Ti-T Target Research Articles

A CFD analysis of the rotating target holder of the 14-MeV neutron generator

An accelerator based 14-MeV neutron generator is installed at Institute for Plasma Research, Gandhinagar to generate high energy neutrons by using a water-cooled rotating tritium target. In this device, neutrons would be generated from the nuclear reaction 3H(D, n)4He by bombarding accelerated deuterium ions on a solid tritium target. The rotating target holder mainly consists of a rotating copper disc water-cooled case mounted on the rotating shaft. The high-energy deuterium ion beam impacted on solid TiT target fitted on the copper case imparting its energy to the case. This energy is taken away from the system through the water passing through the annulus cavity of the shaft. This paper presents details of the engineering CFD (computed fluid dynamics) analysis carried out for optimizing two important parameters of the rotating target. Firstly optimization of the location of flow parameters of the water as mass flow rate and Secondly optimization of speed of the rotating target and the design of fins inside the copper case.

Semiconductor Detector Study for Detecting Fusion Neutrons using Geant4 Simulations

Accurate neutron flux measurements in fusion reactors are essential, in order to determine the feasibility and progress of the reaction as well as for safety issues. Semiconductor neutron detectors exhibit promising characteristics for operation in the extreme environmental conditions of fusion reactors. Silicon, Diamond and Silicon Carbide are the most studied and anticipated materials for constructing detectors with high efficiency and irradiation resistance. The ITER fusion reactor is expected to run D-D plasma measurements in the near future, so the detection of 2.45 MeV neutrons with appropriate detectors is of great and immediate importance. In the present work the study of 2.45 MeV neutrons interactions with a silicon, diamond and silicon carbide detector was made, using GEANT4 [1] simulations, in order to compare their response. An experimental study will follow at the neutron production facility of the TANDEM accelerator of the I.N.P.P. of the NCSR “Demokritos”, with detectors provided by CIVIDEC Instrumentation GmbH, so the geometry of the simulations was built accordingly. A quasi-monoenergetic neutron beam of 2.45 MeV was produced through 3H(p,n) reactions in a TiT target. Due to the low cross section of the reaction, biasing techniques were implemented in the simulation to increase the counting rate and thus producing realistic results. These biasing techniques were studied, with various tests and the parameters affecting the choice of the biasing factor are shown and discussed.

New cross section measurements on tungsten isotopes around 14 MeV neutrons and their excitation functions * *Supported by the National Natural ScienceFoundation of China (11575090)

New cross sections of the 183W(n,α)180mHf, 186W(n,d*)185Ta, 182W(n,p)182Ta, 184W(n,p)184Ta, 182W(n,2n)181W, 184W(n,α)181Hf, and 186W(n,α)183Hf reactions were measured in the neutron energy range of 13.5-14.8 MeV via the activation technique to improve the database and resolve discrepancies. Monoenergetic neutrons in this energy range were produced via the T(d,n)4He reaction on a solid Ti-T target. The activities of the irradiated monitor foils and samples were measured using a well-calibrated high-resolution HPGe detector. Theoretical calculations of the excitation functions of the seven nuclear reactions mentioned above in the neutron energies from the threshold to 20 MeV were performed using the nuclear theoretical model program TALYS-1.9 to aid new evaluations of cross sections on tungsten isotopes. The experimental data obtained were analyzed and compared with that of previous experiments conducted by other researchers, and with the evaluated data available in the five major evaluated nuclear data libraries of IAEA (namely ENDF/B-VIII.0 or ENDF/B-VII.0, JEFF-3.3, JENDL-4.0u+, CENDL-3.2, and BROND-3.1 or ROSFOND-2010), and the theoretical values acquired using TALYS-1.9 nuclear-reaction modeling tools. The new cross section measurements agree with those of some recent experiments and theoretical excitation curves at the corresponding energies. The consistency of the theoretical excitation curves based on TALYS-1.9 with these experimental data is better than that of the evaluated curves available in the five major nuclear data libraries of IAEA.

