Alvager et al 1964 purportedly disproved Ritz's emitter theory in an experiment that generated neutral pions with a vellocity of $v =B.c$ where B is slightly smaller than one. How is the velocity of a neutral pion determined? Does the determination invoke special relativity?
Added: Alvager et al (http://mysite.verizon.net/cephalobus_alienus/papers/Alvager_et_al_1964.pdf) beamed a burst of high energy protons at a beryllium crystal and measured arrival times of burst of emitted photons at downstream detectors. Their theory said that the photons were emitted from decay of neutral pions produced from collision of the protons with beryllium and that these pions had a speed of $v = B.c$. Time intervals between output burst being detected at different detectors indicated that photons were travelling at very close to $1.0c$ rather than at a range of values between $c -k.B.c$ and $c + k.B.c$ with $k>0$ which (they said) would have been the case if emission/ballistic/galilean theory/model applied. ( Sorry I dont know where I got my earlier value of $k.B = 0.2$ from...Actually I got it from Velocity of Gamma Rays from a Moving Source T. A. Filippas and J. G. Fox, Phys. Rev. 135, B1071 – Published 24 August 1964 ).
I pose the question because it seems that Alvager et al were trying to prove special relativity (SR) by assuming pion velocities which were themselves determined assuming SR.
Anna V has answered the question of pion velocity measurement for me (Thankyou!).
Regarding the interpretation of the Alvager experiment the following note is interesting: (http://worldnpa.org/pipermail/memberschat_worldnpa.org/attachments/20090115/db6f6bc5/attachment.pdf).