Proton induced spallation reactions are proposed in current accelerator driven transmutation designs. Hence, new accurate measurements of neutron production using a proton beam are needed.
Barium fluoride is an efficient detector material for neutrons in
a wide energy range [1,2]. The high acceptance BaF
detector system
TAPS is an effective tool for exclusive neutron measurements.
The beam of 190 MeV protons from AGOR was incident on thin W and Ni targets. Neutrons were
detected by TAPS which was configured in 6 blocks of 64 BaF modules
and positioned around the target to cover the polar angles 
from 60
up to 170.
Figure: The neutron
efficiencies of the TAPS detectors for electron-equivalent amplitude
threshold L
= 4 MeV
(full line) and 10 MeV
(dashed line).
The neutron detection efficiencies follow a simple exponential dependence
on amplitude threshold 
for neutron energy 
lower than
20 MeV [1] and higher than 100 MeV up to 1.3 GeV [2]
where 
is the efficiency in the limit of zero
threshold and 
is the slope parameter.
Our new measurements show that this relation is valid also for the intermediate energy range from 20 to 100 MeV. Based on the available data it is possible to calculate the neutron detection efficiency for a given amplitude threshold, see figure 1.
Figure: The neutron production on the W target.
The energy spectra for different angles (left side) and angular distributions
for the low and high energy component (right side).
Preliminary results of the neutron production experiment with the tungsten target are shown in figure 2. The LAHET code was used to calculate the inclusive angular distribution of neutron production. The result of these calculations is in good agreement with the experiment.