[ Identification | Description | Input parameters | Links ]

# The `Union_abs_logger_nD` Component

A logger of absorption as events with Monitor_nD options

## Identification

- Site:
- Author: Mads Bertelsen
- Origin: ESS DMSC
- Date: 19.06.20

## Description

    Part of the Union components, a set of components that work together and thus
    separates geometry and physics within McStas.
    The use of this component requires other components to be used.

    1) One specifies a number of processes using process components
    2) These are gathered into material definitions using Union_make_material
    3) Geometries are placed using Union_box/cylinder/sphere, assigned a material
    4) Logger and conditional components can be placed which will record what happens
    5) A Union_master component placed after all of the above

    Only in step 5 will any simulation happen, and per default all geometries
    defined before this master, but after the previous will be simulated here.

    There is a dedicated manual available for the Union_components

    This component is an absorption logger, and thus placed in point 4) above.

    An absorption logger will log something for each absorption event happening
    in the geometry or geometries on which it is attached. These are specified
    in the target_geometry string. By leaving it blank, all geometries are
    logged, even the ones not defined at this point in the instrument file.
    Multiple geometries are specified as a comma separated list.

    This absorption logger stores absorption as events, with position, velocity,
    time and weight. The Monitor_nD libraries are used to write the event files.
    This version is a close copy of Monitor_nD, having the same interface, though
    the user must be aware that no propagation happens for rays to hit the
    detector pixels, instead it uses the position of absorbed. Use the previous
    keyword to tell Monitor_nD that this is going on.

    This absorption logger needs to be placed in space, the position and velocity
    is recorded in the coordinate system of the logger component.

    It is possible to attach one or more conditional components to this absorption
    logger. Such a conditional component would impose a condition on the state of
    the neutron after the Union_master component that executes the simulation,
    and the absorption logger will only record the event if this condition is true.

    To use the logger_conditional_extend function, set it to some integer value n
    and make and extend section to the master component that runs the geometry.
    In this extend function, logger_conditional_extend[n] is 1 if the conditional
    stack evaluated to true, 0 if not. This way one can check what rays is logged
    using regular McStas monitors. Only works if a conditional is applied to this
    logger.

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default |
target_geometry | string | Comma separated list of geometry names that will be logged, leave empty for all volumes (even not defined yet) | "NULL" |
order_total | 1 | Only log rays that have scattered n times, -1 for all orders | -1 |
order_volume | 1 | Only log rays that have scattered n times in the same geometry, -1 for all orders | -1 |
logger_conditional_extend_index | 1 | If a conditional is used with this logger, the result of each conditional calculation can be made available in extend as a array called "logger_conditional_extend", and one would then access logger_conditional_extend[n] if logger_conditional_extend_index is set to n | -1 |
init | string | Name of Union_init component (typically "init", default) | "init" |
user1 |  |  | "" |
user2 |  |  | "" |
user3 |  |  | "" |
xwidth |  |  | 0 |
yheight |  |  | 0 |
zdepth |  |  | 0 |
xmin |  |  | 0 |
xmax |  |  | 0 |
ymin |  |  | 0 |
ymax |  |  | 0 |
zmin |  |  | 0 |
zmax |  |  | 0 |
bins |  |  | 0 |
min |  |  | -1e40 |
max |  |  | 1e40 |
restore_neutron |  |  | 0 |
radius |  |  | 0 |
options |  |  | "NULL" |
filename | string | Filename of produced data file | "NULL" |
geometry |  |  | "NULL" |
nowritefile |  |  | 0 |
username1 |  |  | "NULL" |
username2 |  |  | "NULL" |
username3 |  |  | "NULL" |

AT ( | , | , |  | ) RELATIVE |  |
ROTATED ( | , | , |  | ) RELATIVE |

## Links

- Source code for `Union_abs_logger_nD.comp`.

[ Identification | Description | Input parameters | Links ]