K. Sagara

TENSOR ANOMALY IN pd RADIATIVE CAPTURE

Cross section and analyzing powers of pd → 3He + γ reaction were measured at Ed = 200 MeV. Low background data were obtained by using a liquid hydrogen target and by detecting 3He. The cross section and Ay are well reproduced by a Faddeev calculation with a 3-nucleon force included, however, Ayy deviates from the calculation and Axx is completely different from the calculation.

Faddeev calculations of proton-deuteron radiative capture with exchange currents

pd capture processes at various energies have been analyzed based on solutions of three-nucleon ~3N!Faddeev equations and using modern NN forces. The application of the Siegert theorem is compared to the explicit use of p- and r-like exchange currents connected to the AV18 NN interaction. Overall good agreement with cross sections and spin observables has been obtained but leaving room for improvement in some cases. Feasibility studies for three-nucleon forces ~3NF’s ! consistently included in the 3N continuum and the 3N bound state have been performed as well.

A BLOW-IN WINDOWLESS GAS TARGET

Abstract A new-type windowless gas target has been developed to realize a dense target with a low gas flow rate. The target is similar to the conventional differentially pumped windowless gas target except that the target gas is blown into the target region from both the side holes of the beam entrance and exit. Due to the gas-confining action caused by the blown-in gas, the target thickness is about twice increased and the target density sharply falls in the holes. Most of the target gas is at rest and the density is uniform. The gas flow rate is the same as that of the conventional target and is about an order of magnitude lower than that of the dense gas-jet target.

A study of nucleon properties in nuclei through (p, 2p) reactions

Abstract The differential cross sections and analyzing powers have been measured for a proton knockout reaction from s 1/2 orbits of several target nuclei aiming at studying nuclear medium effects in the nucleon-nucleon interaction, and in-medium nucleon properties through it. It is confirmed from the cross section data that the reaction mechanism is simple and contribution from the multi-step processes is less than ten percent, only a few percent for a 12 C target case. The analyzing power shows a distinct reduction from the value of the free proton-proton scattering and the target dependence, which is equivalent to the density dependence, of the reduction suggests existence of a medium effect. The study has been extended to the measurement of other spin observables, polarization and spin-transfer coefficients, and a preliminary result is given.

SEARCH FOR SPACE STAR ANOMALY IN pd BREAKUP REACTION AT 13MeV

Systematic measurement of D(p,pp)n cross section has been made at an incident energy of 13MeV around the space star configuration. In spite of the anomaly found in nd breakup cross section, no anomaly has been found in pd breakup.

A bimodal Maxwellian distribution as the equilibrium solution of the two‐particle regime

The Maxwellian distribution known as the one‐particle equilibrium solution is generalized to the two‐particle regime where homogeneous macroscopic fluctuations in the density, the velocity, and the temperature prevail. The equilibrium distribution has the form of a bimodal Maxwellian, namely, the average of two Maxwellians with thermodynamic parameters greater and smaller than the mean values by the root‐mean‐squared fluctuations. This result is shown to hold for monatomic gases with arbitrary intermolecular potentials. Turbulent reaction rate calculated with this distribution can be by the order of magnitude large compared with the Arrhenius law, in other words, far beyond the first order smallness of the temperature fluctuation if the activation energy is sufficiently high.

Strong-focusing in tandem accelerator with alternating voltage gradient

Abstract A new method to obtain low-energy high-intensity beams from a tandem accelerator of a high design-voltage is presented. In this method, the beam undergoes repeated actions of acceleration and deceleration from alternating voltage gradient along the beam axis, so that the beam divergence is minimized. The practical test was carried out at the 10 MV tandem accelerator at Kyushu University, and the beam transmission efficiency at a low operation voltage of 1 MV was found to be an order of magnitude increased. The method also enables the accelerator to stand a high beam load. The necessary changes in the accelerator configuration are quite simple and easily achievable at a low cost.

A ray-trace-type counter telescope for neutron spectrometry

A compact recoil proton counter telescope with two position sensitive proportional counters (PSPCs) for neutron spectrometry has been developed. This counter telescope consists of a radiator (a thin polyethylene film), two PSPCs used as /spl Delta/E detector and a Si-SSD used as E detector. Using the position information extracted from two PSPCs, the three-dimensional trajectory of the recoil proton and the recoil angle can be determined event by event. The performance of this counter telescope was tested by the measurement of 7.2 MeV neutrons produced from D-D reactions, and it was shown that the energy spectra of neutrons could be obtained by determining the energy of each incident neutron using a recoil angle.

High resolution measurement of protons emitted from medium-energy neutron induced reactions by means of a magnetic spectrograph

Abstract The application of a magnetic spectrograph to measurements of medium-energy neutron induced reactions is superior in the intrinsic resolution to ordinary counter telescopes, position sensitive counter telescopes and magnetic quadrupole spectrometers. Protons emitted from the 2 H(n, p)2n reaction were measured with a resolution of about 230 keV FWHM (0.37%) at an incident energy of 63 MeV. The finite geometry effect should be treated separately to analyze the measured spectra.

Cross-sections and analyzing powers for

The cross-sections and analyzing powers for (p, n) reactions on He and He have been measured at a bombarding energy of Tp = 346 MeV and reaction angles of θlab = 9.4 –27. The energy transfer spectra for He(p, n) at large θlab (≥ 16 ) are dominated by quasielastic contributions, and can be reasonably reproduced by plane-wave impulse approximation (PWIA) calculations for quasielastic scattering. By contrast, the known L = 1 resonances in Li are clearly observed near the threshold in the He(p, n) spectra. Because these contributions are remarkable at small angles, the energy spectra are significantly different from those expected for quasielastic scattering. The data are compared with the PWIA calculations, and it is found that the quasielastic contributions are dominant at large θlab (≥ 22 ). The nuclear correlation effects on the quasielastic peak for He(p, n) are also discussed. PACS numbers: 25.40.Kv, 24.70.+s, 25.10.+s, 27.10.+h ∗wakasa@phys.kyushu-u.ac.jp; http://www.kutl.kyushu-u.ac.jp/~wakasa