Experimental results related to deuteron-beam production and its correlation with the neutron yield and hard x-ray production in a low-energy plasma focus device (30 kV, 5 kJ) are presented. After performing corrections in the ion energy spectrum (within an ion energy range from 50 keV to 1.5 MeV) for elastic and inelastic interactions of the ions with the background gas, it is found that the ion density at low ion energy is very high and plays an important role in the neutron production of this plasma focus device.