Measurement of the Effective Neutron Capture Cross Section of Cesium-134 by Triple Neutron Capture Reaction Method

Abstract

The measurement of effective neutron capture cross section() of ¹³⁴Cs was carried out with a method using a triple neutron capture reaction,¹³³Cs(n, γ)¹³⁴Cs(n,γ)¹³⁵Cs(n, γ)¹³⁶Cs. The target used for the experiment was natural cesium(¹³³Cs), and was irradiated for 23 days and 17 hours in the reactor JRR-3 at Japan Atomic Energy Research fnstitute(JAERI). The neutron field of the reactor was monitored by Au/Al and Co/Al alloy wires. A high purity Ge detector was employed for the measurement of γ-rays from the irradiated target and monitor wires. Gamma-rays emitted in the decay of ¹³⁴Cs and ¹³⁶Cs nuclides induced by single and triple neutron capture reactions of ¹³³Cs were seen at the energies of 563, 569. 605, 796, 802, 819, 1,039, 1,048, 1,168 and 1,235 keV. Decays of the 819 and the 1,048 keV γ-ray intensities were followed; it was confirmed that these γ-rays originated in the ¹³⁶Ba, the decay product of ¹³⁶Cs. Data obtained were analyzed with values of neutron capture cross sections of ¹³³Cs and ¹³⁵Cs. The of ¹³⁴Cs obtained is 140.6±8.5 barns and agrees with the value measured by Bayly et al.with a mass analysis method within the limits of error.

KEYWORDS:

• nuclear transmutation
• radioactive wastes
• fission products
• cesium 134
• cesium 136
• activation method
• thermal neutrons
• effective neutron capture cross sections
• gamma ray spectrum
• triple neutron capture reaction
• experimental data