# A midway forward-adjoint coupling method for neutron and photon Monte Carlo transport

## Abstract

The midway Monte Carlo method for calculating detector responses combines a forward and an adjoint Monte Carlo calculation. In both calculations, particle scores are registered at a surface to be chosen by the user somewhere between the source and detector domains. The theory of the midway response determination is developed within the framework of transport theory for external sources and for criticality theory. The theory is also developed for photons, which are generated at inelastic scattering or capture of neutrons. In either the forward or the adjoint calculation a so-called black absorber technique can be applied; i.e., particles need not be followed after passing the midway surface. The midway Monte Carlo method is implemented in the general-purpose MCNP Monte Carlo code. The midway Monte Carlo method is demonstrated to be very efficient in problems with deep penetration, small source and detector domains, and complicated streaming paths. All the problems considered pose difficult variance reduction challenges. Calculations were performed using existing variance reduction methods of normal MCNP runs and using the midway method. The performed comparative analyses show that the midway method appears to be much more efficient than the standard techniques in an overwhelming majority of cases and can bemore »

- Authors:

- Delft Univ. of Technology (Netherlands). Interfaculty Reactor Inst.

- Publication Date:

- OSTI Identifier:
- 687542

- Resource Type:
- Journal Article

- Journal Name:
- Nuclear Science and Engineering

- Additional Journal Information:
- Journal Volume: 133; Journal Issue: 1; Other Information: PBD: Sep 1999

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 66 PHYSICS; 44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; NEUTRON TRANSPORT; PHOTON TRANSPORT; ADJOINT DIFFERENCE METHOD; MONTE CARLO METHOD; RADIATION DETECTORS; RESPONSE FUNCTIONS

### Citation Formats

```
Serov, I.V., John, T.M., and Hoogenboom, J.E.
```*A midway forward-adjoint coupling method for neutron and photon Monte Carlo transport*. United States: N. p., 1999.
Web.

```
Serov, I.V., John, T.M., & Hoogenboom, J.E.
```*A midway forward-adjoint coupling method for neutron and photon Monte Carlo transport*. United States.

```
Serov, I.V., John, T.M., and Hoogenboom, J.E. Wed .
"A midway forward-adjoint coupling method for neutron and photon Monte Carlo transport". United States.
```

```
@article{osti_687542,
```

title = {A midway forward-adjoint coupling method for neutron and photon Monte Carlo transport},

author = {Serov, I.V. and John, T.M. and Hoogenboom, J.E.},

abstractNote = {The midway Monte Carlo method for calculating detector responses combines a forward and an adjoint Monte Carlo calculation. In both calculations, particle scores are registered at a surface to be chosen by the user somewhere between the source and detector domains. The theory of the midway response determination is developed within the framework of transport theory for external sources and for criticality theory. The theory is also developed for photons, which are generated at inelastic scattering or capture of neutrons. In either the forward or the adjoint calculation a so-called black absorber technique can be applied; i.e., particles need not be followed after passing the midway surface. The midway Monte Carlo method is implemented in the general-purpose MCNP Monte Carlo code. The midway Monte Carlo method is demonstrated to be very efficient in problems with deep penetration, small source and detector domains, and complicated streaming paths. All the problems considered pose difficult variance reduction challenges. Calculations were performed using existing variance reduction methods of normal MCNP runs and using the midway method. The performed comparative analyses show that the midway method appears to be much more efficient than the standard techniques in an overwhelming majority of cases and can be recommended for use in many difficult variance reduction problems of neutral particle transport.},

doi = {},

journal = {Nuclear Science and Engineering},

number = 1,

volume = 133,

place = {United States},

year = {1999},

month = {9}

}