Neutron sensing at spallation neutron sources by SERS

Abstract

Neutron detectors are paramount in many applications from medical science to homeland security and aerospace. A miniaturized solid-state device based on a nanostructured-gold thin film grown by pulsed laser ablation under deposition-controlled conditions and functionalized with a monolayer of 4-mercaptophenyboronic acid (4-MPBA) was fabricated as a neutron dose detector. The device is tested with slow neutron detection in the thermal and epithermal energy range at ISIS spallation neutron source (UK). After the neutron irradiation, 4-MPBA is converted into thiophenol (TP), and the chemical modification is monitored by the intensity of related vibrational bands at 1586 cm−1 (4-MPBA) and 1574 cm−1 (TP). The latter are used as a vibrational signature of the absorbed dose by surface-enhanced Raman spectroscopy (SERS). The conversion of 4-MPBA to TP is due to the loss of the boron-containing group after the absorption of a slow neutron by 10B isotope. The I1574/I1586 ratio is used to estimate the ratio of 10B nuclei absorption reactions due to the thermal and epithermal contributions and it is proposed for the development of neutron dosimetry for nuclear medicine, aerospace, and security applications.