ASSIGNMAt

Summary

Defines the correspondence between region indices (or names) and material indices (or names). It defines also regions with magnetic and/or electric fields, and whether synchrotron radiation emission must be activated in vacuum regions with magnetic fields. There is the possibility of selectively changing region material to vacuum/blackhole or an alternate material (and/or switching on/off possible fields) when transporting radioactive decay products. Radioactive decay products originating from regions switched to a different material are ignored. This is helpful for situations where the emissions of an activated object in a complex environment have to be evaluated standalone. ​​ ​​ ​

See also MATERIAL, MGNFIELD, ELCFIELD, SYNCRAD

WHAT(1) > 0:

material index, or material name

≤ 0.0:

resets the default

Default

= 1.0 (blackhole)

WHAT(2) =
lower bound (or name corresponding to it) of the region indices with material index equal or name corresponding to WHAT(1)
(“From region ``WHAT(2)``…”)
Default

= 2.0

WHAT(3) =
upper bound (or name corresponding to it) of the region indices with material index equal or name corresponding to WHAT(1)
(“…to region ``WHAT(3)``…”)
Default

= WHAT(2)

WHAT(4) =
step length in assigning indices
(“…in steps of ``WHAT(4)`` ”)
Default

= 1.0

WHAT(5) = 1.0:

a magnetic field is present (no electric field) in the region(s) defined by WHAT(2), (3), and (4), for both prompt and radioactive decay products

= 2.0:

an electric field is present (no magnetic field) in the region(s) defined by WHAT(2), (3), and (4), for both prompt and radioactive decay products

= 3.0:

both an electric field and a magnetic field are present in the region(s) defined by WHAT(2), (3), and (4), for both prompt and radioactive decay products

= 4.0:

a magnetic field is present (no electric field) in the region(s) defined by WHAT(2), (3), and (4), for prompt products only

= 5.0:

an electric field is present (no magnetic field) in the region(s) defined by WHAT(2), (3), and (4), for prompt products only

= 6.0:

both an electric field and a magnetic field are present in the region(s) defined by WHAT(2), (3), and (4), for prompt products only

= 7.0:

a magnetic field is present (no electric field) in the region(s) defined by WHAT(2), (3), and (4), for radioactive decay products only

= 8.0:

an electric field is present (no magnetic field) in the region(s) defined by WHAT(2), (3), and (4), for radioactive decay products only

= 9.0:

both an electric field and a magnetic field are present in the region(s) defined by WHAT(2), (3), and (4), for radioactive decay products only

= 0.0:

ignored

< 0.0:

resets the default (no field) in the region(s) defined by WHAT(2), (3), and (4)

Default

= 0.0  (ignored)

WHAT(6) =

material index, or material name, for a possible alternate material​ for radioactive decay product transport. All materials are allowed. (See Note 7 below).

Default
= 0.0 : same material as for prompt products (see WHAT(1))
SDUM

= SYNCRON: synchrotron radiation emission is activated in the regions defined by WHAT(2), (3), and (4), for prompt or radioactive decay products or both, depending on WHAT(5).

= SYNCROFF: synchrotron radiation emission is deactivated in the regions defined by WHAT(2), (3), and (4).

Default

: no synchrotron radiation. A blank SDUM is ignored.

Default :
(option ASSIGNMAt not requested): not allowed! Each region must be explicitely assigned a material, or vacuum or blackhole (see Note 3).
No magnetic field, no electric field, and no synchrotron radiation emission is the default for all regions.

Notes

  1. Several ASSIGNMAt definitions are generally necessary to assign a material to all regions. Standard material names and their numbers are listed in Table 5.3They may be redefined and others may be added (see Note 5 to command MATERIAL).

  2. Overlapping region indices can be given in several ASSIGNMAt definitions, each definition overriding the earlier ones. This makes the assigning of materials very convenient (see Example below).
    The same can be done even if region names are used instead of indices: the region numbers correspond to the order in which they appear in the geometry input. Anyway, the name-index correspondence can be found on standard output​ after a short test run.

  3. Option ASSIGNMAt must always be present. If a region has not been assigned a material, the program stops at initialisation time. Notice that this was different in previous versions of FLUKA, where blackhole was assigned by default.

  4. Magnetic field tracking is performed only in regions defined as magnetic field regions by WHAT(5)= 1.0, 3.0, 4.0, 6.0, 7.0, 9.0. It is strongly recommended to define as such only regions where a magnetic field actually exists, due to the less efficient and less accurate tracking algorithm used in magnetic fields. To define a region as one with magnetic field and to return systematically B = 0.0 in that region via the user subroutine MAGFLD must be absolutely avoided (see MGNFIELD).

  5. Electric field tracking is performed only in regions defined as electric field regions by WHAT(5) = 2.0, 3.0, 5.0, 6.0, 8.0, 9.0. It is strongly recommended to define as such only regions where an electric field actually exists, due to the less efficient and less accurate tracking algorithm. Returning E = 0.0 systematically in such a region via ELEFLD must be absolutely avoided (see ELCFIELD).

  6. If synchrotron radiation is switched on, the code checks that the region material is vacuum and that a magnetic field is present. If both conditions are not met, the code stops with an error message.

  7. There is the possibility of selectively changing regions to a different material (and/or switching on/off possible fields) when transporting radioactive decay products. Radioactive decay products originating from regions switched to a different material are ignored. This is helpful for situations where the emissions of an activated object in a complex environment have to be evaluated standalone.

Example (for an input number-based):

*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
MATERIAL        13.0       0.0       2.7      10.0       0.0      0.0 ALUMINUM
ASSIGNMA        10.0       1.0      15.0       0.0       1.0      0.0
ASSIGNMA         2.0       5.0      17.0       6.0      -1.0      0.0
ASSIGNMA         2.0      16.0      18.0       2.0       0.0      0.0
*       The above definitions mean that all regions from 1 to 15 are
*       aluminium with a magnetic field, except regions 5 and 11 which are
*       vacuum without any magnetic field. Regions 16, 17 and 18 are also
*       vacuum without field.
*       Note that in the above example material 10 has been defined
*       overriding the pre-defined FLUKA aluminium material, but keeping
*       the same material number.

The corresponding name-based input cards could be (using arbitrary names):

ASSIGNMA    ALUMINUM  FirstReg     Reg15       0.0       1.0      0.0
ASSIGNMA      VACUUM  FifthReg     Reg17       6.0      -1.0      0.0
ASSIGNMA      VACUUM     Reg16     Reg18       2.0       0.0      0.0