GEANT4 Simulation of the abba/nab Spectrometer: Progress Report

Transcription

1 GEANT4 Simulation of the abba/nab Spectrometer: Progress Report Emil Frlež for the abba/nab Collaboration University of Virginia, Charlottesville abba/nab/panda Common Magnet Meeting North Carolina State University, Raleigh, NC January 8, 2006 p. 1/12

2 Choice of Simulation Software p. 2/12

3 Choice of Simulation Software Mathematica, Penelope, Simion, GEANT3, GEANT4...? p. 2/12

4 Choice of Simulation Software Mathematica, Penelope, Simion, GEANT3, GEANT4...? State-of-the-art object-oriented toolkit written in C++ for the simulation of the passage of particles through matter p. 2/12

5 Choice of Simulation Software Mathematica, Penelope, Simion, GEANT3, GEANT4...? State-of-the-art object-oriented toolkit written in C++ for the simulation of the passage of particles through matter A world-wide collaboration of institutes, experiments, and national organizations contributing resources to the GEANT4 production service and providing mutual support p. 2/12

6 Choice of Simulation Software Mathematica, Penelope, Simion, GEANT3, GEANT4...? State-of-the-art object-oriented toolkit written in C++ for the simulation of the passage of particles through matter A world-wide collaboration of institutes, experiments, and national organizations contributing resources to the GEANT4 production service and providing mutual support Extensive documentation, user manuals, user forum, problem reporting and user support, workshops, video presentations p. 2/12

7 Choice of Simulation Software Mathematica, Penelope, Simion, GEANT3, GEANT4...? State-of-the-art object-oriented toolkit written in C++ for the simulation of the passage of particles through matter A world-wide collaboration of institutes, experiments, and national organizations contributing resources to the GEANT4 production service and providing mutual support Extensive documentation, user manuals, user forum, problem reporting and user support, workshops, video presentations G4: work in progress, while GEANT3/PAW support is discontinued p. 2/12

8 Choice of Simulation Software Mathematica, Penelope, Simion, GEANT3, GEANT4...? State-of-the-art object-oriented toolkit written in C++ for the simulation of the passage of particles through matter A world-wide collaboration of institutes, experiments, and national organizations contributing resources to the GEANT4 production service and providing mutual support Extensive documentation, user manuals, user forum, problem reporting and user support, workshops, video presentations G4: work in progress, while GEANT3/PAW support is discontinued We used GEANT4 version 6.2.p01 (free ;8-) p. 2/12

9 General Code Layout p. 3/12

10 General Code Layout GEANT4 version 6.2.p01 p. 3/12

11 General Code Layout GEANT4 version 6.2.p01 User code written in C++ p. 3/12

12 General Code Layout GEANT4 version 6.2.p01 User code written in C++ Installation from UVa http server: size 1.8M p. 3/12

13 General Code Layout GEANT4 version 6.2.p01 User code written in C++ Installation from UVa http server: size 1.8M Modular user code, contains 125 files p. 3/12

14 General Code Layout GEANT4 version 6.2.p01 User code written in C++ Installation from UVa http server: size 1.8M Modular user code, contains 125 files New modules can be easily added by users without intimate knowledge of over-all code structure p. 3/12

15 Spectrometer Geometry I p. 4/12

16 Spectrometer Geometry I Coordinate system: z = neutron beam axis, x = detector axis p. 4/12

17 Spectrometer Geometry I Coordinate system: z = neutron beam axis, x = detector axis Sensitive detectors: two mm 3 Silicon detectors p. 4/12

18 Spectrometer Geometry I Coordinate system: z = neutron beam axis, x = detector axis Sensitive detectors: two mm 3 Silicon detectors Passive material: two pairs of split Helmholtz coils, transport solenoid magnet, polarized neutron beam coils, and 4 accelerating electrodes p. 4/12

19 Spectrometer Geometry I Coordinate system: z = neutron beam axis, x = detector axis Sensitive detectors: two mm 3 Silicon detectors Passive material: two pairs of split Helmholtz coils, transport solenoid magnet, polarized neutron beam coils, and 4 accelerating electrodes Magnetic and electric fields defined on 1 mm 3 three-dimensional grid p. 4/12

20 Spectrometer Geometry I Coordinate system: z = neutron beam axis, x = detector axis Sensitive detectors: two mm 3 Silicon detectors Passive material: two pairs of split Helmholtz coils, transport solenoid magnet, polarized neutron beam coils, and 4 accelerating electrodes Magnetic and electric fields defined on 1 mm 3 three-dimensional grid Individual detector components can be positioned or switched off p. 4/12

21 Spectrometer Geometry II p. 5/12

22 Spectrometer Geometry II Geometry of magnetic spectrometer with two split pairs, transport solenoid and polarized neutron beam coils p. 5/12

23 Electric and Magnetic Fields p. 6/12

24 Electric and Magnetic Fields Axial and radial components of Nab s magnetic and electric fields used in GEANT4 charged particle transport and spin tracking p. 6/12

25 Input: Cold Neutrons Energy Spectrum p. 7/12

26 Input: Cold Neutrons Energy Spectrum Event generator with realistic neutron energy spectrum at the input of the FNPB neutron guide p. 7/12

