Feasibility Analysis of ^13N＋p Elastic Resonance Scattering

13N（p, γ）^14O is one of the key reactions involved in the hot CNO cycle that takes place in the evolution of massive stars. Its reaction rates are dominated by a 1^- broad resonance state which lies at 5.17 MeV in 14O. However, there are several low-lying levels above the ^13N＋p threshold which might be of relevance to the reaction rates and of importance to the nuclear structure of ^14O. The properties of these levels are not well known, in particular, there is a O^- level missing when comparing with the mirror nucleus ^14C. These incomplete information can be complemented by a study of ^13N＋p elastic resonance scattering.     

Feasibility Analysis of ~(13)N p Elastic Resonance Scattering

13N(p,γ)14O is one of the key reactions involved in the hot CNO cycle that takes place in the evolution of massive stars[1]. Its reaction rates are dominated by a 1-broad resonance state which lies at 5.17 MeV in 14O. However, there are several low-lying levels above the 13N p threshold which might be     

Astrophysical ~(13)N(p,γ)~(14)O Reaction Rate

13N(p,γ)14O is is one of the key reactions in the hot CNO cycle which occurs at stellar temperatures around T9≤0.1. At the energies of astrophysical interest, the 13N(p,γ) 14O reaction is dominated by the     

DETERMINING CARBON—13 ENRICHMENT USING LOW ENERGY PROTONS

The proton-capture reactions 12C(p,γ)^13N and 13C(P,γ)^14N have been studied to determine 13C enrichments.The system has been calibrated by measuring the gamma-rays yield from the 12C(p,γ)13N and 13C(p,γ)^14N reactions as a function of known 13C enrichment.This technique is applicable to the analysis of samples with 13C enrichments between 1% and 90%.     

Studies on absorption coefficients of dual-energy γ-rays and measuring error correction for multiphase fraction determination

In tiffs article, principle and mathematical method of determining the phasc fractions of multiphase flows by using a dual-energy γ-ray system have been described. The dual-energy γ-ray device is composed of radioactive isotopes of ^241Am and ^137Cs with γ-ray energies of 59.5 and 662 keV, respectively. A rational method to calibrate the absorption coefficient was introduced in detail. The modified arithmetic is beneficial to removing the extra Compton scattering from the measured value. The result shows that the dual-energy γ-ray technique can be used in thrce-phase flow with average accuracy greater than 95%, which enables us to determine phase fractions almost independent of the flow regime. Improvement has been achicved on measurement accuracy of phase fractions.     

The Sub-Library of Giant Dipole Resonance Parameters for γ-ray (CENPL-GDP-1.1) (Ⅱ)

In this paper, the experimental data of the photonuclear reactions for the nuclides ~(12)C, ~(14)N, ~(16)O, ~(27)Al and ~(28)Si were fitted with the Lorentz curves describing the giant dipole resonances of the photonuclear reactions and the giant dipole resonance parameters (GDRP) of these nuclides were extracted. These GDRP were compiled in the sub-library of the giant dipole resonance parameters for γ-ray(GDP). An updated edition GDP-1.1(Version 1.1) has been set up and used in the nuclear model calculation widely.     

High-Sensitivity In-Situ Diagnosis of NO_2 Production and Removal in DBD Using Cavity Ring-Down Spectroscopy

A highly-sensitive in-situ diagnosis approach for nitrogen dioxide （NO2） has been developed in dielectric barrier discharge （DBD） based on pulsed cavity ring-down spectroscopy （CRDS）. Absorption bands of NO2 in a spectral region from 508 nm to 509 nm were used, and a detection limit of 17.5 ppb was achieved. At this level of sensitivity, the quantitative and real-time monitoring of the production and removal of NO2 are accomplished for the first time in the discharge region. By measuring the removal amount and rate at different NO2 initial number densities from 1.54 ×10^13 cm^-3 to 2.79 × 10^14 cm^-3, we determined the relationship between them and NO2 initial number densities. The removal amount linearly increases with the initial number density, while the removal rate increases logarithmically. At a lower initial number density, the removal rate is limited. By considering the chemical kinetic mechanism in plasma, a qualitative explanation for the above phenomena is proposed： the additional NO2 produced by discharge limits the removal rate, since the NO2 concentration is dominated by the competition between the forward reactions （production） and the reverse reactions （removal）.     

