THIS IS AN OLD VERSION FROM RICK, DESCRIBING THE SIMC FLAGS. I WILL UPDATE IT WHEN I GET A CHANCE. -JOHN --------- *** SIMC Database Information *** R. M. Mohring *** 21-Oct-1995 *** Documentation Version 0.7 *** This document will describe the fields in the database file *** necessary to run the SIMC code for scattering off hydrogen. STRUCTURE OF THE DBFX FILE: Each cluster of entries in the dbfx file is sectioned off by a header line that looks like "-32767 2 17". These numbers should NOT be changed at all. Suffice it to say that the first number identifies the cluster, and the second lists how many entries are in the cluster. Each line in the dbfx file has a comment associated with it. Hopefully, the comments are reasonably self-explanatory. If not, change them to whatever you like. The comments are merely there to lessen the risk that the person attempting to run the code will incur permanent brain damage upon themselves from looking at a long list of mysterious numbers for too long. EXPLANATION OF RELEVANT FIELDS: *** -32767 RESTSW ****************** mc_smear: Determines whether or not the spectrometer montecarlos use multiple scattering in the detector huts. Set to 1 for TRUE, set to 0 for FALSE. hms_e_flag: Determines if the electron arm is the HMS or the SOS. Note that THE ENTRIES IN THE DATABASE ARE IN TERMS OF ELECTRON and PROTON arms, NOT in terms of HMS/SOS. Set to 1 implies: HMS gets electrons, SOS gets protons. Set to 0 implies: HMS gets protons, SOS gets electrons. *** -32766 EXPERIMENT ****************** Ebeam: Beam energy in MeV. Set to 2015 implies a 2.015 GeV beam. dEbeam: Variation in beam energy in percent. Set to 0.200 implies a 0.2% energy spread (as +/- 0.1%). EXPER.charge: Total amount of charge incident on the target over the course of the run, in milliCoulombs. This translates directly into the number of incident during the course of the run. Set to 62.7 implies 62.7 mC of charge, or 3.9e17 electrons. *** -32765 TARGET ****************** target.A, target.Z, target.mass_amu: Target A, Z, and mass (in amu). target.Arec: This is the A of the recoil nucleus. Set this at something bigger than 999 for hydrogen, since there is no recoil nucleus. target.rho: Target density in g/cm^3. target.thick: Target thickness in mg/cm^2. target.angle: For dealing with slanted solid targets. target.abundancy: Purity of target in percent. *** -32764 HIST ****************** Pm.min, Pm.max: Histogramming limits on missing momentum. Pm.bin, Em.bin: Not used anymore, so just leave them alone. Em.min, Em.max: histogramming limits on missing energy. *** -32763 16.MAIN (electron arm!) ****************** spec.e.P: Central momentum setting of electron arm in MeV. spec.e.th: Angle setting of electron spectrometer in degrees. Note that a positive angle implies beam LEFT looking downstream. (SOS gets positive angle, HMS gets negative angle.) *** -32762 8.MAIN (proton arm!) ****************** spec.p.P: Central momentum setting of proton arm in MeV. spec.p.th: Angle setting of proton spectrometer in degrees. Note that a positive angle implies beam LEFT looking downstream. (SOS gets positive angle, HMS gets negative angle.) *** -32761 16.SPEC (electron arm) ****************** gen.xwid: This sets the transverse spread of the beam in the x direction. This is the full width (in centimeters) of a gaussian centered around x=0 which is used to determine the x position of the scattering event at the target. gen.ywid: This sets the transverse spread of the beam in the y direction. This is the full width (in centimeters) of a gaussian centered around y=0 which is used to determine the y position of the scattering event at the target. spec.e.offset.delta, .x, .y, .z, .opl, .inpl: Various offsets for a more precise definition of the electron spectrometer location relative to the target. Offsets are in cm. *** -32760 8.SPEC (proton arm) ****************** spec.p.offset.delta, .x, .y, .z, .opl, .inpl: Various offsets for a more precise definition of the proton spectrometer location relative to the target. Offsets are in cm. *** -32759 MISC2INT ****************** use_expon: Leave at zero. one_tail: This switch determines where the radiative corrections are applied. Define the incident electron as 1, the scattered electron as 2, and the scattered proton as 3. Setting one_tail to 1.0 performs radiative corrections ONLY on the incident electron. Set to -1.0, it performs radiative corrections on everything EXCEPT the incident electron (i.e. on both the scattered electron and proton.) Set to 0.0, it does it on all three (e, e', and p). NOTE: THIS SWITCH DOES NOT TURN ON THE RADIATIVE CORRECTIONS. IT JUST SPECIFIES WHICH PARTICLES WILL RECEIVE THEM. THE "ON/OFF" SWITCH IS IN THE NEXT GROUP ("SIMULATE.") inttail_mode, intcor_mode: Leave these alone. *** -32758 SIMULATE ****************** ngen: The number of iterations that determines how long SIMC churns for. If abs(ngen) is greater than zero, the program will generate events until it achieves ngen SUCCESSES. The number of attempts will be greater than the number of successes. If abs(ngen) is less than zero, the program will make ngen ATTEMPTS and then stop. The number of contributing events will show up in the histograms. iran: Allows the user to set their own random seed. Leave at zero, and the default is taken. using_rad: **THIS** is the radiative corrections ON/OFF switch. Set at ZERO to turn radiative corrections ON. Set at 1 to turn them OFF. NOTE: remember...ZERO means ON !!! It should be obvious from the histograms, anyway. dofs, thofs, and phofs: These aren't used anymore, but I haven't yet expunged them. gen.*.*.*: Generation limits for event generator. Leave at zero. (These can be tweaked to improve efficiency. See a later version of this manual for details as soon as it comes out.) spectrometer mode: If you want to run coincidences or single-arms, this switch disables/enables the appropriate spectrometer montecarlos. (i.e. if you want to look at electron singles, the code won't bother to run protons through the proton spectrometer.) Set at 0, both e and p arms enabled. Set at -1, only e arm. (singles) Set at -2, only p arm. (singles) IMPORTANT NOTE: To actually run in single arm mode, you must also "open up" the acceptance of the spectrometer you are not using so that events won't get lost at that spectrometer's input. For example, to run electron singles, you should increase the values in "8.SORT (proton arm)" to something like +-50% delta, +-400 mrad in dtheta and phi. using_Eloss: Toggles whether or not ionization losses in the target are calculated. Set at ZERO of energy loss to be calculated. Set at 1 for energy loss to be ignored. *** -32757 16.SORT (electron arm) ****************** These are hard cuts defining the spectrometer acceptances! SPcuts(1).e.delta.min, .max: Min and Max momentum for electron arm, in percent. SPcuts(1).e.dth.min, .max: Min and Max deviation in theta for electron arm, in mrad. SPcuts(1).e.ph.min, .max: Min and Max deviation in phi for electron arm, in mrad. *** -32756 8.SORT (proton arm) ****************** T hese are hard cuts defining the spectrometer acceptances! SPcuts(1).p.delta.min, .max: Min and Max momentum for proton arm, in percent. SPcuts(1).p.dth.min, .max: Min and Max deviation in theta for proton arm, in mrad. SPcuts(1).p.ph.min, .max: Min and Max deviation in phi for proton arm, in mrad.