Photon physics at JLab: Status and prospects 2007-20??

10 July 200710 July 2007 CB@MAMI Collaboration MeetinCB@MAMI Collaboration Meetingg

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Photon physics at JLab:Photon physics at JLab: Status and prospectsStatus and prospects

2007-20??2007-20??

Daniel SoberDaniel Sober

The Catholic University of The Catholic University of AmericaAmerica


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OutlineOutline

Jefferson Lab and Hall BJefferson Lab and Hall B Completed CLAS runsCompleted CLAS runs Future CLAS runsFuture CLAS runs PRIMEX (Hall B Primakoff PRIMEX (Hall B Primakoff

experiment)experiment) Hall D and GlueXHall D and GlueX Photon physics with CLAS12Photon physics with CLAS12


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The Thomas Jefferson National The Thomas Jefferson National Accelerator Facility (JLab)Accelerator Facility (JLab)

5-pass recirculating 5-pass recirculating linear acceleratorlinear accelerator

Maximum energy Maximum energy currently ~5.2 GeV currently ~5.2 GeV

(Planned:(Planned:

~5.7 GeV by 11/07,~5.7 GeV by 11/07,

~6.0 GeV by 10/08, ~6.0 GeV by 10/08,

~6.5 GeV by 6/09)~6.5 GeV by 6/09) 3 experimental halls3 experimental halls Tagged photon facility Tagged photon facility

in Hall Bin Hall B


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Hall BHall B The CLAS detectorThe CLAS detector Polarized electron and tagged photon Polarized electron and tagged photon

beamsbeams Cryogenic and polarized targetsCryogenic and polarized targets


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Performance L = 1034 cm-2 s-1

B dl = 2.5 T m p/p ~ 0.5-1 % ~ 4 acceptance Best suited for multiparticle final states Bremsstrahlung Photon Tagger (E/E

~10-3)

The CEBAF Large Acceptance The CEBAF Large Acceptance Spectrometer (CLAS) in Hall BSpectrometer (CLAS) in Hall B


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Hall B Tagged Photon Hall B Tagged Photon systemsystem


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Recently completed photon run Recently completed photon run periodsperiods

Run E0 PhotonTarget Reactionsperiod (GeV) Pol.

2004 g10 3.77 circ. LD2 pentaquark search, [K, ]

g11 4.02 circ. LH2 pentaquark search, [K, K] PRIMEX 5.75 - C, Pb 0 lifetime by Primakoff effect (non-CLAS)

2005eg3 5.75 circ. LH2 exotic cascade searchg8b 4.05 linear LH2 p, p, p

[p, ‘p, 0p, +n] 2006

TPE test 3.29 →e+,e- 2-photon exchange: Simultaneous e+ and e- scattering

2007g13 several linear LD2 n→K, K, 1.1 to

2.3 GeV[0p, +n]


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• Linearly polarized photon beam to measure photon asymmetries and double polarization observables

• Beamtime from June 26th – Aug 31st 2005

• Lin. Pol. photons on 40cm LH2 target

• 5 coherent peak positions from 1.3 -> 2.1 GeV

• Polarization in excess of 90% achieved

•10 billion events

g8b status report - June 2007

Overview


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production (spin density matrix elements) (Idaho State University)

- production (spin density matrix elements) (Idaho State University)

production (Catholic University of America)

production (Single and double pol. observables)(Glasgow University)

, ’ production (beam asymmetry)(Arizona State University)

n, 0p production (beam asymmetry)(Arizona State University)


Analysis in progress


1010


Preliminary analysis (ASU): p -> p0


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g13 status (ended June 30)g13 status (ended June 30)(linear) + LD2: (linear) + LD2: n n →→ K K, , KK,,

6 coherent peak settings:

1.1 – 1.3 GeV (E0 = 3.3, 3.9, 4.2 GeV)

1.3 – 1.5 GeV (E0 = 4.5 GeV)

1.5 – 1.7 GeV (E0 = 4.7 GeV)

1.7 – 1.9 GeV (E0 = 5.1 GeV)

1.9 – 2.1 GeV (E0 = 5.2 GeV)

2.1 – 2.3 GeV (E0 = 5.2 GeV)


