OPT–PROD

Summary

Requests and controls production of Cherenkov, Transition and Scintillation Radiation in specified materials. ​​​ ​ ​

​

See also OPT–PROP, Generating and propagating optical photons, and examples in Handling optical photons
For SDUM = CERE–OFF: switches off Cherenkov production
WHAT(1)

– WHAT(3): not used

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= CERE–OFF

For SDUM = TRD–OFF: switches off Transition Radiation production

WHAT(1)

– WHAT(3): not used

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= TRD–OFF

For SDUM = SCIN–OFF: switches off Scintillation light production

WHAT(1)

– WHAT(3): not used

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= SCIN–OFF

For SDUM = CERENKOV: switches on Cherenkov production and defines photon energy range

WHAT(1) =

minimum Cherenkov photon emission energy in GeV

Default

= \(2.07\times 10^{-9}\)  (2.07 eV, corresponding to 600 nm)

WHAT(2) =

maximum Cherenkov photon emission energy in GeV

Default

= \(4.96\times 10^{-9}\)  (4.96 eV, corresponding to 250 nm)

WHAT(3) :

not used

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= CERENKOV

For SDUM = CEREN–WV: switches on Cherenkov production and defines photon wavelength​ range

WHAT(1) =

minimum Cherenkov photon emission wavelength in cm

Default

= \(2.50\times 10^{-5}\)  (250 nm, or \(1.2\times 10^6\) GHz)

WHAT(2) =

maximum Cherenkov photon emission wavelength in cm

Default

= \(6.00\times 10^{-5}\)  (600 nm, or \(5\times 10^5\) GHz)

WHAT(3) :

not used

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= CEREN–WV

For SDUM = CEREN–OM: switches on Cherenkov production and defines photon angular frequency​ range

WHAT(1) =

minimum Cherenkov photon angular frequency \(\omega = 2\pi\nu\) in rad/s (\(\nu =\) frequency) in rad/s

Default

= \(3.14\times 10^{15}\) rad/s  (corresponding to 600 nm)

WHAT(2) =

maximum Cherenkov photon emission angular frequency \(\omega = 2\pi\nu\) in rad/s

Default

= \(7.53\times 10^{15}\) rad/s  (corresponding to 250 nm)

WHAT(3) :

not used

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= CEREN–OM

For SDUM = TR–RADIA: switches on Transition Radiation production and defines its energy range not yet implemented !!!

WHAT(1) =

minimum TRD photon emission energy

WHAT(2) =

maximum TRD photon emission energy

WHAT(3) :

not used

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= TR–RADIA

For SDUM = SCINTILL: switches on Scintillation Light production and defines photon energy

WHAT(1) =

\(i_{th}\) scintillation photon emission energy in GeV (\(i_{max}\)=3, see Note 4)

WHAT(2)

> 0: fraction of energy loss going into \(i_{th}\) scintillation photon emission

≤ -100:

forces to use a user routine (see SPHSPC, USFSCI)

≥ -99.0 and ≤ 0.0: ignored

WHAT(3)

: time constant of scintillation light in seconds

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= SCINTILL

For SDUM = SCINT–WV: switches on Scintillation Light production and defines photon wavelength

WHAT(1) =

\(i_{th}\) scintillation photon emission wavelength in cm (\(i_{max}\)=3, see Note 4)

Default

= \(2.50\times 10^{-5}\)  (250 nm, or \(1.2\times 10^6\) GHz)

WHAT(2)

> 0: fraction of energy loss going into \(i_{th}\) scintillation photon emission

≤ -100:

forces to use a user routine (see SPHSPC, USFSCI)

≥ -99.0 and ≤ 0.0: ignored

WHAT(3)

: time constant of scintillation light​ in seconds

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= SCINT–WV

For SDUM = SCINT–OM: switches on Scintillation Light production and defines photon angular frequency range

WHAT(1) =

\(i_{th}\) scintillation photon emission angular frequency \(\omega = 2\pi\nu\) in rad/s, \(\nu =\) frequency. (\(i_{max}\)=3, see Note 4)

Default

= \(3.14\times 10^{15}\) rad/s  (corresponding to 600 nm)

WHAT(2)

= fraction of energy loss going into \(i_{th}\) scintillation photon emission

≤ -100:

forces to use a user routine (see SPHSPC, USFSCI)

≥ -99.0 and ≤ 0.0: ignored

WHAT(3)

: time constant of scintillation light in seconds

WHAT(4)

– WHAT(6): assignment to materials, see below

SDUM

= SCINT–OM

For all previous SDUMs:

WHAT(4) =
lower bound of the indices of materials in which the indicated Cherenkov, Scintillation or TRD photon emission range is defined
(“From material ``WHAT(4)``…”)
Default

= 3.0

WHAT(5) =
upper bound of the indices of materials in which the indicated Cherenkov, Scintillation or TRD photon emission range is defined
(“…to material ``WHAT(5)``…”)
Default

= WHAT(4)

WHAT(6) =
step length in assigning indices
(“…in steps of ``WHAT(6)`` ”)
Default

= 1.0

Default

: (option OPT–PROD not given): no Cherenkov, scintillation or TRD photon production

Notes

  1. Optical photons​ such as those produced by Cherenkov effect are distinguished by their FLUKA name (OPTIPHOT) and by their FLUKA id-number (-1), as shown in Particles transported by FLUKA.

  2. To transport optical photons, it is necessary to define the optical properties​ of the relevant materials by means of option OPT–PROP. Users can also write their own routines USRMED​, which is called at every step and at boundary crossings when activated with MAT–PROP, and FRGHNS​, which defines surface roughness​.

  3. The energy/wavelength/frequency range as defined by OPT–PROD for Cherenkov photon production​ is not necessarily the same as that defined for transport by means of OPT–PROP. The default values, however, are the same.

  4. In case of scintillation light, only monochromatic photons are considered for the moment, with a maximum of \(i\) = 3 different lines. The lines can be defined repeating \(i\) times the OPT–PROD card with SDUM = SCINTILL. The energy lost by ionizing particles is partially spent to produce optical photons, according to the fraction entered in what(2). The sum of what(2) for all OPT-PROD cards in a given material must be <1 (usually much less).

Example:

* Request production of Cherenkov photons with energies between 2 and 3 eV in
* materials 16, 17, 19 and 20, with wavelengths between 300 and 600 nm in
* materials 18, 20 and 22, and with frequencies between 0.5 and 1 million GHz
* in material 21
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
OPT-PROD       2.E-9     3.E-9       0.0      16.0      17.0       0. CERENKOV
OPT-PROD       2.E-9     3.E-9       0.0      19.0      20.0       0. CERENKOV
OPT-PROD       3.E-5     6.E-5       0.0      18.0      22.0       2. CEREN-WV
OPT-PROD     3.14E15   6.28E15       0.0      21.0       0.0       0. CEREN-OM
* Optical photon transport requested between 300 and 500 nm for all materials
* with number between 16 and 21
OPT-PROP       3.E-5     5.E-5     6.E-5      16.0      22.0       0. WV-LIMIT
* User routine USRMED called when an optical photon is going to be transported
* in materials 17 and 21
MAT-PROP         1.0       0.0       0.0       17.       21.       4. USERDIRE

A more detailed example including scintillation light is reported in Handling optical photons.