Missing Resonances and Beyond
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Missing Resonances and BeyondKen Livingston, University of Glasgow, Scotland
Nucleon resonances and complete measurements
Missing nucleon resonances
Jefferson Lab and the N* programme at CLAS
Hyperon results and status of N*
The future
The Jefferson Lab 12GeV upgrade
Future facilities – EIC, ESS, ELI
SCAPA
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Clear indication of resonances
Broad and overlapping
Below energy regime of PQCD
Constituent quark models SU(6) x O(3)
Eg. Forsyth & Cutkosky, Koniuk & Isgur,
Capstick & Roberts
Missing resonances
γp cross section: World Data
Most data is from πN scattering and single π photoproduction.
Cross sections are not enough – need angular distributions and polarization observables.
Hyperons (nucleons with strange quark) are promising (g + N -> + and g + N -> + )
With D13Without D13
Mart & Benhold, Phys. Rev. C 61 012201(R) (1999)
Constituent quark models predict many resonances, but several missing.
Are they wrongly predicted, or difficult to find experimentally?
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Polarization observables in pseudoscalar (0-) meson production
4 Complex amplitudes: 16 real polarization observables.
Complete, model independent, measurement from 8 carefully chosen observables.
I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B95 347 (1975).
πN: high statistics KY recoil: self-analysing
( )
Systematics of detector acceptance cancel out.
Only need to know Plin, the degree of linear polarization.
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A B C
Continuous Electron Beam Accelerator Facility
® E: 0.75 –6 GeV® Imax: 200mA® RF: 1499 MHz® Duty Cycle: 100%® s(E)/E: 2.5x10-5
® Polarization: 80%® Simultaneous
distribution to 3 experimental Halls
Injector
LIN
AC LINAC
Experimental Halls
Jefferson Lab, Virginia, USA
TAGGER
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CEBAF Large Acceptance Spectrometer
Cherenkov Counter e/ separation, 256 PMTsTime of Flight
Plastic Scintillator, 684 PMTs
Drift Chamber35,000 cells
Target + g start counter e mini-torus
Electromagnetic Calorimeterlead/plastic scintillator, 1296 PMTs
Torus Magnet6 Superconductive Coils
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Ee
Ee’
Eg = Ee - Ee’
11m
Amorphous radiatorDiamond radiator
up to 90% linear polarization
Ee
Diamonds
Need to be “perfect” monocrystals
Assessment difficult and expensive
Tagger in Intregrating mode
…. Could we do this at SCAPA?
Hall B Photon Tagger and Coherent Bremsstrahlung
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Polarization observables at CLAS
g + N → N + m
Linear Polarisation
Circular polarisation
Nucleon recoil polarimiter x →
Y +
Hyperons are “self analysing”
Transverse polarized nucleon targets p nLongitudinally polarized nucleon targets p n
Crystal Ball MAMI,D.Watts, Edinburgh.
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0
Single polarization observables Photon asymmetryP Recoil polarization (induced pol. along y)T Target asymmetry
Double polarization observablesOx Polarization transfer along xOz Polarization transfer along z
Polarization observables in g + p → K + Y (Lin Pol Beam, LH2 target)Craig Paterson, Glasgow
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Polarization observables in g + p → K + Y (Lin Pol Beam, LH2 target)Craig Paterson, Glasgow
Good agreement with previous data.Better statisticsMany more bins in CM angle and Energy.
Phot
on A
sym
met
ry g
+ p
→ K
+
D
oubl
e Po
l Obs
Cx
for g
+ p
→ K
+
Gent Regge + Resonance Model(Corthals et al. Phys Rev C73 2006)
Data +Regge background (R) - - - - - - - - -R + core resonances (C) - . - . - . - . -R + C + D13(1900) __________R + C + P11(1900) __ __ __ __
Cos (θcm) K
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• Detect - n, K+
• Σ from - n inv. mass
Sergio Anefalos Pereira, INFN. Phys. Lett. B 688 (2010) 289-293
• CLAS Data ▲ LEPS _____ Gent RPR model
Edwin Munevar, GWU
PREL
IMIN
AR
Y
Polarization observables in g + n → K + Y (Lin Pol Beam, LD2 target)
gn (p) -> 0s 0
(p) gn (p) -> 0
s 0 (p)
1st measurements, P, T, Ox,Oz
PREL
IMIN
AR
Y
Neil Hassall, Glasgow
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Status of N* program - complete measurements
✔ - published, ✔ - acquired, ✔ - running now
Each ✔ ✔ represents a future publication.
