Comparison of theory with experiment for positron production from   high-energy electrons moving along crystal axes
  Various positron distributions are obtained using an approach developed earlier for the description of electron-photon showers in axially aligned single crystals. Based on these distributions, characteristics of the positron yield measured in recent experiments are calculated. Theoretical estimations display a rather good agreement with experimental results obtained using 3 to 10 GeV electrons aligned to the <111> - axis of the tungsten crystals. 
V. N. Baier and V. M. Strakhovenko