Indirect Measurement of 58 keV Resonance of ~(25)Mg(p,γ)~(26)Al via(~7Li,~6He)Reaction

正~(25)Mg(p,γ)~(26)Al is one of the key reactions for Mg-Al cycle in explosive hydrogen burning of stars.Its cross sections at star energies are essential to understand the problem of ~(26)Al and ~(26)Mg abundances.It is very difficult to direct measure the 58 keV resonance in ~(25)Mg(p,γ)~(26)Al reaction.Because of the interference of the     

Theoretical Analysis of Neutron Double-Differential Cross Section of n＋^14N at 14.2 MeV

By using a new reaction model for light nuclei, the double-differential cross section of n＋^14N reactions at En=14.2 MeV have been analyzed. In the case of n＋^14N reactions, the reaction mechanism is very complex, there are over one hundred opened partial reaction channels even at incident energy     

Measurement of Electron Swarm Parameters in Nitrous Oxide

This study has measured the density-normalized effective ionization coefficients （α-η）/N, the electron drift velocity V e and the diffusion coefficient D L in nitrous oxide （N₂O） using a pulsed Townsend technique. The range of the overall density-normalized electric field strength E/N is from 100 Td to 400 Td （1 Td=10 17 V·cm2）. From the above plots of （α-η）/N, we have derived the limiting field strength, （E/N） lim ≈ 150 Td, which is the value of E/N at which （α-η）/N=0.     

Proton induced gamma ray emission analysis of nitrogen

The proton-capture reactions 14N(p,γ)15O and 15N(p,αγ)^12C have been studied to determine their applicabilities to the analysis of materials for 15N enrichment,It is true that precision of the measurement concerned in these techniques cannot compete with mass spectrometry,but their ease of application is of great advantage to the fast handling of very large batches of samples from stable nuclide tracer experiments.     

Diagnosis of Electronic Excitation Temperature in Surface Dielectric Barrier Discharge Plasmas at Atmospheric Pressure

The electronic excitation temperature of a surface dielectric barrier discharge （DBD） at atmospheric pressure has been experimentally investigated by optical emission spectroscopic measurements combined with numerical simulation. Experiments have been carried out to deter- mine the spatial distribution of electric field by using FEM software and the electronic excitation temperature in discharge by calculating ratio of two relative intensities of atomic spectral lines. In this work, we choose seven Ar atomic emission lines at 415.86 nm [（3s^23p^5）5p →（3s^23p^5）4s] and 706.7 nm, 714.7 nm, 738.4 nm, 751.5 nm, 794.8 nm and 800.6 nm [（3s^23p^5）4p → （3s^23p^5）4s] to estimate the excitation temperature under a Boltzmann approximation. The average electron energy is evaluated in each discharge by using line ratio of 337.1 nm （N2（C^3Пu →B3Пg）） to 391.4 nm （N2^＋（B2 ∑u^＋→ ∑g^＋））. Furthermore, variations of the electronic excitation tempera- ture are presented versus dielectric thickness and dielectric materials. The discharge is stable and uniform along the axial direction, and the electronic excitation temperature at the edge of the copper electrode is the largest. The corresponding average electron energy is in the range of 1.6- 5.1 eV and the electric field is in 1.7-3.2 MV/m, when the distance from copper electrode varies from 0 cm to 6 cm. Moreover, the electronic excitation temperature with a higher permittivity leads to a higher dissipated electrical power.     

Measurement Cross Section of D（d, γ）4He Reaction

The study of D（d, γ）^4He radioactive capture reactions at low energy is very important in the fusion diagnose, but it is hard to measure for small yield and serious background. In the present work, several measures were adapted. 1） A big NaI plastic anti Compton spectrometer for low yield of high energy γ-ray was used; 2） The method of the time of flight was employed for rejecting background neutrons and cosmic rays;     

Coal analysis using the pulsed neutron generator

A prototype of elemental analyzer for coal has been developed by using a PFTNA (pulse fast thermal neutron analysis) system. The PFTNA technology is based on the reactions such as (n, γ), (n, n'γ), (n, pγ), etc. by examining the characteristic gamma rays emitted. In our prototype a pulsed neutron generator provides 14 MeV pulse neutrons, which contribute to the separation of spectrum II (the sum of capture and activation spectrum) from spectrum I (the sum of inelastic, capture and activation spectrum), and thus to the measurement of C and O contents in coal. Data management is completed by computer program using the least-square regression method. The experiment in Changshan Power Plant for 3 months showed that the precision of calorific value, whole water, volatile content and ash content is 0.5 kJ/kg, 1.0 wt%, 2.0 wt% and 1.5 wt%, respectively.     

