FLUKA: IONFLUCT
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IONFLUCT
Calculates ionisation energy losses of charged hadrons, muons, and
electrons/positrons with ionisation fluctuations
See also DELTARAY
For any SDUM
's but PRIM-ION:
WHAT(1)
>= 1.0 : restricted energy loss fluctuations (for hadrons
and muons) switched on
=< -1.0 : restricted energy loss fluctuations (for hadrons
and muons) switched off
= 0.0 : ignored
Default
: restricted energy loss fluctuations for hadrons
and muons are activated if option DEFAULTS is missing or
if it is used with SDUM
= CALORIMEtry, EET/TRANSmut,
HADROTHErapy, ICARUS, NEW-DEFAults or PRECISIOn.
With any other SDUM
value, they are not activated.
WHAT(2)
>= 1.0 : restricted energy loss fluctuations (for electrons
and positrons) switched on
=< -1.0 : restricted energy loss fluctuations (for electrons
and positrons) switched off
= 0.0 : ignored
Default
: restricted energy loss fluctuations for electrons
and positrons are activated if option DEFAULTS is missing
or if it is used with SDUM
= CALORIMEtry, EM-CASCAde,
HADROTHErapy, ICARUS, NEW-DEFAults or PRECISIOn.
With any other SDUM
value, they are not activated.
WHAT(3)
: If WHAT(1)
(resp. WHAT(2)
) >=1, WHAT(3)
represents the accuracy
parameter for the ionisation fluctuation algorithm (see [Fas97a])
for hadrons and muons (resp. electrons and positrons).
The accuracy parameter can take integer values from 1 to 4
(corresponding to increasing levels of accuracy)
< 0.0 : resets to default
Default
= 1.0 (minimal accuracy)
WHAT(4)
= lower bound (or corresponding name) of the indices of the
materials in which the restricted energy loss fluctuations are
activated
("From material WHAT(4)
...")
Default
= 3.0
WHAT(5)
= upper bound (or corresponding name) of the indices of the
materials in which the restricted energy loss fluctuations are
activated
("... to material WHAT(5)
...")
Default
= WHAT(4)
WHAT(6)
= step length in assigning indices
("...in steps of WHAT(6)
")
Default
: 1.0
For SDUM
= PRIM-ION:
generation of primary ionisation electrons is switched on (or switched
off, if WHAT(3)
< 0)
Delta rays below threshold for explicit generation are generated anyway:
for close collisions down to the threshold, and for distant collisions down
to an internally computed value, such as to match the input 1st ionisation
potential and the average number of primary ionisations per unit length.
WHAT(1)
= effective 1st ionisation potential (eV)
(meaningless for model 1)
No default
WHAT(2)
= number of primary ionisations per cm for a mimimum ionising
particle (assumed to be a muon+ at beta*gamma = 3). For gases it
must be the value at NTP.
If set = 0 (valid value), only primary electrons related to
close collisions will be produced and WHAT(1)
and WHAT(3)
will be meanigless.
No default
WHAT(3)
= primary ionisation model type (1, 2, 3 or 4)
0 is ignored if a previous call set a value > 0, otherwise it
forces the default
A value < 0 switches off primary ionisation production
Default
: 1
WHAT(4)
= lower bound (or corresponding name) of the indices of the
materials in which the choices represented by WHAT(1)
,(2) and (3)
apply
("From material WHAT(4)
...")
Default
= 3.0
WHAT(5)
= upper bound (or corresponding name) of the indices of the
materials in which the choices represented by WHAT(1)
,(2) and (3)
apply
("... to material WHAT(5)
...")
Default
= WHAT(4)
WHAT(6)
= step length in assigning indices
("...in steps of WHAT(6)
")
Default
: 1.0
SDUM
= PRIM-ION
For SDUM
= SECO-ION: (NOT YET IMPLEMENTED)
generation of secondary ionisation electrons is switched on (or switched
off, if WHAT(3)
< 0). Attention : this feature is not yet available in the
code.
WHAT(1)
= average energy spent per ion couple (primary or secondary (eV))
No default
WHAT(2)
= number of secondary ionisations per cm for a mimimum ionising
particle (assumed to be a muon+ at beta*gamma = 3). For gases it
must be the value at NTP.
If set = 0 (valid value), only primary electrons related to
close collisions will be produced and WHAT(1)
and WHAT(3)
will be meanigless.
No default
WHAT(3)
= secondary ionization flag.
0 is ignored if a previous call set a value > 0, otherwise it
forces the default
A value < 0 switches off primary ionisation production
Default
: 1
WHAT(4)
= lower bound (or corresponding name) of the indices of the
materials in which the choices represented by WHAT(1)
,(2) and (3)
apply
("From material WHAT(4)
...")
Default
= 3.0
WHAT(5)
= upper bound (or corresponding name) of the indices of the
materials in which the choices represented by WHAT(1)
,(2) and (3)
apply
("... to material WHAT(5)
...")
Default
= WHAT(4)
WHAT(6)
= step length in assigning indices
("...in steps of WHAT(6)
")
Default
: 1.0
SDUM
= SECO-ION
Default
(option IONFLUCT not given): ionisation fluctuations are simulated
or not depending on option DEFAULTS as explained above. Explicit
primary ionisation events are never simulated by default.
Notes:
1) The energy loss fluctuation algorithm is fully compatible
with the DELTARAY option.
2) Primary ionisation electron energies are stored in COMMON ALLDLT at
each step in the selected materials.
Use with care and possibly for gases only. The number of primary
ionisations electrons can quickly escalate, particularly when
multiply charged ions are involved. No COMMON saturation crash
should occur since the code is piling up all the remaining primary
electrons into the last COMMON location if no further one is
available, however CPU penalties can be severe if used without wisdom.
Example (number-based):
IONFLUCT 0.0 1.0 3.0 7.0 16.0 3.0
IONFLUCT 1.0 0.0 2.0 8.0 10.0 2.0
DELTARAY 1.E-3 0.0 0.0 10.0 11.0
The same example, name based:
IONFLUCT 0.0 1.0 3.0 NITROGEN MERCURY 3.0
IONFLUCT 1.0 0.0 2.0 OXYGEN ALUMINUM 2.0
DELTARAY 1.E-3 0.0 0.0 ALUMINUM IRON
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