1. PREX Mtg, July 2008R. Michaels, JLab Hall A Monte Carlo -- HAMC Similar to A. Deur’s ``Single Arm Monte Carlo’’ “Fast” Monte Carlo -- not Geant ROOT / C++ Framework For HAPPEX, PVDIS, PREX (& others ?) Work in Progress -- Timeline: Version for co-developers (Kent) -- Sept 2008 Full Report -- Winter Software Meeting

2. PREX Mtg, July 2008R. Michaels, JLab HAMC -- Ingredients Generate random Z location in target Cross-section: (optional) weights for histograms Physics asymmetry Internal & External Bremmstrahlung in target Spectrometer with Acceptance & Transport Models Multiple scattering at material locations Septum option Global variables, histograms, ntuples Outputs to pan & Podd (the physics analyzers) Design: http://hallaweb.jlab.org/parity/prex/hamc

3. PREX Mtg, July 2008R. Michaels, JLab Goals of HAMC EM corrections Syst errors: analyzing power, backgrounds, etc Sensitivity to position, angle, energy Determine optimal detector geometry Strategies for transverse asymmetries Model dependence of R N Target optimization …. etc ….

4. PREX Mtg, July 2008R. Michaels, JLab C++ 101 : Design reflects the Description of Problem “ PREX is a type of experiment which contains a spectrometer, target, etc. In each event the beam (a type of track), scatters from target and produces more tracks, which transport in accord with the spectrometer’s transport model … etc … ” Stuff underlined = the classes “is a type of”  inheritance “contains” or possessive modifier  containment + usage relationships

5. PREX Mtg, July 2008R. Michaels, JLab How to be faster than Geant … Fast transport Fast sampling... etc... 12 3 4 5 6 7

6. PREX Mtg, July 2008R. Michaels, JLab Transport Model  Transport Matrix  Lerose Functions  Guido’s Functions ? Physics  HAPPEX – III  PREX (Diana’s work)  PVDIS The spectrometer’s Spectrometer’s have ``break points’’: Locations where apertures defined (acceptance) where to transport tracks where to do multiple scattering (possibly) Some Design Issues The experiment’s

7. PREX Mtg, July 2008R. Michaels, JLab Global Variables Each class can register variables & put in histograms. Weighted by cross section or not. Histograms tied to ``break points’’ in spectrometer Variables may be iterated between two runs of an experiment (study dependence on variables). ASCII control file Inform which variables to iterate and by how much Define Ntuples, and other misc control of code

8. PREX Mtg, July 2008R. Michaels, JLab Work by Diana Jaunzeikare (Smith College) Horowitz vs FF Parameterization Cross Section vs angle E = 0.85 GeV E = 1.0 GeV E = 1.2 GeV

9. PREX Mtg, July 2008R. Michaels, JLab Asymmetry vs theta. Compare Horowitz to 1 st Order Calc. Work by Diana Jaunzeikare (Smith College) E = 0.85 GeVE = 1.0 GeV E = 1.2 GeV