Digitisation Techniques Applied in Nuclear Experiments (original) (raw)
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Ionization Chamber for Prompt Fission Neutron Investigations
Physics Procedia, 2014
In this work we report recent achievements in design of twin back-to-back ionization chamber (TIC) for fission fragment (FF) mass and kinetic energy measurement. Correlated FF kinetic energies, their masses and the angle of FF in respect to the axes in 3D Cartesian coordinates can be determined from analysis of the heights and shapes of the pulses induced by the fission fragments on the anodes of TIC. Anodes of TIC were designed as consisting of isolated strips each having independent electronic circuitry and special multi-channel pulse processing apparatus. Mathematical formulae provided for FF angles measured in respect to the coordinate axes. It was shown how the point of fission fragments origin on the target plane may be determined using the same measured data. The last feature made the TIC a rather powerful tool for prompt fission neutron (PFN) emission investigation in event-by-event analysis of individual fission reactions from nonpoint fissile source. Position sensitive neutron induced fission detector for neutron-imaging applications with both thermal and low energy neutrons was found as another possible implementation of the designed TIC.
Comparison of digital and analogue data acquisition systems for nuclear spectroscopy
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2010
In the present investigation the performance of digital data acquisition (DA) and analogue data acquisition (AA) systems are compared in neutron-induced fission experiments. The DA results are practically identical to the AA results in terms of angular-, energy-and mass-resolution, and both compare very well with literature data. However, major advantages were found with the digital techniques. DA allows for a very efficient a-particle pileup correction. This is important when considering the accurate measurement of fission-fragment characteristics of highly a-active actinide isotopes relevant for the safe operation of Generation IV reactors and the successful reduction of longlived radioactive nuclear waste. In case of a strong a-emitter, when applying the a-particle pileup correction, the peak-to-valley ratio of the energy distribution was significantly improved. In addition, DA offers a very flexible expanded off-line analysis and reduces the number of electronic modules drastically, leading to an increased stability against electronic drifts when long measurement times are required.
A new approach to prompt fission neutron TOF data treatment
Physics Procedia, 2012
The prompt neutron emission in spontaneous fission of 252 Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. A new mathematical approach, applicable to single events, was developed for prompt fission neutron (PFN) time-offlight distribution unfolding. The main goal was to understand the reasons of the long existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of the fission fragments (FF). Since the 252 Cf (sf) reaction is one of the main references for nuclear data the understanding of the PFN emission mechanism is very important both for nuclear fission theory and nuclear data. The experimental data were taken with a twin Frisch-grid ionization chamber and a NE213-equivalent neutron detector in an experimental setup similar to the well known work of C. Budtz-Jorgensen and H.-H. Knitter. About 2.5×10 5 coincidences between fission fragment (FF) and neutron detector response to prompt fission neutron detection have been registered (~1.6×10 7 of total recorded fission events). Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12-bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The main goal of this work was a detailed description of the prompt fission neutron treatment.
EPJ Web of Conferences, 2014
The measurement of neutron-capture cross sections of many actinides is complicated by the difficulty in separating capture γ-rays from the large fission-fragment prompt γ-rays background. For example, the current estimations of the capture cross section of 233 U show large discrepancies, with differences of more than 20%. To improve the accuracy of data, a new experimental setup for the simultaneous measurement of the neutron-induced capture and fission cross sections was designed, assembled and optimized. The measurements will be performed at the GEel LINear Accelerator (GELINA) neutron time-of-flight facility in Belgium, where neutron cross sections can be measured over a wide energy range with high energy resolution. The fission detector consists of a dedicated multi-plate high-efficiency ionization chamber (IC). The γ-rays produced in capture reaction are detected by an array of C 6 D 6 scintillators. Fission γ−rays are distinguished from capture γ−rays by the anticoincidence signals from the IC and the C 6 D 6 detectors. For the undetected fission events a correction has to be applied based on the efficiency of the IC that should be high and known with a high accuracy. The performance of the IC during dedicated test experiments is presented, focusing on the determination of the detection efficiency.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2016
A twin position-sensitive Frisch grid ionization chamber, intended as a fission fragment detector in experiments to study prompt fission neutron correlations with fission fragment properties, is presented. Fission fragment mass and energies are determined by means of the double kinetic energy technique, based on conservation of mass and linear momentum. The position sensitivity is achieved by replacing each anode plate in the standard twin ionization chamber by a wire plane and a strip anode, both readout by means of resistive charge division. This provides information about the fission axis orientation, which is necessary to reconstruct the neutron emission process in the fully accelerated fragment rest-frame. The energy resolution compared to the standard twin ionization chamber is found not to be affected by the modification. The angular resolution of the detector relative to an arbitrarily oriented axis is better than 7°FWHM. Results on prompt fission neutron angular distributions in 235 U(n,f) obtained with the detector in combination with an array of neutron scintillation detectors is presented as a proof of principle.
Nuclear Fission Investigation with Twin Ionization Chamber
2011
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A Multiparameter Nuclear-fission Experiment: Can All be Obtained at Once?
Physics Procedia, 2013
A large variety of experimental works has been done since the discovery of nuclear fission, aimed at studying different aspects of the phenomenon. Yet our comprehension of the fission process is not complete. This is, among others, due to a certain lack in multi-parameter experimental data. An example here is the correlation between fractional independent yields of fission products and neutron and gamma-ray multiplicities. Fragment-gamma-neutron measurements, especially if correlated with fissionfragment kinetic energies, give the complete set of observables and are therefore of interest from the point of view of modeling and understanding of the fission process. A two-arm spectrometer of fission products (STEFF) has been recently built at the Manchester University. In addition to the identification of masses from complementary fission products, by the double energy / double velocity measurement, the spectrometer is capable of delivering information on their nuclear charges, on the event-by-event basis. The spectrometer also comprises an array of NaI and may house a further array of neutron detectors. In such configuration, STEFF has been used at the ILL neutron guide at the benchmark experiment 235 U(n th , f ). Details on the experiment will be presented, results on the identification of atomic numbers in the light group of fission products will be demonstrated and the perspectives discussed.
NuCLEAR Data as The Alternative Information of Decay and Analyzer
2005
NuCLEAR Data is the name of visual, color-coded computer program of "Chart of Nuclides" or "Segre Chart". The program gives you comprehensive nuclear decay data that include data on alpha, beta, gamma, x-ray decay etc., and comprehensive search by energy, intensity, half life, radiation type or name of nuclide. NuCLEAR Data is able to show visual decay product and could function as Multi Nuclides Identification and Multi Elements Identification Analysis. It is constructed using Visual Basic Compiler. ABSTRAK NuCLEAR Data adalah nama program komputer untuk peta nuklida atau Segre Chart; data tervisual dan dikodekan warna. Program ini memberikan anda data peluruhan nuklir secara komprehensif, yang meliputi peluruhan alpha, beta, gamma, sinar-x dan dapat mencari energi, intensitas, waktu paro, jenis radiasi dan nama nuklida. NuCLEAR Data dapat menampilkan produk peluruhan secara visual dan dapat berfungsi sebagai analisis untuk Identifikasi multi nuklida dan identif...
Digital spectrometer for prompt fission neutron spectrum measurements
EPJ Web of Conferences
This paper presents a digital neutron spectrometer based on simultaneous digitizing of the signals from the fission chamber and a scintillation detector. The scintillation detector is based on stilbene crystal. The intrinsic detection efficiency of the used stilbene crystal and the energy dependence of the light output for the recoil protons were measured. It is shown, that the method allowed us to achieve time resolution of 1.5 ns and an good n/γ separation down to neutron energies of 400 keV.