Research and Development of the Polarized Deuteron Source for the Van de Graaff Accelerator

An attempt is made to develop a polarized deuteron source suited for the Van de Graaff accelerator of Czech Technical University in Prague. We based on Kaminsky’s experiment on channeling deuterons through a Ni single crystal. The setup is described, which contains permanent magnets with a transversal magnetic field to increase the deuteron polarization using Sona-method (zero transition). The measurements of tensor polarization were carried out with TiT target. The result is $${{P}_{{zz}}} = - 0.12 \pm 0.04$$ for a weak field at the target without channeling. The ultimate aim is to produce 14-MeV polarized neutrons which will be used jointly with the frozen-spin polarized deuteron target for measurement $$\Delta {{\sigma }_{T}}$$ and $$\Delta {{\sigma }_{L}}$$ asymmetries in the $$nd$$ ‑transmission experiment.

Estimating the Reactivity of the Yalina-Booster Fast-Thermal Subcritical Assembly without Fuel in the Fast Zone

The geometry and material content of the Yalina-Booster two-zone subcritical assembly driven by external neutron sources are described, along with the instrumentation and conditions of experimental measurements. 252Cf isotope and a neutron generator with a TiT or TiD neutron-producing target are used as external neutron sources. The results are presented from analytical and experimental estimates of the levels of subcriticality in two core configurations: (1) with a fueled core (uranium dioxide of 10% enrichment in the thermal zone and uranium dioxide of 21% enrichment in the fast zone) and (2) with uranium dioxide of 10% enrichment in the thermal zone and without fuel in the fast zone. The calculated effective fractions of delayed neutrons in the considered thermal zone are compared. It is shown that the main kinetic parameters are defined by the thermal zone. The calculated results are compared to experimental ones, and the discrepancies are analyzed.

Experimental and numerical investigations of radiation characteristics of Russian portable/compact pulsed neutron generators: ING-031, ING-07, ING-06 and ING-10-20-120

The present paper discusses results of full-scale experimental and numerical investigations of influence of construction materials of portable pulsed neutron generators ING-031, ING-07, ING-06 and ING-10-20-120 (VNIIA, Russia) to their radiation characteristics formed during and after an operation (shutdown period). In particular, it is shown that an original monoenergetic isotropic angular distribution of neutrons emitted by TiT target changes into the significantly anisotropic angular distribution with a broad energy spectrum stretching to the thermal region. Along with the low-energetic neutron part, a significant amount of photons appears during the operation of generators. In the pulse mode of operation of neutron generator, a presence of the construction materials leads to the “tailing” of the original neutron pulse and the appearance of an accompanying photon pulse at ~3ns after the instant neutron pulse. In addition to that, reactions of neutron capture and inelastic scattering lead to the creation of radioactive nuclides, such as 58Co, 62Cu, 64Cu and 18F, which form the so-called activation radiation. Thus, the selection of a portable neutron generator for a particular type of application has to be done considering radiation characteristics of the generator itself. This paper will be of interest to users of neutron generators, providing them with valuable information about limitations of a specific generator and with recommendations for improving the design and performance of the generator as a whole.

Measurement of Differential Cross Section for the 64Zn(n,α)61Ni Reaction at 2.54, 4.00, and 5.50 MeV

By using a twin-gridded ionization chamber, differential cross-section data of the 64Zn(n,α)61Ni reaction were measured at neutron energies of 2.54, 4.00, and 5.50 MeV. The experiment was performed at the 4.5-MV Van de Graaff accelerator of the Institute of Heavy Ion Physics, Peking University, China. Monoenergetic neutrons of 2.54 MeV were produced through the T(p,n)3He reaction with a solid Ti-T target, and those of 4.00 and 5.50 MeV were produced through the D(d,n)3He reaction with a deuterium gas target. The absolute neutron flux was determined through the 238U(n,f) reaction and a BF3 long counter was used as the neutron flux monitor. Results of the present work are combined with our previous data between 5.0 and 6.5 MeV and compared with other measurements and evaluations.

