WW-THRESh

defines the energy limits for a Russian Roulette/splitting weight window and applies particle-dependent modification factors to the windows defined by WW-FACTOr

See also BIASING, WW-FACTOr, WW-PROFIle

     WHAT(1) >  0.0: upper kinetic energy threshold in GeV for RR/Splitting
                     with a weight window. For low-energy neutrons,
                     corresponding (smallest) group number (included).
             =  0.0: ignored
             <  0.0: any previously selected threshold is cancelled

     WHAT(2) >= 0.0 and < WHAT(1): lower kinetic energy threshold in GeV
                     for RR/Splitting with a weight window. For low-energy
                     neutrons, corresponding (largest) group number
                     (included)
             <  0.0 or > WHAT(1): WHAT(2) is set = WHAT(1)

     WHAT(3) > 0.0: amplification factor used to define the weight window
                    width at the higher energy threshold represented by WHAT(1).
                    The weight window at the higher energy threshold is
                    obtained by multiplying by WHAT(3) the top edge of the
                    window (splitting level) at the lower threshold, and
                    dividing by the same factor the bottom edge
                    (RR-level).
             < 0.0: |WHAT(3)| is used as multiplication factor for the
                    bottom and top levels of every region for the particles
                    selected by WHAT(4-6). That is, for such particle(s) both
                    bottom and  top levels are multiplied by |WHAT(3)|
             Default = 10.0 (amplification factor for the splitting and RR-level
                    at the higher threshold). The particle dependent
                    multiplication factor by default is set = 1.0.

     WHAT(4) = lower bound of the particle numbers (or corresponding particle
               name) to which the indicated weight window energy limits apply
               Note that particle number 40 indicates low-energy neutrons
               (for this purpose only!). Particle number 8 indicates neutrons
               with energy > 20 MeV.
               ("From particle WHAT(4)...").
             Default = 1.0.

     WHAT(5) = upper bound of the particle numbers (or corresponding particle
               name) to which the indicated weight window energy limits apply
               ("...to particle WHAT(5)...").
             Default = WHAT(4) if WHAT(4) > 0, all particles otherwise.

     WHAT(6) = step length in assigning numbers. ("...in steps of
               WHAT(6)").
             Default = 1.0.

     SDUM    = PRIMARY: the weight window applies also to primary
               particles (default)
             = NOPRIMARy: the weight window doesn't apply to primaries

     Default (option WW-THRESh or WW-FACTOr not given): no weight window is
             defined

Notes:

1) This option is only meaningful when WW-FACTOr is also requested. See the Note
1) to that option for more information.

2) For low-energy neutrons, the two energy thresholds are expressed as group numbers, while for all other particles (including high energy neutrons) they are expressed in GeV. Therefore, thresholds for low-energy neutrons must be assigned in a separate WW-THRESh card from other particles.

Example (number based):

 *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
 WW-THRESh        2.0      0.05       2.4       3.0       7.0       0.0
 *  The weight window weight limits for particles 3 to 7 (practically electrons,
 *  positrons and photons, since neutrinos are discarded), which have been set
 *  by WW-FACTOr are applied as such below 50 MeV. Above that energy, the width
 *  of the window is progressively increased up to 2 GeV: at 2 GeV, the upper
 *  weight limit is a factor 2.4 larger and the lower limit a factor 2.4
 *  smaller.

The same example, name based:

 WW-THRESh        2.0      0.05       2.4  ELECTRON    PHOTON       0.0

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