Characterization of RA-1 nuclear reactor neutron flux for a prompt-gamma boron trace detection device

D. MINSKY; A. BURLON; A. KREINER; A. VALDA

Santos, Brasil. Presentación mural

Congreso; V Latinoaerican Symposium on Nuclear Physics, XXVI Reunião de Trabalho sobre Física Nuclear no Brasil; 2003

Sociedade Brasileira de Física

Boron neutron capture Therapy (BNCT) is an alternative for conventional radiotherapy, currently under developmentfor the treatment of some types of cancer. BNCT is based on the selective administration of a 10B-labeled drug totumor cells, followed by a thermal neutron irradiation. The neutrons are captured in 10B nucleus by means of the10B(n,alpha)7Li reaction. 7Li and 4He fragments are released with a large kinetic energy (of the order of 1 MeV each),which they deliver to the tumor cells to cause inactivation. The knowledge of the distribution and concentration of 10B is essential for the success of the therapy, hence a method for evaluating the drugs is needed. In this work, theneutron flux at the entrance of CNEA´s RA-1 nuclear research reactor thermal column was characterized by the foilactivation technique in order to develop a device to quantify 10B concentration in biological samples by prompt-gammaanalysis. The device is essentially a properly shielded  ray detector. The method consists in irradiating the samplewith a thermal-neutron beam and counting the 478 keV  rays emitted immediately after neutron capture in 10B.The characterization requires the measurement of the thermal flux, which is responsible for the capture reaction, andthe epithermal and fast neutron fluxes in order to design the shielding to prevent damage to the detector. A thermalflux of (2.9±0.2)106 neutrons/cm2s, and a (3.0±0.2)105 neutrons/cm2s epithermal plus fast flux were obtained. A shielding for the device is discussed.