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g13: Yields for n → K0 X

Top: invariant mass of p- near m()

Bottom: invariant mass of +- near m(K0)

Left: no cuts

Right: cuts on the other particle

Plots show a 5 GeV run with the coh. edge at 1.9 GeV


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g13 analysis: g13 analysis: nn→→--pp


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TPE (Two-photon exchange) - TPE (Two-photon exchange) - Beyond the Born ApproximationBeyond the Born Approximation

e+p→e+p / e-p→e-p

1 Aon 5%

radiator


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Necessary Tagger Modifications Necessary Tagger Modifications for TPEfor TPE


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The PrimEx ExperimentThe PrimEx ExperimentA. Gasparian et al. (NCA&T, Kentucky, UMass, MIT, A. Gasparian et al. (NCA&T, Kentucky, UMass, MIT,

…… Precision measurement of Precision measurement of lifetime using Primakoff lifetime using Primakoff

effect: effect: + + VV (nuclear target) (nuclear target) → → 00 ( (→→ + + one one of the few quantities in the confinement region that of the few quantities in the confinement region that QCD can calculate preciselyQCD can calculate precisely

Hall B tagger + “HyCal” (dedicated hybrid calorimeter: Hall B tagger + “HyCal” (dedicated hybrid calorimeter: PbW0 PbW044 inner detector, lead glass outer detector) inner detector, lead glass outer detector)

Separate Primakoff from nuclear Separate Primakoff from nuclear production by production by angular distribution.angular distribution.

Require absolute cross section – check normalization Require absolute cross section – check normalization by measurements of Compton scattering and pair by measurements of Compton scattering and pair productionproduction

Preliminary results presented at April 2007 APS Preliminary results presented at April 2007 APS meetingmeeting


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PrimEx ApproachPrimEx Approach

JLab Hall B high resolution high intensity photon tagging facility

New novel high resolution, high acceptance multi-channel calorimeter (HYCAL)

Primakoff effect

PrimEx improvements:


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PrimEx PrimEx HyHybrid brid CalCalorimeter - HyCalorimeter - HyCal

Optimize performance and cost

Hybrid calorimeter:

1152 PbWO4 novel crystal detectors;

576 Pb-glass Cherenkov detectors


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Fit to Extract Fit to Extract 00 Decay Width Decay Width

Combined average from three independent analysis groups:

Γ(0) 7.93 eV 2.10%(stat.)

Interference

Incoherent

Coherent

Primakoff

22

..4

43

3

2Pr

3

sin)(8

QFQ

E

m

Z

d

dme


2020

PrimEx Preliminary ResultPrimEx Preliminary Result

(0) = 7.93eV2.1%2.0%

PrimEx Preliminary Result:

(0) = 7.93eV2.1%(stat)2.0%(syst)

Most recent calculation of hadronic correction in QCD by Ioffe & Oganesian, hep-ph/0701077gives: (0) = 7.93eV ± 1.5% (uncertainty from due to 0/ mixing)


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PrimEx Future PlansPrimEx Future Plans

Publish existing resultsPublish existing results New 6 GeV run to obtain proposed New 6 GeV run to obtain proposed

1% statistics1% statistics 12 GeV proposal: 12 GeV proposal: 00,,,,’ ’

widths and transition form widths and transition form factorfactor


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Future CLAS photon run periodsFuture CLAS photon run periodsRun E0 Photon Target Reactionsperiod (GeV) Pol.

2007g9a 1.8– circ., Longit. Missing resonances in

(FROST) 4.0 linear Pol. H N, K, K, p, +-p

2008g12 >5.7 circ. LH2 Exotic mesons and baryons

2009–2011g9b Various circ., Longit.& Missing resonances in (FROST) linear Transv. N, K, K, p, +-p Pol. H

g16 Various circ., Polarized n→p, +-n, linear HD 0, 0, +


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target: Ø15mm x 50mmbutanol C4H9OH

dilution factor 10/74eff. density: 0.611 g/cm3

operate at ~50mK,repolarize at 0.4K

CLAS Frozen-Spin Target (FROST)CLAS Frozen-Spin Target (FROST)


