Coulomb Sum Rule. Huan Yao Feb 16,2010. Physics Experiment Data Analysis Summary Collaboration APS April Meeting

Transcription

1 Coulomb Sum Rule 2010 APS April Meeting Huan Yao Feb 16, / 17

2 Physics Motivation The test of Coulomb Sum Rule is to shed light on the question of whether or not the properties of nucleons are modified in the nuclear medium. Coulomb Sum Rule states that the integration of the charge response of a nucleus over the full range of energy excitation should be equal to the total charge of the nucleus. SL( q) = 1 Z 0+ q, SL 1 RL( q, ω) dω G E 2 As a result, quenching of the response at high momentum transfer may indicate the possibility of modification of nucleon properties in the nuclear medium. Figure: Data Collection 2 / 17

3 Physics Motivation The test of Coulomb Sum Rule is to shed light on the question of whether or not the properties of nucleons are modified in the nuclear medium. Coulomb Sum Rule states that the integration of the charge response of a nucleus over the full range of energy excitation should be equal to the total charge of the nucleus. SL( q) = 1 Z 0+ q, SL 1 RL( q, ω) dω G E 2 As a result, quenching of the response at high momentum transfer may indicate the possibility of modification of nucleon properties in the nuclear medium. Figure: Data Collection 2 / 17

4 Physics Motivation The test of Coulomb Sum Rule is to shed light on the question of whether or not the properties of nucleons are modified in the nuclear medium. Coulomb Sum Rule states that the integration of the charge response of a nucleus over the full range of energy excitation should be equal to the total charge of the nucleus. SL( q) = 1 Z 0+ q, SL 1 RL( q, ω) dω G E 2 As a result, quenching of the response at high momentum transfer may indicate the possibility of modification of nucleon properties in the nuclear medium. Figure: Data Collection 2 / 17

5 Quasi-elastic Scattering Figure: Quasi-elastic scattering [ d 2 σ dωdω = σ Q 4 M R q 4 L ( q, ω) + Q2 [ where ε( q,ω,θ)= 1+ 2 q2 Q 2 tan2 θ 2 ] 1 R T ( q,ω) 2 q 2 ε So R L = q4 1 Q 4 σ M (ε f ε b ) (ε fσ f ε b σ b ) R T = q2 2ε f ε b Q 2 σ M (ε f ε b ) (σ b σ f ) ] 3 / 17

6 Experimental Setup Figure: Hall A Floor Diagram Inclusive electron quasi-elastic scattering in Jefferson Lab LH 2,LH 2 + Pb, 4 He, 12 C, 56 Fe 4 / 17

7 Kinematic coverage E : GeV P0 : 0.1 4GeV θ0 : 15, 60, 90, 120 Figure: Kinematic coverage. The two solid lines corresponds to q =550 MeV/c and 1000 MeV/c. The two dashed lines corresponds to W = 940MeV/c 2 and 1232MeV/c 2. 5 / 17

8 Outline 1 Physics 2 Experiment 3 Data Analysis Progress Spectrometer Optics NaI (Left Arm) Acceptance Cross Section 4 Summary 5 Collaboration 6 / 17

9 Analysis Progress Beam energy, current and position calibration Spectrometer momentum calibration Gas Cherenkov, NaI, Pre-shower and Shower calibration Liquid target density study. Detector efficiency Optics Acceptance 7 / 17

10 Outline 1 Physics 2 Experiment 3 Data Analysis Progress Spectrometer Optics NaI (Left Arm) Acceptance Cross Section 4 Summary 5 Collaboration 8 / 17

11 Spectrometer Optics Optimization Purpose Optics is used to reconstruct the target quantities from the measured value at VDC in the spectrometer. 9 / 17

12 Outline 1 Physics 2 Experiment 3 Data Analysis Progress Spectrometer Optics NaI (Left Arm) Acceptance Cross Section 4 Summary 5 Collaboration 10 / 17

13 L.CSRBox2.asum_p {L.cer.asum_c>1100&&L.cer.asum_c<2300&&L.tr.n==1&&abs(L.gold.dp)<0.04&&abs(L.gold.th)<0.03&&abs(L.gold.ph)<0.03&&L.CSRBox2.trx>-0.3&&L.CSRBox2.trx<0.1&&abs(L.CSRBox2.try)<0.2} Physics Experiment Data Analysis Summary Collaboration NaI Calibration Purpose The resolution is essential for an extensive study of the low-energy background of the Coulomb Sum Rule. Figure: NaI detector Before Calibration Run 3813 E=739MeV, P0=121MeV/C Lead target, 120 Degree h1 Entries Mean 2186 RMS Figure: NaI calibration 11 / 17

14 Outline 1 Physics 2 Experiment 3 Data Analysis Progress Spectrometer Optics NaI (Left Arm) Acceptance Cross Section 4 Summary 5 Collaboration 12 / 17

15 Acceptance θ tg 500 h1_data_tg_morebins_0 Entries Mean φ tg 500 h1_data_tg_morebins_1 Entries Mean RMS RMS y (m) tg h1_data_tg_morebins_2 Entries dp h1_data_tg_morebins_3 Entries Mean Mean RMS RMS Figure: 3949 Acceptance result ( black: Data red: Simulation ) 13 / 17

16 Outline 1 Physics 2 Experiment 3 Data Analysis Progress Spectrometer Optics NaI (Left Arm) Acceptance Cross Section 4 Summary 5 Collaboration 14 / 17

17 4 He Cross Section Figure: Differential cross section for 4 He with E0=646 MeV,θ=, 60 ( green line: Corresponding to quasi-elastic peak (left) and first inelastic peak (right) ) 15 / 17

18 Summary Good analysis progress. Radiative correction. Rosenbluth separation. Systematic error determination. Expect result by summer. 16 / 17

19 Collaboration 17 / 17