Lateral distribution cosmic ray muon coincidences up to 36 m.

Primary cosmic ray particles comprise about 85 % protons, 12 % helium, 3 % iron, and heavier elements. These particles interact with the Earth's atmosphere, generating the Extensive Air Showers (EAS). Among the particles produced are pions and kaons, which decay into cosmic ray muons. In this research, the lateral distribution of cosmic ray muons was measured using two-fold coincidences. Four NaI (Tl) detectors and the associated electronics were used in the measurements of cosmic ray muons. The detectors were positioned from 0 to 36 m at regular intervals. The muon count rate was observed to decrease as the distance between the detectors increased. The measurements were fitted to the Nishimura-Kamata-Greisen (NKG) function to analyze the lateral distribution. Monte Carlo (MC) simulations of EAS were performed using the Cosmic Ray Simulations for the KAscade Grande (CORSIKA) program. The simulations made use of EPOS and GHEISHA models for high and lower energies respectively.•The measurements for the two-fold coincidence are consistent with the NKG function.•The simulated and measured data were found to be in agreement.•The knowledge gained from the lateral distribution of cosmic ray muons is essential for the understanding of the development of extensive air showers.

Assessment of radioactivity concentration for building materials used in Babadogo Estate, Nairobi City County, Kenya.

Natural radioactive materials in certain conditions can get to hazardous radiological level. The aim of the present work was to evaluate the natural activity concentration from sampled building materials collected from different locations in Babadogo Estate within Nairobi City County. The analysis done using gamma ray spectrometer, which was put into action for spectral data acquisition and then analysis. The activity concentration levels of 238U, 232Th and 40K for the selected samples of building materials was measured by the use of gamma ray spectrometry method. The analyzed data compared with the standard acceptable values. The activity concentration in 40K varied from 55 ± 3 to 2647 ± 132 Bq kg-1, giving an average (sum of all values divided by 33) value of 831 ± 42 Bq kg-1; 238U varied from 39 ± 2 to 3602 ± 180 Bq kg-1, giving average figures of 378 ± 19 Bq kg-1 and 232Th ranged from 5.000 ± 0.300 to 4213 ± 211 Bq kg-1, giving average figure of 290 ± 15 Bq kg-1. The calculated average figures for activity concentration surpassed the world average values of 420, 33 and 45 Bq kg-1 in 40K, 238U and 232Th, respectively.

Human health risk assessment of heavy metal concentration in surface water of Sosian river, Eldoret town, Uasin-Gishu County Kenya.

Heavy metal pollution in surface waters has become a major worldwide issue as people tend to settle where there is readily available source of water like a river. This research evaluates the causes, concentration and associated health risks of heavy metals in River Sosiani as it passes through the town of Eldoret. Seven water samples were collected and analysed for zinc (Zn), copper (Cu) and lead (Pb. The results disclosed that Pb concentrations were estimated to be in the range of 0.06 mg/l to 0.23 mg/l, higher than the permitted limit by WHO of 0.01 mg/l. Cu and Zn concentration levels were below the permissible limits. The chronic daily intake (CDI) indicated that total hazard quotient of non-cancer risk of Pb was above one and the total HI values for children were greatly elevated compared to those of adults in the studied area. This showed a high risk in exposure to Pb. Health human risk was assessed and the incremental life cancer risk (ILCR) values of Pb for children and adults in all sites were found to be negligible with values below 10-6. However, there is higher cancer and non-cancer risk for children than adults as far as lead metal is concerned. Therefore, measures should be taken in accordance with the standards to prevent potential risk of the river pollution.•Human activities make a significant contribution to heavy metal pollution to surface waters which is a threat to humans.•Water from Sosiani River is not safe for use domestically as far as lead metal levels are concerned.•The results of this study can be used by decision makers to develop measures which can improve the quality of water in the river catchment.

MEASUREMENT OF RADON ACTIVITY CONCENTRATION IN UNDERGROUND WATER OF BURETI SUB-COUNTY OF KERICHO COUNTY KENYA.

The activity concentration of radon in underground water of Bureti sub-county was measured using liquid scintillating counter device. The average radon activity concentration in all the water samples was 12.41 Bql-1. The maximum and minimum activity concentrations of radon were 22.5 and 4.57 Bql-1, respectively. In total, 53% of the total samples analysed had radon concentration levels above the US Environmental Protection Agency-recommended limit of 11.1 Bql-1. The annual dose received by an individual as a result of waterborne radon was determined according to the United Nations Scientific Committee on the Effect of Atomic Radiation reports and was found to be 33.23 ðœ‡Svy-1. All the samples recorded a value <100 ðœ‡Svy-1 recommended by the World Health Organization and the European Union council.