Research Article
Calibration of LR-115 Type II SSNTDs and Indoor Radon-222 Assessment in Man, Côte d'Ivoire
Issue:
Volume 14, Issue 1, February 2026
Pages:
1-11
Received:
26 November 2025
Accepted:
14 January 2026
Published:
27 January 2026
Abstract: This study focused on the calibration of LR-115 type II solid-state nuclear track detectors (SSNTDs) and the assessment of indoor radon-222 concentrations in dwellings in Man, Côte d’Ivoire. Detector calibration was performed in a certified radon chamber by exposing the LR-115 to a radon concentration of 2.29 kBq·m⁻3 for 64.33 h. After chemical etching and microscopic analysis, a calibration factor of 198.35 ± 21.43 tr/cm2/kBq·m-3·h was obtained. Twenty-six detectors were then deployed in dwellings for three months. Radon concentrations ranged from 52.13 to 219.4 Bq/m3, with an average of 119.69 ± 13.36 Bq/m3 (120 Bq.m-3). Most measured values were below internationally recommended reference levels; however, several sites (M1, M6, M9, M14 and M18) exceeded 150 Bq·m-3. Apart from geological factors, elevated concentrations were mainly associated with poor ventilation and low foundation height. Excess cancer risk (ECR), estimated using EPA and UNSCEAR coefficients, showed significant spatial variability. According to the EPA model, ECR values ranged from 32 to 98 for site M19 and from 134 to 410 for site M14, while UNSCEAR-based estimates ranged from 41 to 111 at M19 and from 174 to 469 at M14. Corresponding annual effective doses varied between 2.09 and 8.81 mSv·y-1. These findings highlight the spatial variability of indoor radon concentrations linked to local geology and building characteristics, and provide essential baseline data for radon mapping and risk mitigation strategies in Côte d’Ivoire. The results support targeted ventilation improvements and foundation design considerations within existing housing stock without altering measured.
Abstract: This study focused on the calibration of LR-115 type II solid-state nuclear track detectors (SSNTDs) and the assessment of indoor radon-222 concentrations in dwellings in Man, Côte d’Ivoire. Detector calibration was performed in a certified radon chamber by exposing the LR-115 to a radon concentration of 2.29 kBq·m⁻3 for 64.33 h. After chemical etc...
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Research Article
Study on a Parameterized Scalar Field Model
Issue:
Volume 14, Issue 1, February 2026
Pages:
12-17
Received:
22 September 2025
Accepted:
6 November 2025
Published:
16 March 2026
DOI:
10.11648/j.ajpa.20261401.12
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Abstract: In the theory of Brans-Dicke (BD) scalar-tensor gravity, different models have been proposed for different potential functional types, usually by setting the scalar field to the power function form of the cosmic distance factor (power exponent is constant). However, in previous studies, the observational limitation in the solar system range of the coupling parameter (BD coupling parameter) between the BD scalar field and gravity is obtained from negative values to several thousand. In particular, previous studies investigating holographic scalar field models using cosmological holographic principle, in which the BD scalar field is placed in the form of a power function of the cosmic distance factor, have considered the problem of accelerated expansion of the late universe and cosmological coincidence problem, but none of the models have been fully explained. However, the use of a model with the coupling strength of dark matter and dark energy as a non-constant variable requires parameterization, provided that previous studies have been conducted to address the problem of Hubble constant tension and cosmological coincidence. Therefore, in this study, we construct a scalar field model that generalizes the exponent in the expression of the scalar field to a function of the redshift using well-known Jassal-Bagla-Padmanabhan (JBP) parameterization in cosmology, and obtain a cosmological constraint on the BD coupling parameter, in the context of the theory of BD scalar-tensor gravity, not the Einstein’s theory of tensor gravity, and show that the accelerating expansion of the late Universe and cosmological coincidence problem are well explained by the proposed model. First, we solve the continuity equation under the assumption that there is no interaction between matter and the scalar field, and obtain an analytical expression for the energy density of the mass and the BD scalar field. Then, using 580 supernova observations, the best-fitting values of the proposed model parameters and the range of values of the parameters at different confidence levels are obtained by minimizing the chi-square function. We have obtained the result that the scalar field decreases, the BD coupling parameter increases, and the current value of BD coupling parameter is around -1.746, from past to present. Also, the coincidence parameter now converges to 1, so that the problem of cosmic coincidence problem is alleviated by the proposed model, and the rate of change of the gravitational constant is considered.
Abstract: In the theory of Brans-Dicke (BD) scalar-tensor gravity, different models have been proposed for different potential functional types, usually by setting the scalar field to the power function form of the cosmic distance factor (power exponent is constant). However, in previous studies, the observational limitation in the solar system range of the ...
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,
Aka Antonin Koua
