# Bias in Dynamic Monte Carlo Alpha Calculations

## Abstract

A 1/N bias in the estimate of the neutron time-constant (commonly denoted as α) has been seen in dynamic neutronic calculations performed with MCATK. In this paper we show that the bias is most likely caused by taking the logarithm of a stochastic quantity. We also investigate the known bias due to the particle population control method used in MCATK. We conclude that this bias due to the particle population control method is negligible compared to other sources of bias.

- Authors:

- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

- Publication Date:

- Research Org.:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

- Sponsoring Org.:
- USDOE National Nuclear Security Administration (NNSA)

- OSTI Identifier:
- 1169684

- Report Number(s):
- LA-UR-15-20873

TRN: US1600049

- DOE Contract Number:
- AC52-06NA25396

- Resource Type:
- Conference

- Resource Relation:
- Conference: 18th Biennial Nuclear Explosives Code Development Conference (NECDC), Los Alamos, NM (United States), 20-24 Oct 2014

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 42 ENGINEERING; 97 MATHEMATICS AND COMPUTING; ERRORS; MONTE CARLO METHOD; NEUTRON TRANSPORT THEORY; COMPARATIVE EVALUATIONS; CONTROL; PARTICLES; POPULATIONS; STOCHASTIC PROCESSES; M CODES; Time Dependent Monte Carlo, MCATK

### Citation Formats

```
Sweezy, Jeremy Ed, Nolen, Steven Douglas, Adams, Terry R., and Trahan, Travis John.
```*Bias in Dynamic Monte Carlo Alpha Calculations*. United States: N. p., 2015.
Web.

```
Sweezy, Jeremy Ed, Nolen, Steven Douglas, Adams, Terry R., & Trahan, Travis John.
```*Bias in Dynamic Monte Carlo Alpha Calculations*. United States.

```
Sweezy, Jeremy Ed, Nolen, Steven Douglas, Adams, Terry R., and Trahan, Travis John. Fri .
"Bias in Dynamic Monte Carlo Alpha Calculations". United States.
doi:. https://www.osti.gov/servlets/purl/1169684.
```

```
@article{osti_1169684,
```

title = {Bias in Dynamic Monte Carlo Alpha Calculations},

author = {Sweezy, Jeremy Ed and Nolen, Steven Douglas and Adams, Terry R. and Trahan, Travis John},

abstractNote = {A 1/N bias in the estimate of the neutron time-constant (commonly denoted as α) has been seen in dynamic neutronic calculations performed with MCATK. In this paper we show that the bias is most likely caused by taking the logarithm of a stochastic quantity. We also investigate the known bias due to the particle population control method used in MCATK. We conclude that this bias due to the particle population control method is negligible compared to other sources of bias.},

doi = {},

journal = {},

number = ,

volume = ,

place = {United States},

year = {Fri Feb 06 00:00:00 EST 2015},

month = {Fri Feb 06 00:00:00 EST 2015}

}

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