New constraints from Haverah Park data on the photon and iron fluxes of   UHE cosmic rays
  Using data from inclined events ($60^{\circ}<\theta<80^{\circ}$) recorded by the Haverah Park shower detector, we show that above 10^19 eV less than 30% of the primary cosmic rays can be photons or iron nuclei at the 95% confidence level. Above 4 10^19 eV less than 55% of the cosmic rays can be photonic at the same confidence level. These limits place important constraints on some models of the origin of ultra high energy cosmic rays. Details of two new events above 10^20 eV are reported. 
M. Ave (1), J.A. Hinton (2), R.A. Vazquez (1), A.A. Watson (2), and E.   Zas (1) ((1) Departamento de Fisica de Particulas, ...