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 Q², 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 π⁰$ or η channels to study the lower mass states, especially the Δ(1232) and the S₁₁(1535). Many of the higher mass resonances are isospin 1/2 states and couple more strongly to the n π⁺ 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 π⁺ 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 Q² range from 0.3 to 3 GeV², and the full resonance mass range. The electron beam was polarized at about 70%. Data on invariant mass distributions for $\vec{e}p -> e'π⁺n is presented in this thesis. Three resonant enhancement can clearly be identified in all data sets belonging to the Δ(1232), D₁₃(1520), and F₁₅(1680) resonances. The latter two exhibit Q²-dependences which are quite different from the Δ(1232).
Comment: asymmetry
Quantities: A_LU D coeff

Measurements

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ID	Quantity	Beam	Target	Final state	Q²_min, GeV²	Q²_max, GeV²	W_min, GeV	W_max, GeV
E76M1	A_LU	e	p	π⁺n	1.56	1.87	1.1	1.14
E76M2	A_LU	e	p	π⁺n	1.87	2.23	1.1	1.14
E76M3	A_LU	e	p	π⁺n	2.23	2.66	1.1	1.14
E76M4	A_LU	e	p	π⁺n	2.66	3.17	1.1	1.14
E76M5	A_LU	e	p	π⁺n	1.56	1.87	1.14	1.18
E76M6	A_LU	e	p	π⁺n	1.87	2.23	1.14	1.18
E76M7	A_LU	e	p	π⁺n	2.23	2.66	1.14	1.18
E76M8	A_LU	e	p	π⁺n	2.66	3.17	1.14	1.18
E76M9	A_LU	e	p	π⁺n	3.17	3.79	1.14	1.18
E76M10	A_LU	e	p	π⁺n	1.56	1.87	1.22	1.26
E76M11	A_LU	e	p	π⁺n	1.87	2.23	1.22	1.26
E76M12	A_LU	e	p	π⁺n	2.23	2.66	1.22	1.26
E76M13	A_LU	e	p	π⁺n	2.66	3.17	1.22	1.26
E76M14	A_LU	e	p	π⁺n	3.17	3.79	1.22	1.26
E76M15	A_LU	e	p	π⁺n	1.56	1.87	1.26	1.3
E76M16	A_LU	e	p	π⁺n	1.87	2.23	1.26	1.3
E76M17	A_LU	e	p	π⁺n	2.23	2.66	1.26	1.3
E76M18	A_LU	e	p	π⁺n	2.66	3.17	1.26	1.3
E76M19	A_LU	e	p	π⁺n	3.17	3.79	1.26	1.3
E76M20	A_LU	e	p	π⁺n	1.56	1.87	1.3	1.34
E76M21	A_LU	e	p	π⁺n	1.87	2.23	1.3	1.34
E76M22	A_LU	e	p	π⁺n	2.23	2.66	1.3	1.34
E76M23	A_LU	e	p	π⁺n	2.66	3.17	1.3	1.34
E76M24	A_LU	e	p	π⁺n	3.17	3.79	1.3	1.34
E76M25	A_LU	e	p	π⁺n	1.56	1.87	1.34	1.38
E76M26	A_LU	e	p	π⁺n	1.87	2.23	1.34	1.38
E76M27	A_LU	e	p	π⁺n	2.23	2.66	1.34	1.38
E76M28	A_LU	e	p	π⁺n	2.66	3.17	1.34	1.38
E76M29	A_LU	e	p	π⁺n	3.17	3.79	1.34	1.38
E76M30	A_LU	e	p	π⁺n	1.56	1.87	1.38	1.42
E76M31	A_LU	e	p	π⁺n	1.87	2.23	1.38	1.42
E76M32	A_LU	e	p	π⁺n	2.23	2.66	1.38	1.42
E76M33	A_LU	e	p	π⁺n	2.66	3.17	1.38	1.42
E76M34	A_LU	e	p	π⁺n	3.17	3.79	1.38	1.42
E76M35	A_LU	e	p	π⁺n	1.56	1.87	1.46	1.5
E76M36	A_LU	e	p	π⁺n	1.87	2.23	1.46	1.5
E76M37	A_LU	e	p	π⁺n	2.23	2.66	1.46	1.5
E76M38	A_LU	e	p	π⁺n	2.66	3.17	1.46	1.5
E76M39	A_LU	e	p	π⁺n	3.17	3.79	1.46	1.5
E76M40	A_LU	e	p	π⁺n	1.56	1.87	1.5	1.54
E76M41	A_LU	e	p	π⁺n	1.87	2.23	1.5	1.54
E76M42	A_LU	e	p	π⁺n	2.23	2.66	1.5	1.54
E76M43	A_LU	e	p	π⁺n	2.66	3.17	1.5	1.54
E76M44	A_LU	e	p	π⁺n	3.17	3.79	1.5	1.54
E76M45	A_LU	e	p	π⁺n	1.56	1.87	1.54	1.58
E76M46	A_LU	e	p	π⁺n	1.87	2.23	1.54	1.58
E76M47	A_LU	e	p	π⁺n	2.23	2.66	1.54	1.58
E76M48	A_LU	e	p	π⁺n	2.66	3.17	1.54	1.58
E76M49	A_LU	e	p	π⁺n	3.17	3.79	1.54	1.58
E76M50	A_LU	e	p	π⁺n	1.56	1.87	1.58	1.62
E76M51	A_LU	e	p	π⁺n	1.87	2.23	1.58	1.62
E76M52	A_LU	e	p	π⁺n	2.23	2.66	1.58	1.62
E76M53	A_LU	e	p	π⁺n	2.66	3.17	1.58	1.62
E76M54	A_LU	e	p	π⁺n	3.17	3.79	1.58	1.62
E76M55	A_LU	e	p	π⁺n	1.56	1.87	1.62	1.66
E76M56	A_LU	e	p	π⁺n	1.87	2.23	1.62	1.66
E76M57	A_LU	e	p	π⁺n	2.23	2.66	1.62	1.66
E76M58	A_LU	e	p	π⁺n	2.66	3.17	1.62	1.66
E76M59	A_LU	e	p	π⁺n	3.17	3.79	1.62	1.66
E76M60	A_LU	e	p	π⁺n	1.56	1.87	1.66	1.7
E76M61	A_LU	e	p	π⁺n	1.87	2.23	1.66	1.7
E76M62	A_LU	e	p	π⁺n	2.23	2.66	1.66	1.7
E76M63	A_LU	e	p	π⁺n	2.66	3.17	1.66	1.7
E76M64	A_LU	e	p	π⁺n	3.17	3.79	1.66	1.7
E76M65	D coeff	e	p	π⁺n	1.715	3.48	1.12	1.68

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CLAS Physics Database

E99-107 CLAS experiment

Measurements