NeuLAND - FAIR

findings, see figure 4.3. Overall, a very good agreement is found for the two scintillator
materials, the large range of neutron energies and the various energy threshold
settings.
efficiency [%]
40
35
30
25
20
15
10
5
0
20 40 60 80 100 120
neutron energy [MeV]
2.8 MeV exp
5.58 MeV exp
7.89 MeV exp
11.15 MeV exp
15.75 MeV exp
2.8 MeV sim
5.58 MeV sim
7.89 MeV sim
11.15 MeV sim
15.75 MeV sim
efficiency [%]
70
60
50
40
30
20
10
0
1 10
PILOT-Y
0.2 MeV exp
1.0 MeV exp
4.0 MeV exp
0.2 MeV sim
1.0 MeV sim
4.0 MeV sim
10
neutron energy [MeV]
Figure 4.3.: Neutron efficiency as a function of the energy of impinging neutron for the
two plastic scintillator materials. The data (symbols) for the scintillator
NE-110 are displayed on the left hand side [Bet-76] and the data for the
scintillator Pilot-U on the right hand side [Ede-72]. The GEANT4 simulated
neutron efficiencies are presented as solid curves. The legends detail
the different threshold settings in equivalent-electron energies for the experimental
and simulated data.
Second, we compare the simulation to the neutron response of the existing LAND detector
[Bla-92], which has been used since almost 20 years for the detection of fast neutrons.
LAND is used for detection of fast neutrons stemming from the projectile nuclei reacting
in the target. The detector measures the time-of-flight (ToF) of neutrons with respect to
the target with good position and time resolution. With this information the momentum
of neutrons can be determined. The detector covers an area of 2 × 2 m 2 with a depth
of 1 m. It consists of 10 planes. Every plane contains 20 modules, each covering an
area of 200 cm×10 cm and 10 cm depth. The detection principle is based on conversion
of neutrons to protons via reactions in iron. Secondary protons are then detected in
plastic scintillators layers. In order to avoid the stopping of protons in the Fe converter
a sandwich structure with thin layers of iron and scintillators is used. One module of the
detector contains 11 sheets of iron, each 5 mm thick, besides the two outer ones which
have a thickness of 2.5 mm, and 10 sheets of scintillators with a thickness of 5 mm, each.
The scintillation light is read out at both ends of the scintillator with photomultipliers
(for more information see Th. Blaich et al.,[Bla-92]).
This geometry was modeled in detail in the simulation package R 3 BRoot using the
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