PHYSICS

Summary

Allows to override the standard FLUKA defaults for physics processes.

See also EMFCUT, IONTRANS, POLARIZAti, THRESHOLd ​

This command concerns the following physics processes:

1. SDUM = CHARMDECay: flag for charmed hadron and tau transport​

2. SDUM = COALESCEnce: flag to activate the coalescence​ mechanism

3. SDUM = DECAYS: decays of \(\pi^\pm\), \(\mu^\pm\), K\(^\pm\) (e\(\nu_{e}\), \(\mu \nu_{\mu}\), K\(^\pm_{\mu3}\) and K\(^\pm_{e3}\) channels) and K\(_{long}\) (K\(^0_{\mu3}\) and K\(^0_{e3}\) channels) ​

4. SDUM = DELAYNEUtrons: activates or deactivates delayed neutron production following fission

5. SDUM = DPMTHREShold: lower energy threshold(s) for DPMJET ​

6. SDUM = EM–DISSOciation: ion electromagnetic dissociation​

7. SDUM = EVAPORATion: evaporation​

8. SDUM = INFLDCAY: in-flight decay of excited states, isomers, and radioactive isotopes​

9. SDUM = IONBRPAIr: activates or deactivates heavy ion direct pair production and nuclear form factors in delta ray production​​

10. SDUM = IONSPLITting: activates the superposition model​, i.e. ion splitting into nucleons

11. SDUM = ISOMERS: activates or deactivates the explicit assessment of isomeric state production inside the nuclear models​

12. SDUM = LIMITS: sets the maximum (pp) CMS momentum (used for initialization of high energy models, typically DPMJET)​ and/or the maximum momentum for internal tabulations

13. SDUM = NEUTRINO: selects which neutrino interactions are activated​

14. SDUM = PEATHREShold: set the upper thresholds for the Peanut model​

15. SDUM = QMDTHREShold: lower energy thresholds for Rqmd, Myrqmd, Bme and complete fusion ​​​ ​

For SDUM = CHARMDECay:

WHAT(1) :

flag for charmed hadron and tau decays​​

≤ -1.0:

resets to default

= 0.0:

ignored

= 1.0:

charmed hadrons and tau leptons are transported

WHAT(2)

– WHAT(6): not used

Default

:  decay at production, no transport

For SDUM = COALESCEnce:

WHAT(1) :

coalescence flag

≤ 0.0:

false (no coalescence, default)

= 0.0:

ignored

> 0.0:

true, coalescence is activated

WHAT(2)

– WHAT(6): reserved to developers’ use

Default

:  no coalescence

For SDUM = DECAYS:

WHAT(1) :

flag for particle decay

≤ -1.0:

resets to default

= 0.0:

ignored

= 1.0:

maximum accuracy, polarisation​ accounted for in \(\pi\)/K \(\rightarrow \mu\)–\(\nu_{\mu}\)(e–\(\nu_e\)) decays and following \(\mu\) decays

= 2.0:

maximum accuracy, polarisation not accounted for

= 3.0:

phase space-like decays​

100.0 ≤ WHAT(1) < 200.0: leptonic decays​ only are allowed (implemented only for \(\tau\)’ s).

WHAT(1)–100 has the same meaning as above.

200.0 ≤ WHAT(1) < 300.0: hadronic decays​ only are allowed (implemented only for \(\tau\)’ s).

WHAT(1)–200 has the same meaning as above.

Default

= 1.0  (maximum accuracy and polarisation for both hadronic and leptonic decays)

WHAT(2),

WHAT(3): not used

WHAT(4) =

lower bound of the particle id-numbers (or corresponding names) to which the decay flag chosen by WHAT(1) applies

(“From particle ``WHAT(4)``…”)

Default

= 1.0

WHAT(5) =

upper bound of the particle id-numbers (or corresponding names) to which the decay flag chosen by WHAT(1) applies

(“…to particle ``WHAT(5)``…”)

Default

= WHAT(4)

WHAT(6) =

step length in assigning numbers

(“…in steps of ``WHAT(6)`` ”)

Default

= 1.0

For SDUM = DELAYNEUtrons:

WHAT(1)

: flag for activating delayed neutron production after low energy neutron pointwise fission events

= 1.0 : delayed neutron production activated in analogue mode after low energy neutron pointwise fission events

= 2.0 : delayed neutron production activated in weighted mode after low energy neutron pointwise fission events

= 0.0 : ignored

< 0.0 : resets to default

Default = no delayed neutron production after low energy neutron pointwise fission events

WHAT(2)

: flag for activating delayed neutron production after all other particles/energies, apart low energy neutrons, fission events

= 1.0 : delayed neutron production activated in analogue mode after all other particles/energies, apart low energy neutrons, fission events