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CLAS-FROST: CLAS-FROST: →→00p, p, ++nn (sample PWA) (sample PWA)

Sample PWA data generated from SAID SM02

(Recoil, Target asy., all 4 Beam-Target

asymmetries)

redred: : predicted predicted FROST dataFROST data

grea

tly r

educ

ed

grea

tly r

educ

ed

unce

rtai

ntie

s

unce

rtai

ntie

s

1=uncertainty based on world data


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● 1st run period in fall 2007 (long.pol.)● Recent tests successful (20 mW at 200 mK,

100 W at 50 mK – June 2007)● All polarization observables measurable in CLAS will be extracted from data

● Complete set of measurements for KY● “Almost” complete set for N, p● Double/triple pol. obs. for -p, p

minimally model-dependent extraction of N* parameters & potential for discovery of missing states

FROST outlookFROST outlook


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HD Target (“HD-ICE”)HD Target (“HD-ICE”)

Previous operation at LEGS (BNL)Previous operation at LEGS (BNL) DOE funding approved: A. Sandorfi DOE funding approved: A. Sandorfi

and group will move to JLab in early and group will move to JLab in early 20082008

New horizontal cryostat required for New horizontal cryostat required for CLASCLAS

Aim for 2009 installation and runAim for 2009 installation and run


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HD targetHD target

In-Beam-Cryostat for CLASIn-Beam-Cryostat for CLAS

target: Ø25mm x 50mm3g of solid H-D compositedensity: 0.147 g/cm3

2050 cooling wires (Al) Ø50mPV(D)~40%, P(H)~40% or PV(D)~0%, P(H)~80%

LEGS data:


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MM2

(+D)

MM2 (+n) n(p)n(p) 00 (p)(p) ++––pp––(p)(p)

n(p)n(p) 00 00 (p) (p) ++––pp––(( p) p)

E06-101E06-101:: + + frozen-spin in CLAS

r

H rD

• • clean channel-separation;clean channel-separation;

very low backgroundsvery low backgrounds

factors of > 20 reduction infactors of > 20 reduction in beam-time over other targetsbeam-time over other targets

• • high nucleon polarizations high nucleon polarizations

• • in-beam lifetimes > yearin-beam lifetimes > year


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Summary of Frozen-Spin Experimental Summary of Frozen-Spin Experimental ProgramProgram

polarized butanol target (89 days of beam polarized butanol target (89 days of beam time)time)

E02-112: E02-112: pp→→KYKY (K(K++, K, K++00, K, K00++)) E03-105/E04-102: E03-105/E04-102: pp→→00p, p, ++nn E05-012: E05-012: pp→→pp E06-013: E06-013: pp→→++--pp

polarized HD target (85 days)polarized HD target (85 days) E06-101: E06-101: nn→π→π--p,p, nn→→++--n,n,

nn→→KYKY (K(K00, K, K0000, K, K++--))


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CHL-2CHL-2

Upgrade magnets and power supplies

Enhance equipment in existing halls

6 GeV CEBAF1112Add new hall


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Upgrade Beam PropertiesUpgrade Beam Properties

All polarized !

Number of passes for Hall DMax. energy for Hall D

5.512 GeV

Number of passes for Halls A, B, CMax. energy for Halls A, B, C

5 (4, 3, 2, 1)11 GeV (8.8, 6.6, 4.4, 2.2)

Max. current to Halls A + B + CMax. current to Hall D

85 A 5 A

Max. beam powerDuty-cycle

1 MW100%


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The 12 GeV Upgrade: Complementary Equipment The 12 GeV Upgrade: Complementary Equipment in Halls B & C, and a New Hall Din Halls B & C, and a New Hall D

9 GeV tagged polarized photons and a 4 hermetic detector

DD

Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles

CC

CLAS upgraded to higher (1035 cm-2s-1) luminosity and coverage

BB

Retain HRS Pair for continuation of research in which resolution comparable to nuclear level spacing is essential. Use Hall to stage “one-of-a-kind” specialized experiments requiring unique apparatus.

AA


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Photon physics after the 12 Photon physics after the 12 GeV upgrade (2012+)GeV upgrade (2012+)

Hall D: The GlueX experimentHall D: The GlueX experimentDedicated coherent bremsstrahlung beam.Dedicated coherent bremsstrahlung beam.

