[Show abstract][Hide abstract] ABSTRACT: Data on the vector analyzing power A
and the tensor analyzing powers A
, and A
in the reaction \(\vec d\)
d → 3Hp
at the deuteron energy of 200 MeV are presented over a full angular range in the c.m. frame. The signs of the tensor analyzing powers for forward and backward scattering are found to be sensitive to the D/S wave ratio in 3H and in the deuteron. High-precision experimental data are compared with the results of theoretical calculations performed on the basis of the multiple-scatteringmodel by using standard wave functions for the three-nucleon bound states and for the deuteron.
Full-text · Article · Nov 2015 · Physics of Atomic Nuclei
[Show abstract][Hide abstract] ABSTRACT: Differential cross sections of isoscalar and isovector spin-M1 (0 þ → 1 þ) transitions are measured using high-energy-resolution proton inelastic scattering at E p ¼ 295 MeV on 24 Mg, 28 Si, 32 S, and 36 Ar at 0°–14°. The squared spin-M1 nuclear transition matrix elements are deduced from the measured differential cross sections by applying empirically determined unit cross sections based on the assumption of isospin symmetry. The ratios of the squared nuclear matrix elements accumulated up to E x ¼ 16 MeV compared to a shell-model prediction are 1.01(9) for isoscalar and 0.61(6) for isovector spin-M1 transitions, respectively. Thus, no quenching is observed for isoscalar spin-M1 transitions, while the matrix elements for isovector spin-M1 transitions are quenched by an amount comparable with the analogous Gamow-Teller transitions on those target nuclei.
[Show abstract][Hide abstract] ABSTRACT: The review of the recent results on spin effects in few nucleon systems obtained at LHEP-JINR are presented. The data on the deuteron analyzing powers in different reactions in the wide energy range demonstrate the sensitivity to the spin structure of the light nuclei. The future plans on the studies with polarized deuterons from new polarized ion source at Nuclotron will be reported.
Full-text · Article · Jan 2014 · Physics of Particles and Nuclei
[Show abstract][Hide abstract] ABSTRACT: We have developed a monitoring system dedicated for heavy-ion cyclotrons
that incorporates lock-in amplifiers (LIAs) that can measure the beam
phase of signals from phase probe with an amplitude of a few hundred
nanovolts. We have compared the performance of the LIA system with that
of a conventional system that incorporates oscilloscopes (OSCs). It was
confirmed that the LIA system has a much higher precision than the OSC
system by the measurement with a wide dynamic range of beam current.
Isochronism measurements for a ring cyclotron with a low velocity gain
(1.5) were made using both systems and excellent agreement was found
between them. However there was a discrepancy between the beam phase
measurements using the OSC system and the LIA system, for the case of a
ring cyclotron with a high velocity gain of 4.0. It turned out due to a
large radial variation of the phase width of circulating beam bunch
according to a radial distribution of the acceleration voltage. It was
also confirmed that the cable dispersion disturbs the beam-phase
measurement using OSC system.
No preview · Article · Nov 2013 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: A new injector linac “RILAC2”, has recently been constructed at the RIKEN RI Beam Factory. The main part of the RILAC2 is a drift tube linac that consists of three newly designed cavities. These cavities operate in continuous wave (CW) mode at a fixed frequency of 36.5 MHz. Their structure is based on a quarter-wavelength resonator because this is the smallest resonator available in this frequency range among the available structures. We adopted the direct coupling method in the construction of these cavities. A power amplifier was directly coupled to the cavity without a long transmission line to reduce the installation area and simultaneously reduce construction cost. A detailed cavity and coupler design was carried out via simulation. Our work also describes the design process using three-dimensional electromagnetic simulation software. Construction and operation tests are also shown.
No preview · Article · Sep 2013 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The vector analyzing power has been measured for the elastic scattering of neutron-rich 6He from polarized protons at 71 MeV/nucleon. Two approaches based on local one-body potentials were applied to investigate the spin-orbit interaction between a proton and a 6He nucleus. An optical model analysis revealed that the spin-orbit potential for 6He is characterized by a shallow and long-ranged shape compared with the global systematics of stable nuclei. A semi-microscopic analysis with a α + n + n cluster folding model suggests that the inclusion of realistic interaction between a proton and the α core is important in describing the p-6He elastic scattering.
