Bob,
There could be some directionality - but after annihilation the two 511 keV gammas should be emitted in wide cone vectors, such that even if there is a statistically preferred vector… something would show up. They are extremely sensitive. IIRC, it was curious that the Bianchini results were slightly less than background. At the time, this seemed to indicate that whatever was going on in the reactor was creating a spatial zone of energy deficit for gamma radiation – which is just the opposite of expectations. From: Bob Cook Jones-- If the positrons were directionally controlled by the magnetic field, Rossi's meter may not have been able to pick them up. Bob