On the heating mechanism of electron cyclotron resonance thruster immerged in a non-uniform magnetic field

To study the heating mechanism of electron cyclotron resonance thruster(ECRT) immersed in a non-uniform magnetic field, experiments and simulations are performed based on an electron cyclotron resonance plasma source at ASIPP. It is found that the first harmonic of electron cyclotron resonance is essential for plasma ignition at high magnetic field(0.0875 T), while the plasma can sustain without the first and second harmonics of electron cyclotron resonance at low magnetic field(till 0.0170 T). Evidence of radial hollow density profile indicates that upper hybrid resonance, which has strong edge heating effect, is the heating mechanism of low-field ECRT. The heating mode transition from electron cyclotron resonance to upper hybrid resonance is also revealed. Interestingly, the evolutions of electron temperature and electron density with input power experience a ‘delayed' jump, which may be correlated with the different power levels required for cyclotron and ionization. Moreover, when the field strength decreased, the variation of electron density behaves in an opposite trend with that of electron temperature,implying a possible competition of power deposition between them. The present work is of great interest for understanding the plasma discharge in ECRT especially immersed in a non-uniform magnetic field, and designing efficient ECRT using low magnetic field for economic space applications.     

Astrophysical S-factor for ~8B(p, γ)~9C via a Study of the ~8Li(d, p)~9Li Reaction

The 8B(p, γ)9C reaction plays a key role in the 7Be(p, γ)8B(p, γ)9C(α, p)12N chain which is believed to be a breakout path into the hot CNO cycles. 8B(p, γ)9C might be of importance for the evolution of massive stars with very low metallicities where     

Energy Transformation in Mammalian Cell for Low Energy Ion Beam Impinging

This study investigates the stopping power of a mammalian cell for low energy ions. The energy equation of the incident ion has been conducted based on the elastic collision between the pairs of nuclei in order to establish the stopping powers of the mammalian cell for low energy ion implantation. Based on the biological structure of the mammalian cell and the measured thickness of the V79 cell, a physical structural model is proposed that the attached cell is approximately of a model of a constringent multi-membrane structure （C-2M model） in order to analyse the stopping power of the mammalian cell for low energy ions. With this model we have determined the mean line energy transfer, and roughly estimated the depth of ion implantation on the selected Chinese hamster V79 cell for 30 keV N^＋ ions at a flux of 1 × 10^15 ion/cm^2, which is in agreement with those by using Monte Carlo methods.     

New Measurement of Proton Transfer Reactions and Elastic Scattering for 7Li + 13C at 34 MeV

The 13C(7Li, 6He) 14N reaction is measured at E(7Li) = 34 MeV with the Q3D magnetic spectrometer of HI-13 tandem accelerator. Angular distributions at forward angles for proton transfer to the ground and the first excited states in 14N are obtained. In addition, angular distribution for 7Li + 13 C elastic scattering is also measured. The optical potential parameters for the entrance and exit channels of the transfer reactions are derived by fitting the 7Li + 13C and 6Li + 14N elastic scattering experimental data, and their angular distributions are well reproduced by the distorted wave Born approximation calculations. A phase shift of about 2 between the calculations and the experiment data has been found in the earlier (7Li, 6He) study, whereas no such phase shift is observed in the present work.     

Nuclear Astrophysics Experiments in Collaboration with Ruhr University

This paper reports on two nuclear astrophysics experiments performed in collaboration with Ruhr University. In a 12C+ 12C fusion reaction, the 12C(12C, α) 20Ne and 12C( 12C, p) 23Na reactions were studied in the energy range of E = 2.10 MeV to 4.75 MeV using γ-ray spectroscopy. The deduced astrophysical S(E) factor exhibited a new, strong resonance at E = 2.14 MeV, which lay at the high-energy tail of the Gamow peak. The resonance increased the reaction rate of the α-channel by a factor of five near T = 8 × 10~8K. The electron screening in d(d, p)t was studied for a series of deuterated metal, insulator and semiconductor targets. Compared with the measurements performed with a gaseous D2 target, a large effect was observed in most metals, while a comparatively small effect was found in the insulators and semiconductors. Subsequently the temperature dependence of the electron screening in the d(d, p)t reaction was studied for the deuterated metals Pt and Co. Enhanced electron screening decreased with increasing tempera-ture. These data represent the first observations of the temperature dependence of a nuclear cross section.     

Measurement of ^17F（d,n）^18Ne Reaction

Explosive hydrogen burning occurs in very massive （M≥ 10^5-10^8 M） star with high temperature and density. Hot pp chain, hot CNO, hot NeNa-MgAl chain and the flowing γp and ap process will play a prominent role in hydrogen burning as. the temperature goes higher. When the temperature of the star is hither than 10^8 K. high temnerature CNO chain is dominant in hydrogen burning,