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HAMC = H all A M onte C arlo

HAMC = H all A M onte C arlo. C. Contributors: Dustin McNulty, Diancheng Wang. ROOT / C++ Design Somewhat like “SAMC” & “genercone” For HRS only. Uses LeRose transfer functions. Abstract classes: Experiment, Physics, Target

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HAMC = H all A M onte C arlo

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  1. HAMC = Hall AMonte Carlo C Contributors: Dustin McNulty, Diancheng Wang • ROOT / C++ Design • Somewhat like “SAMC” & “genercone” • For HRS only. Uses LeRose transfer functions. • Abstract classes: Experiment, Physics, Target • Used by HAPPEX-3, PVDIS, and PREX. A. Deur, V. Sulkosy D. Lhuillier, K. Paschke, B. Moffit or matrices, or “Guido” fcn.

  2. Applications of HAMC C • Estimate Rates, Asymmetry, Sensitivity to Physics • Design Collimator, Sieve, “A_T” detector. • Design integrating detector & focus at detector • Estimate sensitivities to beam parameters. • Effects of radiative corrections, acceptance.

  3. HAMC Events Objects • Generate beam • Target position uniformly sampled (raster option) • Fill solid angle uniformly • Cross-section computed for rates and weighting • Asymmetry computed (for Parity Expts) • Energy losses (Brehms and dE/dX) with MC methods • Multiple Scattering • Transport to various points in HRS and Septum • Acceptance cuts applied at apertures • Event Analysis on accepted events.

  4. Transport PolynomialsfromJohn LeRose (same)

  5. Transport Polynomials (part 2) thanks, John LeRose Was used to check where electrons scrape; e.g. not in iron of dipole ?

  6. Cross Section Input Shown here for Lead

  7. Does HAMC work ? Yes, well enough for our goals. A problem:Radiative tail out to high loss is underestimated. Use “effective target” size to adjust (reduce) predicted rates.

  8. Comparing HAMC to Real Data This was done for HAPPEX-1, HAPPEX-2, and a Lead test run

  9. More Comparisons …

  10. A Lead Test run in 2005 (using old septum magnet)

  11. PREX Design : At 50the Optimal FOM is at 1.05 GeV (+/- 0.05) RN 1% @ ~1 GeV

  12. Collimator at entrance to spectrometer  Suppressing A_T systematics Paul Souder Aligned in spectrometers to define identical Left / Right scattering angles as well as good up / down symmetry A_T hole Be degrader Insertable blocker to block Be

  13. HAMC Design of Collimator All Events Collimator

  14. Events from A_T hole (Be plug) Main detector A_T detector Measures horizontal A_T systematic. (Vertical is measured from Left/Right spectrometers) Thanks: Dustin McNulty Krishna Kumar Paul Souder

  15. Sieve Slit Design Few more holes drilled to improve coverage and accuracy.

  16. Analysis for Workshops and Future Publication Acceptance Function Credit: C. J. Horowitz

  17. Conclusions re: HAMC C The GOOD • Reproduces data -- well enough. • Has aided in several estimates and design efforts. • Underestimates radiative losses -- maybe another MC better ? • Restricted to HRS and single-arm at the moment. • Might be easy to make a coincidence base class. The BAD

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