysis of simulated data –At the moment only the solenoid field has been added –Will be extended to include beam line on both sides –Short- and long term event reconstruction options are being pursued Status of detector simulations at JLab The JLab simulation working group is also developing –Event generators for various processes –A Fast Monte Carlo to explore acceptance and resolution requirements

12 January actual (simulated) ideal solenoid JLab Hall D: 1.8T solenoid Tracking resolution

12 November JLab CLAS12

electron beam envelopes across FF quads at nominal distance 3 GeV 50 cmp50 cm120 cm G[kG/cm]=-1.14 G[kG/cm]=0.71G[kG/cm]= cm IP

12 November x ~ Q 2 /ys mEIC at JLab, 11 on 60 GeV JLab 12 GeV H1 ZEUS HERA, y=0.004mEIC 3 on 20, y=0.004 x Q 2 (GeV 2 ) s The will overlap with HERA and JLab 12 GeV at a comparable luminosity. – kinematic coverage

12 November L s detector limit synchrotron radiation limits electron current space charge limits ion current at low momentum ERL-Ring Ring-Ring Luminosity scales with ion momentum if cooling can shrink the ion beam (ε p ) e p A medium-energy ring-ring collider provides a high luminosity over a range in s, not only at the end point. Luminosity