Jefferson Lab and the 12GeV Upgrade Nuclear Physics UK Community Meeting Cosener’s 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) Polarisation observables in strangeness production CLAS12 BigBite (Hall A) G en - neutron electric form factor Super BigBite GlueX (Hall D)

CLAS - Missing resonances and resonance spectroscopy Constituent quark models predict many resonances. Some missing – undetected or wrongly predicted ? Most data from pion beam expts. Coupling to photon, particularly strange channels. Cross sections not enough to separate broad, overlapping resonances. Angular distributions and polarisation observables. Ideal – tagged, polarized photons at CLAS Particle Data Group star ratings

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.

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

Preliminary results -    Photon Asymmetry 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

Preliminary results -    Double polarization observable O x Results compared with Regge-Plus-Resonance model from Gent group - Large Polarization transfers - Some evidence for an important role for missing D 13 (1900) state - Poor agreement at low energy - Huge addition (> 500 points) to the database of measurements for constraining theory. PRELIMINARY Overview New, precision measurements on pion, eta, strangeness, single and double polarization observables in progress. Data taking with polarised target will be completed in spring First ever “complete measurement” on K Lambda, K Sigma soon. New, high precision range of polarisation

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 > 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

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

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 one for coh peak at 1.9 and 2.1GeV SAID MAID Nakayama and Haberzettl effective lagrangian model

g8b preliminary results -    Results compared with previous results from GRAAL 7, 50MeV Energy bins > 1475MeV Good agreement with previous results 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). P Recoil pol.

g13 meson photoproduction, polarized photons on LD 2  n (p)   p  p  Daria Sokhan, Edinburgh MAID SAID Previous data PRELIMINARY g13a circularly polarized photons ~2GeV, ~2.6GeV electron beam ~2 months beamtime g13b linearly polarized photons 1.3, 1.5, 1.7, 1.9, 2.1, 2.3 GeV coh peak ~ 2months beamtime Single charge particle trigger ~7kHz event rate

g13 meson photoproduction, polarized photons on LD 2  p (n)      n  Russell Johnstone, Glasgow See talk in Hadron Spectroscopy session  n (p)   s     p  Neil Hassall, Glasgow PRELIMINARY 1 st results Cos  cm ( ) Each plot is 50MeV photon energy bin MeV photon asymmetry 

Meson photoproduction with linearly and circularly polarized photons on polarized target E02-112: γp→KY (K + Λ, K + Σ 0, K 0 Σ + )‏ E03-105/E04-102: γp→π 0 p, π + n E05-012: γp→ηp E06-013: γp→π + 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 Target Pol > 80%, Relaxation time > 1600hrs – better that design goals 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

Recoil polarimetry possibilities ? g8b data  + p →  + n with (n,p) scatter (detect  + p) M x (  p→  + +X)  ++ n p  Start counter K.Livingston Angle between P n calc and P p measured  x and y (transverse) components of nucleon polarisation n(  ) =n o (  ){1+A(  )[P y cos(  )–P x sin(  )] - How to do this for 4  detector Nucleon polarimeter for D. Watts, Edinburgh Graphite

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

scheduled 2010 g8b (lin. pol. on LH2) cooking complete, analysis well developed Photon asymmetries for   p,   n, ,  ’ ,  : prelim. results. P, T Ox, Oz for ,  : g13 (lin., circ. pol on LD2) cooking in progress, analysis beginning Some very preliminary results for photon asymmetry. g9 (lin, circ pol on L/T pol butanol) cooking about to begin 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. (E. Pasyuk). eg6 4He target, Bonus detector coherent meson production. (S.Stepanyan talk on Friday) scheduled 2009 HDice (A.Sandorfi, F.Klein) Polarized HD target –further extesion of polarization observables scheduled 2010 CLAS12 Tagger will only tag up to 6GeV primary beam Development of Quasi real photon beam (Q 2 ~0) S.Stepanya, R.DeVita, M. Battaglieri Post target tagger – linearly polarized High rates