Investigating the influence of gamma ray energies and steel fiber on attenuation properties of reactive powder concrete Shatha D. Mohammed 1 • Wasan Z. Majeed 2 • Nesreen B. Naji 2 • Nada Mahdi Fawzi 1 Received: 7 January 2017 / Revised: 29 March 2017 / Accepted: 31 March 2017 Ó Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Chinese Nuclear Society, Science Press China and Springer Nature Singapore Pte Ltd. 2017 Abstract The effect of gamma ray energies and volume ratio of micro steel fiber (1 and 1.5%) on attenuation properties of reactive powder concrete (70 MPa compres- sive strength) was investigated. Different characteristics have been considered such as linear attenuation coefficient, mass attenuation coefficient, and half-value thickness. Sodium iodide crystal with a gamma ray spectrometer and collimated beam of gamma ray has been implemented to perform the experimental test. Three sources (Cs-137, Co- 60, and Bi-207) with energies of (0.662, 1.17 1.33, 0.569, and 1.063) MeV were adopted in the test. The results obtained indicated that mass attenuation coefficient is proportioned inversely with gamma ray energies and directly with a volume ratio of micro steel fiber. The linear attenuation coefficient and half-value thickness of the tes- ted samples have been calculated and discussed. The obtained results showed that increasing the volume ratio of steel fiber has modified the adequacy of the reactive powder concrete as a shielding element since it increases the density and reduces the half-value thickness. Keywords Radiation shielding Á Attenuation properties Á Gamma radiation Á Density Á Reactive powder concrete 1 Introduction In nuclear science, radiation protection is considered one of the most essential topics. Shielding from gamma rays can be considered as the most difficult one due to the enormous amount of energy held by gamma photons, and since they have no mass and charge, they can readily penetrate into the matter. Radiation shielding is commonly used to protect medical patients and workers from exposure to direct and secondary radiation during diagnostic imaging in hospitals and radiological facilities. The effectiveness of radiation shielding varies significantly with the attenuation properties of the component materials, material thickness, and radiation energy [1], thus there is always a need to develop materials that can be used as shielding material. In a case of nuclear radiation shielding, a huge amount of shielding materials are required, therefore, it is necessary to investigate the efficiency of the available materials, experimentally, before using them [2]. Generally, it is not fare to consider the concrete as a simple mixture of cement, water, and aggregates. It often contains varies mineral components, chemical admixtures, fibers, etc. These com- ponents are usually affecting the characteristics of concrete shielding structures [1]. Also, the cement industry is one of the most common structural materials used in constructions such as home, hospital [3]. For this reason, the type and quantity of aggregates and admixtures are important com- ponents for radiation protection properties of concrete and for its physical and mechanical properties. Different researchers in the field of radiation shielding have been published using different construction materials, different geometries, and different nuclear radiation sources. More- over, a lot of studies are related with linear and mass attenuation coefficients of different materials such as & Nesreen B. Naji nesreen.naji@yahoo.com 1 Department of Civil, College of Engineering, University of Baghdad, Baghdad, Iraq 2 Department of Physics, College of Science, University of Baghdad, Baghdad, Iraq 123 NUCL SCI TECH (2017)28:153 DOI 10.1007/s41365-017-0305-9