The N1003 Time Correlation Analyser (TCA) is based upon years of development and experimental work at JRC Ispra, Italy. The data reduction method, involving an analysis of the frequency distribution of the neutron pulse train, is based on the interpretation model developed by Dr W. Hage of JRC Ispra. The algorithms based on the model are currently used in Europe and the USA. The N1003 has been developed by ANTECH in conjunction with and under licence from the Institute for Safety Technology of the Joint Research Centre Ispra of the CEC., for optimised neutron multiplicity counting.
Plutonium in bulk form and plutonium present in radioactive waste generates neutrons from spontaneous fission events, from (α,n) reactions and from induced fission events caused by primary neutrons. Neutron pair correlation provides the necessary tools to determine the spontaneous fission rate and the mass of the plutonium. This is true if the isotopic composition of the plutonium in the sample is known, in which case the ratio formed by the (α,n) reaction rate and the spontaneous fission neutron emission rate can be calculated.
If neutron multiplication is neglected, then the detection probability that depends on the self shielding of the plutonium in the matrix can be eliminated. It is necessary to know the effective number of neutron singles and the effective number of correlated doubles in order to solve for two unknowns. Both quantities can be obtained from the N1003, which is also capable of measuring the correlated triples used in multiplicity analysis.
Single neutron pair and triple correlation neutron measurements can be performed simultaneously by the N1003. This is achieved using the two different and independent methods of measurement, the signal trigger and the periodic trigger operation modes. Data analysis is carried out for triple correlation using algorithms implemented in software and based on the interpretation model of Hage. For pair correlation (conventional coincidence counting), the passive coincidence counting software algorithms are implemented in the system.
- 16 Simultaneous observation intervals (gate widths) for all trigger methods
- Configurations for maximum sustained input count rates ranging from 300 kHz to over 1 MHz
- Burst buffer permits short term count rate of 10 MHz
- LCD parameter display and external host computer control
- Automated, embedded microprocessor operation with diagnostic functions
- Automated measurement procedure with user selectable bad data rejection facility
- User friendly interface software using Microsoft Windows XP and Microsoft Windows 7
- User selectable pre-delay and gate widths
- Designed for the measurement of plutonium bearing waste and safeguards measurements of bulk plutonium
- Full implementation of neutron multiplicity electronics
- Applicable to a wide range of passive neutron count rates from waste to bulk material with a high α ratio
- Neutron multiplicity measurement method constitutes an absolute technique and calibration is not required
- Easy to use
|Trigger methods||Signal trigger, Delayed signal trigger, Periodic trigger|
|Observation intervals||16 initial interval size (gate width) selectable 0.4 – 25.6 μsec, Minimum selectable 0.4 μsec – 3.2 μsec, Maximum selectable 25.6 μsec to 409.6 μsec|
|Pre-delay||Selectable 0 to 15 μsec in steps of 1.0 μsec|
|Delayed trigger||1024 μsec|
|Input signal||TTL positiv going pulse with Schmitt trigger|
|Count rate||Maximum sustained input count rate between 300 kHz and 1 MHz|
|Pulse pair resolution||40 nsec|
|HV PSU current||4 mA|
|Repetition||Single and continuous modes|
|Recorded multiplicity||0 – 255|
|Measurement time||3 hours minimum|
|Number of cycles||0 – 999|
|High voltage||0 – 2500 Vdc programmable detector supply|
|Low voltage||5 V / 12 Vdc amplifier bias supply|