NE213 Scintillator Research Articles

The Breakup Cross Section of the D+D Reaction at 6.94 MeV

The D+D reactions are well known and widely used for a variety of purposes, mainly because of the use of the D(d , n )3 He reaction as a mono-energetic neutron source. The least studied of the D+D reactions is the D(d , n )pD reaction known as the deuteron breakup reaction, which produces a continuum of neutrons at energies below the monoenergetic peak. The neutron energy distribution as a function of angle for the cross section, , of the D(d ,n )pD reaction has been measured using a 6.94-MeV pulsed deuteron beam incident upon a D2 gas target. The time-of-flight technique was used to determine the energy of the neutrons detected in an array of two lithium glass scintillators and one NE-213 scintillator. The breakup cross section was determined as low as 225-keV neutron energy in the lithium glass detectors.

The3H(d,γ)5He Reaction forEc.m.≤ 300 keV

The 3 H(d , γ )5 He reaction has been measured using a 500-keV pulsed deuteron beam incident on a stopping titanium tritide target at Ohio University’s Edwards Accelerator Laboratory. The time-of-flight (TOF) technique has been used to distinguish the γ -rays from neutrons detected in the bismuth germinate (BGO) γ -ray detector. A stilbene scintillator and an NE-213 scintillator have been used to detect the neutrons from the 3 H(d , n )4 He reaction using both the pulse-shape discrimination and TOF techniques. A newly-designed target holder with a silicon surface barrier detector to simultaneously measure α -particles to normalize the neutron count was incorporated for subsequent measurements. The γ -rays have been measured at laboratory angles of 0°, 45°, 90°, and 135°. Information about the γ -ray energy distribution for the unbound ground state and first excited state of 5 He can be obtained experimentally by comparing the BGO data to Monte Carlo simulations. The 3 H(d , γ )/3 H(d , n ) branching ratio has also been determined.

Measurement of Double Differential Neutron Yields from Thick Aluminum Target Irradiated by 9 MeV Deuteron

Abstract Double differential neutron yields from a thick aluminum target irradiated by 9 MeV deuterons were measured at the Kyushu University Tandem accelerator Laboratory (KUTL). An NE213 liquid organic scintillator (50.4 mm thick and 50.4 mm in diameter) was used as a neutron detector. Neutron yields from the target were measured at nine angles between 0° and 140°. The neutron energy spectra were obtained by means of an unfolding method using FORIST code with the response function of the NE213 scintillator calculated by SCINFUL-QMD code. The experimental result was compared with other measured data at 5 and 40 MeV and the calculation based on intra-nuclear cascade of Liege (INCL) model in PHITS code.

Digital neutron-gamma discrimination in a wide energy range using pulse reconstruction method

In this research, based on pulse reconstruction method, digital storage oscilloscopes with an 8-bit digital-to-analog convertor was used to successfully perform the neutron-gamma discrimination with NE213 (or its equivalent BC501A) scintillator anode pulses at minimum discrimination bias value of 95 keVee (or keV electron equivalent). Also, a 100 mCi 241Am–Be source and micro-Curie gamma ray sources (137Cs and 22Na) were used for the system calibration and discrimination studies. The results confirm the feasibility and simplicity of the proposed method.

Measurements and parameterization of neutron energy spectra from targets bombarded with 120 GeV protons

The energy spectra of neutrons were measured by a time-of-flight method for 120GeV protons on thick graphite, aluminum, copper, and tungsten targets with an NE213 scintillator at the Fermilab Test Beam Facility. Neutron energy spectra were obtained between 25 and 3000MeV at emission angles of 30°, 45°, 120°, and 150°. The spectra were parameterized as neutron emissions from three moving sources and then compared with theoretical spectra calculated by PHITS and FLUKA codes. The yields of the theoretical spectra were substantially underestimated compared with the yields of measured spectra. The integrated neutron yields from 25 to 3000MeV calculated with PHITS code were 16–36% of the experimental yields and those calculated with FLUKA code were 26–57% of the experimental yields for all targets and emission angles.

Measurement of 100- and 290-MeV/A Carbon Incident Neutron Production Cross Sections for Carbon, Nitrogen and Oxygen

Neutron double-differential cross sections from carbon ion incident on carbon, nitrogen and oxygen targets have been measured for neutron energies down to 0.6 MeV in wide directions from 15∘ to 90∘ with 100- and 290-MeV/A incident energies at the Heavy Ion Medical Accelerator in Chiba (HIMAC), National Institute of Radiological Sciences. Two sizes of NE213 scintillators were used as neutron detectors in order to enable neutron energy from below one to several hundred MeV. The neutron energy was measured by the time-of-flight technique between the beam pickup detector and an NE213 scintillator. By using the experimental data, the validity of the calculation results by the PHITS code was examined.

