Experiments%20with%20%20%20%20%20%20%20Frozen-Spin%20Target%20and%20%20%20%20%20%20%20Polarized%20Photon%20Beams

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Experiments with
Frozen-Spin Target and Polarized
Photon Beams
FROST
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polarized photon beams
? CLASg8 poster
linearly pol. beam (coherent bremsstrahlung)
circularly pol. beam (long. pol. electrons)
tagged flux 50MHz (for kgt0.5 E0)
10MHz (coh.peak)
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• CLAS polarized targets

existing dynamically pol. NH3 target P80,
P35 (deuterized) pol. magnet 5.1 T (Helmholtz
coils)
reduces 4p acceptance to ?lt65o
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• CLAS frozen-spin target

target Ø15mm x 50mm butanol C4H9OH dilution
factor 10/74 eff. density 0.611 g/cm3
operate at 50mK, repolarize at 0.4K
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• CLAS frozen-spin target

longitudinal polarization solenoidal coil (0.5T
?B/B0.2) ? online NMR
transverse polarization racetrack coil
(0.3T ?B/B0.5) NEW DEVELOPMENT!
size Ø5cmx11cm
size Ø5cmx20cm
max. Pol.96, average 80-85 (trelax30d)
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Proposed Experiments

• E02-112 ?p?KY (K?, KS0, K0S)
• E03-105/E01-104 ?p?p0p, pn
• E05-012 ?p??p
• in preparation ?p?pp-p, ?p??p
• reactions off neutrons/deuterons ??

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goal of exp. program

• resonance parameters
• search for missing resonances

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FROST
determine mass, width, coupling of all resonances
up to 2.0 GeV
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Experiment and Theory
Experiment cross section, spin observables
(beam-target) E, F, G, H, (beam-recoil) Cx,Cz,
Ox,Oz, (target-recoil) Lx,Lz, Tx,Tz, (beam/target-
VM) CBV, CTV, CBTV
s,ds/dO (single) Sy,P,T Sp, T20, T21,T22
Reaction Theory dynamical frameworks
Amplitude analysis ?multipole ampl., ?phase
shifts
PWA SES
Theory LQCD, quark models, QCD sum rules,
CC res. param. extraction
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beam target polarization

• 4 (12) complex amplitudes for 0- (1-) meson
  production
• 8 ( 68) measurements
• FROST all 4 combinations of beam (lin,circ) and
  target (long,trans)
• for ?, S0, additionally recoil polar.
  complete set
• all observables as fcts of vs and cos?
• use algebraic relations to check for systematics

from CLAS g1, g8, g11 data
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beam target polarization
Extraction of spin observables via Fourier
analysis of polarized cross section in each
(E,cos?) bin
aorientation of photon polarization ßorientation
of target polarization PTlinear photon
polarization Pocircular photon
polarization Pzlongitudinal target
polarization Pxytransverse target polarization
FROST 6 polar. observ. for p0p,pn,?p statistics
3-5 (lt8 for ?) systematics 3-5 (beam,
target, E, S, eff. dilution fac.) 6-8
P, F, G, H
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data extraction
?p??p
dilution factor
(Dbut10/740.135) yields for free/bound
nucleons Deff0.3-0.5
estimated from He/H CLAS data and MC FROST
additional carbon target, averaged yields
?p?pN
?p?K?
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?p?p0p, pn
gt 5000 data points single pol. 2-3x
double pol. 7-8x
said database hardly any double-pol. obs. FROST
wide coverage E?0.6-2.0 GeV,?cm15-150o fine
binning ?Elt25MeV, ??cm10-15o
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?p?p0p, pn
most cases only 1st excited state in PW well
known
after FROST experiment we expect
red sample PWA (MC data)
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?p?p0p, pn (sample PWA)
sample PWA using MC data generated from SM02
greatly reduced uncertainties
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?p?p0p, pn
impact on single energy solutions
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?p?KY (K?, KS0, K0S)
present data insufficient to perform single
energy fits
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?p?KY (K?, KS0, K0S)
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?p?KY (K?, KS0, K0S)
FROST all 16 polar. observ. for K?, KS0,
K0S statistics 5-10 (lt15 for S) systematics
3-5 (beam, target, P, S, dilution fac.)
6-8 E, F, G, H, Cx,z, Ox,z, Lx,z, Tx,z
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?p??p
ds/dO compared to model (Y.Oh, H.S. Lee)
purple t-channel (Pomeron, p, ?) and u-channel
(N-pole) green s-channel black sum
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?p??p
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outlook

• 1st run period in fall 2006 (long.pol.)
• cryostat being tested in test lab
• all polarization observables measurable
• in CLAS will be extracted from data
• complete set of measurements for KY
• almost complete set for pN, ?p
• double/triple pol. obs. for pp-p, ?p
• least model dependent extraction of N
  parameters
• potential for discovery of missing
  states