Direct measurement of 12 C+ 4 He 16 O+ total cross section was made at E cm = 2.4, 1.5 and 1.2 MeV, and preliminarily measurement was made at 1.0 MeV.A thick windowless 4 He target was developed and the low-energy 12 C beam intensity was increased by modifying our tandem accelerator. 16O recoils were detected after removing large 12 C backgrounds.Remaining obstacle is 16 O backgrounds produced by stray beams.Prospects for future experiments of 12 C+ 4 He 16 O+ cross section down to E cm =0.7 MeV are presented.

Background The design of deuteron accelerator neutron source facilities requires reliable yield estimation of gamma-rays as well as neutrons from deuteron-induced reactions. We have so foar measured systematically double-differential thick target neutron yields (DDTTNYs) for carbon, aluminum, titanium, copper, niobium, and SUS304 targets. In the neutron data analysis, the events of gamma-rays taken simultaneously were treated as backgrounds. In the present work, we have re-analyzed the experimental data for a thick carbon target with particular attention to gamma-ray events. Materials and Methods Double-differential thick target gamma-ray yields from carbon irradiated by 5 and 9 MeV deuterons were measured using an NE213 liquid organic scintillator at the Kyushu University Tandem accelerator Laboratory. The gamma-ray energy spectra were obtained by an unfolding method using FORIST code. The response functions of the NE213 detector were calculated by EGS5 incorporated in PHITS code. Results and Discussion The measured gamma-ray spectra show some pronounced peaks corresponding to gamma-ray transitions between discrete levels in residual nuclei, and the measured angular distributions are almost isotropic for both the incident energies. Conclusion PHITS calculations using INCL, GEM, and EBITEM models reproduce the spectral shapes and the angular distributions generally well, although they underestimate the absolute gamma-ray yields by about 20%. Keywords: Deuteron, Gamma-ray, NE213, Unfolding, PHITS

Direct measurement of C-12+He-4 -> O-16+gamma total cross section was made at E-cm = 2.4, 1.5 and 1.2 MeV, and preliminarily measurement was made at 1.0 MeV. A thick windowless He-4 target was developed and the low-energy C-12 beam intensity was increased by modifying our tandem accelerator. O-16 recoils were detected after removing large C-12 backgrounds. Remaining obstacle is O-16 backgrounds produced by stray beams. Prospects for future experiments of C-12+He-4 -> O-16+gamma cross section down to E-cm = 0.7 MeV are presented.

A blow-in type windowless thick He gas target has been developed to measure 4He(12C,16O) γ cross section for astrophysical interests. We use a 12C beam of energy from 6 to 2.8 MeV and detect 16O recoils at forward angles. Numerous 12C backgrounds have been rejected by particle identification techniques. 16O backgrounds from the target are not many but fatally harmful. Our techniques to reduce the 16O backgrounds are described.

cross section measurement employing a direct O-16 detection method for the reaction energies from E-cm = 2.4 to 0.7 MeV is planned at Kyushu University Tandem Laboratory (KUTL). To perform this experiment and to obtain quantitative information about the cross section to within an error of 10%, we have developed several instruments, including a blow-in type windowless gas target, a recoil mass separator and a RF-deflector. The measurements at E-cm = 2.4 and 1.5 MeV have been performed with these instruments.For measuring at E-cm < 1.2 MeV, a hybrid detector employing both, an ionization chamber and a silicon detector was developed to reduce the carbon backgrounds more efficiently. The oxygen ions were clearly separated from carbon background by using the energy deposit in the ionization chamber. Experiment of E-cm = 1.2 MeV was performed and the cross section was obtained.

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 (50.4mm thick and 50.4mm 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 Liège (INCL) model in PHITS code.

Double differential neutron yields from carbon target irradiated by 5 MeV and 9 MeV deuterons were measured at the Kyushu University Tandem Accelerator Laboratory.A carbon target was thick enough to stop the incident deuterons in the target.An NE213 liquid organic scintillator was employed to detect neutrons emitted from the target and placed at several directions from 0° to 140°.To estimate the contribution of scattered neutrons from the floor and walls, neutron yields were measured with an iron shadow bar located in front of the scintillator.The measured energy spectrum was derived by an unfolding method with FORIST and MAXED codes using the response functions of the NE213 scintillator calculated with the SCINFUL-QMD code.The incident energy dependence of total thick target neutron yields for carbon was investigated over the energy range from 5 to 50 MeV and the empirical formula was obtained.The measured neutron energy spectra were also compared with the calculations by PHITS code.

After ππ-exchange three-nucleon force (ππ3NF) was found in 1998, many experiments were made on 3N reactions and discrepancies between experiments and calculations with ππ3NF were reported. Origins of these remaining discrepancies have not been found yet. We briefly review experiments and the discrepancies in Nd scattering, Nd breakup and pd capture at intermediate energy, and review also recent systematic investigation on Space-Star anomaly and Quasi-Free Scattering anomaly in pd breakup at low energy.

