Akademik Veri Yönetim Sistemi
Communications Faculty of Sciences University of Ankara Series A2-A3: Physical Sciences and Engineering, cilt.63, sa.2, ss.93-117, 2021 (TRDizin)
Abstract. This study shows the design, implementation, and test results of a lowcost portable radiation-detector system relies on a directionally designed multi
detector probe that works in Geiger-Müller counting mode with a single chip
solution. The proposed system can perform the functions of detecting the ionizing
radiation source, counting gamma and showing the direction and angle of the
gamma source relative to the position of the device. The radiation direction finding
(RDF) system consists of a radiation probe and electronic sections that are mounted
in a metal box. The probe has a has a cast housing made of lead material and it has
8 directional slots for placing the optically isolated PIN diode arrays where each
array consists of 4 parallelly connected BPW 34 PIN model diode. The lead housing
also blocks incident rays from unintended directions and provides a directional
sensing for PIN diodes. The metal box contains 8 low noise amplifiers and pulse
shaping detector boards that are assigned to each channel of PIN diode arrays, a
signal inverter board, a step-up high voltage board, a 12 V battery and a parallel
processing FPGA board with an embedded VHDL software that can process all 8
channels simultaneously and execute the direction estimation algorithm. The
system also has an adjustable detector bias voltage and the applied voltage can be
displayed on a seven-segment display located in front of the unit so that different
models of PIN diodes can be used and tested with different bias voltage levels. It
also has a HMI touch screen unit and user interface for displaying the Cpm or Cps
values of each channel; a 360-degree scale showing the direction of the source with
its pointer and an indicator showing the direction of the source numerically in
degrees. The system works as a gamma detector and the source direction can also
be detected within ±45° interval. The success of system within this interval is
99.22%. The detector was tested with low to high energy gamma sources (241Am,
9.761 μCi, 59.54 keV, 137Cs 661, 3.7 MBq, keV and 60Co, μCi, 1173 and 1332 keV)
and showed good sensitivity performance level in gamma ray detection. The major