activates gamma interactions with nuclei
(see also EMF, MUPHOTON)
For all SDUM's except MUMUPAIR/MUMUPRIM:
WHAT(1) : flag to switch on nuclear interactions of photons:
=< -1.0 : reset to default (no photonuclear interactions)
= 0.0 : ignored
= 1.0 : photonuclear interactions are activated at all
energies
= 2.0 : photonuclear interactions are activated only in
the high energy range (above 0.7 GeV)
= 3.0 : photonuclear interactions are activated only in
the region of the Delta resonance
= 4.0 : only quasi-deuteron interactions are activated
= 5.0 : only Giant Dipole Resonance interactions are
activated
>= 10.0 : interpreted as ih + id * 10 + iq * 100 + ig * 1000
where ih = 1 to activate High-energy interactions
id = 1 to activate Delta Resonance
iq = 1 to activate Quasi-deuteron
ig = 1 to activate Giant Resonance
and each is = 0.0 otherwise
Default = 0.0 (no photonuclear interaction)
WHAT(2), WHAT(3) : not used
WHAT(4) = lower index bound of materials where the indicated
photonuclear interactions are activated
("From material WHAT(4)..."
Default = 3.0
WHAT(5) = upper index bound of materials where the indicated
photonuclear interactions 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 = MUMUPAIR/MUMUPRIM:
WHAT(1) : flag to switch on muon pair production by photons:
= -1: resets to default (no muon pair production)
= 0: ignored
> 0: interpreted as ich + iqe * 10 + iin * 100 + ids * 1000
where ich = 1 to activate muon pair coherent production
iqe = 1 to activate muon pair incoherent quasielastic production
iin = 1 to activate muon pair incoherent inelastic production
ids = 1 to activate muon pair deep inelastic production
and each is = 0.0 otherwise
Default: no muon pair production by photons
WHAT(2) = interaction length biasing factor
= 0: ignored
0 < |WHAT(2)| < 1: the interaction length of the photon is reduced
by a factor |WHAT(2)|
1 =< |WHAT (2)|: a possible previous biasing factor is reset to the
default value (no biasing)
0< WHAT(2) < 1: the primary particle always survives with reduced
weight
-1 < WHAT(2) < 0: Russian Roulette is played to decide if the
primary particle will be killed, or survive with its original
weight
Default: no biasing
WHAT(3) : not used
WHAT(4) = lower index bound of materials where the indicated
photomuon production mechanisms are activated
("From material WHAT(4)..."
Default = 3.0
WHAT(5) = upper index bound of materials where the indicated
photomuon production mechanisms are activated
("...To material WHAT(5)..."
Default = WHAT(4)WHAT(6) = step length in assigning indices ("...in steps of
WHAT(6)").
Default = 1.0.
SDUM = MUMUPRIM: photomuon production biasing applied to primaries only
Default (option PHOTONUC not given): photon interactions with
nuclei as well as photomuon production are not simulated
Note: Muon photonuclear interactions (via virtual photons) are
not handled by PHOTONUC but by MUPHOTON.
Because photonuclear cross sections are much smaller than
photon cross sections for electromagnetic interactions with
atoms and electrons, analogue simulations of photonuclear
interactions are very inefficient.
Generally, it is recommended to use PHOTONUC in combination
with LAM-BIAS to increase artificially the frequency of
photonuclear interactions. See the Notes to option LAM-BIAS
for more details.
High-energy photonuclear interactions are also activated
by WHAT(1) and WHAT(4) in option EMF. However, this is a
duplicate that eventually will be removed.
Example 1:
* Giant Resonance and Quasideuteron photonuclear interactions are requested
* in material 18. The photon hadronic interaction length is artificially
* shortened by a factor 0.02 in order to improve statistics
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
PHOTONUC 1100.0 0.0 0.0 18.0 0.0 0.0
LAM-BIAS 0.0 0.02 18.0 7.0 0.0 0.0
Example 2:
* Photonuclear interactions are requested at all energies in materials
* 3, 7, 11 and 15. The photon hadronic interaction length is shortened
* by a factor 0.025
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
PHOTONUC 1.0 0.0 0.0 3.0 15.0 4.0
LAM-BIAS 0.0 0.025 0.0 7.0 0.0 0.0