No preview · Article · Aug 2013 · Few-Body Systems
[Show abstract][Hide abstract] ABSTRACT: A complete set of analyzing powers for the dd->3Hp reaction at the kinetic
beam energy of 200 MeV has been measured in the full angular range in the c.m.
frame. The observed signs of the tensor analyzing powers Ayy, Axx, and Axz at
forward and backward directions have clearly demonstrated the sensitivity to
the ratio of the D- and S-wave components of the triton and deuteron,
respectively. The new high-precision data are compared with the prediction of
the relativistic multiple-scattering model by using standard wave functions of
the three-nucleon bound state and of the deuteron.
Full-text · Article · May 2013 · Physical Review C
[Show abstract][Hide abstract] ABSTRACT: Since the extraction of the first beam in late 2006, the RIKEN Radioactive Isotope Beam Factory (RIBF) has been successfully operating with the aim of accessing the unexplored region on the nuclear chart, far from the stability line. The continuous efforts over these six years have significantly enhanced the performance of the RIBF accelerator complex. Thus far, we have achieved the target intensity of 1,000 pnA for helium and oxygen beams and about half of the target intensity for the calcium beam. The intensity of uranium beams, however, is still to be improved, requiring extensive measures to reach the target intensity. To address this situation, we constructed a 28-GHz superconducting electron cyclotron resonance ion source and a new injector linac. Furthermore, we developed a helium gas charge stripper as an alternative to the standard carbon-foil stripper. This paper presents recent results obtained in the commissioning of the new injector system, the report of the R&D work on the gas charge stripper, and a brief summary of the present performance of the RIBF accelerator complex.
[Show abstract][Hide abstract] ABSTRACT: The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution (3He,t) charge-exchange experiment on the double-beta (ββ) decaying nucleus 96Zr. The experiment was carried out at the Osaka University Research Center for Nuclear Physics (RCNP) with a 420 MeV incident 3He beam and the Grand Raiden magnetic spectrometer. A final-state energy resolution of 32 keV was achieved. A large fraction of the low-energy GT− strength is identified in a single state at 694 keV. A similar observation has been made in a 96Mo(d,2He)96Nb experiment at 120 keV resolution for the GT+ strength. It is found that this single state makes up nearly 100% of the nuclear matrix element for the 96Zr two-neutrino double-beta (2νββ) decay.
Full-text · Article · Nov 2012 · Physical Review C
[Show abstract][Hide abstract] ABSTRACT: The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution (3He,t) charge-exchange experiment on the double-beta (ββ) decaying nucleus 100Mo. The experiment was carried out at the Osaka University Research Center for Nuclear Physics (RCNP) with a 420 MeV incident 3He beam and the Grand Raiden magnetic spectrometer. A final-state energy resolution of 33 keV was achieved. It was found that nearly the entire low-energy (up to ≈4 MeV) GT− strength is concentrated in the ground-state transition to 100Tc, which is interpreted as a result of the particular neutron and proton sub-shell occupancies. The impact on the matrix elements for the two-neutrino double-beta (2νββ) decay and the use of 100Mo as a neutrino detection material is discussed.
No preview · Article · Oct 2012 · Physical Review C
[Show abstract][Hide abstract] ABSTRACT: The vector Ay and tensor analyzing powers Ayy and Axx for dp- elastic
scattering were measured at Td = 880 MeV over the c.m. angular range from 60 to
140 degrees at the JINR Nuclotron. The data are compared with predictions of
different theoretical models based on the use of nucleon-nucleon forces only.
The observed discrepancies of the measured analyzing powers from the
calculations require the consideration of additional mechanisms.
Full-text · Article · Jul 2012 · Physics Letters B
[Show abstract][Hide abstract] ABSTRACT: A 76Ge(3He,t)76As charge-exchange experiment at an incident energy of 420 MeV has been performed with an energy resolution of 30 keV. The Gamow-Teller GT− strength distribution in 76As, which is the intermediate nucleus in the double-beta (ββ) decay of 76Ge, has been extracted. An unusually strong fragmentation of the GT− strength is observed even at low excitation energies of Ex⩽5 MeV. By combining the data with those for GT+ transitions from a recent 76Se(d,2He)76As measurement, the nuclear matrix element for the 76Ge 2νββ decay has been evaluated. A lack of correlation among the GT transition strengths feeding the same levels from the two different directions is observed. The impact on the 76Ge 2νββ decay nuclear matrix element is discussed.
