  We present a study of diffractive associated jpsi + gamma production at the
Fermilab Tevatron and LHC based on the Ingelman-Schlein model for hard
diffractive scattering and the factorization formalism of NRQCD for quarkonia
production. We find that this process (p + pbar to p + jpsi + gamma + X) can be
used to probe the gluon content of the Pomeron and test the assumption of
diffractive hard scattering factorization. Using the renormalized Pomeron flux
factor D simeq 0.11 (0.052), the single diffractive jpsi + gamma production
cross section at 4<P_T< 10 GeV, -1<eta<1 region is found to be of the order of
3.0 pb (8.5 pb), the ratio of single diffractive to inclusive production is
0.50% (0.15%) in central region at the Tevatron (LHC) for the gluon fraction in
the Pomeron f_g = 0.7, independent of the values of color-octet matrix
elements.
