NeuLAND - FAIR

section were used. From a Gaussian fit to the relative energy distributions obtained from
phase-space simulations we derived a resolution of σ(Erel)=13, 19, and 38 keV for the
three bar sizes at 15.5 m. As a consequence, at this distance to the target only the bars
with a cross section of 3 × 3 cm 2 and 5 × 5 cm 2 fulfill the design criterion of σ ≤ 20 keV.
At a distance of 35 m we obtained a relative energy resolution of σ(Erel)=7, 10, and
18 keV for the three bar cross sections. For the longer flight path the bars with a cross
section of 10 × 10 cm 2 match the requirements as well. However, here we assumed an
ideal time resolution. The relative energy distribution is shown in figure 4.8 derived from
a similar R 3 BRoot simulation for a distance of 35 m between the target and NeuLAND
to the target for the three bar sizes. The resulting resolutions are in very good agreement
to the ones derived from phase-space simulations. Exemplarily, for the bar with a cross
section of 5 × 5 cm 2 , a value of σ(Erel)=10 keV was obtained, identical to the findings
using the phase-space simulations.
events
400
200
3x3cm , σ
0
0 0.1 0.2 0.3
(MeV)
2
Erel
=0
t
2
5x5cm , σ =0
t
2
10x10cm , σ
Figure 4.8.: Study of the effect of granularity of NeuLAND on the resolution of relative
energy distributions, simulated using R 3 BRoot. Relative energy spectra are
shown for scintillator bar cross sections of 3×3 (dashed blue line), 5×5 (solid
red line), and 10×10 cm 2 (solid blue line). One-neutron events were emitted
from 132 Sn with Erel = 100 keV at 600 AMeV. NeuLAND was located at a
distance of 35 m to the target, the time resolution was set to zero, in order
to investigate only the effect of granularity.
As the next step, the influence of the time resolution on the energy resolution was
46
=0
t