= 0.0 : ignored

< 0.0 : resets to default

Default = no delayed neutron production after all other particles/energies, apart low energy neutrons, fission events

WHAT(3)

: Maximum precursor T1/2 to be considered for delayed neutron production

> 0.0 : maximum T1/2 (s) to be considered for delayed neutron tron precursors

= 0.0 : ignored

< 0.0 : resets to default

Default = maximum T1/2 for delayed neutron precursors set at 150 s

WHAT(4)

: not used

WHAT(5)

: not used

WHAT(6)

: not used

Default (no PHYSICS option with SDUM = DELAYNEUtrons): delayed neutrons are not produced in pointwise low energy neutron fission events, and in all other fission events

Note: When using group-wise low energy neutron cross sections, all fission neutrons are produced prompt, with an overall average multiplicity given by <nu> = <nu_prompt> + <nu_delay>. Hence there is no way to switch on/off delayed neutron production, or to score them separately with the correct time distribution. If detailed production of delayed neutrons is requested, please use pointwise cross sections.

For SDUM = DPMTHREShold:

WHAT(1) =

minimum DPMJET kinetic energy for hadrons (GeV)​

≤ 0.0:

ignored

Default

= 20 TeV

WHAT(2) =

minimum DPMJET kinetic energy for ions (GeV/n)​

≤ 0.0:

ignored

Default

= 5 GeV/n

WHAT(3) =

minimum Rqmd kinetic energy for ions (GeV/n)​

< 0.05

GeV/n: forced to be = 0.05 GeV/n

Default

= 0.125 GeV/n

WHAT(4) =

smearing (\(\pm \Delta\)E, GeV/n) for the Rqmd-DPMJET switch energy​

< 0.0:

resets to 0

Default

:  2 GeV/n

WHAT(5) =

smearing (\(\pm \Delta\)E, GeV/n) for the FLUKA-DPMJET switch energy for h-A interactions​

< 0.0:

resets to 0

Default

:  10 TeV

WHAT(6) =

flag for restricting DPMJET h–A interactions to primary particles only

≤ -1.0:

resets to default (false)

= 0.0:

ignored

> 0.0:

sets to true

Default

= -1.0  (no restriction to primary particles only)

Default

(no PHYSICS option with SDUM = DPMTHREShold): DPMJET is called for h–A interactions above 20 TeV and for A–A interactions down to 5 GeV/n. Rqmd is called between 5 and 0.125 GeV/n.

Warning: to activate ion interactions refer to the IONTRANS card.

Warning: The FLUKA executable must be built with the DPMJET and Rqmd libraries to perform A–A interactions above 125 MeV/n (see the ldpmqmd script in $FLUPRO/flutil). DPMJET must also be linked for h-A interactions above 20 TeV​

For SDUM = EM–DISSOciation:

WHAT(1) :

flag for activating ion electromagnetic dissociation​

≤ -1.0:

resets to default (no em-dissociation)

= 0.0:

ignored

= 1.0:

no em-dissociation

= 2.0:

projectile and target em-dissociation activated

= 3.0:

projectile only em-dissociation activated

= 4.0:

target only em-dissociation activated

Default

= 1.0  (no em-dissociation)

WHAT(2) :

flag for \(\mu^\pm\) electromagnetic dissociation

≤ -1.0:

resets to default (\(\mu^\pm\) em-dissociation activated)

= 0.0:

ignored

= 1.0:

\(\mu^\pm\) em-dissociation activated

= 2.0:

\(\mu^\pm\) em-dissociation off

Default

= 1.0  (\(\mu^\pm\) em-dissociation activated)

WHAT(3) :

flag for deuteron electromagnetic dissociation

≤ -1.0:

resets to default (deuteron projectile em-dissociation activated)

= 0.0:

ignored

= 1.0:

deuteron projectile em-dissociation activated, deuteron target em-dissociation on/off according to WHAT(1)

= 2.0:

deuteron em-dissociation off

Default

= 1.0  (deuteron projectile em-dissociation activated)

WHAT(4)

– WHAT(6): not used

For SDUM = EVAPORATion:

WHAT(1) :

flag for FLUKA evaporation model = \(i_0 + 100 \times Z_{max} + 10000 \times A_{max}\), where:

	\(i_0\)	≤	-1.0:	resets to default (new model, no heavy fragment evaporation​)
		=	0.0:	ignored
		=	1.0:	old evaporation model​
				(OBSOLETE: kept for developers’ use only)
		=	2.0:	new evaporation model​, no heavy fragment evaporation
		=	3.0:	new evaporation model, with heavy fragment evaporation
				(CPU expensive: see Note 1 below)
		=	4.0:	same as 2, overriding possible checks
	\(Z_{max}\)	:	(optional, default maximum possible \(Z\)) maximum \(Z\) of the emitted fragments
			(meaningful only for \(i_0=3\))
	\(A_{max}\)	:	(optional, default maximum possible \(A\)) maximum \(A\) of the emitted fragments
			(meaningful only for \(i_0=3\))

Default

= 2.0 new evaporation model, no heavy fragment evaporation, except for PRECISIOn, for which the default is 90403 (heavy fragments up to \(Z=4\), \(A=9\)).

