sets different energy transport cut-offs for hadrons, muons and
neutrinos
(see also EMFCUT, LOW-BIAS, THRESHOLd)
The meaning of WHAT(1) depends also on the value of WHAT(5).
For WHAT(5) = 0.0 :
WHAT(1) < 0.0 : kinetic energy cut-off (GeV)
> 0.0 : momentum cut-off (GeV/c)
For WHAT(5) >= 1.0 :
WHAT(1) < 0.0 : gamma cut-off (Lorentz factor, = E/mc**2)
> 0.0 : eta cut-off (= beta*gamma = v/c E/mc**2)
Default (WHAT(1) = 0.0): the cut-off is 0 for neutrinos,
and 0.0196 GeV for high-energy neutrons.
For any other hadrons, and for muons:
if option DEFAULTS is missing, or is present with
SDUM = NEW-DEFAults or SHIELDINg, the default cut-off
kinetic energy is 0.01 GeV.
If SDUM = HADROTHErapy, ICARUS or PRECISIOn, the default
cut-off kinetic energy is 0.0001 GeV.
If SDUM = CALORIMEtry, the default cut-off kinetic energy
is = 0.001 * m/m_p GeV (m = particle mass, m_p = proton mass)
In any other case, the default cut-off is 0.050 GeV.
(For low-energy neutrons, the threshold is set by option LOW-BIAS
and for e+e- and photons by EMFCUT, see Notes below).
WHAT(2) = lower bound of the particle id-numbers to which the cut-off
applies ("From particle WHAT(2)...").
Default = 1.0
WHAT(3) = upper bound of the particle id-numbers to which the cut-off
applies ("...to particle WHAT(3)...").
Default = WHAT(2)WHAT(4) = step length in assigning numbers
("...in steps of WHAT(4)")
Default = 1.0.
WHAT(5) : depending on its value, cut-off values indicated by
WHAT(1) are assigned to kinetic energy, momentum, gamma or
eta (see WHAT(1))
WHAT(6) = 1.0 restricts the given cut-off to charged particles only
Default: the cut-off applies to all particles indicated by
WHAT(2-4)SDUM : not used
Default (option PART-THR not given): thresholds as described above
for WHAT(1) = 0.0.
Note: When applied to neutrons, the cut-off energy defined by
PART-THRes refers to the energy boundary between high-energy and
low-energy neutrons, i.e. the upper limit of the first energy
group in the multigroup transport scheme (see 10}). The actual
cut-off for low-energy neutrons must be set by option LOW-BIAS.
If PART-THR is used to set an energy cut-off for high-energy
neutrons, and that cut-off is larger than the higher energy
boundary of the first group declared explicitly with LOW-NEUT
or implicitly via DEFAULTS, the cut-off is forced to coincide
with it. Be careful NOT to set the neutron cut-off LOWER than the
higher energy boundary of the first neutron group: the results
are unpredictable and there is no check in the program!
See 10} for details on neutron energy groups.
If low-energy neutron transport is not requested (explicitly via
LOW-NEUT or implicitly via DEFAULTS), the energy of neutrons
below threshold is deposited on the spot.
Option PART-THR acts on all particles excepted e+ e- and
photons, while EMFCUT option is used to set to transport electrons,
positrons and photons.
When the energy of a charged particle becomes lower than the
cut-off defined by PART-THR, and if such cut-off is lower
than 100 MeV, the particle is not stopped, but is ranged
out to rest in an approximate way. Its kinetic energy is
deposited uniformly over the residual range if the latter
is contained within a single region; otherwise a new residual
range is calculated at each boundary crossing and the residual
kinetic energy is distributed accordingly. If applicable, such
a particle eventually decays at rest or is captured. All other
forms of transport are ignored excepted curved paths in
magnetic fields (multiple scattering, delta ray production,
inelastic or elastic collisions, and INCLUDING DECAY IN
FLIGHT). Magnetic fields are taken into account but only
very roughly, since the continuous slowing down of the
particles is not simulated. Antiprotons and pi-minus are
always ranged out to rest (without allowance for decay) and
made to annihilate on a nucleus.
If the cut-off is higher than 100 MeV, however, the
particles are stopped in place without any further treatment.
If this happens at a boundary crossing where the material of
the region entered is vacuum, a printed message warns the
user that energy is being deposited in vacuum.
Example:
* A threshold of 2 MeV (kinetic energy) is requested for heavy charged
* particles with id-numbers between 1 and 11 (protons, antiprotons and
* muons). A threshold of Gamma (E/m) = 2 will apply for pions and kaons
* (numbers from 13 to 16). For all other particles, the defaults will apply.
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
PART-THR -0.002 1.0 11.0 0.0 0.0 1.0
PART-THR -2.0 13.0 16.0 1.0 1.0 0.0
