Measurement of energetic (>6 MeV) particles in wire array pinches on PBFA Z

Summary form only given. Sandia National Laboratories has modified the PBFA II accelerator into a Z-pinch configuration. To date, PBFA Z has generated X-ray yields exceeding 1 MJ and 100 TW. The loads consist of cylindrical, tungsten wire arrays. Nuclear activation and shielded scintillator measurements indicate that particles are being produced in the pinch that have energies that greatly exceed the nominal applied voltage of 2.5 to 3 MV. In particular, we have observed Co-56 and Mn-52m activation on the stainless steel cathodes. The only credible production mechanisms for these nuclides in PBFA Z are (p,n) reactions on Fe-56 and Cr-52. Since the thresholds for these reactions are 5.44 and 5.98 MeV, respectively, we argue that protons having energies greater than about 6 MeV are produced in the pinch. In addition, we have observed significant photon signals on a plastic scintillator that was shielded by 6 cm of lead. Simple gamma-ray attenuation arguments suggest that there is a considerable fluence of photons having energies greater than 1 MeV. These photons could be gamma rays produced in prompt (p,/spl gamma/) reactions and/or bremsstrahlung X-rays produced by energetic electrons.