### Abstract

A procedure for determining the effective thickness of non-uniform irregular-shaped samples via radiative capture is described. In this technique, partial γ-ray production cross sections of a compound nucleus produced in a neutron-capture reaction are measured using Prompt Gamma Activation Analysis and compared to their corresponding standardized absolute values. For the low-energy transitions, the measured cross sections are lower than their standard values due to significant photoelectric absorption of the γ rays within the bulk-sample volume itself. Using standard theoretical techniques, the amount of γ-ray self absorption and neutron self shielding can then be calculated by iteratively varying the sample thickness until the observed cross sections converge with the known standards. The overall attenuation, thus, provides a measure of the effective sample thickness illuminated by the neutron beam. This procedure is illustrated through radiative neutron capture using powdered oxide samples comprising enriched ^{186}W and ^{182}W from which their tungsten-equivalent effective thicknesses are deduced to be 0.077(3) mm and 0.042(8) mm, respectively.

Original language | English |
---|---|

Pages (from-to) | 38-44 |

Number of pages | 7 |

Journal | Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms |

Volume | 362 |

DOIs | |

Publication status | Published - Nov 1 2015 |

### Fingerprint

### Keywords

- (n, γ) radiative capture
- Neutron attenuation
- Partial γ-ray production cross sections
- Prompt Gamma Activation Analysis (PGAA)
- γ-Ray absorption

### ASJC Scopus subject areas

- Instrumentation
- Nuclear and High Energy Physics

### Cite this

*Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms*,

*362*, 38-44. https://doi.org/10.1016/j.nimb.2015.09.003

**Determination of the effective sample thickness via radiative capture.** / Hurst, A. M.; Summers, N. C.; Szentmiklósi, L.; Firestone, R. B.; Basunia, M. S.; Escher, J. E.; Sleaford, B. W.

Research output: Contribution to journal › Article

*Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms*, vol. 362, pp. 38-44. https://doi.org/10.1016/j.nimb.2015.09.003

}

TY - JOUR

T1 - Determination of the effective sample thickness via radiative capture

AU - Hurst, A. M.

AU - Summers, N. C.

AU - Szentmiklósi, L.

AU - Firestone, R. B.

AU - Basunia, M. S.

AU - Escher, J. E.

AU - Sleaford, B. W.

PY - 2015/11/1

Y1 - 2015/11/1

N2 - A procedure for determining the effective thickness of non-uniform irregular-shaped samples via radiative capture is described. In this technique, partial γ-ray production cross sections of a compound nucleus produced in a neutron-capture reaction are measured using Prompt Gamma Activation Analysis and compared to their corresponding standardized absolute values. For the low-energy transitions, the measured cross sections are lower than their standard values due to significant photoelectric absorption of the γ rays within the bulk-sample volume itself. Using standard theoretical techniques, the amount of γ-ray self absorption and neutron self shielding can then be calculated by iteratively varying the sample thickness until the observed cross sections converge with the known standards. The overall attenuation, thus, provides a measure of the effective sample thickness illuminated by the neutron beam. This procedure is illustrated through radiative neutron capture using powdered oxide samples comprising enriched 186W and 182W from which their tungsten-equivalent effective thicknesses are deduced to be 0.077(3) mm and 0.042(8) mm, respectively.

AB - A procedure for determining the effective thickness of non-uniform irregular-shaped samples via radiative capture is described. In this technique, partial γ-ray production cross sections of a compound nucleus produced in a neutron-capture reaction are measured using Prompt Gamma Activation Analysis and compared to their corresponding standardized absolute values. For the low-energy transitions, the measured cross sections are lower than their standard values due to significant photoelectric absorption of the γ rays within the bulk-sample volume itself. Using standard theoretical techniques, the amount of γ-ray self absorption and neutron self shielding can then be calculated by iteratively varying the sample thickness until the observed cross sections converge with the known standards. The overall attenuation, thus, provides a measure of the effective sample thickness illuminated by the neutron beam. This procedure is illustrated through radiative neutron capture using powdered oxide samples comprising enriched 186W and 182W from which their tungsten-equivalent effective thicknesses are deduced to be 0.077(3) mm and 0.042(8) mm, respectively.

KW - (n, γ) radiative capture

KW - Neutron attenuation

KW - Partial γ-ray production cross sections

KW - Prompt Gamma Activation Analysis (PGAA)

KW - γ-Ray absorption

UR - http://www.scopus.com/inward/record.url?scp=84941909546&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84941909546&partnerID=8YFLogxK

U2 - 10.1016/j.nimb.2015.09.003

DO - 10.1016/j.nimb.2015.09.003

M3 - Article

AN - SCOPUS:84941909546

VL - 362

SP - 38

EP - 44

JO - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

JF - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

SN - 0168-583X

ER -