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H all A M onte C arlo -- 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:
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Hall AMonte 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
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
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 RN • Target optimization …. etc ….
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
How to be faster than Geant … • Fast transport • Fast sampling 7 6 3 5 2 1 4 . . . etc . . .
Some Design Issues The spectrometer’s Transport Model Transport Matrix Lerose Functions Guido’s Functions ? The experiment’s Physics HAPPEX – III PREX (Diana’s work) PVDIS Spectrometer’s have ``break points’’: Locations where apertures defined (acceptance) where to transport tracks where to do multiple scattering (possibly)
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
Cross Section vs angle Work by Diana Jaunzeikare (Smith College) E = 0.85 GeV Horowitz vs FF Parameterization E = 1.0 GeV E = 1.2 GeV
Work by Diana Jaunzeikare (Smith College) Asymmetry vs theta.CompareHorowitz to 1st Order Calc. E = 1.2 GeV E = 0.85 GeV E = 1.0 GeV