How to use PHITS-UDM

Contents

• How to use PHITS-UDM

  • How to write input files

  • Explanation of sample code / How to create user code

How to write input files

[ parameters ] section

To use the PHITS-UDM, the following parameter must be written in the [ parameters ] section.

Parameter	Value	Description
iudmodel	=0	Off PHITS-UDM (default)
	=1	On PHITS-UDM

Example)

[ parameters ]

iudmodel = 1

[ user defined interaction ] section

Describe the following four types of information:

1. Number of interaction modules to use

   • Assign the number to n_int

2. Names of the interaction to used

   • The string assigned to Name in the corresponding user code udm_int_*.f90.

3. Biassing factor

   • You should set it to 1 by default.

   • Setting a value greater than 1 increase the frequency of interactions with small cross sections. In this case, the weight of the generated particles are less than 1.

4. Parameters

   • Enter the parameters for each interaction module.

   • If no parameters are needed, do not enter any.

   • If you have more than one, enter them separated by spaces.

Example)

[ user defined interaction ]
  n_int = 3

$ Name               Bias   Parameters
  my_interaction_1   1
  my_interaction_2   100    900000
  my_interaction_3   100    900000  1.1  2.2

[ user defined particle ] section

Describe the following four types of information:

1. Number of particle modules to use

   • Assign the number to n_part

2. Names of the particle to used

   • The string assigned to Name in the corresponding user code udm_part_*.f90.

3. kf-code

   • Enter the kf-code you want to assign to the particle.

   • For particles not defined in PHITS, the allowed kf-code range is as follows: \(900000 \le \text{|kf-code|} \le 999999\)

4. Parameters

   • Enter the parameters for each particle module.

   • If no parameters are needed, do not enter any.

   • If you have more than one, enter them separated by spaces.

Example)

[ user defined particle ]
  n_part = 2

$ Name             kfcode   Parameters
  my_particle_1    900000
  my_particle_2   -999999   1.0  2.0

Explanation of sample code / How to create user code

See this note.

User code must be written in Fortran 90. Fortran 90 is a simple language and does not require complex syntax to write user code. Even if you are unfamiliar with programming, you can create your user code by referring to [User Code Collection].