by Gurevich, A.V., Karashtin, A.N., Chubenko, A.P., Duncan, L.M., Ryabov, V.A., Shepetov, A.S., Antonova, V.P., Kryukov, S.V., Piscal, V.V., Ptitsyn, M.O., Vildanova, L.I., Shlyugaev, Yu.V., Zybin, K.P.
Published in Physics letters. A (24.05.2004)