Analytical capability of neutron sensor incorporated into UNCOSS ROV Project meeting and workshop: Dubrovnik 30th November and 01st December 2011

Side view of the neutron based explosive detector.

Project meeting and workshop: Dubrovnik 30th November and 01st December 2011

Iron cylinder filled with the real sediment, on the left, and shell filled with 6.1 kg of TNT surrogate (Si3C7H3N3O6), on the right. For the performance assessment in water, the plastic tank (on the right) was filled with water up to the top of the objects.

Gamma and time spectra corresponding to the shell filled with 6.1 kg of TNT surrogate (Si3C7H3N3O6) in air, for a 30 min acquisition with an average neutron emission of 2.4 x 10 7 n/s. The time and energy spectra have been obtained by selecting pixels 4 and 5.

Gamma and time spectra corresponding to the iron cylinder filled with sediments in air, for a 30 min acquisition with an average neutron emission of 2.4 x 10 7 n/s. The time and energy spectra have been obtained by selecting pixels 4 and 5.

Energy spectra in air of the iron cylinder filled with sand (in green) Vs. shell filled with TNT surrogate (in red). Note that the energy spectra were adjusted to a same 2.24 MeV titanium peak pulse height. Below a zoom on C and O peaks.

‘’Surveyor’’

The gamma ray spectra of a 155 mm shell filled with the Si3C7H3N3O6 (gray) and the cylinder filled with the sea sediment (black). 9 ns time window. The gamma ray spectra of a real 155 mm shell (black) and the cylinder filled with the sea sediment (red). 9 ns time window

Spectrum was fitted with the assumption that it contains only carbon, oxygen and iron contributions. Contribution of the other elements like chlorine or sodium was ignored. The fitting procedure was done by using Eq. (1) where the sum was done over the channel (ch) number. (1) Carbon, Oxygen and Iron are pure elemental spectra. Parameters ''a'', ''b'' and ''c'' are fitting parameters called carbon content, oxygen content and iron content, respectively.

Oxygen, Carbon and Iron content for two different targets in dependance on the rotation angle 155 mm grenade155 mm cylinder filled with sand Angle of rotationOxygenCarbonIronOxygenCarbonIron 22°0.90± ± ± °0.865± ± ± °0.857± ± ± ± ± ± °0.804± ± ± ± ± ±0.01

Normal distribution for carbon content in the background and in the explosive devices

Detection probability of the real 155 mm shell for the rotattion angle 26 0 and the false positive 10 %! Measurement Time (s) Detection probability (%) False negative (%)

Detection probability of the real 155 mm shell for the rotattion angle 26 0 and the false positive 5 %! Measurement Time (s) Detection probability (%) False negative (%)

Detection probability of the real 155 mm shell for the rotattion angle 26 0 and the false positive 0.13 %! Measurement Time (s) Detection probability (%) False negative (%)

‘’Surveyor’’ One alpha pixel It is possible to rotate the neutron generator In the fitting procedure it was assumed that the gamma ray spectra contained the contribution from the iron, oxygen and carbon only Time resolution ~2 ns ‘’Uncoss Rov’’ 3x3 alpha pixels It is not possible to rotate the neutron generator In the fitting procedure it was assumed that the gamma ray spectra contained the contribution from the more than three chemical elements Time resolution ~5 ns

Summary In order to improve time resolution electronics was send back to Saclay In order to produce a better TNT simulant a new chemicals were ordered Avio bomb was considered to be used as a secondary target