Triton Production Research Articles

Light charged particle emission induced by neutrons with energies between 25 and 65 MeV on oxygen. II. Tritons and alpha-particles

Double-differential cross sections for fast neutron induced triton and alpha-particle production on oxygen, are reported at seven incident neutron energies between 30 and 65 MeV. Angular distributions were measured at laboratory angles between 20 degrees and 160 degrees. Energy-differential, angle-differential and total cross sections are reported. Experimental cross sections are compared with existing experimental data and with theoretical model calculations.

Triton and alpha-particle production in neutron-induced reactions on carbon at En=42.5, 62.7, and 72.8 MeV.

Double-differential cross sections for fast neutron-induced triton and alpha-particle production on carbon are reported at three incident neutron energies: 42.5, 62.7, and 72.8 MeV, complementing our previous results for proton and deuteron emissions. Angular distributions were measured at laboratory angles between 20\ifmmode^\circ\else\textdegree\fi{} and 160\ifmmode^\circ\else\textdegree\fi{} in steps of 10\ifmmode^\circ\else\textdegree\fi{}. Procedures for data taking and data reduction are described. Results for double-differential, energy-differential, and total cross sections are presented. The measurements are compared to existing data and to nuclear model calculations which include preequilibrium and equilibrium decay mechanisms. \textcopyright{} 1996 The American Physical Society.

Neutron-induced particle production in the cumulative and noncumulative regions at intermediate energies

The first systematic measurements of neutron-induced inclusive production of protons, deuterons, tritons and charged pions on carbon, copper and bismuth in the bombarding energy range of 300–580 MeV and in the angular interval from 51° to 165° have been analyzed in the framework of the cascade-exciton model. The role of single-particle scattering, the effects of rescattering, the pre-equilibrium emission and “coalescence” mechanism in particle production in the cumulative (i.e., kinematically forbidden for quasi-free intranuclear projectile-nucleon collisions) and noncumulative regions are discussed. A weak sensitivity of the inclusive distributions to the specific reaction mechanisms and a need of correlation and polarization measurements are noted.

Neutron emission profile measurements during the first tritium experiments at JET

During a series of experiments with tritium (T) in deuterium (D) plasmas in the Joint European Torus (JET), the temporal evolution and the two dimensional (2-D) spatial profiles of the 2.5 and 14 MeV neutron emissivities from D-D and D-T fusion reactions were inferred from measurements with the JET neutron emission profile monitor. These experiments, involving triton production from D-D fusion, beam deposition and diffusion, D-T fusion, and tritium removed from wall tiles, were investigated in four plasma scenarios: (i) In high performance deuterium plasmas with deuterium neutral beam injection, the 14 MeV neutron emissivity due to triton burnup was observed. (ii) In discharges with 1% tritium beam injection, neutron emissivity ratios showed that approximately the same deposition profiles resulted from tritium as from deuterium beams. A thermalized tritium diffusion experiment was performed in which the T-D density ratio was found to be spatially constant across the plasma; in conjunction with similar particle source profiles, this indicates that deuterium and tritium have similar particle transport properties. (iii) In two high performance discharges for which two of the sixteen neutral beam sources operated with 100% tritium, the production rate of 14 MeV neutrons reached 6 × 1017 n.s-1 The alpha particle 2-D birth profile was directly inferred from the measured 14 MeV neutron emissivity profile. Both the axial 14 MeV neutron emissivity and the axial ion temperature saturated before the maximum global emission was reached. (iv) During the tritium cleanup phase, residual tritium entering the plasma produced a spatially constant ratio of tritium to deuterium, confirming the similarity of their particle transport properties

Collector probe measurement of fusion tritons in TFTR

The production of fusion tritons in the Tokamak Fusion Test Reactor (TFTR) has been measured using Si collector probes. Four probes at two toroidal and two poloidal positions were exposed to about 1200 plasma discharges over a six month period and subsequently analyzed using high-sensitivity secondary-ion mass spectrometry (SIMS). SIMS depth profiles show that the incident tritons had an average projected range of about 10 μm in the Si, which is characteristic of 1 MeV tritons produced by DD fusion. The triton fluences observed at the various sample locations ranged from 5×1011 to 5×1012 T/cm2. First-orbit loss code calculations, scaled by the measured total neutron production during the exposure period, were used to predict the expected triton fluence to the samples. The predicted and observed triton fluences agree to within an order of magnitude.

Neutron-induced production of protons, deuterons and tritons on copper and bismuth

Inclusive cross sections for production of protons, deuterons and tritons by neutrons in the energy range of 300–580 MeV on copper and bismuth have been measured at five angles between 54° and 164°. The systematic dependence of the invariant cross sections on incident energy and emission angle are evaluated. For the study of the mass-number dependence earlier data on carbon are included. The results are discussed on the basis of different models, like quasi-two-body sealing or moving-source model.

Multiconfiguration resonating-group theory of 8Li.

