1. Kinematics Related Systematic Uncertainties via MCEEP P.E. Ulmer Old Dominion University 12/11/02 Hall A Analysis Workshop

2. Breaking News: Cross sections depend on kinematics! Uncertainties run wild! Coincidence cross section can vary strongly with kinematics. Results in systematic uncertainties: –need to evaluate changes in cross section for variations of kinematical quantities. Account for kinematical constraints: –For example, fixed missing mass. –May include constraints from various calibration measurements, such as H(e,ep) Must acceptance average derivatives. Its a snap with new MCEEP tools: –Cross sections handled at present. –Other observables could be added easily. –Satisfaction guaranteed or your money back.

3. Procedure MCEEP Hbook file Process MCEEP Ntuple: Get cross sections for variations of kinematical quantities Determine cross section derivatives and total uncertainty, including any kinematical correlations

4. Process Ntuple Fortran Program: systerr Start with MCEEP Ntuple, containing Transport coordinates at target Vary nine quantities, in turn: (beam, scatt. electron, ejectile) x (delta, phi, theta) Produce new Ntuple, consisting of original variables plus 10 cross sections (nominal and nine shifted). Program links to MCEEP subroutines and has access to its physics models.

5. Acceptance Average PAW: systerr.kumac Error sum: positive definite quantity –Must first acceptance average. Sum the weights: –Produce vectors of summed cross sections (10 in total). –Bin vectors in terms of any kinematical quantity within Ntuple. Diagnostic histograms: –Fractional derivatives of cross section with respect to each of the nine varied kinematical quantities.

6. Combine Errors Fortran Program: toterr Produce cross section uncertainty, given kinematical uncertainties and correlations. For each bin, form:

7. www.physics.odu.edu/~ulmer/mceep /mceep.html –Includes: Sources Installation Instructions User manual –In particular, see: ~/mceep/systerr/README JLAB-TN-02-015 Systematic Uncertainties in E89-003 (K. Fissum & P.E. Ulmer) See: http://hallaweb.jlab.org/publications/Technotes/ files/2002/02-015.ps More Information

8. Figures Both figures are based on Experiment E94-004 D(e,ep)n cross section vs. Pm –Cross section derivatives for each of the nine quantities: Kinematics centered on Pm=100 MeV/c Units: fractional derivatives per 1 mr or per 10^-3 in momentum. –Total error vs. Pm All kinematics for E94-004 included, from Pm=0 to Pm=500 MeV/c (central values) Uncorrelated analysis Correlated analysis: assumes constraints from 1H(e,ep)