# A Weighted Point Model for the Thermal Neutron Multiplicity Assay of High-Mass Plutonium Samples

## Abstract

A weighted point model for thermal neutron multiplicity counting has been developed for the assay of impure plutonium metal samples. Weighting factors are introduced for the spontaneous fission and ({alpha},n) contributions to the doubles and triples rates to account for the variations in neutron multiplication in these samples. The weighting factors are obtained from Monte Carlo simulations using the MCNPX code, which supports the simulation of spontaneous fission sources and can tally the source and detected neutron multiplicity distributions. Systematic behavior of the weighting factors was studied as a function of sample mass and geometry. Simulations were performed to evaluate the potential accuracy of assays performed with weighted point model analysis. Comparisons with experimental data are presented. The possible use of quads rates is explored.

- Authors:

- Publication Date:

- Research Org.:
- Office of Scientific and Technical Information, Oak Ridge, TN; Los Alamos National Laboratory (LANL), Los Alamos, NM

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 876505

- Report Number(s):
- LA-14157

TRN: US0601047

- DOE Contract Number:
- W-7405-ENG-36

- Resource Type:
- Technical Report

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; GEOMETRY; MULTIPLICITY; NEUTRONS; PLUTONIUM; SIMULATION; SPONTANEOUS FISSION; THERMAL NEUTRONS

### Citation Formats

```
Krick, M S, Geist, W H, and Mayo, D R.
```*A Weighted Point Model for the Thermal Neutron Multiplicity Assay of High-Mass Plutonium Samples*. United States: N. p., 2005.
Web. doi:10.2172/876505.

```
Krick, M S, Geist, W H, & Mayo, D R.
```*A Weighted Point Model for the Thermal Neutron Multiplicity Assay of High-Mass Plutonium Samples*. United States. doi:10.2172/876505.

```
Krick, M S, Geist, W H, and Mayo, D R. Sat .
"A Weighted Point Model for the Thermal Neutron Multiplicity Assay of High-Mass Plutonium Samples". United States. doi:10.2172/876505. https://www.osti.gov/servlets/purl/876505.
```

```
@article{osti_876505,
```

title = {A Weighted Point Model for the Thermal Neutron Multiplicity Assay of High-Mass Plutonium Samples},

author = {Krick, M S and Geist, W H and Mayo, D R},

abstractNote = {A weighted point model for thermal neutron multiplicity counting has been developed for the assay of impure plutonium metal samples. Weighting factors are introduced for the spontaneous fission and ({alpha},n) contributions to the doubles and triples rates to account for the variations in neutron multiplication in these samples. The weighting factors are obtained from Monte Carlo simulations using the MCNPX code, which supports the simulation of spontaneous fission sources and can tally the source and detected neutron multiplicity distributions. Systematic behavior of the weighting factors was studied as a function of sample mass and geometry. Simulations were performed to evaluate the potential accuracy of assays performed with weighted point model analysis. Comparisons with experimental data are presented. The possible use of quads rates is explored.},

doi = {10.2172/876505},

journal = {},

number = ,

volume = ,

place = {United States},

year = {2005},

month = {10}

}