The nucleus $^{8}\mathrm{Li}$ is studied with a multiconfiguration resonating-group calculation which consists of n${+}^{7}$Li, t${+}^{5}$He, n${+}^{7}$${\mathrm{Li}}^{\mathrm{*}}$, and $^{4}$H+\ensuremath{\alpha} cluster configurations. With no adjustable parameters, the results show that the calculated level spectrum agrees well with experiment and with the empirical level spectrum obtained by Knox, Resler, and Lane using an extensive R-matrix analysis. A calculation employing only the n${+}^{7}$Li configuration is found to be generally inadequate. Among the configurations t${+}^{5}$He, n${+}^{7}$${\mathrm{Li}}^{\mathrm{*}}$, and $^{4}$H+\ensuremath{\alpha} which are employed to enlarge the model space, the n${+}^{7}$${\mathrm{Li}}^{\mathrm{*}}$ configuration is shown to be the most important from an overall viewpoint. Comparisons between calculated and experimental scattering and reaction cross sections have also been made. Here one finds that the calculation explains all the main features of measured results. In particular, the triton production cross section of the $^{7}\mathrm{Li}$(n,n't)\ensuremath{\alpha} reaction is well reproduced. The calculated n${+}^{7}$Li total reaction cross section turns out to be somewhat too small, being equal to around 75% of the experimental value.

Time resolved measurements of triton burnup in JET plasmas

Triton production from one branch of the deuteron-deuteron fusion reaction is routinely measured at 6 ms time intervals in JET plasma discharges by recording the 2.5 MeV neutrons produced in the other branch using a set of calibrated fission chambers. The burnup of the tritons is measured by detecting the 14 MeV t-d neutrons with a 0.2 cm3 Si(Li) diode. The 2.5 MeV neutron flux can be used in a simple time dependent calculation based on classical slowing-down theory to predict the 14 MeV neutron flux. The measured flux and the triton slowing-down time are systematically lower than the values estimated from the key plasma parameters but the differences are within the experimental errors.

Production of protons, deuterons and tritons on carbon by intermediate energy neutrons

Inclusive cross sections for production of protons, deuterons and tritons on carbon by neutrons in the energy range of 300–580 MeV were determined at nine angles between 51° and 165°. The invariant cross sections are well represented by an exponential fit, E dσ d 3p ∝ exp (−Bp 2) . The slope parameters exhibit a systematic dependence on incident energy and emission angle. The results are discussed on the basis of the model of quasi-two-body scaling.

Triton confinement and energy-loss studies with a time-resolved neutron detector (abstract)

The expected results are presented for a fast, selective 14-MeV neutron detector which should be capable of separately measuring the confinement and energy loss of fast tritons for the first time. The tritons, from D–D reactions in a deuterium plasma, are observed when they collide with deuterons while slowing down, producing a characteristic 14-MeV neutron. Triton experiments are an excellent test for the confinement of fusion-produced alphas in a self-sustained reactor, which is critically dependent on plasma heating by the alphas. The triton production rate is pulsed by injecting a burst of deuterium using a neutral-beam heating source. The temporal distribution of the 14-MeV neutron flux is determined by the confinement and slowdown rate of the tritons. The expected flux is calculated as a function of time for the predicted triton transport, anomalous particle losses, and anomalous energy-loss rates, thus demonstrating how the various effects can be separately determined.

“Backward” production of protons, deuterons, tritons, 3He, 4He and pions in the interaction of 400 GeV protons with nuclei

Results of measurements of inclusive cross sections, p(400 GeV) + ( 6 Li, Ta) → ( p, d, t, 3 He, 4 He, π ±) + X at 90° and 160° (lab) for detected particles in the momentum range 0.1 to 1.4 Gev/ c are reported. The A dependence of these cross sections is also presented for 6Li, Be, C, Al, Cu, and Ta, at a momentum of 0.7 GeV/ c. This cross section dependence increases faster than A, at different rates for observed π +, p, d, and t, and considerably more steeply than such cross sections at low incident energies (near 1 GeV).

Inclusive Cross Sections for 180° Production of High-Energy Protons, Deuterons, and Tritons inp-Nucleus Collisions at 600 and 800 MeV

The inclusive cross sections, measured up to large values of effective mass ($\ensuremath{\equiv}\frac{{q}^{2}}{2\ensuremath{\nu}}$), are well fitted by $\frac{d\ensuremath{\sigma}}{{d}^{3}p}={B}_{x}\mathrm{exp}(\ensuremath{-}\frac{{\ensuremath{\alpha}}_{x}{p}^{2}}{2{m}_{x}})$. Values of ${B}_{x}$ and ${\ensuremath{\alpha}}_{x}$ are given for Be, C, Cu, and Ta at the incident proton energy of 600 MeV and for Ag, Ta, and Pt at 800 MeV. Extremely large $\frac{d}{p}$ and $\frac{t}{p}$ ratios and large $A$ and ${q}^{2}$ dependences of the relative cross sections are observed.

Production of energetic he nuclei and tritons in 24 GeV/c proton interactions with Ag and Br nuclei

708 stars withNh⩾7 have been analysed to study the production mechanism of fast He nuclei and tritons. On the basis of the\(\bar D\)-distribution for He nuclei, it has been concluded that the majority of the He nuclei in the momentum range (0.6÷1.5) GeV/c are3He. The frequencies of emission of tritons and He nuclei have been observed to be nearly equal. The shape of the energy spectrum of3He nuclei is similar to the one obtained for tritons. It has been suggested that the pick-up as well as the pion absorption by nuclear α-clusters present near the nuclear surface may be operating in the production of these particles.

