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7.14} Scoring options

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 Any result in a Monte Carlo calculation is obtained by adding up the
 contributions to the "score", or "tally" of a detector defined by the user.
 A detector is the Monte Carlo equivalent of a measurement instrument. Each
 "estimator" (detector type) is designed to estimate one or more radiometric
 quantities, and the final score is a statistical estimation of the average
 value of the corresponding population. As in experimental measurements, it is
 possible to calculate a standard deviation by running several independent
 calculations.

 No default detector is available: each scoring option must be explicitly
 requested. There are different input options corresponding to different types
 of detector. The simplest is SCORE which provides energy deposition
 (proportional to dose) or star density in every region of the geometry. "Stars"
 is an old name for inelastic hadron reactions which derives from early
 experiments with nuclear emulsions.

 The same quantities can be scored in a uniform spatial mesh independent of
 geometry, called a "binning", by means of option USRBIN. There are several
 types of binnings: Cartesian, 2D-cylindrical, 3D-cylindrical and even more
 complex phase space structures. In addition to dose and star density, it is
 possible to use USRBIN to score particle fluence distributions in space. USRBIN
 results are often displayed as colour plots where each colour corresponds to a
 pre-defined range of values. A post-processing program for this purposes
 (PAWLEVBIN) is available in the directory $FLUPRO/flutil, and a GUI interface
 can be downloaded from the FLUKA website www.fluka.org.

 Fluence, averaged over the volume of a given geometry region, can be calculated
 with options USRTRACK and - less often - USRCOLL. The first is a "track-length
 estimator" (it estimates fluence as volume density of particle trajectory
 lengths), and the second is a "collision estimator" (fluence is estimated as
 volume density of collisions weighted with the particle mean free path). Of
 course, USRCOLL can be used only in a region of matter, while USRTRACK works
 also in vacuum. Both options provide fluence differential energy spectra.

 Another common scoring option is USRBDX, which also calculates fluence, but
 averaged over the boundary between two geometry regions. It is a "boundary
 crossing estimator", which estimates fluence as the surface density of crossing
 particles weighted with the secant of the angle between trajectory and normal
 to the boundary at the crossing point. Option USRBDX can also calculate
 current, i.e. a simple counter of crossings, not weighted by inverse cosine:
 but despite a widespread credence, current is only seldom a quantity worth
 calculating. The results of USRBDX can account on request for particles
 crossing the boundary from either side or from one side only, and are in the
 form of double-differential energy and angular spectra. The angle considered
 is again that with the normal at the crossing point.

 USRYIELD is a multi-purpose estimator option, which can estimate several
 different double-differential quantities. The main one is an energy-angle
 double-differential yield of particles escaping from a target, the angle in
 this case being with respect to a fixed direction. Energy and angle can be
 replaced by many other variables which are mostly of the same kind, such as
 momentum and rapidity. But it is possible also to score yields as a function of
 charge and LET (linear energy transfer).

 Production of residual nuclei can be obtained with command RESNUCLEi.
 The results, which are closely related to induced activity and dose rate from
 activated components, may include nuclei produced in low-energy neutron
 interactions, provided the corresponding information is available in
 the neutron cross section library for the materials of interest.


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