Presentation on theme: "Missing Resonances and Beyond Ken Livingston, University of Glasgow, Scotland Nucleon resonances and complete measurements Missing nucleon resonances."— Presentation transcript:
Missing Resonances and Beyond Ken Livingston, University of Glasgow, Scotland Nucleon resonances and complete measurements Missing nucleon resonances Jefferson Lab and the N* programme at CLAS Hyperon results and status of N* The future The Jefferson Lab 12GeV upgrade Future facilities – EIC, ESS, ELI SCAPA
Clear indication of resonances Broad and overlapping Below energy regime of PQCD Constituent quark models SU(6) x O(3) Eg. Forsyth & Cutkosky, Koniuk & Isgur, Capstick & Roberts Missing resonances γp cross section: World Data Most data is from πN scattering and single π photoproduction. Cross sections are not enough – need angular distributions and polarization observables. Hyperons (nucleons with strange quark) are promising ( and With D 13 Without D 13 Mart & Benhold, Phys. Rev. C 61 012201(R) (1999) Constituent quark models predict many resonances, but several missing. Are they wrongly predicted, or difficult to find experimentally?
Polarization observables in pseudoscalar (0 - ) meson production 4 Complex amplitudes: 16 real polarization observables. Complete, model independent, measurement from 8 carefully chosen observables. I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B95 347 (1975). πN: high statistics KY recoil: self-analysing () Systematics of detector acceptance cancel out. Only need to know P lin, the degree of linear polarization.
A B C Continuous Electron Beam Accelerator Facility E: 0.75 –6 GeV I max : 200A RF: 1499 MHz Duty Cycle: 100% (E)/E: 2.5x10 -5 Polarization: 80% Simultaneous distribution to 3 experimental Halls Injector LINAC Experimental Halls Jefferson Lab, Virginia, USA TAGGER
CEBAF Large Acceptance Spectrometer Cherenkov Counter e/ separation, 256 PMTs Time of Flight Plastic Scintillator, 684 PMTs Drift Chamber 35,000 cells Target + start counter e mini-torus Electromagnetic Calorimeter lead/plastic scintillator, 1296 PMTs Torus Magnet 6 Superconductive Coils
EeEe E e’ E = E e - E e’ 11m Amorphous radiator Diamond radiator up to 90% linear polarization EeEe Diamonds Need to be “perfect” monocrystals Assessment difficult and expensive Tagger in Intregrating mode …. Could we do this at SCAPA? Hall B Photon Tagger and Coherent Bremsstrahlung
Polarization observables at CLAS + N → m Linear Polarisation Circular polarisation Nucleon recoil polarimiter x → Y Hyperons are “self analysing” Transverse polarized nucleon targets p n Longitudinally polarized nucleon targets p n Crystal Ball MAMI, D.Watts, Edinburgh.
Single polarization observables Photon asymmetry P Recoil polarization (induced pol. along y) T Target asymmetry Double polarization observables O x Polarization transfer along x O z Polarization transfer along z Polarization observables in + p → K + Y (Lin Pol Beam, LH 2 target) Craig Paterson, Glasgow
Polarization observables in + p → K + Y (Lin Pol Beam, LH 2 target) Craig Paterson, Glasgow Good agreement with previous data. Better statistics Many more bins in CM angle and Energy. Photon Asymmetry + p → K + Double Pol Obs C x for + p → K + Gent Regge + Resonance Model ( Corthals et al. Phys Rev C73 2006 ) Data + Regge background (R) - - - - - - - - - R + core resonances (C) -. -. -. -. - R + C + D 13 (1900) __________ R + C + P 11 (1900) __ __ __ __ Cos (θ cm ) K
Detect - n, K + Σ from - n inv. mass Sergio Anefalos Pereira, INFN. Phys. Lett. B 688 (2010) 289-293 CLAS Data ▲ LEPS _____ Gent RPR model Edwin Munevar, GWU PRELIMINARY Polarization observables in + n → K + Y (Lin Pol Beam, LD 2 target) n (p) s p n (p) s p st measurements P, T, Ox,Oz PRELIMINARY Neil Hassall, Glasgow
