= For thia reason it makee it particularly difficult to use a counting inetrument at a pulse accelerator site, The average gamma rate level at such a site may be small, the average level may be rather emall and a typical example of an electron synchroton, the duty cycle may run to 400 microseconds per second and this means to get the instantaneous dose rate one has to multiply the average dose rate by at least 2500, Our final consideration & that had we a perfect flux measuring device with a perfectly flat response to all neu- trom energy, nonetheless we shall have to know something about the neutron energy spectron in order to make an estimate of the permissible flux in a particularregion, At precent our spectro knowledge depends on knowing the maximum originals energy of the neutrons in performing paraffine and cadmium absorption measurements with a free detector. However, should the neutron be pro-~ duced to say 400 MEV or something on this order, then our information is hardly reliable, 9