Ben C. Perry, Linfield College / Michigan State University

Title:

Authors: B.C. Perry (Linfield College); A. Galonsky, J. Kruse, J. Weiner (NSCL, Michigan State University); F. Deak, A. Horvath, A. Kiss (Eotvos University, Hungary); Z. Seres (Hungarian Academy of Sciences, Hungary)

Abstract: Two neutron walls in a close-packed array were constructed in 1995 at the NSCL for the purpose of detecting single or multiple neutrons in their final state.  The walls each consist of 25 pyrex cells filled with NE-213 liquid scintillator.  A cell is two meters 
long with a photo multiplier tube (PMT) at each end for neutron velocity and horizontal position determination.  The intention was to make a large area neutron detector that had a greater efficiency than its predecessor.  Since their construction the walls have been used in several experiments.     A data analysis problem occurred in several experiments on the "neutron walls" at the National Superconducting Cyclotron Laboratory (NSCL).  In a hope to try and explain the error it was postulated that the wall efficiency might have been lower than originally thought.  A sequential or phase space break-up of the parent nucleus can occur so a Monte-Carlo simulation was made to calculate the fractional yield efficiency of the walls using these models.  The fractional yield efficiency was calculated and found to be the answer to the analysis problem.