Status of N* program - complete measurementsσΣTPEFGH TxTxTxTx TzTzTzTz LxLxLxLx LzLzLzLz OxOxOxOx OzOzOzOz CxCxCxCx CzCzCzCz Proton target pπ 0 ✔✓✓✓✓✓✓ nπ + ✔✓✓✓✓✓✓ pη✔✓✓✓✓✓✓ pη’✔✓✓✓✓✓✓ pω✔✓✓✓✓✓✓ K+ΛK+ΛK+ΛK+Λ✔✓✓✔✓✓✓✓✓✓✓✓✓✓✔✔ K+Σ0K+Σ0K+Σ0K+Σ0✔✓✓✔✓✓✓✓✓✓✓✓✓✓✔✔ K 0* Σ + ✔✓✓✓ Neutron target pπ - ✔✓✓✓✓✓✓ pρ - ✓✓✓✓✓✓✓ K-Σ+K-Σ+K-Σ+K-Σ+✓✓✓✓✓✓✓ K0ΛK0ΛK0ΛK0Λ✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓ K0Σ0K0Σ0K0Σ0K0Σ0✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓✓ K 0* Σ 0 ✓✓ PhD awarded - S. Fegan FROST 2 new students – HDIce (running now)
Spin density matrix elements in bins ΔW = 10 MeV, for W = 1.7–2.4 GeV in blue - blue shades. Previous world data in red. Search for baryon states in γp ➝ pω ➝ pπ + π - (π 0 ) M. Williams, et al. (CLAS), Phys.Rev.C80:065208,2009 M. Williams, et al. (CLAS), Phys.Rev.C80:065209,2009 F 15 (2000)/G 17 (219 0) ω production is dominated by the well known F 15 (1680), D 13 (1700) and G 17 (2190), and a predicted “missing” F 15 (2000). Status of N* program
The JLab 12GeV upgrade (15min) CHL -2 Upgrade of the arc magnets Construction of the new Hall D Beam Power: 1MW Beam Current: 90 µA Max Pass energy: 2.2 GeV Max Enery Hall A-C: 10.9 GeV Max Energy Hall D: 12 GeV Upgrade of the instrumentation of the existing Halls
< 6 GeV Spectroscopy with CLAS12 Low Q Tagging Facility or Forward Tagger Electron scattering at “0” degrees (LowQ, post-target tagging): low Q 2 virtual photon real photon Photons tagged by detecting the scattered electron Quasi-real photons are linearly polarized and the polarization can be determined event by event Highly segmented calorimiter BGO Opportunity to test / develop at SCAPA? Hadron spectroscopy Heavy mass baryon resonances (Cascades and - ) Meson spectroscopy H target and search for exotics 4 He and other gas targets Focus on Generalized Parton Distributions
GlueX: Confinement and the search for QCD exotics Simplest quark-structure is a meson Confinement: Quarks cannot exist alone + = ( , K) J PC = 1 --, 1 ++ Hybrid Meson or , , , … ? + = ( , ) J PC = 0 -+, 1 -+, 2 -+ 0 +-, 1 +-, 2 +- Exotic! Use a real photon beam Excite the glue: Study hybrid mesons G. Bali
GlueX: Confinement and the search for QCD exotics Glasgow: Diamond selection Coherent bremsstrahlung Polarimetry SCAPA ?
Wider context 2016 2012 MAX IV EIC ? USA Sweden Romania Germany Sweden Scotland SCAPA 2020 Long standing Glasgow collaborations
SCAPA Scottish Centre for the Application of Plasma-based Accelerators “Harnessing plasma waves as radiation and particle sources” Dino Jaroszynski Laser Wakefield Acceleration Ultra-short, ultra-intense laser pulses from commercially available table-top terawatt femtosecond lasers. Electron bunches: Mean energy above 1 GeV, an energy spread of about 1% and a peak current exceeding 1 kA. Protons: Yes please
0.1 – 1 GeV plasma filled capillary undulator 1 J 40 fs 800 nm wakefield accelerator 6.5 MeV photo- injector laser optical self-injection SCAPA ALPHA-X running now ~20fs Diamond Many of these make this SCAPA needs the expertise of nuclear physicists …. today! Beam characterization We already do this: Nature Physics 7, 867–871 (2011) D.Hamilton ++ Polarimetry Spectrometers and beam conditioning Detectors Data Acquisition / analysis SImluation Providing expertise opens many doors EDUCATION EDUCATION EDUCATION Undergraduates PhD students Young postdocs. Opportunities for nuclear physicists Detector development RF PMTs, GEMs, Diamond detectors Diamonds Quality assessment, channeling radiation, polarimetry Fundamentsl Hadron and Nuclear Physics Lifetime measurements The unknown, open doors to ESS, ELI Compact Muon Source (next slide) RF PMTs (J.Annand, Glasgow + Yerevan) ps timing resolution 500MHz rate capability