Coincidence Measurement of 189W Decay Gamma Rays

To our knowledge, the earliest work concerning W decay was done by Flegenheimer et al. in 1963. They determined the half-life of W to be 11min. A maximum energy of around 1.4MeV for W was obtained. In 1965, Kauranen and Ihochi studied W through the Os(n, ) W reaction. Its half-life was determined to be 11:5 0:3min. An end-point energy of 2:5 0:2MeV for the -spectrum of W was obtained. Its ten rays with energies of 94, 130, 178, 222, 258, 360, 417, 550, 855, and 955 keV were found. A cascade of two rays at 222 and 258 keV was observed. In ref. 3, Mirzadeh et al. investigated W decay via the Os(n, ) W reaction. Through the measurement of singles spectra, they observed two rays with energies of 260.4 and 421.7 keV from W decay and got their relative intensities. In 1997, Yang et al. made a singles -ray spectrum measurement by using an HPGe detector. Twenty two rays which can be assigned to the decay of W were found. Eighteen of these rays were observed for the first time. Subsequently in 2003, Wu and Niu gave a sample decay scheme (Fig. 1) including two rays of W at 222.0 and 260.4 keV based on the -ray data of Yang et al. and the reaction data of Hirning et al. But until now, no precise coincidence measurement for W rays was made. The present work is to check the coincidence relations inferred from previous work. The measurement of rays from W decay was taken with X– and – coincidence methods in our experiments. The (n, ) and (n, ) reactions were proved to be efficient ways for producing W in previous work. So in this work, we selected the Os(n, ) W reaction to produce W. The present experiments were performed using 14MeV neutrons from the 600-kV Cockcroft–Walton accelerator at the Institute of Modern Physics, Chinese Academy of Sciences. 14MeV neutrons were produced by the reaction of TiT targets with deuterons. W activities were produced using irradiation of isotopically enriched Os metallic powder of 100mg/cm with 14MeV neutrons. Osmium targets each were irradiated for 30min to fit the 10.7min half-life of W. And then they were transported into a lead-shielded room by an improved rabbit system. The measurement started 20 s after the end of irradiation with a planar HPGe detector (for X-ray and low energy -ray measurement) and a clover detector which consists of four coaxial N-type Germanium detectors. The former has an energy resolution of 0.6 keV for the 122 keV line of Co, an active diameter of 32mm, and a sensitive depth of 10mm; each of the latter has a 25% efficiency and an energy resolution of 2.1 keV for the 1332 keV line of Co. The two detectors were placed face to face on both sides of the source in the lead-shielded room. The measurement lasted 30min to fit the half-life of W. The count rate of single detector was about 100/s in the experiment. The coincidence window width of 100 ns was chosen. Thus the infection of the chance coincidence was not significant. The procedure mentioned above was repeated many times to improve the counting statistics. (X)-ray singles events and three parameter coincidence (X)– –t were recorded with a Multi-Parameter Data Acquisition System, where t was the time of each event after the beginning of a counting period. During the irradiation, several radioactive isotopes of Os, Re, and W were produced by (n,2n), (n, ), (n,p) and (n, ) reactions, respectively. It was not possible to observe rays from W decay through singles spectra because of the lower W yield and the large backgrounds from other nuclides produced in the experiments. The X– coincidence measurement was made so as to obtain rays from W decay. A part of the -ray spectrum in coincidence with 61.1 keV Re K 1 and 59.7 keV Re K 2 X rays is presented in Fig. 2.

(n, α) Reaction Cross Sections of 44Ca, 45Sc, and 51V Nuclei from 13.6 to 14.9 MeV

Cross sections were measured for the 44Ca(n,α)41Ar, 45Sc(n,α)42K, and 51V(n,α)48Sc reactions at neutron energies from 13.6 to 14.9 MeV. The neutrons were produced via the 3H(d,n)4He reaction on a neutron generator using a solid TiT target. The activation technique was used, and induced gamma activities were measured by a high-resolution gamma-ray spectrometer. Corrections were made for the effects of gamma-ray attenuation, random coincidence (pulse pileup), coincidence summing, dead time, neutron flux fluctuations, and low-energy neutrons. Statistical model calculations taking into account precompound effects were performed for all the reactions investigated, and the experimental results were reproduced well except for the (n,α) reaction on the 45Sc target. Also, comparisons with the recent experimental data showed good agreement.