WHAT(2)

– WHAT(6): not used

For SDUM = INFLDCAY:

WHAT(1) :

flag for (de)activating the decay in flight of ion excited states

< 0.0:

deactivated

= 0.0:

ignored

> 0.0:

activated default depends on the chosen DEFAULT

WHAT(2) :

absolute minimum mean life (s) for excited states for being transported and decayed in flight

< 0.0:

reset to default (\(10^{-16}\))

= 0.0:

ignored

> 0.0:

new value

WHAT(3) :

flag for (de)activating the decay in flight of ion isomeric states

< 0.0:

deactivated

= 0.0:

ignored

> 0.0:

activated default is deactivated

WHAT(4) :

absolute minimum mean life (s) for isomeric states for being transported and decayed in flight

< 0.0:

reset to default (\(\tau=10^{6}/log(2)\))

= 0.0:

ignored

> 0.0:

new value

WHAT(5) :

flag for (de)activating the decay in flight of radio- active isotopes

< 0.0:

deactivated

= 0.0:

ignored

> 0.0:

activated default is deactivated

WHAT(6) :

absolute minimum mean life (s) for radioctive isotopes for being transported and decayed in flight

< 0.0:

reset to default (\(\tau=10^{6}/log(2)\))

= 0.0:

ignored

> 0.0:

new value

For SDUM = IONBRPAIr:

WHAT(1) :

flag for (de)activating heavy ion direct pair production

< 0.0:

heavy ion direct pair production is deactivated

= 0.0:

ignored

> 0.0:

activated (it still requires heavy pair production activated via PAIRBREM for the required materials)​

Default

= 1.0  (heavy ion direct pair production is activated in the materials defined by PAIRBREM)

WHAT(2) :

flag for (de)activating heavy ion bremsstrahlung (not yet implemented)

WHAT(3) :

flag for (de)activating nuclear form factor effects in heavy ion delta ray production

< 0.0:

nuclear form factor effects are deactivated

= 0.0:

ignored

> 0.0:

nuclear form factor effects are activated (it still needs delta ray production activated via DELTARAY for the required materials)​

Default

= 1.0  (nuclear form factor effects in heavy ion delta ray production are activated in the materials defined by DELTARAY)

WHAT(4)

– WHAT(6): not used

For SDUM = IONSPLITting:

WHAT(1) :

flag for activating ion splitting into nucleons

≤ -1.0:

false, no ion splitting

= 0.0:

ignored

≥ 1.0:

true, ion splitting is activated

Default

= -1.0  (no ion splitting)

WHAT(2) =

minimum energy for ions (GeV/n) above which splitting into nucleons will be performed

≤ 0.0:

ignored

Default

= 0.1  GeV/n

WHAT(3) =

maximum energy for ions (GeV/n) below which splitting into nucleons will be performed

≤ 0.0:

ignored

Default

= 5  GeV/n

WHAT(4) =

minimum A for which ion splitting into nucleons will be performed

≤ 0.0:

ignored

Default

= 2

WHAT(5) =

maximum A for which ion splitting into nucleons will be performed

≤ 0.0:

ignored

Default

= 500

WHAT(6) :

flag for the ion splitting minimum threshold

= 0.0:

sharp threshold for kinetic energy per nucleon larger than WHAT(2) (deprecated)

= 1.0:

probability according to \(1 - \exp{-\frac{E_k/n}{E_{min}}}\) where \(E_{min}\)=WHAT(2) and \(E_k/n\) is the kinetic energy per nucleon of the current ion

= 2.0:

splitting at the first nonelastic interaction if no model is available. It requires full transport selected for all ions concerned. WHAT(2), WHAT(3) are still honored in the same way as for for 0.0, however the minimum energy should be set compatible with the ion cross section thresholds rather than not

< -1.0:

resets to default

= 3.0:

deuteron splitting at an interaction point computed with a parameterised formula; as for 1.0 for heavier ions.

