The Effects of Boron on the Electron Paramagnetic Resonance Spectra of Alanine Irradiated with Thermal Neutrons

Abstract

The effects of boric acid admixture on the intensity and line structure of EPR spectra of free radicals produced in alanine by thermal neutrons are presented. The EPR signal enhancement, up to a factor of 40 depending on the boron concentration, is related to additional energy deposition in alanine crystals by the disintegration products resulting from the capture of a thermal neutron by boron, 10B(n,alpha)7Li. The changes in the shape of the EPR spectra observed by changing the microwave power are due to the differences in the microwave power saturation of the free radicals produced by a low-LET radiation and those produced by the high-LET components of the radiation after the neutron capture reaction.

Formation of different types of paramagnetic centers in the alanine dosimeters exposed to alpha and gamma radiation - Study by EPR spectroscopy

“…Dependence of the X/Y ratio for alpha-IAD versus the X/Y ratio for gamma-IAD is presented in Fig 10a . The linear regression slope of this dependence gives the parameter S = 0.65±0.01. This value is close to the value S = 0.69±0.03 obtained by (Ciesielski et al, 1995(Ciesielski et al, , 1998 for the products of nuclear reaction of neutrons with alanine and boron mixture (0.84 MeV lithium ions and 1.5 MeV alpha particles).…”

“…In order to compare with results of other authors (Ciesielski et al 1995(Ciesielski et al , 1998, we have measured dependences of amplitudes of X and Y components of gamma-and alpha-IAD on the mw power. Amplitudes of the X and Y lines were measured as differences between their maximum and minimum at same field positions for spectra measured at different mw power.…”

The alanine detector in BNCT dosimetry: Dose response in thermal and epithermal neutron fields

“…[10][11][12][13] Most studies on neutrons have been carried out with fast neutron energies in the MeV region and without distinction of dose components. [14][15][16] Charged and uncharged ionizing particles generate radicals in alanine. These are detected and quantified using electron spin resonance (ESR) spectrometry.…”

A preliminary optimization of alanine blends for ESR dosimetry in a mixedn–γ field: Monte Carlo simulation

“…Many studies have been carried out to determine the ESR response of various dosimeters that are composed of a powder mixture of boron compounds and an ESR sensitive material such as alanine, for measurement in either neutron beams or mixed n-γ fields [19,[24][25][26][27]. Their main objective has been to achieve a significant increase in the amount of energy deposition in the ESR…”