σ Σ T P E F G H Tx Tz Lx Lz Ox Oz Cx Cz
Proton target
pπ0 ✔ ✓ ✓ ✓ ✓ ✓ ✓
nπ+ ✔ ✓ ✓ ✓ ✓ ✓ ✓
pη ✔ ✓ ✓ ✓ ✓ ✓ ✓
pη’ ✔ ✓ ✓ ✓ ✓ ✓ ✓
pω ✔ ✓ ✓ ✓ ✓ ✓ ✓
K+Λ ✔ ✓ ✓ ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✔ ✔
K+Σ0 ✔ ✓ ✓ ✔ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✔ ✔
K0*Σ+ ✔ ✓ ✓ ✓
Neutron target
pπ- ✔ ✓ ✓ ✓ ✓ ✓ ✓pρ- ✓ ✓ ✓ ✓ ✓ ✓ ✓K-Σ+ ✓ ✓ ✓ ✓ ✓ ✓ ✓K0Λ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓K0Σ0 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓K0*Σ0 ✓ ✓
PhD awarded - S. Fegan FROST2 new students – HDIce (running now)
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• Spin density matrix elements in bins ΔW = 10 MeV, for W = 1.7–2.4 GeV in blue - blue shades.
• Previous world data in red.
Search for baryon states in γp pω pπ➝ ➝ +π-(π0)
M. Williams, et al. (CLAS) , Phys.Rev.C80:065208,2009
M. Williams, et al. (CLAS) , Phys.Rev.C80:065209,2009
F15(2000)/G17(2190)
ω production is dominated by the well known F15(1680), D13(1700) and G17(2190), and a predicted “missing” F15(2000).
Status of N* program
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The JLab 12GeV upgrade (15min)
CHL-2
Upgrade of the arc magnets
Construction of the new Hall D
Beam Power: 1MWBeam Current: 90 µAMax Pass energy: 2.2 GeVMax Enery Hall A-C: 10.9 GeVMax Energy Hall D: 12 GeV
Upgrade of the instrumentation of the existing Halls
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< 6 GeV
Spectroscopy with CLAS12
Low Q Tagging Facility or Forward Tagger
Electron scattering at “0” degrees (LowQ, post-target tagging): low Q2 virtual photon real photon
Photons tagged by detecting the scattered electron
Quasi-real photons are linearly polarized and the polarization can be determined event by event
Highly segmented calorimiter BGOOpportunity to test / develop at SCAPA?
Hadron spectroscopyHeavy mass baryon resonances (Cascades and -)
Meson spectroscopyH target and search for exotics4He and other gas targets
Focus on Generalized Parton Distributions
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GlueX: Confinement and the search for QCD exotics
Simplest quark-structure is a meson
Confinement: Quarks cannot exist alone
+ =(, K) JPC = 1-- , 1++
Hybrid Mesonor , , , … ?
+ =(, ) JPC = 0-+, 1-+, 2-+
0+-, 1+-, 2+-
Exotic!
Flux
tube
forms
between
Use a real photon beam
Excite the glue:Study hybrid mesons
G. Bali
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GlueX: Confinement and the search for QCD exotics
Glasgow:Diamond selectionCoherent bremsstrahlungPolarimetry SCAPA ?
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Wider context
20162012
MAX IV
EIC ?USA
Sweden
Romania
Germany
Sweden
Scotland SCAPA
2020
Long standing Glasgow
collaborations
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SCAPAScottish Centre for the Application of Plasma-based Accelerators
“Harnessing plasma waves as radiation and particle sources” Dino Jaroszynski
Laser Wakefield Acceleration
Ultra-short, ultra-intense laser pulses from commercially available table-top terawatt femtosecond lasers. Electron bunches:Mean energy above 1 GeV, an energy spread of about 1% and a peak current exceeding 1 kA.
