5.3.20. Definition of angular distribution¶
When dir = data is specified, an angular-distribution subsection starting with a-type = as shown below is required. Items with (D=***) are omissible.
5.3.20.1. a-type = 1, (11)¶
An arbitrary angular distribution is specified by giving angular boundary points a(i) and the integrated value of the source particle generation probability w(i) in each bin. The boundary points are given in \(\cos\) for 1 and in degrees for 11. The integral number of particles generated in each bin is proportional to w(i). For continuous energy distribution with double differential type (e-type = 41, 42, 51, 52), if all w(i) are set to 0, the angular distribution specified by the e-type is used as is.
na =: Number of angular groups. Data are given in free format as follows.
(a(i), w(i), i = 1, |na|), a(|na|+1)
5.3.20.2. a-type = 4, (14)¶
The same angular distribution as a-type = 1, (11) is generated. However, whereas a-type = 1, (11) represents the angular distribution by adjusting the number of generated particles, a-type = 4, (14) represents it by generating the same number of particles in all angular bins and making the integrated particle weight in each bin equal to w(i). For continuous energy distribution with double differential type (e-type = 41, 42, 51, 52), if all w(i) are set to 0, the angular distribution specified by the e-type is used as is. The boundary points are given in \(\cos\) for 4 and in degrees for 14. The integral number of particles generated in each bin is proportional to q(i).
na =: Number of angular groups. Data are given in free format as follows.
(a(i), w(i), i = 1, |na|), a(|na|+1)
By default, q-type = 0, the same number of particles is generated in each bin. When q-type = 1 and q(i) is specified, the integrated number of generated particles in each bin is proportional to those values.
q-type = 0, 1: Generation-number option, D = 0.
For 0, q(i)=1 in all bins, and there is no following data.
For 1, the generation number ratio q(i) in each bin is given in the following line.
(q(i), i = 1, na)
5.3.20.3. a-type = 5, (15)¶
The angular distribution, \(d\varphi/d\Omega\), is given by an arbitrary function g(x). The boundary points are given in \(\cos\) for 5 and in degrees for 15.
g(x) =: A function written in Fortran format. Here, x represents the angle. Internal variables and constants can be used. Example: g(x) = exp(-c1*x**2).
nn =: Number of angular groups.
ag1 =: Lower cutoff value of the angular distribution.
ag2 =: Upper cutoff value of the angular distribution.
5.3.20.4. a-type = 6, (16)¶
The same angular distribution as a-type = 5, (15) is generated. However, whereas a-type = 5, (15) represents the angular distribution by adjusting the number of generated particles, a-type = 6, (16) represents it by generating the same number of particles in all angular bins and changing particle weights in proportion to the arbitrary function \(g(x)\). The boundary points are given in \(\cos\) for 6 and in degrees for 16.
g(x) =: A function written in Fortran format. Here, x represents the angle. Internal variables and constants can be used. Example: g(x) = exp(-c1*x**2).
nn =: Number of angular groups. By default, q-type = 0, the same number of particles is generated in each bin. When q-type = 1 and q(i) is specified, the integrated number of generated particles in each bin is proportional to those values.
ag1 =: Lower cutoff value of the angular distribution.
ag2 =: Upper cutoff value of the angular distribution.
q-type = 0, 1: Generation-number option, D = 0.
For 0, q(i)=1 in all bins, and there is no following data.
For 1, the generation number ratio q(i) in each bin is given in the following line.
(q(i), i = 1, nm)