Search for exotic mesons at ESearch for exotic mesons at E > 9 GeV> 9 GeV Hall B: CLAS-12Hall B: CLAS-12

No planned tagger upgrade in base equipment.No planned tagger upgrade in base equipment.

New torus magnet and detectors, emphasizing New torus magnet and detectors, emphasizing forward acceptance, electron beamforward acceptance, electron beam

experiments (GPDs)experiments (GPDs)


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Hall D (GlueX): Research Hall D (GlueX): Research

ProgramProgram Search for Gluonic Excitations

Hybrid (qqg) spectrum expected between 1.5 and 2.5 GeV/c2

Exotics do not mix with normal qq mesons ALSO: ss spectroscopy

Only five states established Photon has a large virtual (ss) component

Other physics KK threshold Radiative decays of excited vector mesons


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PhotoproductionPhotoproduction

More likely to find exotic hybrid mesons using beams of photons.

Lowest-mass hybrids predicted to be in JPC=1-+ nonet.Photon linear polarization constrains the production mechanism.


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Ideal Photon Beam Energy for Ideal Photon Beam Energy for GlueXGlueXBased on:

• maintain sufficient photon flux/polarization (via coherent bremsstrahlung)

• maintain sufficient meson yield for high mass (2.5 GeV) region

• separate baryon from meson resonances

Figure-of-merit (P2 x N) for

M = 2.5 GeV and E0 = 12 GeV


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Photon beam and experimental areaPhoton beam and experimental area

Top View

75 m

Tagger AreaExperimental

Hall D

Electron beam

Coherent Bremsstrahlungphoton beam

Solenoid-Based

detectorCollimator

PhotonBeam dump

East arc

North linac

Tagger area

Hall D

ElectronBeam dump


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GlueX Detector in Hall DGlueX Detector in Hall D

Tagger Spectrometer(Upstream)

Hermetic detectionof charged and neutral particles


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Hall-D taggerHall-D tagger

two-magnet design with horizontal deflection hodoscope: variable ‘microscope’ & coarse fixed

array photon spectrum:

coherent and incoherent bremsstrahlung

deflected e-beam

primary e-beam


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CLAS12CLAS12 – 12 GeV Upgrade of Hall – 12 GeV Upgrade of Hall BB

CLAS12• Hall B with CLAS12 is a major part of the upgrade to 12 GeV

• PAC30 recommended approval of a broad initial physics program.

• Many components are in R&D or design phases: Drift chambers, SVT, calorimeter, Cerenkov counter, TOF counters, s.c. magnets.

• CD-2 review in summer 2007.


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Future of the Hall B TaggerFuture of the Hall B Tagger

Maximum EMaximum E0 0 = 6.2 GeV at I = 2400 A= 6.2 GeV at I = 2400 A At 12 GeV operation, Hall B will have choice At 12 GeV operation, Hall B will have choice

of of 2.2, 4.42.2, 4.4, 6.6, 8.8, 11 GeV., 6.6, 8.8, 11 GeV. Desirable to raise tagger capability to 6.6 Desirable to raise tagger capability to 6.6

GeV: new power supply, add yoke iron?GeV: new power supply, add yoke iron? More speculative: Dump electrons in More speculative: Dump electrons in

tagger yoke? (background test July 2007). tagger yoke? (background test July 2007). New end-point tagger under consideration – New end-point tagger under consideration –

no detailed design, no funds in initial no detailed design, no funds in initial upgrade.upgrade.


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SummarySummary 2007-2011 2007-2011

Intensive program in N* photoproduction usingIntensive program in N* photoproduction using polarized beams and frozen-spin polarized polarized beams and frozen-spin polarized

targetstargets(butanol and HD) in Hall B.(butanol and HD) in Hall B.

After the 12 GeV upgrade:After the 12 GeV upgrade:Exotic meson (gluonic excitations) program in Exotic meson (gluonic excitations) program in

Hall D.Hall D.Future of photon physics in Hall B is uncertain.Future of photon physics in Hall B is uncertain.

Documents

Photon physics at JLab: Status and prospects 2007-20??