In astrophysics, 4He(12C,16O)γ reaction places an important role. At Kyushu University Tandem accelerator Laboratory (KUTL), the measurement of 4He(12C,16O)γ cross section is in progress in the energy range of astrophysical nuclear reaction. Since the charge state of product 16O ions after passing through the gas target is spread and only one charge state can be measured at terminal detector, it is necessary to know the charge state distribution of 16O ions passing through the He gas target precisely. Here, we report the charge state distribution of the 16O recoils both experimentally and theoretically. Experimentally, we measured the equilibrium charge state distribution of 16O ions in the windowless helium gas target with the beam energy of primary 16O ions at 7.2, 4.5, and 3.45MeV at KUTL. The measured results showed a Gaussian distribution for the charge state fraction. Theoretically, we proposed a framework for the charge state distribution study. Charge state distribution was computed by solving a set of differential equations including a series of charge exchange cross sections. For the ionization cross section, plane-wave Born approximation was applied and modified by taking target atomic screening as a function of momentum transfer into account. For the capture cross section, continuum distorted wave approximation was applied and the influence of the gas target density was taken into account in the process of electron capture. Using above charge exchange cross sections, the charge state evolution was simulated. According to the equilibrium distribution, we compared the theoretical calculation to the experimental data. After taking into account the density effects in the charge exchange process, the theoretical charge state distributions shows a good agreement with the experimental data. Both experimental and theoretical results are useful to understand the charge fraction of recoil oxygen created via 4He(12C,16O)γ reaction, especially in the energy range of astrophysical nuclear reaction.

Space Star (SS) anomaly in nd breakup cross section was first reported in 1989 at E (n) = 13 MeV (Strate et al. in Nucl Phys A 501:51, 1989), but its origin has not been found yet. In order to obtain suggestions for its origin, we made systematic measurements of pd breakup cross section around SS. In SS configuration, three outgoing nucleons form an equilateral triangle and the triangle is perpendicular to the beam axis. Necessity of the equilateral and perpendicular conditions of SS anomaly was investigated by systematic experiments. Also energy dependence of SS anomaly is being studied at energies from E (p) = 7.5 to 13 MeV.

A fusion reaction of 12C+4He→16O+γ is one of the main reactions in He-burning of stars and important for nucleosynthesis. The fusion cross section at stellar energy of Ecm=0.3 MeV has not been determined precisely yet in spite of efforts for about 40 years. We plan to measure directly the total fusion cross section down to 0.7 MeV at Kyushu University Tandem accelerator Laboratory and to estimate the cross section at 0.3MeV by extrapolation. We have already measured the cross sections at 2.4 MeV and 1.5 MeV. The measurement at Ecm=1.2 MeV is in progress.

A cross section measurement employing a direct 16O detection method for the reaction energies from E cm = 2.4 to 0.7 MeV is planned at Kyushu University Tandem Laboratory. To perform this experiment and to obtain quantitative information about the cross section to within an error of 10%, we have developed several instruments, including a blow-in type windowless gas target and a ionization chamber. A target thickness of 24 × 3.9 Torr cm was achieved using the developed gas target. The particle identification was successfully performed by using the energy deposit in the ionization chamber. Experiments were performed at E cm = 2.4 and 1.5 MeV using the developed instruments and the cross sections were obtained.

Cross sections of pd breakup reaction at E (p) = 250 MeV were measured systematically in single-proton detection and in two-proton coincidence detection. Measured cross section is up to two times higher than calculated ones. The enhancement of breakup cross section is similar to reported enhancement in pd elastic scattering cross section. Origins of this enhancement are discussed.

We measured pd breakup cross section at E d = 19 MeV (E/A = 9.5 MeV) at Star configuration at 120° ≤ inclination angle α ≤ 180°, i.e. apart from Space Star configuration (α = 90°), and found that pd Star cross section at 120° ≤ α ≤ 180° agree with pd calculation, contrary to Köln data. By our systematic experiments on Star configurations so far and recent reliable pd calculations, existence of Space Star anomaly has been established in pd breakup at E/A = 9.5 and 13 MeV. Also it has been confirmed that no anomaly exist at Star configurations apart from Space Star.

Space Star anomaly in Nd breakup reaction below 20 MeV is well-known. Also, Quasi-Free Scattering (QFS) anomaly in Nd breakup reaction below 40 MeV has been reported from several experiments. Origin(s) of QFS anomaly has not been known, similarly to origin(s) of SS anomaly. We have been making a systematic measurement on pp-QFS cross section, previously at E (p) = 9.5 MeV and 13 MeV and recently at 7.5 and 19 MeV. We used an unpolarized p-beam to correctly measure only cross section. Our data agreed well with pd calculation by A. Deltuva. So far, no pp-QFS anomaly has been found in our experiments.

12C+4He fusion reaction at E cm  = 0.3 MeV is one of the main reaction in 4He-burning in stars, and is very important in nuclear synthesis. However the fusion cross section has not been determined yet in spite of 40 years efforts in the world. Recently we succeeded in the measurement at 1.5 MeV. We have a plan to make direct measurement of the total fusion cross section down to 0.7 MeV at Kyushu University Tandem accelerator Laboratory (KUTL), and to determine the cross section at 0.3 MeV by extrapolation.

Space Star (SS) anomalies in nd and pd breakup reactions below 20 MeV were reported since 1989, but their origin has not been found yet. We have considered two conditions for the SS anomalies : condition (a) where three outgoing nucleons form an equilateral triangle and condition (b) in which the triangle is perpendicular to the beam axis. The condition (b) was investigated by our previous systematic experiments on pd breakup. In the present study, we started systematic experiments for the condition (a).

We report on a proton radiation damage experiment on P-channel CCD newly developed for an X-ray CCD camera onboard the ASTRO-H satellite. The device was exposed up to 109 protons cm−2 at 6.7MeV. The charge transfer inefficiency (CTI) was measured as a function of radiation dose. In comparison with the CTI currently measured in the CCD camera onboard the Suzaku satellite for 6 years, we confirmed that the new type of P-channel CCD is radiation tolerant enough for space use. We also confirmed that a charge-injection technique and lowering the operating temperature efficiently work to reduce the CTI for our device. A comparison with other P-channel CCD experiments is also discussed.