Experimental test of the probability density function of true value of   Poisson distribution parameter by single observation of number of events
  The empirical probability density function for the conditional distribution of the true value of Poisson distribution parameter on one measurement is constructed by computer experiment. The analysis of the obtained distributions confirms that these distributions are gamma-distributions. 
S.I. Bityukov, V.A. Medvedev, V.V. Smirnova, Yu.V. Zernii