MULTIDETECTOR SYSTEM FOR NANOSECOND TAGGED NEUTRON TECHNOLOGY BASED ON HARDWARE SELECTION OF EVENTS M. Karetnikov, T. Khasaev, S. Korotkov All-Russia Research Institute of Automatics K. Balygin, A. I. Klimov, E. Meleshko Russian National Centre Kurchatov Institute

Principles of tagged neutron technology Detectors and DAQ system Comparision of analog and digital front-end electronics Experimental demonstration Outline Outline

D-T Reaction Kinematics

4 Tagged Neutron Device

Pixelized alpha-detector 64-pixel and 192-pixel 9-pixel

Cross- sections of inelastic neutron scattering CarbonNitrogen Oxygen Iron

3D neutron activation analysis (voxalization) Accuracy:  t  rad,  t  =1 ns  x=5 cm,  y=5 cm

Chemical Composition of High Explosives and Innocent Materials n O = O/(C+N+O) ; n C = C/(C+N+O) ; n N = N/(C+N+O) – TATP n O = O/(C+N+O) =0.4 n C = C/(C+N+O) = 0.6 n N = N/(C+N+O) =0

Event (apha-gamma coincidence) 1. Number (ID) of alpha-detector pixel 2. Time between apha-gamma signals with 1 ns resolution 3. Gamma -ray amplitude. 4. Number (ID) of gamma-detector Tasks for DAQ system Intensity of neutron generators :10 8 s –1. Counting rate of alpha- detector :2x10 6 s –1, Counting rate of gamma-detector :10 5 1/s.

Timing and Energy Analyzing  8-18 ns Alpha-detector Gamma-detector LYSO  4-12 ns BGO  8-22 ns Leading edgeSpectrum Leading edge Spectrum Problems of Timing:  Change of Amplitude by an order of magnitude.  Leading edge front) fluctuations.

Two approaches for the DAQ system for tagged neutron devices: (1) preliminary online selection of events by hardware and transmission of only useful events to a computer (2) complete digitization of signals from all detectors and data- stream transmission to the computer for subsequent processing

TDC is initiated by the gamma- detector signal, the signal of alpha-particle is delayed and serves as a STOP signal for TDC. The number of enabled gamma- detectors can be increased via installation of additional gamma- channel modules without deterioration of counting rate. Tuning of CFD and charge- sensitive amplifier parameters to meet signal parameters

12 Gamma-Detector Stationary Set-Up for Explosives Detection

Compact DAQ Unit for Mobile System  Intrinsic time resolution of hardware:  0.1 ns;  Interface: Bluetooth;  64-channel Alpha Inputs  4-channel Gamma Inputs.  Size: 175x165x265 mm;  Power Supply: 12 V Battery

Digital signal processing (DVIN)Analog front-end electronis (MATA) Advantages Versatility, can be used for processing of signals from various detectors. No need in hardware tuning for specific detectors. Higher rate of events processing (up to /s in perspective systems). Operation with any reasonable number of detectors without decrease of rate of events processing. Application of complex algorithms for off- line and on-line processing of signals, zero- line correction, recovery of superimposed pulses Low power consumption (<50 W). More accurate and stable timing. Disadvantages High power consumption (140 W).Necessity of tuning of CFD and charge- sensitive amplifier parameters to meet signal falling and rising edges. Necessity for extension of short signals for meaningful number of samples. Comparison of digital and analog methods for signal processing.

Time stamp drift during neutron generator operation Digital signal processingAnalog front-end electronis

Experiments in VNIIA, KAERI, Kurchatov Institute 3.6% Amplitude Resolution (FWHM 4.44 MEV Peak 1.0  0.1 ns Time Resolution (FWHM) ING-27 Neutron Generator LYSO Gamma- Detector Shielding Graphite

Identification of Heterogeneous Structures (Experiment # 1) Tagged neutrons

Identification of Heterogeneous Structures (Experiment # 1)

Identification of Heterogeneous Structures (Experiment # 2) Tagged neutrons

Identification of Heterogeneous Structures (Experiment # 2)

2017 year 256 pixel alpha-detector 48 gamma-detectors Counting rate of alpha- detector :8x10 6 s –1, Total counting rate of allgamma-detector :10 6 1/s. Sizable (up to 10 ns) and movable time window Future Plans