Determination of thermal neutron radiative capture cross section of 6Li

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Abstract

The thermal neutron radiative capture cross section of 6Li was determined relative to the 1H(n,γ) reaction emitting the 2223.25 keV γ-ray. The sample used was a mixture of enriched 6Li2CO3 and melamine. Background correction was performed by considering the scattering effect of the sample. The determined thermal neutron radiative capture cross section of 6Li was 37.7 ± 3.0 mb.

Introduction

The thermal neutron capture cross section of 6Li(n,γ)7Li is small, and only a few measured data have been reported. These are, however, not consistent well [1].

Due to the simple structure of the nuclear levels of 7Li, the radiative capture cross section of 6Li can be obtained simply by summing the partial cross sections for the two primary transitions. An exhaustive listing of previously reported data for partial cross sections of the primary transition γ-rays of 6Li(n,γ)7Li and the radiative capture cross section is shown in Table 1. The cross sections vary by ∼30%, from 29 to 53 mb. In contrast, the 7Li cross section has been reported consistently as being about 45 mb [4], [5], [6], [8], [9]. This study was performed to accurately measure the capture cross section of 6Li by observing the primary transition γ-rays and carefully considering background variation depending on the amount of neutron scattering from target samples.

Section snippets

Experiment

Measurements were performed at a thermal neutron beam line at HANARO of the Korea Atomic Energy Research Institute. A detailed description of the facility is given elsewhere [10], [11]. The true integrated neutron flux at the sample position was increased to 1.0 × 108 n/cm2 s, and the Cd-ratio was over 200. A HPGe detector with a relative efficiency of 43% was used. Typical resolution (FWHM) was 2.5 keV for the 60Co 1332 keV γ-ray. In the original installation, LiF tiles were attached inside the lead

Analysis and results

Among the background peaks in this study, the typical capture γ-rays from Pb, Fe, Al have been reported [10], [16] and Mn was newly added after many hours measurement because of small count rate. Background peaks interfering with the 6Li peak were identified originating from Fe and Mn, as shown in Fig. 2, Fig. 3. In Fig. 4, 1H peak was interfered by Ge peaks [17], too. Peak areas were analyzed with HYPERMET code [18]. It fits the region by a Gaussian function with skew parameters and a

Conclusions

The radiative capture cross section of 6Li was determined in this study using enriched samples of confirmed abundance. The relative measurement with comparator 1H was performed to consider the varying irradiation condition. Background peaks originating from common materials interfered with the 6Li peaks. They could not be resolved by mathematical analysis routine. Therefore, the background peaks in the Li peak region were effectively estimated by considering the size of the scattering effect

Acknowledgement

This work was supported by the Nuclear R&D Program of the Korean Ministry of Science and Technology.

References (21)

  • G.L. Molnár et al.

    Appl. Radiat. Isot.

    (2000)
  • Y. Nagai et al.

    Nucl. Instr. and Meth. B

    (1991)
  • S.H. Byun et al.

    Nucl. Instr. and Meth. A

    (2002)
  • Z. Kis et al.

    Nucl. Instr. and Meth. A

    (1998)
  • P.J.J. Kok et al.

    Nucl. Instr. and Meth. B

    (1985)
  • S.R. Biegalski et al.

    Nucl. Instr. and Meth. B

    (2006)
  • G.W. Phillips et al.

    Nucl. Instr. and Meth. B

    (1976)
  • S.F. Mughaghab, INDC(NDS)-440 (2003)...
  • G.A. Bartholomew et al.

    Can. J. Phys.

    (1957)
  • L. Jarczyk et al.

    Helv. Phys. Acta

    (1961)
There are more references available in the full text version of this article.

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1

Present address: Radiological and Medical Research Center, Korea Institute of Radiological and Medical Sciences, Seoul 139-709, South Korea.

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