THRESHOLd

Summary

Defines the energy threshold for star density scoring.
Sets thresholds for elastic and inelastic hadron reactions. ​​ ​

​

See also PART–THR
WHAT(1)

and WHAT(2): not used

WHAT(3) =

threshold kinetic energy for hadron elastic scattering

Default

:  same as for particle transport (set by option PART–THR or by default (i.e. the minimum one for which the present FLUKA physics can work, typically 0.02 GeV depending on the hadron)

WHAT(4) =

threshold kinetic energy for hadron inelastic reactions

Default

:  same as for particle transport, as defined by option PART–THR or by default. The default thresholds are: 0.001 GeV for all neutral hadrons except neutrons, 0.02 GeV for high energy neutrons, the Coulomb barrier for charged hadrons, 0.0 for particles which annihilate at rest — but the latter will not undergo any inelastic interaction between the interaction threshold, typically around 0.001 GeV, and 0.0.

WHAT(5) :

not used

WHAT(6) =

threshold kinetic energy for star scoring

Default

:  the same values as set for inelastic reactions (see WHAT(4) above)

SDUM

: not used

Default

(option THRESHOLd not given): the threshold for star scoring is set at 20 MeV for protons and neutrons, and at 50 MeV for all other hadrons

Notes

  1. The possibility to change the threshold for elastic scattering or inelastic collisions (WHAT(3) and WHAT(4)) is not to be used in normal transport problems, but is made available to investigate the relative importance of different processes on the studied problem.

  2. For reasons explained in Note 3 to command SCORE (SCORE), it is recommended to set the threshold for star scoring (WHAT(6)) equal to 0.050 GeV overriding the default of 0.020 GeV. A 0.050 GeV cutoff was used in the past to establish so-called \(\omega\)-factors​ which are still currently used to estimate induced activity (see [Ran70b, Hof75a, Hof75b]). Stars defined in this way do not include those produced by annihilating particles​.

  3. The threshold for star scoring requested by option THRESHOLd applies only to the output related to options SCORE and USRBIN (USRBIN). The number of stars reported in the summary statistics​ at the end of the standard output​ is always based on the actual energy thresholds for nonelastic interactions (except for neutrons for which stars are reported above 20 MeV).

Example 1:

*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
THRESHOLd        0.0       0.0       2.0       0.0       0.0       0.0
*  Switch off elastic scattering of hadrons below 2 GeV

Example 2:

*...+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
THRESHOLd        0.0       0.0       0.0       0.0       0.0      0.05
*  Score stars only above 50 MeV