27 Input: Cold Neutrons Energy Spectrum Event generator with realistic neutron energy spectrum at the input of the FNPB neutron guide Neutron spectrum at the input to the FNPB neutron guide. Long wavelength structure is artificial bin aliasing combined with low statistics. p. 7/12

28 e and p Tracking and n Spin Transport p. 8/12

29 e and p Tracking and n Spin Transport Integrate 12 variables: x, y, z, p x, p y, p z, E, t, s, s x, s y, s z p. 8/12

30 e and p Tracking and n Spin Transport Integrate 12 variables: x, y, z, p x, p y, p z, E, t, s, s x, s y, s z Use Cash-Karp Runge-Kutta-Fehlberg 4/5 method [ref. Numerical Recipes in C, 2nd Ed.] p. 8/12

31 e and p Tracking and n Spin Transport Integrate 12 variables: x, y, z, p x, p y, p z, E, t, s, s x, s y, s z Use Cash-Karp Runge-Kutta-Fehlberg 4/5 method [ref. Numerical Recipes in C, 2nd Ed.] Equations of motion in a combined electric and magnetic field p. 8/12

32 e and p Tracking and n Spin Transport Integrate 12 variables: x, y, z, p x, p y, p z, E, t, s, s x, s y, s z Use Cash-Karp Runge-Kutta-Fehlberg 4/5 method [ref. Numerical Recipes in C, 2nd Ed.] Equations of motion in a combined electric and magnetic field Spin components are treated utilizing Thomas-BMT equation p. 8/12

33 e and p Tracking and n Spin Transport Integrate 12 variables: x, y, z, p x, p y, p z, E, t, s, s x, s y, s z Use Cash-Karp Runge-Kutta-Fehlberg 4/5 method [ref. Numerical Recipes in C, 2nd Ed.] Equations of motion in a combined electric and magnetic field Spin components are treated utilizing Thomas-BMT equation 0.1 mm step size, processing time 0.2 sec/per event p. 8/12

34 Input to the Code p. 9/12

35 Input to the Code Detector version p. 9/12

36 Input to the Code Detector version Magnetic and electric field maps p. 9/12

37 Input to the Code Detector version Magnetic and electric field maps Neutron beam time structure, neutron beam (y, z) profiles, neutron energy spectrum and neutron polarization p. 9/12

38 Input to the Code Detector version Magnetic and electric field maps Neutron beam time structure, neutron beam (y, z) profiles, neutron energy spectrum and neutron polarization Choice of integration method, maximum tracking step size, minimum integration step, maximum time-of-flight p. 9/12

39 Input to the Code Detector version Magnetic and electric field maps Neutron beam time structure, neutron beam (y, z) profiles, neutron energy spectrum and neutron polarization Choice of integration method, maximum tracking step size, minimum integration step, maximum time-of-flight Detector energy thresholds, energy/time resolutions, pedestals, random coincidences, and noise p. 9/12

40 Output of the Code p. 10/12

41 Output of the Code Pre-defined HBook4 or ROOT histograms p. 10/12

42 Output of the Code Pre-defined HBook4 or ROOT histograms PAW Ntuples or ROOT trees digitizing individual events p. 10/12

43 Output of the Code Pre-defined HBook4 or ROOT histograms PAW Ntuples or ROOT trees digitizing individual events Simulated energy depositions and (energy,time) pairs in sensitive detectors on event-per-event basis in ASCII format p. 10/12

44 Output of the Code Pre-defined HBook4 or ROOT histograms PAW Ntuples or ROOT trees digitizing individual events Simulated energy depositions and (energy,time) pairs in sensitive detectors on event-per-event basis in ASCII format Single event display using OpenGL or Wired p. 10/12

45 Monte Carlo Statistics Sample p. 11/12

46 Monte Carlo Statistics Sample Required experimental statistics decays p. 11/12

47 Monte Carlo Statistics Sample Required experimental statistics decays Number of Monte Carlo events should be an order of magnitude higher p. 11/12

48 Monte Carlo Statistics Sample Required experimental statistics decays Number of Monte Carlo events should be an order of magnitude higher So far we analyzed simulation runs with 10 7 events executed on a single Linux node p. 11/12

49 Monte Carlo Statistics Sample Required experimental statistics decays Number of Monte Carlo events should be an order of magnitude higher So far we analyzed simulation runs with 10 7 events executed on a single Linux node Physics parameters will be extracted from comparison of data with simulation p. 11/12

50 Monte Carlo Statistics Sample Required experimental statistics decays Number of Monte Carlo events should be an order of magnitude higher So far we analyzed simulation runs with 10 7 events executed on a single Linux node Physics parameters will be extracted from comparison of data with simulation Practical options are (1) to use parallelized G4 code on Linux clusters or (2) to run a code on a supercomputer p. 11/12

51 To-Do-List (Preliminary) p. 12/12

52 To-Do-List (Preliminary) Refine EM field maps p. 12/12

53 To-Do-List (Preliminary) Refine EM field maps Refine the (active/passive) geometry of the detector p. 12/12

54 To-Do-List (Preliminary) Refine EM field maps Refine the (active/passive) geometry of the detector Code in the adiabatic tracking of charged particles p. 12/12

55 To-Do-List (Preliminary) Refine EM field maps Refine the (active/passive) geometry of the detector Code in the adiabatic tracking of charged particles Test the parallelized code p. 12/12