Default

= 2.0

For SDUM = ISOMERS:

WHAT(1) :

flag for activating explicit calculation of isomers

< 0.0:

isomer explicit calculation is deactivated

= 0.0:

ignored

> 0.0:

activated

Default

=  1.0:isomer explicit calculation os activated

WHAT(2)

– WHAT(6): not used

For SDUM = LIMITS:

WHAT(1) :

set the maximum (pp) CMS momentum (used for initialization of high energy models, typically DPMJET), and, if larger than the one of the BEAM card, the maximum momentum for all internal tabulations

< 0.0:

reset to default

= 0.0:

ignored

> 0.0:

maximum (pp) CMS momentum (GeV/c)

Default

:  determined by the BEAM card​

WHAT(2)

– WHAT(6): not used

For SDUM = NEUTRINO:

WHAT(1) :

flag for activating quasielastic (QE) neutrino interactions​

= 1.0:

QE neutral current (NC) activated

= 2.0:

QE charged current (CC) activated

= 3.0:

QE NC and CC activated

< 0.0:

no QE interactions

= 0.0:

ignored

Default

= 3.0  (QE NC and CC activated)

WHAT(2) :

flag for activating resonant (RES) neutrino interactions​

= 1.0:

RES neutral current (NC) activated

= 2.0:

RES charged current (CC) activated

= 3.0:

RES NC and CC activated

< 0.0:

no RES interactions

= 0.0:

ignored

Default

= 3.0  (RES NC and CC activated)

WHAT(3) :

flag for activating deep inelastic (DIS) neutrino interactions​

= 1.0:

DIS neutral current (NC) activated

= 2.0:

DIS charged current (CC) activated

= 3.0:

DIS NC and CC activated

< 0.0:

no DIS interactions

= 0.0:

ignored

Default

= 3.0  (DIS NC and CC activated)

WHAT(4) :

flag for activating charm production (CHA) in DIS neutrino interactions​

= 1.0:

CHA neutral current (NC) activated (not yet implemented)

= 2.0:

CHA charged current (CC) activated

= 3.0:

CHA NC and CC activated (NC not yet implemented)

< 0.0:

no CHA interactions

= 0.0:

ignored

Default

= 3.0  (CHA CC activated, but NC not yet implemented)

WHAT(5) :

not used

WHAT(6) :

flag for performing (forced) interations when there is a(n) (anti)neutrino beam particle

≥ 1.0:

forced interactions for (anti)neutrino beam particles nare performed

= 0.0:

ignored

≤ -1.0:

forced interactions for (anti)neutrino beam particles not performed (hence no neutrino interactions, propagation only

Default

= 1.0  (forced interactions performed for (anti)neutrino beams)

For SDUM = PEATHREShold:

WHAT(1) =

maximum Peanut kinetic energy for nucleons (GeV)

≤ 0.0:

ignored

WHAT(2) =

maximum Peanut kinetic energy for pions (GeV)​

≤ 0.0:

ignored

WHAT(3) =

maximum Peanut kinetic energy for kaons (GeV)

≤ 0.0:

ignored

WHAT(4) =

maximum Peanut kinetic energy for \(\bar{K}\)s (GeV)

≤ 0.0:

ignored

WHAT(5) =

maximum Peanut kinetic energy for antinucleons (GeV)

≤ 0.0:

ignored

WHAT(6) =

maximum Peanut kinetic energy for (anti)hyperons (GeV)

≤ 0.0:

ignored

Default

(no PEATHREShold option): Peanut is called up to 100 TeV kinetic energy, or the DPMJET threshold energy if linked, for all hadrons

For SDUM = QMDTHREShold:

WHAT(1)

not used

WHAT(3), WHAT(4)

not used

WHAT(2) :

minimum Bme kinetic energy for ions (GeV/n)

≤ 0.0:

ignored

WHAT(5) :

maximum kinetic energy for ion complete fusion (GeV/n)

WHAT(6) :

smearing (\(\pm\Delta E\), GeV/n) for the Bme-Rqmd switch energy

< 0.0:

set = 0.0

Default

= 0.025 GeV/n

Default

(option PHYSICS not given): standard FLUKA treatment of physics processes

Note

1. In order to achieve accurate results for residual nuclei​ production or fragment production with ion beams the evaporation of heavy fragments​ must be activated. This, however, is not the default since it can bring a significant CPU burden, and is not needed for most applications. The CPU burden is maximal for problems with heavy targets, high energy beams, and no electro-magnetic particle transport. It is often negligible for problems with electro-magnetic transport activated down to low thresholds.

Example:

* Only hadronic decays are allowed for tau+ and tau- (id-number 41 and 42)
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
PHYSICS        201.0       0.0       0.0      41.0      42.0       0. DECAYS
* Maximum accuracy requested for decay of pi+ and pi-(id-number 13 and 14),
* but without accounting for polarisation
* Phase space
PHYSICS          2.0       0.0       0.0      13.0      14.0       0. DECAYS
* New evaporation model requested
PHYSICS          2.0       0.0       0.0       0.0       0.0       0. EVAPORAT