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E99-107 CLAS experiment

Spokespersons
V. D. Burkert, R. Minehart
Year
2005
Abstract
An extensive program is currently underway at the Jefferson Laboratory to study the excitation of nucleon resonances with electromagnetic probes. The CEBAF Large Acceptance spectrometer (CLAS) is well suited for the study of a broad rang of kinematics in the invariant mass W, photon virtuality Q^2, and has nearly complete angular coverage for the hadronic resonance decays. Until recently most of the resonance studies using electron beams have employed the single pi0 or eta channels to study the lower mass states, especially the Delta(1232) and the S_11(1535). Many of the higher mass resonances are isospin 1/2 states and couple more strongly to the n pi+ channel. The extraction of resonance information requires the analysis of the angular distribution in the hadronic center-of-mass system. With CLAS this channel becomes now fully accessible as the pi+ is measured in nearly the full azimuthal and polar angular ranges. High statistics data have been taken with a variety of beam energies ranging from 1.5 GeV to 5.75 GeV covering a Q^2 range from 0.3 to 3 GeV^2, and the full resonance mass range. The electron beam was polarized at about 70%. Data on invariant mass distributions for e p -> e' pi+ n is presented in this thesis. Three resonant enhancement can clearly be identified in all data sets belonging to the Delta(1232), D_13(1520), and F_15(1680) resonances. The latter two exhibit Q^2-dependences which are quite different from the Delta(1232).
Quantities
dσ/dΩ

