CHL-2CHL-2

Enhance equipment in existing halls

Add new Add new hallhall

Jefferson Lab, latest results and the 12GeV UpgradeKen Livingston, University of Glasgow.

Nuclear Physics UK Community MeetingCosener’s House 11th & 12th June 2009

CEBAF, Jefferson Lab, Virginia. 6 GeV racetrack configuration. > 200uA to 3 experimental areas

CLAS Spectrometer (Hall B) Polarisation observables in strangeness production

BigBite (Hall A) Gen - neutron electric form factor

“Highest priority”

STFC Programmatic review

Jlab 12GeV Upgrade $310M

Highest priority in the DoE/NSF NSAC long range plan

Approval to begin construction phase (CD3) in 2008.

CLAS 12 (Hall B)

Generalised Parton Distributions (GPDs)

Quasi-Real photon beam

Super BigBite (Hall A)

Form factors, compton scattering

GlueX (Hall D)

QCD exotics

• > 1000 scientists, 200 institutes, 20 countries

• No annual costs, No running costs.

• We provide expertise and additional hardware.

• Value for money.

• UK groups – Glasgow, Edinburgh (UWS ?)

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

Polarisation observables

+ N → m

Linear Polarisation Glasgow, K.Livingston

Circular polarisation Nucleon recoil

polarimiter x → Y

Hyperons are “self analysing”

Transverse polarised nucleon targets

Longitudinally polarised nucleon targets

Strangeness productionGlasgow D. Ireland, K.Livingston

Single pion productionEdinburghD.Watts

Polarisation observables in pseudoscalar meson production

g target recoil Observable

4 Complex amplitudes - 16 real polarisation observables.

A complete measurement from 8 carefully chosen observables.

I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B95 347 (1975).I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B95 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 - and

Craig Paterson, Glasgow

pppp

Single polarization observablesPhoton asymmetryP Recoil polarization (induced pol. along y)T Target asymmetry

Double polarization observablesOx Polarization transfer along xOz Polarization transfer along z

figure by R.Schumacher, CMU

Preliminary results - Craig Paterson, Glasgow

Photon Asymmetry

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

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Preliminary results - Double polarization observable Ox

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.

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Summary: polarisation observables, towards a complete measurement and missing resonances. • New, precision measurements on p, 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 FIX THIS TEXT

Hall A – BigBite and Neutron Electric Form FactorJ. Annand, D. Hamilton, Glasgow

Dump

TargetElectron arm

Gen - the charge distribution inside the neutron

Neutron arm

Galster

q(2q) DSE

CQM - MillerpQCD

VMD

FSI correction not applied

Hall A• 2 High resolution spectrometers• Specific kinematics• High current > 30uA

• extras ....

Hall A @ 12GeV Super BigBite J. Annand, D. Hamilton, Glasgow

Super BigBite

• Modular spectrometer / polarimiter• Option of RICH from Hermes for Kaons• 4 A rated proposals on Form Factors

GEMs

- Magnet: 48D48 - 46 cm gap, 2.5 Tm- Solid angle is 70 msr at angle 15°- GEM chambers with 70 μm resolution- Momentum resolution is 0.5% for 5 GeV/c- Angular resolution is 0.3 mrad

Proton form factors transverse charge & current densities.

Last 50 years

Structure functions,quark longitudinalmomentum & spin distributions

Last 40 years

?

Correlated quark momentum and helicity distributions in transverse space - GPDs

Last 10 years

CLAS 12 Generalised Parton Distributions (GPDs)R.Kaiser, B.Seitz, Glasgow

CLAS 12 GPDs via DVCS

• HERMES now complete.

• CLAS 12 optimised for DVCS.

• Polarised targets, Asymmetry measurement

• High luminosity to reach high XB

• Glasgow GPD programme will move from HERMES -> CLAS12 (spokepsersons on 3 approved proposals)

• Example of the provision of expertise.

CLAS12 EC

TOF

Cerenkov

Torus

Drift Chambers

Cerenkov

Central Detector

BeamlineIEC

Luminosity > 1035cm-2s-1G.Rosner – CLAS12 steering committeeB. Seitz, M. Hoek, uChan PMT for CTOF

Existing tagging spectrometer can’t tag beam > 6GeV

Quasi Real Photon BeamCalorimiter to tag Q2~0 electrons

Linearly polarizedparasitic

K. Livingston, D.Ireland, GlasgowD.Watts, D. Glazier, Edinburgh

With Jlab, + INFN, Italy.

GlueX exotic hybrid mesons

JPC = 0+-, 1-+, 2+-

Flux tube model

– Provides a framework to understand gluonic excitations.

– Conventional mesons have the color flux tube in the ground state. When the flux tube is excited hybrid mesons emerge. For static quarks the excitation level above the ground state is ~1 GeV.

