THE FIFTH STRUCTURE FUNCTION. Liam Murray Research Advisor: Dr. Gerard Gilfoyle

Transcription

1 1 THE FIFTH STRUCTURE FUNCTION Liam Murray Research Advisor: Dr. Gerard Gilfoyle

2 Overview 2 Scientific Background History of Modern Atomic Physics Standard Model The Hadronic Model Versus Quantum Chromodynamics The Significance of the Fifth Structure Function Objective Experimental Background CEBAF CEBAF Large Acceptance Spectrometer CLAS Experimental Setup Extracting the Longitudinal-Transverse Asymmetry (Summer 2012) Kinematics Mathematical Approach Computational Approach Simulation of CLAS: Testing the Accuracy of Measurements (Summer 2013) Fitting the Asymmetry Simulating a Reaction in CLAS Results Conclusions References Acknowledgements

3 3 Scientific Background

4 History 4 Democritus (400 BC) atomos End of the 19 th Century à 1930s Electrons, nuclei, ions, photons Modern Era 1964 Quark or Ace

5 The Standard Model 5 Sheldon Glashow 12 Elementary Particles: Spin 1/2 4 Force Mediating Partices: Spin 1 Quark: Non-whole number electron charge Lepton: Whole number electron charge

6 The Hadronic Model 6 Interactions between hadrons Nuclei approximated as collections of protons and neutrons Low Energy Success

7 Quantum Chromodynamics (QCD) 7 Color force Interactions of quarks and gluons making up hadrons Asymptotic Freedom Confinement 3 tons of force between High Energy Success Difficulty Testing

8 The Hadronic Model Vs. QCD 8 Goal: Better understand the behavior of quarks at intermediate energies

9 Significance of the Fifth Structure Function 9 Explore the quark-gluon structure of atomic nuclei First, we need to understand atomic nuclei as collections of protons and neutrons. The Structure of the Deuteron Important place to start our understanding of atomic nuclei Helicity Asummetry A LT à Fifth Structure Function Seldom-measured part of Deuteron W.F. where Proton- Neutron force is expected to dominate

10 Objective 10 Measure the largely unknown component of the deuteron wave function (the fifth structure) 2 H(e,e p)n Reaction Never completed in this energy range Test the accuracy of our analysis Monte Carlo Simulation

11 11 Experimental Background

12 CEBAF 12 Continuous Electron Beam Accelerator Facility Newport News, Virginia 1 mile long Max: 5.7 GeV Beam Energy

13 CEBAF 13 Injector North/South Linear Accelerators SRF technology Recirculating Arcs Experimental Halls

14 Hall B: CLAS 14 CEBAF Large Acceptance Spectrometer ton, three-story, spectrometer Six identical Sectors Nearly 4π Solid Angle

15 Hall B: CLAS 15 Superconducting Toroidal Magnet Drift Chambers Cherenkov Counters Time-of-Flight Scintillators Electromagnetic Calorimeters

16 Hall B: CLAS 16 Toroidal Magnet Provides a magnetic field Two magnetic polarity settings (Normal/Reversed)

17 Hall B: CLAS 17 Drift Chambers Detector for particles with ionizing radiation Detects both presence and location of radiation Quasi-Geiger counter (I. Lab) Three Regions

18 Hall B: CLAS 18 Cherenkov Detectors Allow us to differentiate between pions and electrons Detects electromagnetic radiation emissions

19 Hall B: CLAS 19 Time-of-Flight Scintillators Lighter and heavier particle differentiation Scintillators: Variety of materials Detection possible by photo multiplier tubes

20 Hall B: CLAS 20 Electromagnetic Calorimeters Differentiate electrons and neutral particles Comprised of alternating layers of lead/scintillator Particles interact in the lead creating a shower of photons in the scintillator

21 Hall B: CLAS 21 Trajectory Charge Momentum Energy Scattering Angle Velocity

22 Experimental Setup GeV beam Both normal and reversed magnetic torus polarities Dual, co-linear liquid hydrogen-deuterium cell target

23 Extracting the Asymmetry (Summer )

24 Extracting the Asymmetry 24 Kinematics of the 2 H(e,e p)n reaction Quasi-elastic collisions

25 Extracting the Asymmetry 25 Mathematical Approach Differential Cross Section d 5 σ dq 2 dp m dφ pq dω e dω p = σ ± = σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ + hσ LT ' sinφ pq Helicity Asymmetry A h (Q 2,p m,φ pq ) = σ + σ σ + +σ

26 Extracting the Asymmetry 26 Mathematical Approach Differential Cross Section Ψ 2 d 5 σ dq 2 dp m dφ pq dω e dω p = σ ± = σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ + hσ LT ' sinφ pq Helicity Asymmetry A h (Q 2,p m,φ pq ) = σ + σ σ + +σ

27 Extracting the Asymmetry 27 Mathematical Approach Differential Cross Section d 5 σ dq 2 dp m dφ pq dω e dω p = σ ± = σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ + hσ LT ' sinφ pq p m = p p - q Helicity Asymmetry A h (Q 2,p m,φ pq ) = σ + σ σ + +σ NOT ZERO FOR OUT-OF-PLANE MEASUREMENTS!