500L Compact Muon Source at SCAPA Assay of radioactive waste: Glasgow applied project with NNL There exists, somewhere, a large stockpile of barrels of unclassified radioactive waste. Need to determine the existence of high Z materials. Scattering of Muons. Muons from cosmic rays. Method is very promising. Rate of cosmic muons ~5Hz / m 2 Assay will take 10s of years not feasible. Need a muon beam
1 GeV 10Hz Wakefield accelerator Light solid target Brem radiator Magnetic element Simulated using Geant 4 and MAID2007, D. Hamilton, Glasgow Similar to method used at ISIS Rate Estimate Compact muons: ~9kHz / m 2 Compared to Cosmic muons ~5Hz / m 2 Compact Muon Source at SCAPA Compact, made from “standard components”. >10 3 rate increase over cosmics. Pion beam to do hadron physics (eg pion lifetime measurement with RF PMTs) Muon beam for materials science. γn ➝ pπ - ➝ l = 7.8m)
Summary Missing Resonances Lots of progress internationally. Strangeness very important – 1 st complete measurement Next few years should see definitive results. Jlab 12 CLAS12 and GlueX Continuing spectroscopy Heavier baryons Hybrid mesons SCAPA Many new opportunities Physics Detector development Education Compact muon source
p (n) n Russell Johnstone, Glasgow K production on n. Deuterium target PRELIMINARY photon asymmetry How good a “free” neutron target is Deuterium ? G13. Compare photon asymmetry of p (n) n with p (free and bound p) × Free ● Quasi free Free and quasi-free proton Quasi free neutron good approx. to free, here. Cos cm (-1.0 - +1.0) Each plot is 200MeV photon energy bin 1100-2150MeV
G13 n (p) s p n (p) s p Neil Hassall, Glasgow K production on n. Deuterium target
Tagging spectrometer with high rate, good energy and timing resolution High precision goniometer (GWU) High quality, thin diamond (Glasgow) Tight photon beam collimation (ISU) Polarimetry “A device called a goniometer tilts the diamond, much like a lady turning her hand to admire the sparkle of a new ring.” - JLAB On Target Magazine Peak > 90% pol. CLAS coherent bremsstrahlung facility Photon energy P > 90%
Measurements with photon beam profile detector D. Glazier, Glasgow 1 st Measurement of 2D photon enhancement for coherent bremsstrahlung (MAMI,Mainz) paper in preparation Good agreement with coherent bremstrahlung calculations Improvements in incoherent component, collimation + multiple scattering. No evidence of high energy photons from quasi channeling. Investigation of 2D strip detector for polarimetry Coherent peak at 300Mev, MAMI electron beam energy 855MeV below peakcoherent peakabove peak
Photon Asymmetry, , extracted from cos(2 ) fit to azimuthal kaon distribution Fits shown for 1 energy bin 340 (20E, 17 ) kinematic bins Almost full angular coverage g8b preliminary results -
g8b preliminary results - Results compared with previous results from GRAAL 7, 50MeV Energy bins 1175 -> 1475MeV Good agreement with previous results PRELIMINARY
Results compared with previous results from LEPS 6, 100MeV Energy bins 1550 -> 2050MeV More bins for our data!!! Increase the angular coverage to backward angles PRELIMINARY g8b preliminary results -
Use reaction with a known photon asymmetry Can be high statistics Very good relative monitor of polarization Combined beam, target polarization. Non-indpendent – depends on specific expt Need very good systematics or calibration Awaiting MAMI polarized target and polarised photon beam in 2 nd half of 2007 Polarimetry: from hadronic reaction R. Beck, Mainz -> Bonn Recent preliminary results from JLab (g8b) Proton target Back to back charge particles in Start Counter Atomic or hardonic ? Asymmetry from ~20mins DAQ data Constant with E from 1.3GeV – 1.9GeV
Resonances Pythagoras (c. 500 B.C.) Notes on a string which sound harmonious have simple ratios. 1 st Resonance model Created a system for tuning instruments The 1st musical scale … and then the universe Music of the Spheres If there is insufficient data even the wackiest of models cannot be ruled out.
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