Angular Anisotropy of the

The angular distributions of \(\) particles emitted from the \(\) reaction were measured at 7.5\(\) intervals from 60\(\) to \(\) for incoming deuteron energies of 100, 150, and 200 keV using 50 and 80 \(\)g/cm\(\) thick TiT targets. The overall uncertainty of 0.16% of the data made it possible to determine Legendre-polynomial coefficients up to \(\). The results are compared with an \(\)-matrix parameterization. The measured angular anisotropies present the first experimental evidence of \(\)-wave contributions to the cross section in the vicinity of the \(\)\(\)-wave resonance in \(\)He.

Excitation functions and isomeric cross section ratio of the 58Ni(n,p)58Com,g reactions from 2 to 15 MeV.

The cross sections for the {sup 58}Ni({ital n},{ital p}){sup 58}Co{sup {ital m},{ital g}} reactions were measured in the neutron energy range 2.1--14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Neutrons were produced via the {sup 2}H({ital d},{ital n}){sup 3}He and {sup 3}H({ital d},{ital n}){sup 4}He reactions using solid TiD, TiT, and deuterium gas targets. The isomeric cross section ratio was determined in the 5.38--12.2 MeV range and at 14.8 MeV neutron energy. Statistical model calculations taking into account precompound effects were performed for the formation of the isomeric and ground states of the {sup 58}Co. The calculational results based on the ``back-shifted`` level density model agree well with the measured excitation functions and render possible the selection of the most probable values of isomeric cross section ratios among the discrepant data obtained around 2 and 14 MeV neutron energies.

Excitation functions and isomeric cross section ratios of the 63Cu(n, alpha )60Com,g, 65Cu(n, alpha )62Com,g, and 60Ni(n,p)60Com,g processes from 6 to 15 MeV.

Excitation functions were measured for the $^{63}\mathrm{Cu}$(n,\ensuremath{\alpha}${)}^{60}$${\mathrm{Co}}^{\mathit{m}}$, $^{65}\mathrm{Cu}$(n,\ensuremath{\alpha}${)}^{62}$${\mathrm{Co}}^{\mathit{m}}$, and $^{65}\mathrm{Cu}$(n,\ensuremath{\alpha}${)}^{62}$${\mathrm{Co}}^{\mathit{g}}$ reactions over the neutron energy range of 6.3 to 14.8 MeV. Use was made of the activation technique in combination with high resolution \ensuremath{\gamma}-ray spectroscopy. The nuetrons were produced via the $^{2}\mathrm{H}$(d,n${)}^{3}$He reaction using a deuterium gas target at a variable energy compact cyclotron (${\mathit{E}}_{\mathit{n}}$=6.3--11.9 MeV) and via the $^{3}\mathrm{H}$(d,n${)}^{4}$He reaction using a solid Ti-T target at a neutron generator (${\mathit{E}}_{\mathit{n}}$=13.7--14.8 MeV). From the available experimental data isomeric cross section ratios were determined for the isomeric pair $^{60}\mathrm{Co}^{\mathit{m},}$g in $^{63}\mathrm{Cu}$(n,\ensuremath{\alpha}) and $^{60}\mathrm{Ni}$(n,p) reactions, and for the pair $^{62}\mathrm{Co}^{\mathit{m},}$g in the $^{65}\mathrm{Cu}$(n,\ensuremath{\alpha}) reaction. Statistical model calculations taking into account precompound effects were performed for the formation of both the isomeric and ground states of the products. The calculational results on the total (n,p) and (n,\ensuremath{\alpha}) cross sections agree well with the experimental data; in the case of isomeric states, however, some deviations occur. The experimental isomeric cross section ratios are reproduced only approximately by the calculation; at 15 MeV the spin distribution of the level density has a significant effect on the calculation. For low-lying levels the isomeric cross section ratio depends strongly on the spins of the levels involved and not on their excitation energies. At a given neutron energy the population of the higher spin isomer appears to be higher in the (n,\ensuremath{\alpha}) process than in the (n,p) reaction.

