Jefferson Lab and the 12 Ge V Upgrade

Jefferson Lab and the 12 Ge. V Upgrade Ken Livingston, University of Glasgow Nuclear Physics UK Community Meeting Cosener’s House 11 th & 12 th June 2009 • Overview of Jefferson Lab and the 12 Ge. V upgade programme • CLAS Spectrometer (Hall B) • • • Polarisation observables in strangeness production CLAS 12 Big. Bite (Hall A) • • • Gen - neutron electric form factor Super Big. Bite Glue. X (Hall D)

CLAS - Missing resonances and resonance spectroscopy Particle Data Group star ratings • 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

Polarization observables Linear Polarisation Circular polarisation g+N→N+m →Y+ Longitudinally polarized nucleon targets Transverse polarized nucleon targets Nucleon recoil polarimiter x Hyperons are “self analysing”

Polarization observables in pseudoscalar meson production 4 Complex amplitudes - 16 real polarization observables. A complete measurement from 8 carefully chosen observables. Observ able g target recoil I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B 95 347 (1975).

Polarization observables - a simple example, • Systematics of detector acceptance cancel out. • Only need to know Plin, the degree of linear polarization.

Preliminary results - +L and +S 0 Craig Paterson, Glasgow gp -> +L -> +pp- gp -> +S 0 -> +Lg -> +pp-g Single polarization observables Photon asymmetry P Recoil polarization (induced pol. along y) T Target asymmetry Double polarization observables Ox Polarization transfer along x Oz Polarization transfer along z L 0 figure by R. Schumacher, CMU

Preliminary results - +L Photon Asymmetry Results compared with previous results from LEPS 6, 100 Me. V Energy bins 1550 -> 2050 Me. V More bins for our data PR EL IM IN A R Y Increase the angular coverage to backward angles

Preliminary results - +L Double polarization observable Ox Results compared with Regge-Plus-Resonance model from Gent group - Large Polarization transfers - Poor agreement at low energy - Huge addition (> 500 points) to the database of measurements for constraining theory. PR EL IM IN A R Y - Some evidence for an important role for missing D 13(1900) state 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 2010. • First ever “complete measurement” on K Lambda, K Sigma soon. • New, high precision range of polarisation

CLAS coherent bremsstrahlung facility • Tagging spectrometer with high rate, good energy and timing resolution • High quality, thin diamond (Glasgow) • Tight photon beam collimation (ISU) • Polarimetry P en hot er on gy • High precision goniometer (GWU) P > 90% Peak > 90% pol. “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

Measurements with photon beam profile detector D. Glazier, Glasgow 1 st Measurement of 2 D photon enhancement for coherent bremsstrahlung (MAMI, Mainz) paper in preparation below peak coherent peak above peak Coherent peak at 300 Mev, MAMI electron beam energy 855 Me. V • Good agreement with coherent bremstrahlung calculations • Improvements in incoherent component, collimation + multiple scattering. • No evidence of high energy photons from quasi channeling. • Investigation of 2 D strip detector for polarimetry

g 8 b preliminary results - K+L +L Photon Asymmetry, , extracted from cos(2 f) fit to azimuthal kaon distribution Fits shown for 1 energy bin 340 (20 E, 17 q) kinematic bins Almost full angular coverage

g 8 b preliminary results - K+ 0 Results compared with previous results from GRAAL PR EL IM IN A R Y 7, 50 Me. V Energy bins 1175 -> 1475 Me. V Good agreement with previous results

g 8 b preliminary results - K+ 0 Results compared with previous results from LEPS 6, 100 Me. V Energy bins 1550 -> 2050 Me. V More bins for our data!!! PR EL IM IN A R Y Increase the angular coverage to backward angles

Polarimetry: from pair (e+, e-) production H. Schmieden, Bonn • Well described by QED, but experimentally difficult – small opening angle e+ • Pair production simulations by Kharkov group e • Polarimeter built and tested at Sping 8, recently tested at Jlab Peak > 90% pol. PRELIMINARY K. Livingston, Glasgow • 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. J. Santoro, CUA