Measurements

ID Quantity Beam Target Final state Q2min,
GeV2 		Q2max,
GeV2 		Wmin,
GeV 		Wmax,
GeV
E14M1 dσ/dΩ e p π+n 1.72 1.72 1.15 1.15
E14M2 dσ/dΩ e p π+n 1.72 1.72 1.17 1.17
E14M3 dσ/dΩ e p π+n 1.72 1.72 1.19 1.19
E14M4 dσ/dΩ e p π+n 1.72 1.72 1.21 1.21
E14M5 dσ/dΩ e p π+n 1.72 1.72 1.23 1.23
E14M6 dσ/dΩ e p π+n 1.72 1.72 1.25 1.25
E14M7 dσ/dΩ e p π+n 1.72 1.72 1.27 1.27
E14M8 dσ/dΩ e p π+n 1.72 1.72 1.29 1.29
E14M9 dσ/dΩ e p π+n 1.72 1.72 1.31 1.31
E14M10 dσ/dΩ e p π+n 1.72 1.72 1.33 1.33
E14M11 dσ/dΩ e p π+n 1.72 1.72 1.35 1.35
E14M12 dσ/dΩ e p π+n 1.72 1.72 1.37 1.37
E14M13 dσ/dΩ e p π+n 1.72 1.72 1.39 1.39
E14M14 dσ/dΩ e p π+n 1.72 1.72 1.41 1.41
E14M15 dσ/dΩ e p π+n 1.72 1.72 1.43 1.43
E14M16 dσ/dΩ e p π+n 1.72 1.72 1.45 1.45
E14M17 dσ/dΩ e p π+n 1.72 1.72 1.47 1.47
E14M18 dσ/dΩ e p π+n 1.72 1.72 1.49 1.49
E14M19 dσ/dΩ e p π+n 1.72 1.72 1.51 1.51
E14M20 dσ/dΩ e p π+n 1.72 1.72 1.53 1.53
E14M21 dσ/dΩ e p π+n 1.72 1.72 1.55 1.55
E14M22 dσ/dΩ e p π+n 1.72 1.72 1.57 1.57
E14M23 dσ/dΩ e p π+n 1.72 1.72 1.59 1.59
E14M24 dσ/dΩ e p π+n 1.72 1.72 1.61 1.61
E14M25 dσ/dΩ e p π+n 1.72 1.72 1.63 1.63
E14M26 dσ/dΩ e p π+n 1.72 1.72 1.65 1.65
E14M27 dσ/dΩ e p π+n 1.72 1.72 1.67 1.67
E14M28 dσ/dΩ e p π+n 1.72 1.72 1.69 1.69
E14M29 dσ/dΩ e p π+n 2.05 2.05 1.15 1.15
E14M30 dσ/dΩ e p π+n 2.05 2.05 1.17 1.17
E14M31 dσ/dΩ e p π+n 2.05 2.05 1.19 1.19
E14M32 dσ/dΩ e p π+n 2.05 2.05 1.21 1.21
E14M33 dσ/dΩ e p π+n 2.05 2.05 1.23 1.23
E14M34 dσ/dΩ e p π+n 2.05 2.05 1.25 1.25
E14M35 dσ/dΩ e p π+n 2.05 2.05 1.27 1.27
E14M36 dσ/dΩ e p π+n 2.05 2.05 1.29 1.29
E14M37 dσ/dΩ e p π+n 2.05 2.05 1.31 1.31
E14M38 dσ/dΩ e p π+n 2.05 2.05 1.33 1.33
E14M39 dσ/dΩ e p π+n 2.05 2.05 1.35 1.35
E14M40 dσ/dΩ e p π+n 2.05 2.05 1.37 1.37
E14M41 dσ/dΩ e p π+n 2.05 2.05 1.39 1.39
E14M42 dσ/dΩ e p π+n 2.05 2.05 1.41 1.41
E14M43 dσ/dΩ e p π+n 2.05 2.05 1.43 1.43
E14M44 dσ/dΩ e p π+n 2.05 2.05 1.45 1.45
E14M45 dσ/dΩ e p π+n 2.05 2.05 1.47 1.47
E14M46 dσ/dΩ e p π+n 2.05 2.05 1.49 1.49
E14M47 dσ/dΩ e p π+n 2.05 2.05 1.51 1.51
E14M48 dσ/dΩ e p π+n 2.05 2.05 1.53 1.53
E14M49 dσ/dΩ e p π+n 2.05 2.05 1.55 1.55
E14M50 dσ/dΩ e p π+n 2.05 2.05 1.57 1.57
E14M51 dσ/dΩ e p π+n 2.05 2.05 1.59 1.59
E14M52 dσ/dΩ e p π+n 2.05 2.05 1.61 1.61
E14M53 dσ/dΩ e p π+n 2.05 2.05 1.63 1.63
E14M54 dσ/dΩ e p π+n 2.05 2.05 1.65 1.65
E14M55 dσ/dΩ e p π+n 2.05 2.05 1.67 1.67
E14M56 dσ/dΩ e p π+n 2.05 2.05 1.69 1.69
E14M57 dσ/dΩ e p π+n 2.44 2.44 1.15 1.15
E14M58 dσ/dΩ e p π+n 2.44 2.44 1.17 1.17
E14M59 dσ/dΩ e p π+n 2.44 2.44 1.19 1.19
E14M60 dσ/dΩ e p π+n 2.44 2.44 1.21 1.21
E14M61 dσ/dΩ e p π+n 2.44 2.44 1.23 1.23
E14M62 dσ/dΩ e p π+n 2.44 2.44 1.25 1.25
E14M63 dσ/dΩ e p π+n 2.44 2.44 1.27 1.27
E14M64 dσ/dΩ e p π+n 2.44 2.44 1.29 1.29
E14M65 dσ/dΩ e p π+n 2.44 2.44 1.31 1.31
E14M66 dσ/dΩ e p π+n 2.44 2.44 1.33 1.33
E14M67 dσ/dΩ e p π+n 2.44 2.44 1.35 1.35
E14M68 dσ/dΩ e p π+n 2.44 2.44 1.37 1.37
E14M69 dσ/dΩ e p π+n 2.44 2.44 1.39 1.39
E14M70 dσ/dΩ e p π+n 2.44 2.44 1.41 1.41
E14M71 dσ/dΩ e p π+n 2.44 2.44 1.43 1.43
E14M72 dσ/dΩ e p π+n 2.44 2.44 1.45 1.45
E14M73 dσ/dΩ e p π+n 2.44 2.44 1.47 1.47
E14M74 dσ/dΩ e p π+n 2.44 2.44 1.49 1.49
E14M75 dσ/dΩ e p π+n 2.44 2.44 1.51 1.51
E14M76 dσ/dΩ e p π+n 2.44 2.44 1.53 1.53
E14M77 dσ/dΩ e p π+n 2.44 2.44 1.55 1.55
E14M78 dσ/dΩ e p π+n 2.44 2.44 1.57 1.57
E14M79 dσ/dΩ e p π+n 2.44 2.44 1.59 1.59
E14M80 dσ/dΩ e p π+n 2.44 2.44 1.61 1.61
E14M81 dσ/dΩ e p π+n 2.44 2.44 1.63 1.63
E14M82 dσ/dΩ e p π+n 2.44 2.44 1.65 1.65
E14M83 dσ/dΩ e p π+n 2.44 2.44 1.67 1.67
E14M84 dσ/dΩ e p π+n 2.44 2.44 1.69 1.69
E14M85 dσ/dΩ e p π+n 2.91 2.91 1.15 1.15
E14M86 dσ/dΩ e p π+n 2.91 2.91 1.17 1.17
E14M87 dσ/dΩ e p π+n 2.91 2.91 1.19 1.19
E14M88 dσ/dΩ e p π+n 2.91 2.91 1.21 1.21
E14M89 dσ/dΩ e p π+n 2.91 2.91 1.23 1.23
E14M90 dσ/dΩ e p π+n 2.91 2.91 1.25 1.25
E14M91 dσ/dΩ e p π+n 2.91 2.91 1.27 1.27
E14M92 dσ/dΩ e p π+n 2.91 2.91 1.29 1.29
E14M93 dσ/dΩ e p π+n 2.91 2.91 1.31 1.31
E14M94 dσ/dΩ e p π+n 2.91 2.91 1.33 1.33
E14M95 dσ/dΩ e p π+n 2.91 2.91 1.35 1.35
E14M96 dσ/dΩ e p π+n 2.91 2.91 1.37 1.37
E14M97 dσ/dΩ e p π+n 2.91 2.91 1.39 1.39
E14M98 dσ/dΩ e p π+n 2.91 2.91 1.41 1.41
E14M99 dσ/dΩ e p π+n 2.91 2.91 1.43 1.43
E14M100 dσ/dΩ e p π+n 2.91 2.91 1.45 1.45
Created in SINP MSU, CLAS Collaboration