Measurements of contaminated d + D neutrons in d + T neutron fields by using a 3He proportional counter

Contamination of d + D neutrons, which originate from deuteron implantation on a Ti-T target, has been measured by using a 3He proportional counter. This simple method is useful and helpful to evaluate the contamination of d + D neutrons in d + T neutron fields in the neutron energy region from 14 to 20 MeV.

Contribution of fast protons produced by 3He(d, p) 4He reactions in the neutron field of A T(d, n) 4He source

Protons produced by the 3He(d, p) 4He reaction in a Ti-T target were directly detected in free air by a proton recoil telescope for neutron fluence measurement at mean deuteron energies from 0.24 MeV to 3.23 MeV. These results emphasize the care that must be taken in d + T neutron sources using the associated particle technique, and also in the calibration of neutron detectors which are sensitive to the protons from the 3He(d, p) 4He reaction, in the case of a thinner target wall backing.

A Deuteron Energy Loss Evaluation in a Solid Ti-T Target Used for the T(d,n)4He Reaction

A simple method for the measurement of the loss of deuteron energy in a solid Ti-T target of a neutron generator is described. The method is based on a comparison of the results of measurements of ...

Some improvements on a Ti-T target system for the production of 14 MeV neutrons.

Some improvements on a Ti-T target system for the production of 14 MeV neutrons.

Preliminary results on the time resolution of a plastic scintillator neutron counter of large area for neutrons of 16 MeV

The time resolution measurements of a plastic scintillator neutron detector of large are (200×15 cm 2) are reported. For neutrons of 16 MeV, obtained with the T(d, n) 4He reaction and a solid Ti-T target, the corrected time resolution turns out to be equal to 670 ps, for a proton threshold energy of 10 MeV.

Production of DT neutrons by means of TiT targets and analyzed atomic deuteron beams

The behaviour of TiT targets during irradiation with a pure beam of atomic deuteron ions was investigated. The dependence on time of the absolute DT neutron yield and the build-up of DD neutron intensity was determined at a constant current density of 0.3 mA/cm 2 for both a 2 Ci and 5 Ci/sq-inch TiT target. Half-lives of 12 mAh/cm 2 and 18 mAh/cm 2 for the DT neutron yield were observed in these two cases. These half-lives are more than an order of magnitude longer than those observed using TiT targets in low-energy accelerators with unanalyzed beams. The DD neutron intensity rises approximately proportional with the irradiation time and reaches a saturation value of about 0.3% of the initial DT yield or 30% of the yield of a TiD target at the end of one half-life. The results suggest that the effect of replacement of tritium by the implanted deuteron is less than hitherto assumed and most of the deuterons are capable of diffusing out of the target without interaction with the tritium. It appears that the short half-lives observed with the use of unanalyzed beams are mainly due to sputtering and radiation damage caused by heavy-ion contaminants always present in unanalyzed beams.

A clean effectively cooled Ti-T target system giving a high yield of 14 MeV neutrons

A target system has been developed for producing a high yield of 14 MeV neutrons from the T(d,n) reaction in tritium-titanium targets. The target lifetime is increased by using a liquid-nitrogen-cooled vapour trap and an all-metal construction of the target mounting system. The targets are effectively cooled with water flowing directly behind the substratum. The neutron yield dropped to half its initial value after the irradiation with an integrated current of more than 20 C of 300 keV deuterons per cm 2 target area. With this system, small samples may be placed only about 2 mm from the neutron source. The small over-all dimensions also allow larger samples to be positioned close to the target, and there is only a small amount of neutron-scattering material near the target.

Neutron flux measurement by counting the associated 3He particles from the T(p,n) reaction corresponding to 500 keV neutron energy

This paper continues an earlier publication 1) about counting associated 3He particles from the T(p,n) reaction. Even with a simpler experimental set-up than described there (without electrostatic separation of the Coulomb scattered protons) but with Ti-T targets having thinner Al backings (200 μg/cm 2 Al) it is possible to shift the energy of the associated neutrons down to 500 keV with a slight increase in accuracy. The results of this method were compared with those from n-p scattering in a methane-filled proportional counter. Agreement was found within 0.8%.