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Persistent URL http://purl.org/net/epubs/work/11215443
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Record Id 11215443
Abstract Monitoring of stray radiation at workplaces characterised by mixed fields with radiation spectra extending over a wide energy range is a difficult task. These mixed fields are usually dominated by neutrons with a more or less pronounced photon contribution, but other radiation components (electrons, muons, pions and protons) cannot always be neglected. Measurements in such complex radiation environments can lead to huge variations in detector readings, due to differences in their energy response function and sensitivity. With the aim of evaluating the performance of various active monitors in a well-characterised mixed field, an intercomparison campaign was carried out in 2012 at the CERN-EU reference field (CERF) facility(1). The CERF stray radiation field is generated by a positive hadron beam (2/3 protons and 1/3 positive pions) with momentum of 120 GeV c21 impinging on a copper target placed inside an irradiation cave. The secondary particles produced in the target traverse an 80-cm concrete shield on top. This roof shield produces an almost uniform radiation field over an area of2`2 m2 located at 908 with respect to the incoming beam direction, divided in 16 squares of 50`50 cm2. Each element of this ‘grid’ represents a reference exposure location (concrete top, CT). The energy distributions of the particles (mainly neutrons) at the various exposure locations were obtained in the past by Monte Carlo simulations performed with the FLUKA code(2,3). The beam is delivered to the CERF facility from the super proton synchrotron (SPS) with a typical intensity of 108 particles per SPS spill. The spill duration (beam extraction time) is 10 s over an SPS cycle of 45 s. The beam spot is approximately rectangular, 30 mm` 40 mm. The beam monitoring is provided by an air-filled ionisation chamber (IC) placed in the beam a few meters upstream of the target. One IC count corresponds to 2.2.104 beam particles(1).
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Journal Article Radiation Protection Dosimetry Advance Access (2013): 1-6. Cockcroft-13-51.pdf 2013