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Experimental Techniques Where do we come from, where are we going?

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. Topics. Beams Targets Detectors Electronics + DAQ New facilities Trends.

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Experimental Techniques Where do we come from, where are we going?

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  1. Experimental TechniquesWhere do we come from,where are we going? Bernhard A. Mecking Jefferson Lab Gordon Conference on Photonuclear Reactions August 1 - 6, 2004 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. 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 coverage J/Psi (October 1974) • polarized beam and target nucleon spin structure • precise data for gN pN tests of Chiral PT • polarization + Rosenbluth data for Gep/Gmp importance of 2g effects? • investigation of KN final states penta-quark? BAM, Gordon Conference 2004

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

  6. MAMI Microtron 3. Stage BAM, Gordon Conference 2004

  7. CEBAFContinuous Electron Beam Accelerator Facility recirculating arcs Properties Emax 5.8 GeV Imax200mA Pe 85% beams 3 accelerating structures CHL RF separators BAM, Gordon Conference 2004

  8. Electron Accelerator Beam Quality Beam Profile in Hall B obtained with dual wire scanner 10nA to Hall B, 100mA to Hall A Beam Energy Spread in Hall A Line synchrotron light interference monitor continuous non-destructive measurement dE/E x 10-5 4 s = 130mm 2 0 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? 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, Pe~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, Pe~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) BAM, Gordon Conference 2004

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

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

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

  14. Photon Beams History bremsstrahlung beams (endpoint, endpoint difference) tagged bremsstrahlung (first use at Cornell 1953) laser backscattering g + e g + e (benefiting from synchrotron light rings) Present status tagged bremsstrahlung routine with cw beam (MAMI, ELSA, CEBAF) • photon flux 107- 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) BAM, Gordon Conference 2004

  15. Laser Backscattering: GRAAL at ESRF variable collimator interaction region tagging system ESRF 6 GeV e cleaning magnet Be mirrorlaser optics laser intensity, position, and polarization monitoring laser fixed collimator Performance laser energy 3.53 eV photon energy (550 – 1470) MeV resolution 16 MeV (FWHM) intensity 2.106/sec Laser hut BAM, Gordon Conference 2004

  16. HIgS 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 injector 1.2 GeV Ring optical klystron 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 108/sec • energy definition via collimation (no tagging) BAM, Gordon Conference 2004

  17. 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 > 108/sec FEL e-gun dump dump SC linac single-turn synchrotron light source BAM, Gordon Conference 2004

  18. H/D Polarized Targets Electron beams dynamically polarized target (NH3, 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~5.1034cm-2s-1 (for polarized component) problems: nuclear background, magnet blocking acceptance BAM, Gordon Conference 2004

  19. Polarized Solid State Target for CLAS BAM, Gordon Conference 2004

  20. H/D Polarized Targets Electron beams dynamically polarized target (NH3, 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~5.1034cm-2s-1 (for polarized component) problems: nuclear background, magnet blocking acceptance Photon beams (frozen spin target) • same substance, same polarizing technique but freeze spin at low T (50mK) and lower field (0.5T) small magnet coil (transparent to particles) • 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) BAM, Gordon Conference 2004

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

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

  23. Polarized 3He Targets Hall A 3He target Physics interests • few-body structure • good approximation for polarized free n (Pn=87 % and Pp=2.7 %), requires corrections for nuclear effects Standard technique: • optical pumping of Rb vapor, followed by polarization transfer to 3He through spin-exchange collisions • target polarization measured by EPR/NMR Performance • 40cm long target (10atm, Ie=12mA) • luminosity ~2.1036cm-2s-1 • average polarization 42% 25 Gauss Latest development: • optical pumping of Rb/K mixture 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 BAM, Gordon Conference 2004

  25. MAMI 3-Spectrometer Setup all magnet coils resistive BAM, Gordon Conference 2004

  26. HRS 4GeV/c Spectrometer Pair in Hall A DW 7 msr dp/p 10-4 Dp/p 10-1 all magnet coils super-conducting detector hut Q ‘optical bench’ target D Q Q beam 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) BAM, Gordon Conference 2004

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

  29. Crystal Barrel at ELSA CB: prior service at LEAR 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 BaF2 crystals with veto counters • particle ID via fast/slow scintillation light First experiments • D+ magnetic moment from gp ppog • rare h-decays CB TAPS CB: prior service at SPEAR, DORIS, BNL BAM, Gordon Conference 2004

  31. Crystal Ball at MAMI BAM, Gordon Conference 2004

  32. LEPS at SPring-8 BAM, Gordon Conference 2004

  33. CLAS in Maintenance Position Operating conditions (e-scattering luminosity 1034cm-2s-1 hadronic rate 106/sec Moller e rate 109/sec e-trigger Cer. + calorimeter event size 5 kBytes trigger rate 4,000/sec data transfer rate 20 Mbytes/sec 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 BAM, Gordon Conference 2004

  35. Data Acquisition (a personal experience) Tagged photon beam operation at the Bonn 500 MeV Synchrotron time mid 1970’s duty-cycle 3% bunch separation 6 nsec tagged beam intensity 105/sec magnetic spectrometer DW=100 msr data rate 1/10 sec on-line computer Nova memory (16 bit) 32kB core clock speed 1.5 MHz 500 MeV Synchrotron 20-channel Internal tagging system radiator B magnetic spectrometer Improvement factors expected 100% duty-cycle 30 2 nsec bunch separation 3 4p spectrometer 100 overall 10,000 How to handle 1000 events per second?? BAM, Gordon Conference 2004

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

  37. New Facilities HIgS MAMI Upgrade CEBAF 12 GeV Upgrade e-ion Collider BAM, Gordon Conference 2004

  38. MAMI Upgrade Program • add double-sided microton HDSM to increase energy to 1.5 GeV • first beam in 2005 • add experimental equipment • Crystal Ball • Kaon Spectrometer BAM, Gordon Conference 2004

  39. 6 GeV CEBAF add Hall D (and beam line) 12 Upgrade magnets and power supplies CHL-2 Properties Emax 12 GeV Imax80mA beams 3 • 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 BAM, Gordon Conference 2004

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

  41. Medium Acceptance Device Spectrometer in Hall A Technology 2 SC magnets 120cm circular aperture cosQ+cos2Q windings 6 Tesla max. field Properties DW 30 msr Pmax 7 GeV/c Dp/p 30% dp/p 5.10-3 HRS MAD D+Q detector package D+Q target support structure BAM, Gordon Conference 2004

  42. Forward Cerenkov Forward EC Forward DC Inner Cerenkov Central Detector Preshower EC Forward TOF Torus Cold Ring Coil Calorimeter Upgraded CLAS (CLAS++) 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~1033cm-2s-1 • ELIC add 30-150 GeV p-ring to 3-7 GeV single-turn CEBAF, L~1033-35cm-2s-1 could also recirculate 5 GeV to get 25 GeV for fixed target experiments BAM, Gordon Conference 2004

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

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