Polarimetry: from hadronic reaction R. Beck, Mainz -> Bonn 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 Recent preliminary results from JLab (g 8 b) • Proton target • Back to back charge particles in Start Counter • Atomic or hardonic ? • Asymmetry from ~20 mins DAQ data • Constant with E from 1. 3 Ge. V – 1. 9 Ge. V

g 8 b: July 2005 Polarized photon energy range: 1. 3 – 2. 1 Ge. V Events (single charged particle in CLAS): 10 billion preliminary results: p 0 p, p+n. Mike Dugger, ASU CLAS data High statistics. Good agreement with previous measurement. SAID Data set extends to photon energy up to 2. 1 Ge. V

g 8 b preliminary results: hp, h’p Mike Dugger, ASU SAID MAID Nakayama and Haberzettl effective lagrangian model High stats for h. First measurement of S for h’ Good agreement with previous measurements. 2 Eg bins one for coh peak at 1. 9 and 2. 1 Ge. V Data set extends to photon energy up to 2. 1 Ge. V

g 8 b preliminary results - +L Results compared with previous results from GRAAL PR EL IM IN A R Y 7, 50 Me. V Energy bins 1175 -> 1475 Me. V Good agreement with previous results

g 8 b preliminary results - +L Ox/Oz extracted from fit to 2 d asymmetry T Target asymmetry from 2 d asymmetry (not shown) P Recoil pol. from acceptance corrected proton dist. g 8 b GRAAL CLAS J. W. C. Mc. Nabb, et al. (CLAS) Phys. Rev. C 69, 042201(R) (2004).

g 13 meson photoproduction, polarized photons on LD 2 gn (p) -> p+p (p) • g 13 b linearly polarized photons • 1. 3, 1. 5, 1. 7, 1. 9, 2. 1, 2. 3 Ge. V coh peak • ~ 2 months beamtime • Single charge particle trigger • ~7 k. Hz event rate PR EL IM IN A R Y g 13 a circularly polarized photons • ~2 Ge. V, ~2. 6 Ge. V electron beam • ~2 months beamtime • Daria Sokhan, Edinburgh MAID SAID Previous data

g 13 meson photoproduction, polarized photons on LD 2 gn (p) -> K 0 s L 0 (p) gp (n) -> +L 0 (n) Neil Hassall, Glasgow Russell Johnstone, Glasgow R 1 st E re LIM su IN lts A PR photon asymmetry Y See talk in Hadron Spectroscopy session Cosqcm (-0. 8 - +0. 8) Each plot is 50 Me. V photon energy bin 1050 -2450 Me. V

g 9 FROST – FROzen Spin Target Meson photoproduction with linearly and circularly polarized photons on polarized target E 02 -112: E 03 -105/E 04 -102: E 05 -012: E 06 -013: γp→KY (K+Λ, K+Σ 0, K 0Σ+) γp→π0 p, π+n γp→ηp γp→π+π-p g 9 a running conditions November 3, 2007– February 12, 2008 Longitudianally polarized target Circularly and linearly polarized photon beam 0. 5 -2. 4 Ge. V Trigger: at least one charged particle in CLAS Target Pol > 80%, Relaxation time > 1600 hrs – better that design goals

g 9 a. FROST sample analysis of gp p+n Eugene Pasyuk, ASU • Select p+ applying cut on b vs. p • Vertex cuts • Select missing neutron butanol 12 C Helicity asymmetry E CH 2 butanol e r P 12 C CH 2 ry a in im l Based on ~2% of statistics Raw asymmetry

Recoil polarimetry possibilities ? n(q, f) =no(q){1+A(q)[Pycos(f)–Pxsin(f)] - How to do this for 4 p detector x and y (transverse) components of nucleon polarisation Nucleon polarimeter for CB@MAMI, D. Watts, Edinburgh q Graphite p g Start counter K. Livingston q n p+ Mx(gp→p++X) Angle between Pncalc and Ppmeasured

g 8 b preliminary results - +L Full lamba polarization ? With circularly polarized photons – “fully polarized lambda” R. Bradford et al. (The CLAS Collaboration), Phys. Rev. C 75, 035205 (2007). - Full polarization at forward angles IM EL PR (P 2 + Ox 2+Oz 2)1/2 IN A R Y - Not repeated over full kinematic range - More relations can be tested

• g 8 b (lin. pol. on LH 2) cooking complete, analysis well developed • Photon asymmetries for p 0 p, p+n, h, h’ KL, K : prelim. results. • P, T Ox, Oz for KL, K : • g 13 (lin. , circ. pol on LD 2) cooking in progress, analysis beginning • Some very preliminary results for photon asymmetry. • g 9 (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 g 9 b for the first time we will have complete set of observables in scheduled 2010 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). eg 6 4 He 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 • CLAS 12 • Tagger will only tag up to 6 Ge. V primary beam • Development of Quasi real photon beam (Q 2~0) S. Stepanya, R. De. Vita, M. Battaglieri • Post target tagger – linearly polarized • High rates