Angular distribution measurements of ^ { 2 } H ( ^ { 7 } Be , ^ { 7 } Be ) ^ { 2 } H and ^ { 2 } H ( ^ { 7 } Be , ^ { 8 } B ) n reactions at E _ { c . m . } \sim 4.5 MeV were performed to extract the astrophysical S _ { 17 } ( 0 ) factor using the asymptotic normalization coefficient ( ANC ) method .
For this purpose a pure , low emittance ^ { 7 } Be beam was separated from the primary ^ { 7 } Li beam by a recoil mass spectrometer operated in a novel mode .
A beam stopper at 0 ^ { \circ } allowed the use of a higher ^ { 7 } Be beam intensity .
Measurement of the elastic scattering in the entrance channel using kinematic coincidence , facilitated the determination of the optical model parameters needed for the analysis of the transfer data .
The present measurement significantly reduces errors in the extracted ^ { 7 } Be ( p , \gamma ) cross section using the ANC method .
We get S _ { 17 } ( 0 ) = 20.7 \pm 2.4 eV b .