28 Extracting the Asymmetry 28 A h (Q 2,p m,φ pq ) = σ + σ σ + +σ (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ +σ LT' sinφ pq ) (σ A h (Q 2,p m,φ pq ) = L +σ T +σ LT cosφ pq +σ TT cos2φ PQ σ LT' sinφ pq ) (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ +σ LT' sinφ pq )+ (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ σ LT' sinφ pq ) 2(σ A h (Q 2,p m,φ pq ) LT' sinφ pq ) 2(σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ ) A h (Q 2,p m,φ pq ) σ LT' sinφ pq σ L +σ T = A' LT sinφ pq

29 Extracting the Asymmetry 29 (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ +σ LT' sinφ pq ) (σ A h (Q 2,p m,φ pq ) = L +σ T +σ LT cosφ pq +σ TT cos2φ PQ σ LT' sinφ pq ) (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ +σ LT' sinφ pq )+ (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ σ LT' sinφ pq ) 2(σ A h (Q 2,p m,φ pq ) LT' sinφ pq ) 2(σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ ) A h (Q 2,p m,φ pq ) σ LT' sinφ pq σ L +σ T = A' LT sinφ pq

30 Extracting the Asymmetry 30 (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ +σ LT' sinφ pq ) (σ A h (Q 2,p m,φ pq ) = L +σ T +σ LT cosφ pq +σ TT cos2φ PQ σ LT' sinφ pq ) (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ +σ LT' sinφ pq )+ (σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ σ LT' sinφ pq ) 2(σ A h (Q 2,p m,φ pq ) LT' sinφ pq ) 2(σ L +σ T +σ LT cosφ pq +σ TT cos2φ PQ ) A h (Q 2,p m,φ pq ) σ LT' sinφ pq σ L +σ T = A' LT sinφ pq

31 Extracting the Asymmetry 31 Computational Approach C++ code CERN ROOT package A h, Normal Polarity, p m =0.30 GeV/c A h, Reversed Polarity, p m =0.30 GeV/c

32 Results (Summer 2012) 32 The asymmetry A LT Red: sinφ pq -weighted average Blue: fits to A h from above

33 33 Simulation of CLAS (Summer 2013)

34 Simulation of CLAS 34 Simulating a reaction in CLAS QUEEG txt2part QSIM gppjlab RECSIS n10tmaker h2root eod5root

35 Simulation of CLAS 35 QUEEG Generates quasi-elastic electron events

36 Simulation of CLAS 36 txt2part Converts the output files into BOS data files BOS: CLAS data format

37 Simulation of CLAS 37 GSIM Simulates CLAS Based on GEANT3

38 Simulation of CLAS 38 Fitting the Asymmetry (C.A. Copos) Incorporated into Monte Carlo simulation to model the Fifth Structure Function δ A' LT (p m ) = 1 p 2 4 m +δ 2 p m 1+δ 3 p m +δ 4 p 2 m +δ 5 p 4 6 m +δ 6 p m

39 Simulation of CLAS 39 gppjlab Makes the GSIM output look real n Knocks out dead scintillators and wires

40 Simulation of CLAS 40 RECSIS Standard program for reconstruction of CLAS data

41 Simulation of CLAS 41 n10tmaker Converts the output into hbook ntuples

42 Simulation of CLAS 42 h2root Convers the ntuples into ROOT ntuples

43 Simulation of CLAS 43 eod5root The analysis code in ROOT to extact A LT Code used in Summer 2012

44 Results (Summer 2013) 44 Testing the analysis Red: simulated data Blue: bin-averaged fit Black: Fit to data

45 Conclusion 45 Extracted the asymmetry A LT from fits to the helicity asymmetry Normal and reversed polarities Comparison to sinφ pq -weighted method Validated our analysis Generated Monte Carlo events modeled after data Events passed through simulation and then our analysis code

46 Acknowledgements 46 Dr. Gerard Gilfoyle Keegan Sherman University of Richmond Physics Department Calina Copos (UR 10) Kristen Greenholt (UR 07)

47 References 47 Copos, C.A. Testing Analysis Algorithms for the 2H(e,e p)n Reaction. Richmond, VA, Print. "Experimental Hall B." Jefferson Lab. N.p., n.d. Web. 24 Feb Gilfoyle, G.P., et. Al. Measurements of the Fifth Structure Function of the Deuteron. Richmond, VA, Print. Greenholt, Kristen. Extracting the Fifth Structure Function and Hadronic Fiducial Cuts for the CLAS E5 Data Run at Jefferson Laboratory. Richmond, VA, Print. Smith, Timothy Paul. Hidden Worlds: Hunting for Quarks in Ordinary Matter. Princeton, NJ: Princeton UP, Print. The Frontiers of Nuclear Science: A Long Range Plan; US Department of Energy/National Science Foundation, Washington, DC, 2007.