If a non-thermalised positronium enters a pore, how to calculate the number of collisions with its internal surface before annihilation having the positronium's energy and lifetime?

- Did Tao-Eldrup and its extensions consider this type of interactions  or only the interaction with a certain thickness of the pore walls (delta R) was considered?

- For conventional Positron annihilation lifetime NOT pulsed slow positron beam, can we determine such a number of collision?

Thanks in advance