Eur. Phys. J. A 3, 213–215 (1998) T HE EUROPEAN P HYSICAL JOURNAL A c  Springer-Verlag 1998 Short note Further measurement of the 7 Be(p,γ ) 8 B cross section at low energies with the coulomb dissociation of 8 B T. Kikuchi 1a , T. Motobayashi 1 , N. Iwasa 2 , Y. Ando 1 , M. Kurokawa 2 , S. Moriya 1 , H. Murakami 1 , T. Nishio 1 , J. Ruan (Gen) 1 , S. Shirato 1 , S. Shimoura 1 , T. Uchibori 1 , Y. Yanagisawa 1 , T. Kubo 2 , H. Sakurai 2 , T. Teranishi 2 , Y. Watanabe 2 , M. Ishihara 2.3 , M. Hirai 3 , T. Nakamura 3 , S. Kubono 4 , M. Gai 5,6 , R.H. France III 6 , K.I. Hahn 2b , Th. Delbar 7 , P. Lipnik 7 , C. Michotte 7 1 Department of Physics, Rikkyo University, 3 Nishi-Ikebukuro, Toshima, Tokyo 171, Japan 2 RIKEN (Institute of Physical and Chemical Research), Hirosawa, Wako, Saitama 351-01, Japan 3 Department of Physics, University of Tokyo, Hongo, Bunkyo, Tokyo 113, Japan 4 Center for Nuclear Study (CNS), University of Tokyo, Tanashi, Tokyo 188, Japan 5 Department of Physics, U46, University of Connecticut, 2152 Hillside Rd., Storrs, CT 06269-3046, USA 6 A.W. Wright Nucl. Structure Lab., Department of Physics, Yale University, New Haven, CT 06511, USA 7 Institut de Physique Nucl´ eaire, Universit´ e Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium Received: 15 August 1998 Communicated by P. Kienle Abstract. We have measured the dissociation of 8 B in the Coulomb field of 208 Pb at Ein=51.9 MeV/nucleon and extracted the cross section of the 7 Be(p,γ) 8 B reaction at 0.4 ≤ E rel ≤ 3 MeV, which is of importance for the 8 B solar-neutrino production rate. The extracted astrophysical S17 factors are consistent with our earlier Coulomb dissociation measurement, and agree with the values deduced from the direct capture measurements by Filippone et al., Vaughn et al. and Hammache et al. The S factor at zero energy was extracted to be 18.9±1.8 eV-b with the help of theoretical energy-dependence. PACS. 25.40.Lw Radiative capture – 35.60.-t Reactions induced by unstable nuclei – 25.70.De Coulomb excitation – 25.70.Mn Projectile and target fragmentation – 26.65.+t Solar neutrinos The Coulomb dissociation of 8 B in the field of 208 Pb was studied for the first time at RIKEN[1,2] in order to in- vestigate the 7 Be(p,γ ) 8 B reaction at low energies. The latter radiative capture process is essential for estimat- ing the high-energy neutrino flux relevant to the solar neutrino puzzle[3]. From the Coulomb dissociation cross sections, the astrophysical S 17 -factor of the 7 Be(p,γ ) 8 B reaction was extracted at center-of-mass energies ranging from 0.6 MeV to 1.7 MeV[1,2]. The results are consistent with the 7 Be(p,γ ) 8 B reaction cross sections measured by Filippone et al.[4] and Vaughn et al.[5]. In a recent paper [6] we report a new measurement on detailed angular distributions of the Coulomb dissociation of 8 B from which the E2 contribution to the E1-dominant a Present address: Optical CAD Systems Development De- partment, Canon Inc. 3 Shimomaruko, Ohta, Tokyo 146-8501, Japan b Present address: University of Houston, 4800 Calhoun Road, Houston, TX 77204, USA Correspondence to : motobaya@rikkyo.ac.jp cross section was extracted. The resultant small E2 com- ponent supports our earlier analysis assuming a pure E1 contribution. From the same experiment, new values of the E1 cross section and, in turn, the astrophysical S fac- tors were derived again. Due to the great interest in the 7 Be(p,γ ) 8 B reaction, we publish the S factors from our second experiment. The experiment was performed at the radioactive beam line RIPS[7] at RIKEN (the Institute of Phys- ical and Chemical Research). Secondary 8 B beams of 2×10 4 s -1 bombarded a 50 mg/cm 2 208 Pb target. The av- eraged energy of 8 B in the target is 51.9 MeV/nucleon. The detection system consisted of a ΔE-E plastic scin- tillator hodoscope and a NaI(Tl) detector array DALI[8]. The former detected the reaction products, proton and 7 Be, in coincidence, and the latter was used for measuring the γ rays from the first excited state of 7 Be at 429 keV. These γ rays are associated with the 8 B→ 7 Be * (429 keV)+p dissociation process which cannot be discrimi- nated by the hodoscope data alone. The energy and an- gle of each fragment were measured by its time-of-flight