1. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 1 Experimental Techniques Where do we come from, where are we going? Bernhard A. Mecking Jefferson Lab Gordon Conference on Photonuclear Reactions August 1 - 6, 2004

2. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 2 Topics Beams Targets Detectors Electronics + DAQ New facilities Trends I apologize in advance to everybody whose favorite topic I have left out.

3. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 3 Technical Progress and Discovery Intimate connection between establishing a new technical capability and a quantum leap in understanding General field tightly coupled to advances in vacuum and surface technology, RF, electronics and computing, beam dynamics, simulation Specific Examples deep-inelastic scattering scaling quarks) e + e - collisions + large acceptance coverageJ/Psi (October 1974) polarized beam and targetnucleon spin structure precise data for  N  Ntests of Chiral PT polarization + Rosenbluth data for G e p /G m p importance of 2  effects? investigation of KN final statespenta-quark?

4. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 4 Experiment Schematics Accelerator target (polarized) Source (pol.) Data conversion modules Data acquisition and storage Detector beam

5. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 5 Electron Accelerators History linear accelerators (HEPL Mark III 1 GeV in 1950, SLAC 20 GeV in 1967, Saclay, MIT, NIKHEF) synchrotrons (Bonn 0.5 and 2.5 GeV, Daresbury, DESY 6 GeV) common features: pulsed RF or changing magnetic field, limits duty-cycle and beam quality Present status 100% duty-cycle operation using low-gradient warm accelerator structures + many passes (MAMI) superconducting accelerator structures + few passes (CEBAF) Future developments higher gradients for e + e - colliders (cost, not duty-cycle important) energy recovery for FEL, synchrotron light sources, electron beam cooling, etc. own community: MAMI C, CEBAF 12 GeV upgrade electron-ion collider

6. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 6 MAMI Microtron 3. Stage

7. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 7 CEBAF Continuous Electron Beam Accelerator Facility accelerating structures CHL RF separators Properties E max 5.8 GeV I max 200  A P e 85% beams 3 recirculating arcs

8. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 8  E/E x 10 -5 Electron Accelerator Beam Quality Beam Profile in Hall B obtained with dual wire scanner 10nA to Hall B, 100  A to Hall A Beam Energy Spread in Hall A Line synchrotron light interference monitor continuous non-destructive measurement 4 2 0  = 130  m

9. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 9 Electron Accelerators History linear accelerators (HEPL Mark III 1 GeV in 1950, SLAC 20 GeV in 1967, Saclay, MIT, NIKHEF) synchrotrons (Bonn 0.5 and 2.5 GeV, DESY 6 GeV) common features: pulsed RF or changing magnetic field, limits duty-cycle and beam quality Present status 100% duty-cycle operation using low-gradient warm accelerator structures + many passes (MAMI) superconducting accelerator structures + few passes (CEBAF) Future developments high gradients for e + e - colliders (cost, not duty-cycle important) energy recovery for FEL, synchrotron light sources, electron beam cooling, etc. own community: MAMI C, CEBAF 12 GeV upgrade electron-ion collider?

10. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 10 Polarized Electron Sources History 1977: first parity violation experiment at SLAC (e D e’X, DIS) GaAs photocathode, dye laser, P e ~37% (theoretical max. of 50%) rapid polarization reversal via Pockels cell experimental asymmetry ~6. 10 -5 (syst. errors 10x smaller) Present status same technique strained GaAs or super-lattice, RF pulsed Ti-sapphire laser, P e ~85% systematic errors < 2. 10 -8 (E158 at SLAC) polarization measurement at ~ 1% level (Moller and Compton scattering) Future Developments modest push for higher polarization smaller systematic errors higher current (many mA required for linac-ring collider)

11. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 11 Photon Beams History bremsstrahlung beams (endpoint, endpoint difference) tagged bremsstrahlung (first use at Cornell 1953)

12. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 12 First Use of Tagged Photon Beam fast (5 nsec) coincidence setup Hans Bethe Boyce McDaniel

13. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 13 First Use of Tagged Photon Beam fast (5 nsec) coincidence setup Hans Bethe Boyce McDaniel

14. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 14 Photon Beams History bremsstrahlung beams (endpoint, endpoint difference) tagged bremsstrahlung (first use at Cornell 1953) laser backscattering  + e  + e (benefiting from synchrotron light rings) Present status tagged bremsstrahlung routine with cw beam (MAMI, ELSA, CEBAF) photon flux 10 7 - 8 /sec, limited by accidentals or low-energy background laser backscattering routine (HIGS, LEGS, GRAAL, LEPS@SPring8) high polarization at endpoint, tagging required, luminosity limited by parasitic operation Future developments tagged bremsstrahlung beam has reached full potential luminosity limitation in laser backscattering may be helped by continuous injection at full energy (ANL, SPring8)

15. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 15 Laser Backscattering: GRAAL at ESRF fixed collimator tagging system interaction region variable collimator cleaning magnet ESRF 6 GeV e Laser hut laser Performance laser energy3.53 eV photon energy(550 – 1470) MeV resolution 16 MeV (FWHM) intensity2. 10 6 /sec laser intensity, position, and polarization monitoring Be mirror laser optics

16. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 16 HI  S Photon Source at TUNL Principle use DUKE 1.2 GeV FEL to produce UV laser light laser photons backscatter off subsequent electron bunch Present capabilities mostly <20 MeV operation due to lifetime considerations Future capabilities upgrade underway to allow for full-energy injection installation of OK-4 optical klystron (capable of producing up to 12 eV, mirrors?) maximum energy 200 MeV maximum flux 10 8 /sec energy definition via collimation (no tagging) injector 1.2 GeV Ring optical klystron

17. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 17 dump Future Source of High-Energy Photons? Method collide laser light from FEL with electrons from single-turn light source Potential photon energy (with 12 eV laser) 2.4 GeV from 5 GeV ring 4.8 GeV from 8 GeV ring photon energy resolution <1% (collimation, no tagging) flux > 10 8 /sec SC linac e-gun FEL dump single-turn synchrotron light source

18. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 18 H/D Polarized Targets Electron beams dynamically polarized target (NH 3, butanol) polarize free e at high field (~5T) and low T (~1K) use microwave transitions to transfer e polarization to H or D maximum luminosity L~5. 10 34 cm -2 s -1 (for polarized component) problems: nuclear background, magnet blocking acceptance

19. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 19 Polarized Solid State Target for CLAS

20. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 20 H/D Polarized Targets Electron beams dynamically polarized target (NH 3, butanol) polarize free e at high field (~5T) and low T (~1K) use microwave transitions to transfer e polarization to H or D maximum luminosity L~5. 10 34 cm -2 s -1 (for polarized component) problems: nuclear background, magnet blocking acceptance Photon beams (frozen spin target) 1.same substance, same polarizing technique but freeze spin at low T (50mK) and lower field (0.5T) small magnet coil (transparent to particles) 2.HD molecule, brute force polarization at 15T and 10mK potential advantage: lower dilution due to nuclear component (first success at LEGS, also in preparation for GRAAL)

21. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 21 Setup for GDH experiment at MAMI tagged photon beam Bonn Frozen Spin Target

22. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 22 Bonn Frozen Spin Target (GDH Experiment at MAMI) Butanol with porphyrexid (radiation doped) Butanol with titryl radical (chemically doped) Improvement of polarization of deuterated butanol during 2003 running period (based on detailed ESR studies of different materials at U. of Bochum)

23. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 23 Polarized 3 He Targets Physics interests few-body structure good approximation for polarized free n (P n =87 % and P p =2.7 %), requires corrections for nuclear effects Standard technique: optical pumping of Rb vapor, followed by polarization transfer to 3 He through spin-exchange collisions target polarization measured by EPR/NMR Performance 40cm long target (10atm, I e =12  A) luminosity ~2. 10 36 cm -2 s -1 average polarization 42% Hall A 3 He target 25 Gauss Latest development: optical pumping of Rb/K mixture

24. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 24 Particle Detection: Focusing Magnetic Spectrometers advantage high momentum resolution possible (due to point-to-point imaging from target _ > detector) detectors far away from target (behind magnetic channel) - insensitive to background - can operate at very high luminosity disadvantage coverage in solid angle and momentum range is limited examples 3-spectrometer setup at MAMI Hall A HRS at JLab

25. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 25 MAMI 3-Spectrometer Setup ABC configurationQSDDD p max [MeV/c]665810490  msr  285.628  min 18 7  p/p [%] 201525 all magnet coils resistive

26. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 26  msr  p/p10 -4  p/p10 -1 HRS 4GeV/c Spectrometer Pair in Hall A Q Q Q D beam target detector hut ‘optical bench’ all magnet coils super-conducting

27. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 27 Particle Detection: Large Acceptance Detectors advantage: large coverage in solid angle and momentum range possible for - multi-particle final states - luminosity limited (photon tagging, polarized target) disadvantage: resolution and luminosity limited, large # of channels ($$) examples optimized for photon detection SASY (BNL LEGS) LAGRANGE (GRAAL) Crystal Barrel (ELSA) Crystal Ball (MAMI) optimized for charged particle detection HERMES (HERA) LEPS (SPring-8) CLAS (CEBAF)

28. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 28 LAGRANGE at GRAAL Components 480 BGO crystals (21X o ) with PMT readout,  -coverage: 25 o - 155 o wire chambers for charged particle tracking forward TOF and photon detection in lead/scintillator sandwich detector liquid hydrogen target lead/ scintillator sandwich BGO calorimeter scintillator barrel cylindrical wire chambers photon beam

29. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 29 Crystal Barrel at ELSA CB: prior service at LEAR

30. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 30 Crystal Ball - TAPS Combination Crystal Ball central detector 672 NaI crystals 80 MHz FADC electronics (collaboration with CMS) TAPS forward detector 528 BaF 2 crystals with veto counters particle ID via fast/slow scintillation light First experiments  + magnetic moment from  p p  o  rare  -decays CB: prior service at SPEAR, DORIS, BNL TAPS CB

31. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 31 Crystal Ball at MAMI

32. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 32 LEPS at SPring-8

33. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 33 CLAS in Maintenance Position Operating conditions (e-scattering luminosity10 34 cm -2 s -1 hadronic rate10 6 /sec Moller e rate10 9 /sec e-triggerCer. + calorimeter event size5 kBytes trigger rate4,000/sec data transfer rate20 Mbytes/sec

34. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 34 Electronic Instrumentation History 1950’s: modules in crates; lab (CalTech) or proprietary company (EG&G) standards 1960’s: NIM standard (mechanical and electrical, no bus specified) 1970’s: CAMAC standard (bus system, limited success for industrial control) 1978: FASTBUS standard (high channel density, no industrial use) 1981: VME standard (flexible, many industrial applications) Trends number of industrial suppliers going down reasons: custom solutions needed for high-density on-detector electronics large size collaborations (e.g. LHC) have enough expertise large projects provide financial incentive for detector-specific developments

35. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 35 How to handle 1000 events per second?? Data Acquisition (a personal experience) Tagged photon beam operation at the Bonn 500 MeV Synchrotron timemid 1970’s duty-cycle3% bunch separation6 nsec tagged beam intensity10 5 /sec magnetic spectrometer  100 msr data rate1/10 sec on-line computerNova memory (16 bit) 32kB core clock speed 1.5 MHz Improvement factors expected 100% duty-cycle 30 2 nsec bunch separation 3 4  spectrometer100 overall 10,000 500 MeV Synchrotron 20-channel Internal tagging system radiator magnetic spectrometer B

36. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 36 Development of Raw Data Volume source: Ian Bird ‘Moore’s law’ for CPU power GByte/year,,,,,

37. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 37 New Facilities HI  S MAMI Upgrade CEBAF 12 GeV Upgrade e-ion Collider

38. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 38 MAMI Upgrade Program 1.add double-sided microton HDSM to increase energy to 1.5 GeV first beam in 2005 2.add experimental equipment Crystal Ball Kaon Spectrometer

39. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 39 6 GeV CEBAFCHL-2 Upgrade magnets and power supplies 12 add Hall D (and beam line) Upgrade Experimental Equipment Glue-X detector in new Hall D MAD spectrometer in Hall A upgraded CLAS in Hall B SHMS spectrometer in Hall C Properties E max 12 GeV I max 80  A beams 3

40. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 40 Hall D: GlueX Detector forward drift chambers lead-glass calorimeter forward time-of-flight Cerenkov cylindrical drift chambers Target vertex detector 2 meters barrel calorimeter + central ToF SC solenoid (LASS, MEGA) tagged photon beam

41. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 41 M edium A cceptance D evice Spectrometer in Hall A Properties  30 msr Pmax 7 GeV/c  p/p 30%  p/p 5. 10 -3 Technology 2 SC magnets 120cm circular aperture cos  cos  windings 6 Tesla max. field HRS MAD D+Q target support structure detector package

42. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 42 Upgraded CLAS (CLAS ++ ) Forward TOF Preshower EC Forward EC Forward Cerenkov Forward DC Inner Cerenkov Central Detector Coil Calorimeter Torus Cold Ring

43. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 43 Future Facility: Electron-Ion Collider? Physics motivation study processes at high c.m.s energy and low x ~10 -(3-4) especially gluon distribution functions Technical challenges high luminosity (high bunch charge, electron beam cooling) polarization control for both beams Technical approaches eRHIC add 10 GeV e-ring to 250 GeV RHIC, L~10 33 cm -2 s -1 ELIC add 30-150 GeV p-ring to 3-7 GeV single-turn CEBAF, L~10 33-35 cm -2 s -1 could also recirculate 5 GeV to get 25 GeV for fixed target experiments

44. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 44 Ion Linac and pre - booster IR Beam Dump Snake CEBAF with Energy Recovery 3-7 GeVelectrons30-150 GeV light ions Solenoid - booster IR Beam Dump Snake CEBAF with Energy Recovery 3-7 GeVelectrons30-150 GeV light ions Solenoid - IR Beam dump Snake CEBAF with Energy Recovery 3-7 GeV electrons 30-150 GeV light ions Solenoid Electron Injector Electron cooling ELIC Electron-Light Ion Collider Layout from Lia Merminga at EIC Workshop, JLab 03/15/2004 Ion linac and pre-booster

45. Thomas Jefferson National Accelerator Facility BAM, Gordon Conference 2004 45 Future Trends Experiments: coverage, polarization observables, accuracy Accelerators: energy, helicity correlated effects, dedicated collider? Detectors focusing magnetic spectrometers:energy, acceptance, resolution large acceptance spectrometers: luminosity balance between charged and neutrals cooperation with HEP Electronics/DAQ local intelligence DAQ rates on-line analysis