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Measurement of the analyzing power in the Primakoff process with a high-energy polarized proton beam

1990; American Physical Society; Volume: 64; Issue: 4 Linguagem: Inglês

10.1103/physrevlett.64.357

1092-0145

David C. Carey, R. N. Coleman, M. Corcoran, J.D. Cossairt, A. A. Derevschikov, D. P. Grosnick, D. Hill, K. Imai, A. Konaka, K. Kuroda, F. Lehar, A. de Lesquen, D. Lopiano, F. Luehring, T. Mäki, Shoji Makino, A. Masaike, Yu. A. Matulenko, A. Meschanin, A. Michalowicz, D. H. Miller, K. Miyake, T. Nagamine, Toshiaki Nakano, F. Nessi-Tedaldi, M. Nessi, C. Nguyen, S. B. Nurushev, Y. Ōhashi, G. Pauletta, A. Penzo, G. C. Phillips, A. L. Read, J. B. Roberts, L. van Rossum, G. Salvato, P. Schiavon, Tatsushi Shima, V.L. Solovyanov, H. Spinka, R. W. Stanek, R. Takashima, F. Takéutchi, N. Tamura, N. Tanaka, D. G. Underwood, A. Vasiliev, A. Villari, J. L. White, A. Yokosawa, T. Yoshida, A. Zanetti,

Particle physics theoretical and experimental studies

The analyzing power (spin-dependent azimuthal asymmetry) has been observed for the first time in the nuclear Coulomb coherent production process, the ``Primakoff process,'' with the use of the newly constructed 185-GeV/c Fermilab polarized proton beam. We have observed a large asymmetry of this process in the regions of \ensuremath{\Vert}t'\ensuremath{\Vert}0.001 (GeV/c${)}^{2}$ and 1.36(${\ensuremath{\pi}}^{0}$p)1.52 GeV/${c}^{2}$, where the Coulomb process is predominant. The measured asymmetry is consistent with the analyzing power of the existing low-energy \ensuremath{\gamma}+p\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$+p data.