iy ae B& ~ ‘ Ne t” keon> i - 7} , eeTAX«4: Nk ate a The instrument to be sensitive to gamma radiation and the wall of the chamber to be composed of a material with the atomic number less than ten such that the instrument would be wave length independent from all X and garma radiation with enerries above 5 Kvp, and beta particles with energies less than 1.0 MEV to be excluded, h, The circuit time constant to be such that 90% 4. The instrument: to operate under the above requirements over ranges of temperatures from mimus 5° C to 70° C and with the relative humidity of 95% af ' je ‘ ’ wh]? IMCLASSIFIED | of the final reading of the instrument would be reached within 10 seconds or less. for a period of twenty-four hours. The instruments to be baitety operated with ¢a battery Life which would provide operation for 30 days at a rate of S hours continuous each day, Batteries to be easily checked and replaced, Standard Army-Navy types of batteries suitable for tropical use were desired, It was realized that some of the above specifivations would not be completely met and same relaxation of the requirements were anticipated, On 6 January 1946 a letter was recoived from Lr. Adrian Dahl (AEC) who had been attempting to place the contract for the MX with the National Technical Laboratories, The National Technical laboratories requested the following changes be mide in the specifi-~ cations outlined above: a. b. Ce d. e. The warm-up period should be increased from one minute to two minutes, The microphonic specifications be modified to include a sero shift of not more than 2% of full scale on any one of the drops during ths microphonics tests, Range of temperature from mimis 5° C to 50° ¢ with operation up to and above 70° C desired, The battery life to be 25 days at a rate of 8 hours continuous each day. The maximum exposure readable on the rroposed instrument would be 5000 mr per hour, ~18-+ ee” * ?