NE213/BC501A scintillator−lightguide assembly response to 241Am−Be neutrons: An MCNPX−PHOTRACK hybrid code simulation

The response of an NE213 (or its BICRON equivalent, BC501A) scintillator attached to different sizes of polished/painted lightguides when exposed to 241Am–Be neutrons has been simulated. This kind of simulation basically needs both particle and light transports: the transport of neutrons and neutron-induced charged particles such as alphas, protons, carbon nuclei and so on has been undertaken using MCNPX whilst the scintillation light transport has been performed with PHOTRACK codes. The comparison between simulated and experimental response functions of NE213 attached to different sizes of polished/painted lightguides and also the influence of length/covering of lightguide on the detection efficiency and uniformity of the scintillator–lightguide assembly response have been studied.

On timing response improvement of an NE213 scintillator attached to two PMTs

A 5cm diameter by 6cm height NE213 scintillator attached to two XP2282 PHOTONIS photomultiplier tubes (PMTs) exposed to 241Americium–Berylium (Am–Be) neutron–gamma source has been used for timing response studies. The neutron–gamma discrimination (NGD) measurements based on a modified zero-crossing (ZC) method show that the discrimination quality, usually expressed in figure-of-merit (FoM) and peak-to-valley (P/V) values, has been improved. The timing response evaluated with Monte Carlo light transport code, PHOTRACK, also verifies this improvement.

A comparison study on three different radiation detectors used for liquid levelmetry

In this paper, three different radiation detectors (BF3 counter, NE213 and BGO scintillators) and an (241)Am-Be isotopic neutron-gamma source have been used for a typical liquid levelmetry. The study shows that the use of the Am-Be source together with an NE213 scintillator has the best performance.

Modeling NE213 scintillator response to neutrons using an MCNPX-PHOTRACK hybrid code

This paper reports on how to generate the response function of an NE213 scintillator when exposed to mono-energetic neutrons using the PTRAC card of the MCNPX code. The light transport part of the simulation has been undertaken with the Monte Carlo PHOTRACK code. The comparison confirms that the simulated response function represents a promising agreement with the previously published simulations and experiments.

Lightguide influence on timing response of scintillation detectors

In this paper, using zero-crossing method, the neutron–gamma discrimination has been discussed to estimate the contribution of light transport on the timing characteristics of scintillation detectors. Both experimental and simulation verifications for the influence of lightguide length on the neutron–gamma discrimination quality of a 2×2 in. NE213 scintillator have been presented.

Measurement of neutron-induced proton-production energy spectra with NE213 scintillator

Abstract Many benchmark data are required for the improvement of theoretical model implemented in a Monte Carlo code for particle transport. To acquire the benchmark data, we measured energy spectra of protons emitted from graphite, aluminum, and iron targets bombarded with continuous-energy neutrons, which enable simultaneous measurements at the incident energies from 100 to 600 MeV at a time. The neutron flux incident on the target was measured with a 238 U fission ionization chamber. Protons emitted from the target were measured with three ΔE–E detectors consisting of a thin NE102A scintillator and a thick NE213 liquid scintillator. In the analysis, the pulse shape discrimination of the NE213 scintillator enable us to distinguish events for a charged particle stopping in the scintillator from events for a charged particle penetrating the scintillator. Experimental results were compared with calculations by the PHITS code coupled with the JENDL-HE file, the Bertini model implemented in the PHITS code, and the PEANUT model in the FLUKA code.

Light yield and n-γ pulse-shape discrimination of liquid scintillators based on linear alkyl benzene

The relative light yields of NE-213 and LAB-based liquid scintillators to electrons were determined in the electron energy range 5-1600 keV using a combination of monoenergetic photon sources and a Compton spectrometer. The light yield was found to be proportional to energy for both types of scintillator and expected deviations below 100 keV were described successfully applying Birks' law. Digital pulse-shape discrimination in a mixed n-γ field of a 252Cf source was investigated for LAB+PPO and LAB+PPO+bis-MSB and compared to NE-213. In combination with these two solutes, LAB shows poorer abilities to separate neutron-induced pulses from photon-induced ones.

Neutron-Gamma Pulse Shape Discrimination with a NE-213 Liquid Scintillator by Using Digital Signal Processing Combined with Similarity Method

Neutron-Gamma Pulse Shape Discrimination with a NE-213 Liquid Scintillator by Using Digital Signal Processing Combined with Similarity Method. Measurement of mixed neutron-gamma radiation is difficult because a neuclear detector is usually sensitive to both radiations. A new attempt of neutron-gamma pulse shape discrimination for a NE-213 liquid scintillator is presented by using digital signal processing combined with an off-line similarity method. The output pulse shapes are digitized with a high speed digital oscilloscope. The n-γ discrimination is done by calculating the index of each pulse shape, which is determined by the similarity method, and then fusing it with its corresponding pulse height. Preliminary results demonstrate good separation of neutron and gamma-ray signals from a NE-213 scintillator with a simple digital system. The results were better than those with a conventional rise time method. Figure of Merit is used to determine the quality of discrimination. The figure of merit of the discrimination using digital signal processing combined with of line similarity method are 1.9; 1.7; 1.1; 1.1; and 0.8 ; on the other hand by using conventional method the rise time are 0.9; 0.9; 0.9; 0.7; and 0.4 for the equivalent electron energy of 800 ; 278 ; 139 ; 69 ; and 30 keV.

