The energy straggling of proton beams in ${\mathrm{SiO}}_2$ has been measured in the energy range from 30 to 1500 keV using the transmission, nuclear reaction analysis and Rutherford backscattering techniques. The experimental results are compared with theoretical models. We observe that at energies around 200 keV the values obtained are larger than theoretical estimations. The straggling effect produced by the electron bunching in molecular media was calculated and it was found to be a possible cause of these differences at intermediate energies.

• Received 7 May 2003

DOI:https://doi.org/10.1103/PhysRevA.68.042903