Copyright © 2011 by JSME 19 th International Conference on Nuclear Engineering May 16-19, 2011, Chiba, Japan. Paper number: ICONE 19-43137 FLUX PROFILE ANALYSIS IN BORON CONCENTRATED PARAFFIN WAX USING β-γ COINCIDENE TECHNIQUE Khurram Mehboob 1,2 1 College of Nuclear Science and Technology Harbin Engineering University Harbin, China khurram@hrbeu.edu.cn Cao Xinrong 1 1 College of Nuclear Science and Technology Harbin Engineering University Harbin, China. caoxinrong@hrbeu.edu.cn Sajjad Ahmed 2 2 Department of physics Govt. College Satellite Town Rawalpindi, Pakistan. Dr,sajjadahmed@hotmail.com INTRODUCTION Many ideas and techniques of atomic and nuclear physics are based on the properties of the radioactive elements and their radiations. Neutron Activation Technique (NAT) is used for neutron flux mapping in homogenous boron concentrated paraffin wax. For this purpose, gold foils as activator detectors were prepared by irradiating process in an Americium-Beryllium ( 241 Am– 9 Be) neutron field. After this, the induced activity was measured by time coincidence method using a Sodium iodide (thallium) NaI (Tl) crystal detector and organic scintillation “Anthracene” detector for gamma ray and beta particle detection respectively. The flux profile was mapped by measuring induced activity. Errors in measurements and calculations were estimated by Poisson distribution. THEORY AND MEASURING METHODS Gold foils can be used as the activator detector. The nuclear interaction on gold is 197 Au (n, γ) 198 Au.This reaction is induced to prepare 198 Au radioisotope. Relation for Incident flux and induced activity is shown in following equation. () ( ) (1 ) (1 ) At M E t t t a c m N W e e e act A φ λ λ λ σ × = − − − − − (1) The model used for induced activity measurements due to irradiation is described as follow. () N N At N tc γ β = (2) The induced activity was measured by 2π-β-γ coincidence method by irradiating the foils in paraffin with homogenous boron concentration tank. Foils were activated at different radii form the source. CONCLUSSIONS Flux profile mapped as the function of paraffin thickness decreases drastically and shows a good argument to the theoretical predicted flux. Theoretical predicted flux expands by considering the source as the point source. Errors are calculated by Poisson distribution. Calculated errors were found to increases exponently. Nominal effects were found for relative an induce activity measurements. 2π-β-γ Coincidence to NAA method is applicable for neutron flux profile mapping in paraffin wax with homogenous boron concentration. REFERENCES B.E Tomlin, R. et al., 2008, “γ-γ coincidence spectrometer for instrumental neutron Activation analysis”, J. Nuclear Instruments and Methods in Physics Research, Vol. 589, pp 243–249 Han Yull Hwang, T.et al., 1999, “Measurement of accidental coincidences for higher activity sources”, J. Nuclear Instruments and Methods in Physics Research, Vol. 425 pp 488 491. Han Yull Hwang, J. et al, 2002, “Measurement of accidental coincidences in β–γ coincidence counting using non-equal dead times”, J. Nuclear Instruments and Methods in Physics Research, Vol. 48, pp 562–56. D. Nichiporova, V. et al., 2004, “Measurement of the activity of 11 C and 22 Na sources using a 4 π- β- γ coincidence system”, J. Applied Radiation and Isotopes, Vol. 60 pp. 703– 716. J. B. BIRKS, 1962, J. PROC. PHYS. SOC. “The Fluorescence and Scintillation Decay Times of Crystalline Anthracene”, VOL. 79, pp 494-496 G.F. Knoll, 1989 “Radiation Detection and Measurement”, 2 nd edition, John Willy and Sons, New York. 226 & 235. URL http://www.kayelaby.npl.co.uk/atomic_and_nuclear_physics/ 4_7/4_7_3.htm