A comparative study on neutron-gamma discrimination with NE213 and UGLLT scintillators using zero-crossing method

The neutron-gamma discrimination capability of the new-type UGLLT liquid scintillator has been compared with NE213 (or its Bicron equivalent, BC501A). An Am-Be combined neutron-gamma isotopic source and a zero-crossing circuitry were used to explore various biases resulting the optimum figure of merits (FOMs) of 1.52 and 1.18 for NE213 and UGLLT at 170 keVee bias, respectively. The study shows that the UGLLT scintillator can be a good alternative for NE213 in pulse-shape discrimination experiments.

Study of Pulse Shape Discrimination of Sub-MeV Neutrons From Gamma-Rays with Liquid Scintillator

We have studied pulse shape discrimination of sub-MeV neutron from spallation nuclear reactions. Neutron measurements were carried out with a 2-inch NE213 scintillator viewed by a phototube (HAMAMATSU H1949) for the carbon-carbon reaction at 290 MeV/n. Neuron energies were measured with the TOF technique by using a timing pick-up plastic scintillator. Output signals of detectors were digitized and stored with a digitizer (Acqiris DC282). The digital pulse shape discrimination (DPSD) has been investigated through comparison between three different analyzing algorithms. Effects on the neutron-gamma (n/g) discrimination were also investigated after the subtraction of background and abnormal events. Moreover, in order to realize better n/g discrimination the detector system was cooled down to about zero degrees centigrade by Peltier devices to suppress the dark current of the phototube which would be the main cause distorting pulse shapes. Experimental studies were made in terms of the temperature dependence of detector performance including pulse shape.

Measurement of absolute response functions and detection efficiencies of an NE213 scintillator up to 600 MeV

Absolute neutron response functions and detection efficiencies of an NE213 liquid scintillator that was 12.7 cm in diameter and 12.7 cm in thickness were measured for neutron energies between 15 and 600 MeV at the Weapons Neutron Research facility of the Los Alamos Neutron Science Center. The experiment was performed with continuous-energy neutrons on a spallation neutron source by 800-MeV proton incidence. The incident neutron flux was measured using a 238U fission ionization chamber. Measured response functions and detection efficiencies were compared with corresponding calculations using the SCINFUL-QMD code. The calculated and experimental values were in good agreement for data below 70 MeV. However, there were discrepancies in the energy region between 70 and 150 MeV. Thus, the code was partly modified and the revised code provided better agreement with the experimental data.

Response function and relative efficiency measurementsof the BC501A scintillator by usinga 252Cf fast fission chamber

The response function and relative efficiency of a Φ50.8 mm×50.8 mm BC501A scintillator has been measured by using a252Cf fast fission chamber. In this method,a multi-parameter data acquisition system is employed to take the time-of-flight (TOF),pulse shape discrimination (PSD) and recoil energy (RE. note: fission neutron induces recoil proton while the prompt gamma ray induces Compton recoil electron) of the fission neutron and prompt gamma ray in an event-by-event mode with a TOF gate. The off-line data analysis method for separating the prompt gamma ray from the fission neutron as well as its contribution to the TOF spectrum and RE spectrum to obtain the relative efficiency and response function is discussed in detail. An accurate calibration of the effective neutron detection threshold is carried out by a linear extrapolation of the section around the point of inflexion in the relative efficiency plots using neutron energy directly. The relative efficiency with 0.51 MeV effective neutron detection threshold agrees with the Monte Carlo calculation result of NEFF. The response function from 0.5 MeV to 5 MeV generally agrees with the published experimental result of the NE213 scintillator of the same size.

Measurement and analysis of neutron flux spectra in a neutronics mock-up of the HCLL test blanket module

Fast neutron and gamma-ray flux spectra and time-of-arrival spectra of slow neutrons have been measured in a neutronics mock-up of the European Helium-Cooled Lithium–Lead Test Blanket Module with the aim to validate nuclear cross-section data. The mock-up was irradiated with fusion peak neutrons from the DT neutron generator of the Technical University of Dresden. A well characterized cylindrical NE-213 scintillator was inserted into two positions in the LiPb/EUROFER assembly. Pulse height spectra from neutrons and gamma-rays were recorded from the NE-213 output. The spectra were then unfolded with experimentally obtained response matrices of the NE-213 detector. Time-of-arrival spectra of slow neutrons were measured with a 3He counter placed in the mock-up, and the neutron generator was operated in pulsed mode. Monte Carlo calculations using the MCNP code and nuclear cross-section data from the JEFF-3.1.1 and FENDL-2.1 libraries were performed and the results are compared with the experimental results. A good agreement of measurement and calculation was found with some deviations in certain energy intervals.

Neutron and Ion Beams Emitted from Plasma Focus (112.5 J) Device

Preliminary results of recent experiments performed within the Mather-type 112.5 J plasma focus device are presented. The ion beams from the focus device operated with deuterium filling at 1 mbar were registered using CR-39 solid state nuclear track detectors (SSNTD) and a Faraday cup detector for time-resolved measurements. The time-resolved neutron emission from the focus region measurements was detected with a photomultiplier tube (IP-28) optically coupled with a plastic scintillator NE 102.