No preview · Article · Jul 2012 · Physical Review C
[Show abstract][Hide abstract] ABSTRACT: A gas target system has been developed for nuclear scattering experiments with a highly dispersive spectrometer at small scattering angles including 0°. The system is equipped with a gas cell that has a wide beam window of 44 mm in width and 14 mm in height. The size is sufficient to pass a dispersed beam, which is essential for high energy-resolution measurement. A gas handling system allows target gas that is often limited in quantity, to be collected for reuse. Typical areal density is 1 mg/cm2 for 20Ne or 36Ar gas. The target can be operated either at room temperature or at the liquid nitrogen temperature. The gas target has been employed in a proton inelastic-scattering experiment at 295 MeV with the Grand Raiden spectrometer at the Research Center for Nuclear Physics. A good energy resolution of 20 keV (FWHM) has been achieved at scattering angles of 0–4.5°.
Full-text · Article · Jun 2012 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
[Show abstract][Hide abstract] ABSTRACT: The experiment with polarized deuteron beam was performed at energies 140, 200 and 270 MeV at RIKEN, Japan, in December 2000. The high-momentum structure of the 3He, 3H and deuteron was investigated. For this purpose the angular dependence of the tensor and vector analyzing powers were measured for the reactions d+d→3H+p and d+d→3He+n. In this report the results on the tensor Axx, Ayy and vector Ay analyzing powers at 270 MeV are presented.
Full-text · Article · May 2012 · International Journal of Modern Physics A
[Show abstract][Hide abstract] ABSTRACT: The data on the vector Ay and tensor Ayy, Axx, Axz analyzing powers for the and reactions at Ed = 200 and 270 MeV are presented. The data demonstrate large values of analyzing powers and their strong variation versus the scattering angle. The observed negative sign of the tensor analyzing powers for these reactions at small angles clearly demonstrate the sensitivity to the D/S ratio of the 3H and 3He wave functions, respectively. The calculations performed within one-nucleon exchange model with the use of the standard three-nucleon bound state wave functions fail to reproduce the data on the tensor analyzing powers.
No preview · Article · Jan 2012 · International Journal of Modern Physics A
[Show abstract][Hide abstract] ABSTRACT: Analyzing powers measurement Ay, Ayy and Axx for the d - p elastic scattering were performed at the Internal Target Station of Nuclotron at JINR at Ed = 880 and 2000 MeV. These data are necessary to obtain the information on the 3NF structure and the relativistic effects. They are also important for development of the efficient deuteron beam polarimetry at high energies. The results of the analyzing powers at Ed = 880 MeV covered the angular range from 60 to 140° in the c.m.s. are compared with several theoretical calculations. The preliminary data on the analyzing powers measurement Ay, Ayy at Ed = 2000 MeV are discussed.
No preview · Article · Jan 2012 · International Journal of Modern Physics A
[Show abstract][Hide abstract] ABSTRACT: The cluster structures of the excited states in 11B and 13C were discussed by measuring the isoscalar monopole strengths in the inelastic α scattering at Eα = 388 MeV. It was found that the , , and states in 13C are candidates for the α cluster states with a 3α + n molecular configuration.
No preview · Article · Jan 2012 · International Journal of Modern Physics E
[Show abstract][Hide abstract] ABSTRACT: A new linac injector called RILAC2 has been successfully commissioned at the RIKEN RIbeam factory (RIBF). RILAC2 can accelerate very heavy ions with a mass-to-charge ratio(m/q) of 7, such as 124Xe20+ and 238U35+ from a28-GHz superconducting electron cyclotron resonance ion source (SC-ECRIS), up to an energyof 680 keV/u in the cw mode. The key features of RILAC2 are the powerful SC-ECRIS; improvedrf voltage stability, rf phase stability, and vacuum level compared to the existing linacinjector; and the compact equipment yet to be installed in the azimuthally varying field(AVF) cyclotron vault. Beam acceleration was first achieved on December 21, 2010. Afterconducting several beam acceleration tests in 2011, we started to operate RILAC2 to supplybeams for experiments conducted at the RIBF.
[Show abstract][Hide abstract] ABSTRACT: In RIKEN Nishina center, the experiment on the super heavy element (Z=113) search has been carried out since 2003. The RILAC has been supplying a 70Zn beam with energies around 5.5MeV/nucleon. The beam intensity is required around 1 pμA on the target. So far two events for Z=113 have been observed during a net irradiation time of 10,345 hours (431 days) with a total dose 1.1 x 1020. The heavy operation of RILAC will be reported.