NeuLAND - FAIR

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Nclusters
Figure 4.13.: Number of clusters in NeuLAND from 600 AMeV neutrons for multiplicities
of 1 (black), 2 (green), 3 (red), 4 (blue), 5 (yellow) and 6 (magenta).
Calorimetric Properties
Several quantities are regarded here in order to investigate their information content
with respect to the number of incident neutrons. The left part of figure 4.14 shows
the total energy deposited Edep in NeuLAND as a function of incident neutron number.
We see a clear and linear increase of the mean value of Edep, however the distributions
overlap for consecutive neutron numbers. When studying the multiplicity, the number
of hits with valid entries in NeuLAND, a similar behaviour is observed, see right part
of figure 4.14. As in the case of number of clusters, see figure 4.13, no clear separation
is possible for each of the regarded parameters. However, we can gain a more clear
separation by correlating two of the above mentioned quantities. The best separation
of neutrons is obtained when combining the number of clusters and the total energy
deposited. We observe an anti-correlation, as displayed for neutron multiplicities of 1 to
6 in figure 4.15 for 600 AMeV neutrons.
The cuts indicated in the individual spectra allow for a very satisfactory neutron separation,
as presented in the combined presentation in figure 4.16. The determination of
neutron multiplicities is derived from the conditions in the two-dimensional plane. In
the case displayed here cuts were chosen in a manner, that strongly suppresses a shift
towards higher neutron multiplicities. Additionally, we chose the upper cut for a neutron
multiplicity of four generously, a reasonable assumption for cases where the cross section
for higher neutron multiplicities either drastically drops or vanishes (see the discussion
of GDR studies for 136 Sn with a separation energy for 5 neutrons of S5n=19.6 MeV and
the case of 4 correlated neutrons in section 4.5.4). Depending on the cross sections for
different neutron multiplicities and the investigated physics case, cuts can be optimized
to suppress either too high or too low neutron multiplicities.
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