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Cosmic ray (CR) sources leave signatures in the isotopic abundances of CRs.Current models of Galactic CRs that consider supernovae (SNe) shocks as themain sites of particle acceleration cannot satisfactorily explain the higher${\rm ^{22}Ne/^{20}Ne}$ ratio in CRs compared to the interstellar medium.Although stellar winds from massive stars have been invoked, their contributionrelative to SNe ejecta has been taken as a free parameter. Here we present atheoretical calculation of the relative contributions of wind terminationshocks (WTSs) and SNe shocks in superbubbles, based on the hydrodynamics ofwinds in clusters, the standard stellar mass function, and stellar evolutiontheory. We find that the contribution of WTSs towards the total CR productionis at least $25\%$, which rises to $\gtrsim 50\%$ for young ($\lesssim 10$ Myr)clusters, and explains the observed $^{22}{\rm Ne}/^{20} {\rm Ne}$ ratio. Weargue that since the progenitors of apparently isolated supernovae remnants(SNRs) are born in massive star clusters, both WTS and SNe shocks can beintegrated into a combined scenario of CRs being accelerated in massiveclusters. This scenario is consistent with the observed ratio of SNRs to$\gamma$-ray bright ($L_\gamma \gtrsim 10^{35}$ erg s$^{-1}$) star clusters, aspredicted by star cluster mass function. Moreover, WTSs can accelerate CRs toPeV energies, and solve other longstanding problems of the standard supernovaparadigm of CR acceleration.

Realistic modeling of wind and supernovae shocks in star clusters: addressing ${\rm ^{22}Ne/^{20}Ne}$ and other problems in Galactic cosmic rays