Presentation on theme: "Jefferson Lab and the 12GeV Upgrade Nuclear Physics UK Community Meeting Coseners House 11 th & 12 th June 2009 Ken Livingston, University of Glasgow Overview."— Presentation transcript:
Jefferson Lab and the 12GeV Upgrade Nuclear Physics UK Community Meeting Coseners House 11 th & 12 th June 2009 Ken Livingston, University of Glasgow Overview of Jefferson Lab and the 12 GeV upgade programme CLAS Spectrometer (Hall B) Latest results from the measurement of polarisation obresvables CLAS12 BigBite (Hall A) Latest results on G en - neutron electric form factor Super BigBite GlueX (Hall D)
Missing resonances and resonance spectroscopy Cross sections not enough to separate broad, overlapping resonances Angular distributions and polarization observables.
Polarization observables + N m Linear Polarisation Circular polarisation Nucleon recoil polarimiter x Y Hyperons are self analysing Transverse polarized nucleon targets ? Longitudinally polarized nucleon targets
Polarization observables in pseudoscalar meson production g target recoil Observable 4 Complex amplitudes - 16 real polarization observables. A complete measurement from 8 carefully chosen observables. I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B (1975).
Polarization observables - a simple example, Systematics of detector acceptance cancel out. Only need to know P lin, the degree of linear polarization.
CLAS data SAID High statistics. Good agreement with previous measurement. Data set extends to photon energy up to 2.1GeV g8b: July 2005 Polarized photon energy range: 1.3 – 2.1 GeV Events (single charged particle in CLAS): 10 billion preliminary results: p + n. Mike Dugger, ASU
g8b preliminary results: p p Mike Dugger, ASU High stats for. Good agreement with previous measurements. Data set extends to photon energy up to 2.1GeV First measurement of for 2 E bins SAID MAID Nakayama and Haberzettl effective lagrangian model
g8b preliminary results - and Craig Paterson, Glasgow p p p p 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 figure by R.Schumacher, CMU
g8b preliminary results - Results compared with previous results from GRAAL 7, 50MeV Energy bins > 1475MeV Good agreement with previous results PRELIMINARY
g8b preliminary results - Results compared with previous results from LEPS 6, 100MeV Energy bins > 2050MeV More bins for our data Increase the angular coverage to backward angles PRELIMINARY
g8b preliminary results - O x /O z extracted from fit to 2d asymmetry T Target asymmetry from 2d asymmetry (not shown) P Recoil pol. from acceptance corrected proton dist. G8b GRAAL CLAS J.W.C. McNabb, et al. (CLAS) Phys. Rev. C 69, (R) (2004).
g8b preliminary results - Double polarization ovservable O x Results compared with Regge-Plus-Resonance model from Gent group - Large Polarizations! - Some evidence for an important role for missing D 13 (1900) state - Poor agreement at low energy PRELIMINARY
g8b preliminary results - Full lamba polarization ? With circularly polarized photons – fully polarized lambda R. Bradford et al. (The CLAS Collaboration), Phys. Rev. C 75, (2007). - Full polarization at forward angles - Not repeated over full kinematic range - More relations can be tested PRELIMINARY (P 2 + O x 2 +O z 2 ) 1/2
g13 meson photoproduction, polarized photons on LD 2 n (p) p p Daria Sokhan, Edinburgh MAID SAID Previous data
g13 meson photoproduction, polarized photons on LD 2 p (n) n Russell Johnstone, Glasgow n (p) s p Neil Hassall, Glasgow
Meson photoproduction with linearly and circularly polarized photons on polarized target E02-112: γpKY (K + Λ, K + Σ 0, K 0 Σ + ) E03-105/E04-102: γpπ 0 p, π + n E05-012: γpηp E06-013: γpπ + π - p g9a running conditions November 3, 2007– February 12, 2008 Longitudianally polarized target Circularly and linearly polarized photon beam GeV Trigger: at least one charged particle in CLAS g9 FROST – FROzen Spin Target
butanol 12 CCH 2 Helicity asymmetry E Raw asymmetry g9aFROST sample analysis of gp + n Eugene Pasyuk, ASU Select + applying cut on vs. p Vertex cuts Select missing neutron Based on ~2% of statistics Preliminary butanol 12 CCH 2
Circularly polarized photon beam on longitudinally polarized target E P, Lx/Lz, Cx/Cz Linearly polarized photon beam on longitudinally polarized target, G, P, (Tx/Tz) Ox/Oz Circularly polarized photon beam on transversely polarized target T, F, P, Tx/Tz, Cx/Cz Linearly polarized photon beam on transversely polarized target, H, T, P, (Lx/Lz) Upon completion of g9b for the first time we will have complete set of observables in Kaon photoproduction and nearly complete for all other mesons, which will allow model independent extraction of the amplitude for subsequent extraction of baryon resonances and their properties. g9a Complete g9b scheduled for 2010 g9 FROST outlook
Recoil polarimetry possibilities (D. Watts, Edinburgh) + p + n with (n,p) scatter (detect + p) M x ( p + +X) + n p
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
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
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%
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 -
Results compared with previous results from GRAAL 7, 50MeV Energy bins > 1475MeV Good agreement with previous results PRELIMINARY
Results compared with previous results from LEPS 6, 100MeV Energy bins > 2050MeV More bins for our data!!! Increase the angular coverage to backward angles PRELIMINARY g8b preliminary results -
Pair production simulations by Kharkov group Polarimeter built and tested at Sping8, recently tested at Jlab e+e-e+e- Polarimeter to be based on Jlab design Microstrip detectors, or pixel detectors (Atlas group) Bonn student completed 10 months exchange in Glasgow now to be full time in Bonn. Polarimetry: from pair (e +,e - ) production H.Schmieden, Bonn Well described by QED, but experimentally difficult – small opening angle PRELIMINARY J.Santoro, CUA Peak > 90% pol. K.Livingston, Glasgow