Kinematics
kinematics for ultra peripheral collisions for SPS fixed-target experiments:
For an A+A collision,
158
GeV and
0.931
GeV:
g+A coherent collision with R(A=Indium) ~ 1.2*A^(1/3) ~ 5.8 fm (= 5.8
fm/[0.197
GeV fm] = 29.4
GeV) as seen from the nucleus at rest:
omega_max = gamma_beam/R = 170./29.4 = 5.78
GeV sqrt(s)_{g+A}_max = sqrt(m2.+2.*omega_max*m) = sqrt(0.9312+2*5.78*0.931) = 3.4
GeV
so an Indium beam (with R = 5.8 fm) with K_beam = 158
GeV seems to be very close to the kinematical limit to produce a J/Psi ... (e.g., for comparison, a SPS Pb-beam (R~7. fm) will produce an even softer gamma spectrum with omega_max~4.78
GeV and, correspondingly, sqrt(s)_{gA} =
3.12
GeV).
Related work