Assimilation of a cylindrical geometry inside a Rossi counter

Single event distributions were measured in neutron fields of different energies to appraise the response of Rossi type proportional counters operating in helix mode. Spectra acquired with tissue-equivalent and carbon walled counters operating in conventional and helix modes exemplify the intrinsic differences in chord length distributions for sensitive volumes of different shapes. An active volume in the form of an elongated cylinder was empirically assessed for the helix mode of operation following exposure to a known dose. This volume definition enabled conversion of pulse height data to absorbed dose spectra in lineal energy. Calibration of spectra was possible by identifying cut-off edges discerned for different particle species. The dosimetric data were consistent with those obtained when running the counters conventionally and demonstrate the suitability of helix mode for time-resolved kerma assessments in high energy neutron fields. (author)