Design and construction of an extended range Bonner spectrometer

In this work we describe the design and construction of an extended range Bonner sphere spectrometer (Bss) intended to be used in the measurement of the energy spectra of neutrons produced by cosmic radiation. A single Bss spectrometer designed and constructed, has been used for a long time as neutron monitor at the tandem accelerator of the National Institute for Nuclear Research (ININ, Mexico). The extended spheres added are 10 and 6 inch diameters with copper, bismuth and lead as inner shells. The measurements are to be initiated at the Physics Institute UNAM Mexico and at the Mexican Nuclear Center, near 3000 meters high. (Author)