1. TWO-CHANNEL SPECTROMETRIC SYSTEM BASED ON UNCOOLED Si-DETECTORS AND GADOLINIUM CONVERTER FOR THERMAL NEUTRONS REGISTRATION
G.P. Vasiliev1, V.M. Dubina1, S.K. Kiprich1, O.A. Kaplij1, M.I. Maslov1,
V.D. Ovchinnik1, S.M. Potin1, V. Sharyy2, M.Yu. Shulika1, G.P. V.I. Yalovenko1
1National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine;
2The French Alternative Energies and Atomic Energy Commission (CEA), Saclay, France

2. PROTOTYPE OF A TWO-DETECTOR TWO-CHANNEL SPECTROMETER FOR REGISTRATION OF THERMAL NEUTRONS BASED ON UNCOOLED SILICON DETECTOR AND METALLIC GADOLINIUM CONVERTER *) 1 3 2 1 4 3 2
1 - sealed detectors, 2 - spectrometric channels, 3 - amplitude-to-digital converters
1 - sealed detectors, 2 - preamplifiers, 3 – signal shapers, 4 - power supply units
*) G.P.Vasiliev, O.S.Deiev, V.M.Dubina et al.TECHNIQUE OF THERMAL NEUTRONS REGISTRATION BY TWO-CHANNEL
SPECTROMETRIC SYSTEM BASED ON UNCOOLED Si-DETECTORS AND GADOLINIUM CONVERTER

3. ENERGY RESOLUTION AND STABILITY OF THE TWO-DETECTOR TWO-CHANNEL SPECTROMETER PROTOTYPE FOR THERMAL NEUTRONS REGISTRATION
Long-term stability testing results of a two-channel spectrometric detection system prototype for 15 days duration.
One or less of one noise event in the channel per day in the channel range. The blue (detector without Gd) and green (detector with Gd) lines coincide with the exception of the range from 600 to 800 channels. In this range of channels two CXR gadolinium peaks initiated by cosmic radiation are observed (green line).
Measurements results of the γ-radiation spectrum of an isotope source of 241Am by an uncooled silicon detector: The blue peak corresponds to a line with an energy of keV of the 241Am source. The energy resolution is 0.9 keV.

4. MEASUREMENT OF THE THERMAL NEUTRONS FLUX DENSITY (FLUENCE)
1, 2 – 78 and 71 keV conversion electron peaks
3 – 59,5 keV CXR of 241Am
4, 5 – 48,7 and 43 keV CXR of Gd
The spectral distributions of the 239Pu-Be (α, n) radiation of a neutron source, measured using a prototype spectrometric system with a thickness of paraffin moderator 4 cm. Measurement time T1 = seconds. The density of the thermal neutron flux Wn is determined from the relation:
Wn = ∑е-•Kn/0,25•∆T , 1/cm2c,
Wn is the neutron flux density; Σе- is the sum of conversion electrons measured in a certain interval energy for a certain period of time with the help of a two-channel spectrometric system prototype. Kn is the coefficient of correspondence of the sum of conversion electrons to the number of thermal neutrons, measured over the same time period by a calibration device. To determine the coefficient Kn a range of conversion electron energies of keV is applied. For calibration, the standard PM-21P device was used to determine the compliance factor. The value of the Kn coefficient from the obtained data is

5. RE-DETERMINATION OF THE DENSITY OF THE THERMAL NEUTRONS FLOW
1, 2 – 78 and 71 keV conversion electron peaks
3 – 59,5 keV CXR of 241Am
4, 5 – 48,7 and 43 keV CXR of Gd
The spectral distributions of the 239Pu-Be (α, n) radiation of a neutron source, measured repeatedly with the help of a spectrometric system prototype with a thickness of a paraffin moderator of 4 cm. The measurement time is T = seconds. The value of the coefficient of correspondence Kn obtained during the repeated measurement is

6. TWO-DETECTOR TWO-CHANNEL SPECTROMETER PROTOTYPE FOR REGISTRATION OF THERMAL NEUTRONS ON THE BASIS OF UNCOOLED SILICON DETECTORS AND METALLIC GADOLINIUM CONVERTER 1 2 3 4 5 4 3 2 1
The spectral distribution of radiation detected by uncooled Si detectors: CXR lines Gd 48.7 keV (1) and 43 keV (2); line keV 241Am (3); the conversion electrons are 71 keV (2) and 78 keV (1).
The spectral distribution of conversion electrons from gadolinium detected by the detector is 71 keV (1), 78 keV (2), 131 keV (3), and 173 keV (4).

7. TWO-DETECTOR TWO-CHANNEL SPECTROMETER FOR REGISTRATION OF THERMAL NEUTRONS BASED ON UNCOOLED SILICON DETECTOR AND METALLIC GADOLINIUM CONVERTER 2 3 4 1
1 - Detectors with preamps
2 – Spectrometer
3 - ADC;
4 - Laptop

8. RESULTS OF MEASUREMENTS ON THE SPECTROMETER MONITOR
Blue curve - detector with interlayer of polyethylene Green curve - detector without interlayer Red spectrum - conversion electrons obtained by automatic subtraction of spectra.

9. The work contains the results of studies conducted with the grant support of the State Fund for Fundamental Research on competition project No. Ф79 / The study was conducted within the IDEATE of the International Associated Laboratory (LIA).

10. THANKS FOR YOUR ATTENTION !