Production of fast deuterons and tritons in high-energy nuclear interactions

The production of fast deuterons and tritons by three primary beams of 6.2 GeV/c protons, 16.2 GeV/c pions and 28 GeV/c protons has been investigated in nuclear emulsion. The experimental results, for the production of deuterons and tritons in the momentum range of 1 to 5 GeV/c are presented and the possible mechanisms for their production are discussed.

Tritiumausbeuten der Reaktionen Ni(?,t) und Pd(?,t) mit 36,2 MeV und 49,2 MeV Bremsstrahlung

The yield of triton production from Ni and Pd with bremsstrahlung of maximum energy 36.2 and 49.2 MeV was measured relative to the yield of the reaction C(ν, n) C11. The tritium was extracted from the irradiated samples by heating them to 500 °C in hydrogen. It was then transfered into a low-level gas counter. The ratio of the yields at 49.2 MeV was found to be (4.6 ± 0.4) 10−3 for Ni and (6.1 ± 1.0) 10−3 for Pd. Statistical model calculations show good agreement for Ni; for Pd however the experimental yield exceeds the theoretical prediction by two orders of magnitude.

Ausbeute der Reaktion Ag(?,t) mit Bremsstrahlung bis zu 55,7 MeV

The yield of triton production from silver irradiated with bremsstrahlung ranging in maximum energy between 31.2 and 55.7 MeV was measured relative to the C(γ, n)C11-reaction. The silver targets were dissolved in nitric acid, the water converted to hydrogen gas, and the tritium activity counted in a low-level Geiger counter. Above threshold, the quantityσ y (approximately equal to the bremsstrahlung-weighted cross section) increases roughly linearly with maximum energy and reaches (19±1) μb at 55.7 MeV. A comparison with the statistical theory of nuclear evaporation shows that the experimental yields exceed the theoretical predictions by a factor of 100 to 1000.

Production of deuterons and tritons in high-energy proton and pion interactions with emulsion nuclei

From the analysis of medium-energy particles (0.41<β<0.77) produced in 23 and 24 GeV/c proton interactions with the nuclei of emulsion, 19 deuterons and 4 tritons were identified. At the most 4 deuterons can be attributed to the direct p-\(\mathcal{N}\) collision with beam protons. In the same velocity interval, a similar analysis from 17 GeV/c π− interactions yielded 11 deuterons and one triton. Deuteron production cross-section in proton interactions is found to be nearly double that in pion interactions in the momentum range investigated. Copious production of deuterons in the low-energy range is explained as due to the pick-up process by the cascade nucleons in the energy band around 600 MeV for which the cross-section is known to be appreciable.

Production of Tritons, Deuterons, Nucleons, and Mesons by 30-GeV Protons on A1, Be, and Fe Targets

The momentum spectra of particles emerging at 30\ifmmode^\circ\else\textdegree\fi{} to a 30-GeV proton beam impinging upon various targets were measured using time-of-flight techniques. Intensities of protons, antiprotons, $\ensuremath{\pi}$ mesons, $K$ mesons, deuterons, and tritons in the range 1 to 3 GeV/c are given. Particular attention is given to the tritons and deuterons emitted from the different targets. Possible mechanisms for their production are discussed.

Re´actions nucle´aires de spallation induites sur le thorium par des protons de 150 et 82 MeV

Spallation reactions of thorium by 150 MeV and 82 MeV protons were studied by radiochemical isolation of Pa, Th, Ac and Ra isotopes and measurements of absolute cross sections. Calculations were carried on for comparison, by assuming a model of nuclear reactions by direct interaction and neutron evaporation (Serber-Jackson). Fission-evaporation competition at each step of evaporation was assumed. The agreement is very satisfactory for (p, pxn) reactions. However, experimental values are nearly twice the calculated ones for radium and actinium. Several reasons are discussed in order to explain this discrepancy. Direct interaction occurs also for alpha fragments, deuterons and tritons. Cross sections for alpha particle and triton production were measured at various energies. The formation of tritium is explained in terms of indirect pick up.

The production of tritons and C14in the terrestrial atmosphere by solar protons

Recently Begemann [1959] has confirmed the results of Craig [1957] and Begemann and Libby [1957] that the natural production rate of tritons is greater than might be expected from production by the cosmic-ray flux in the atmosphere. Two mechanisms have been considered to explain this discrepancy: (a) accretion of solar-produced tritons by the earth, as suggested by B. Feld and J. Arnold; and (b) additional production by the low-energy component of the cosmic radiation at times of minimum solar activity. The integrated flux of primary cosmic-ray particles varies with solar activity, and by a factor of 2 to 4 during a solar-activity cycle. The purpose of this note is to point out a third source, namely, intense fluxes of eneretic solar protons which could produce tritons and C14 in the terrestrial atmosphere at times near the maximum of the solar-activity cycle.