Protons: Yes please
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0.1 – 1 GeVg = 200 -
2000 plasma filled
capillary
undulator
1 J 40 fs 800 nm
wakefield accelerator
6.5 MeV photo-injector
laser
optical self-injection
SCAPAALPHA-X running now
~20fs
Diamond
Many of these make this
SCAPA needs the expertise of nuclear physicists …. today!
Beam characterizationWe already do this: Nature Physics 7, 867–871 (2011) D.Hamilton ++Polarimetry
Spectrometers and beam conditioning
Detectors
Data Acquisition / analysis
SImluation
Providing expertise opens many doors
EDUCATION EDUCATION EDUCATIONUndergraduates
PhD students
Young postdocs.
Opportunities for nuclear physicists
Detector developmentRF PMTs, GEMs, Diamond detectors
DiamondsQuality assessment, channeling radiation, polarimetry
Fundamentsl Hadron and Nuclear Physics Lifetime measurements The unknown, open doors to ESS, ELI
Compact Muon Source (next slide)
RF PMTs (J.Annand, Glasgow + Yerevan)ps timing resolution500MHz rate capability
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500L
Compact Muon Source at SCAPA
Assay of radioactive waste: Glasgow applied project with NNL
There exists, somewhere, a large stockpile of barrelsof unclassified radioactive waste.
Need to determine the existence of high Z materials.
Scattering of Muons.Muons from cosmic rays.
Method is very promising.Rate of cosmic muons ~5Hz / m2
Assay will take 10s of years not feasible.
Need a muon beam
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1 GeV10Hz
Wakefield accelerator
Light solid targetBrem radiator Magnetic element
Simulated using Geant 4 and MAID2007, D. Hamilton, Glasgow
Similar to method used at ISIS
Rate Estimate
Compact muons: ~9kHz / m2
Compared toCosmic muons ~5Hz / m2
Compact Muon Source at SCAPA
Compact, made from “standard components”.>103 rate increase over cosmics.Pion beam to do hadron physics (eg pion lifetime measurement with RF PMTs)Muon beam for materials science.
γn pπ➝ - - ➝ m- nm- (l = 7.8m)
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Summary
Missing ResonancesLots of progress internationally.Strangeness very important – 1st complete measurementNext few years should see definitive results.
Jlab 12CLAS12 and GlueX Continuing spectroscopy
Heavier baryonsHybrid mesons
SCAPA Many new opportunities
PhysicsDetector developmentEducationCompact muon source
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gp (n) -> +0 (n) Russell Johnstone, Glasgow
K production on n. Deuterium target
PREL
IMIN
ARY
p
hoto
n as
ymm
etry
How good a “free” neutron target is Deuterium ?
G13. Compare photon asymmetry of gp (n) -> +0 (n) with gp -> +0 (free and bound p)
0
0
× Free● Quasi free
Free and quasi-free protonQuasi free neutron good approx. to free, here.
Coscm (-1.0 - +1.0)Each plot is 200MeV photon energy bin1100-2150MeV
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G13 gn (p) -> 0s 0 (p) gn (p) -> 0
s 0 (p)Neil Hassall, Glasgow
K production on n. Deuterium target
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• 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
energ
y
P > 90%
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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
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+ Photon Asymmetry, , extracted from cos(2) fit to azimuthal kaon distribution
Fits shown for 1 energy bin340 (20E, 17) kinematic binsAlmost full angular coverage
g8b preliminary results - +
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g8b preliminary results - +0
Results compared with previous results from GRAAL7, 50MeV Energy bins1175 -> 1475MeVGood agreement with previous results
PREL
IMIN
AR
Y
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Results compared with previous results from LEPS6, 100MeV Energy bins1550 -> 2050MeVMore bins for our data!!!
Increase the angular coverage to backward angles
PREL
IMIN
AR
Y
g8b preliminary results - +0
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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
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Resonances
Pythagoras (c. 500 B.C.)Notes on a string which sound harmonious have simple ratios.
1st Resonance modelCreated a system for tuning instruments The 1st musical scale
… and then the universe
Music of the SpheresIf there is insufficient data even the wackiest of models cannot be ruled out.