– The excitation of the flux tube, when combined with the quarks, can lead to spin-parity quantum numbers that cannot be obtained in the quark model (JPC - exotics).

– The decay of hybrid mesons leads to complex final states.

Hall-D, GlueX ++

Lead GlassDetector

Solenoid

Electron Beam from CEBAF

Tracking

TargetCerenkovCounter

Time ofFlight

BarrelCalorimeter

Note that tagger is

80 m upstream ofdetector

Coherent BremsstrahlungPhoton Beam

• Tagger Magnet design, G. Yang, Glasgow• Coherent brem facility and diamonds – K.Livingston, G.Yang, Glasgow

• Hall D additional physics potential. High linear polarization, high intensity 2-6GeV.• Development of recoil polarimiter – D.Watts, Edinburgh.

Conclusion

• Jefferson Lab is the world’s leading facility for hardon physics.

• UK Groups (Glasgow, Edinburgh) have leading role in current programme.

• High quality measurements from Hall A, Hall B

NSAC Long Range Plan (2007) Recommendation 1 of 4

We recommend the completion of the 12 GeV Upgrade at Jefferson Lab.

- It will enable three-dimensional imaging of the nucleon, revealing hidden aspects of its internal dynamics.

- It will complete our understanding of the transition between the hadronic and quark/gluon descriptions of nuclei.

- It will test definitively the existence of exotic hadrons, long-predicted by QCD as arising from quark confinement.

- It will provide low-energy probes of physics beyond the Standard Model complementing anticipated measurements at the highest accessible energy scales.

• UK Groups have opportunity, at very low cost, to participate

We are here

2014

• 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

Photo

n

ener

gy

P > 90%

Measurements with photon beam profile detectorD. Glazier, Glasgow

1st 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 peak coherent peak above 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 GRAAL7, 50MeV Energy bins

1175 -> 1475MeV

Good agreement with previous results

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Results compared with previous results from LEPS6, 100MeV Energy bins

1550 -> 2050MeV

More bins for our data!!!

Increase the angular coverage to backward angles

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g8b preliminary results -

• Pair production simulations by Kharkov group

• Polarimeter built and tested at Sping8, recently tested at Jlab

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-) productionH.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 2nd half of 2007

Polarimetry: from hadronic reactionR. 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’pMike 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

SAIDMAIDNakayama and Haberzettleffective lagrangian model

g8b preliminary results -

Results compared with previous results from GRAAL7, 50MeV Energy bins

1175 -> 1475MeV

Good agreement with previous results

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g8b preliminary results -

Ox/O

z extracted from fit to 2d asymmetry

T Target asymmetry from 2d asymmetry (not shown)

P Recoil pol. from acceptance corrected proton dist.

g8bGRAALCLAS J.W.C. McNabb, et al. (CLAS) Phys. Rev. C 69, 042201(R) (2004).

P R

ecoi

l pol

.

g13 meson photoproduction, polarized photons on LD2

n (p)ppDaria Sokhan, Edinburgh

MAIDSAID

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• 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 LD2

p (n)nRussell Johnstone, GlasgowSee talk in Hadron Spectroscopy session

n (p)s p

Neil Hassall, Glasgow

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1st r

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Coscm (-0.8 - +0.8)Each plot is 50MeV photon energy bin 1050-2450MeV

pho

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asy

mm

etry

Meson photoproduction with linearly and circularly polarized photons on polarized target

E02-112: γp→KY (K+Λ, K+Σ0, K0Σ+)E03-105/E04-102: γp→π0p, π+n E05-012: γp→ηpE06-013: γp→π+π-p

g9a running conditions

November 3, 2007– February 12, 2008Longitudianally polarized targetCircularly and linearly polarized photon beam 0.5-2.4 GeVTrigger: at least one charged particle in CLASTarget Pol > 80%, Relaxation time > 1600hrs – better that design goals

g9 FROST – FROzen Spin Target

butanol 12C CH2

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 statisticsPrelim

inarybutanol 12C CH2

Recoil polarimetry possibilities ?

g8b data+ p → + n with (n,p) scatter (detect +p)

Mx(p→++X)

+

n

p

Start counter

K.LivingstonAngle between Pn

calc and Ppmeasured

x and y (transverse) components of nucleon polarisation

n() =no(){1+A()[Pycos()–Pxsin()] - How to do this for 4 detector

Nucleon polarimeter for CB@MAMI, 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, 035205 (2007).

- Full polarization at forward angles

- Not repeated over full kinematic range

- More relations can be tested

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(P

2 +

Ox2 +

Oz2 )

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 (Q2~0) S.Stepanya, R.DeVita, M. Battaglieri

• Post target tagger – linearly polarized• High rates

Jefferson Lab and the 12GeV Upgrade

Nuclear Physics UK Community MeetingCosener’s House 11th & 12th 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)

• Gen - neutron electric form factor

• Super BigBite

• GlueX (Hall D)