Bulletin of the American Physical Society
3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 54, Number 10
Tuesday–Saturday, October 13–17, 2009; Waikoloa, Hawaii
Session BE: Mini-Symposium on Developments in Re-accelerated Rare Isotope Beam Physics I |
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Chair: Michiharu Wada, RIKEN Nishina Center Room: Kohala 2 |
Wednesday, October 14, 2009 7:00PM - 7:30PM |
BE.00001: Stopped and re-accelerated rare isotope beams at FRIB at MSU Invited Speaker: FRIB, the US's ``Facility for Rare Isotope Beams'' to be built at Michigan State University (MSU), will be based on a 400 kW, 200 MeV/u heavy ion driver linac. Once realized, FRIB will be a world-leading rare isotope beam facility. FRIB will provide a wide variety of high-quality beams of unstable isotopes at unprecedented intensities. Exciting research perspectives will be opened not only with fast, but also with stopped and reaccelerated beams. FRIB will be able to build on rare isotope beam capabilities that exist or under development at the NSCL. High-precision Penning trap mass measurements with stopped rare isotopes are successfully conducted since several years, laser spectroscopy is in preparation and ReA3, a modern reaccelerator, is presently being built. [Preview Abstract] |
Wednesday, October 14, 2009 7:30PM - 7:45PM |
BE.00002: Reacceleration of rare isotopes at the NSCL - The ReA3 project Stefan Schwarz, Georg Bollen, Chris Compton, Marc Doleans, Walter Hartung, Oliver Kester, Mikhail Kostin, Felix Marti, Peter Miller, Xiaoyu Wu, Richard York, Qiang Zhao Rare-isotope beams in the energy range of a few 100 keV/u to up to several MeV/u allow for experiments such as low-energy Coulomb excitation and transfer reaction studies and for the precise study of astrophysical reactions. NSCL is currently constructing the so-called ReA3 expansion, a reaccelerator with design end energy of 3 MeV/u for $^{238}$U. The reaccelerator will be coupled to a gas stopper at the NSCL fragmentation facility to provide rare isotope beams of nuclides not available at ISOL facilities in this energy range. An Electron Beam Ion Source/Trap (EBIS/T) will be used to boost the acceleration process by providing highly charged ions at an energy of $\sim$12keV/u. The charge breeder is followed by a room-temperature radiofrequency quadrupole (RFQ) and a series of superconducting linear accelerator structures housed in three cryo modules. The status of the re-accelerator project and the planned layout will be presented. [Preview Abstract] |
Wednesday, October 14, 2009 7:45PM - 8:00PM |
BE.00003: RIPS upgrade and physics programs Hideki Ueno, Akihiro Yoshimi, Koichiro Asahi The upgrade of RIPS has been proposed in the phase-II program of RIKEN RI Beam Factory (RIBF) project. In this upgrade, the former fragment separator RIPS will be equipped with a new beam line that delivers beams of 115$A$-MeV heavy io ns extracted from the IRC cyclotron by skipping the final acceleration of SRC. This beam energy is high enough to produce radioactive isotope beams (RIBs) via the projectile-fragmentation reaction. Thus, compared with RIBs produced in the present AVF-RRC acceleration scheme, their production yield are drastically increased by this upgrade, especially in the mass region heavier than Kr. Remarkably, RIPS further enhances research opportunities on spin-related subjects such as nuclear structure studies through electromagnetic nuclear moments: it has been revealed that RIBs produced at this energy can be spin-oriented independently of their atomic and chemical properties. Also, the research subjects include not only nuclear moments but also material science by means, e.g., of the $\beta$-NMR, $\gamma$-PAD, $\gamma$-PAC, laser, and in-beam M\"ossbauer methods, because RIBs of this energy allow for a scheme to implant them into sample materials with limited thickness and thus stopped-RI type experiments will be conveniently carried out. [Preview Abstract] |
Wednesday, October 14, 2009 8:00PM - 8:15PM |
BE.00004: Precision laser and microwave spectroscopy of radioactive Be isotopes provided from a projectile fragment separator RIPS A. Takamine, M. Wada, T. Sonoda, T. Nakamura, Y. Yamazaki, Y. Kanai, T.M. Kojima, T. Kubo, K. Okada, P. Schury, H. Iimura, I. Katayama, S. Ohtani, H. Wollnik, H.A. Schuessler Radioactive Be isotope beams from RIKEN RIPS at approximately 1 GeV were thermalized in an RF ion guide gas cell and extracted by a combination of DC and inhomogeneous RF electric fields. The extracted ions were transported via a carbon-OPIG to a linear RF trap located in UHV environment. They were further cooled down to 10$^{-6}$~eV by laser cooling for precision atomic spectroscopy. The ground state hyperfine splitting of $^7$Be and $^{11}$Be were measured directly with accuracies of 10$^{-7}$ by microwave-laser double resonance method. The optical transition frequencies for 2$s_{1/2}$-2$p_{3/2}$ transition of $^7$Be, $^9$Be, $^{10}$Be, and $^{11}$Be ions were also measured with accuracies of 10$^{-9}$ by laser-laser double resonance method. These experiments aim to independently measure the nuclear charge and magnetization radii by the isotope shift and the Bohr-Weisskpf effect, respectively, especially for one neutron halo nucleus $^{11}$Be. We discuss the RF-carpet ion guide technique and the results of spectroscopy experiments. [Preview Abstract] |
Wednesday, October 14, 2009 8:15PM - 8:30PM |
BE.00005: OROCHI experiment - nuclear laser spectroscopy in superfluid helium for rare radioisotopes Takeshi Furukawa Spin and electromagnetic moments are one of the most important quantities for nuclear structure investigations. To determine those for rarely produced radioisotopes (RI), we now develop a new laser spectroscopic method on RI atoms stopped in superfluid helium (He II), named \textit{OROCHI} (\underline {O}ptical \underline {R}I-atom \underline {O}bservation in \underline {C}ondensed \underline {H}elium as \underline {I}on-catcher). The method enables us to measure the atomic Zeeman and hyperfine splittings in a rare isotope (yield: $<$ 1 particle/sec) for the determination of the spin and moments, utilizing the absorption spectra characteristic of an atom immersed in He II To confirm the feasibility of the \textit{OROCHI} method, we have demonstrated successful determinations of nuclear spins and moments for the stable Rb and Cs isotopes by measuring the Zeeman and hyperfine resonance in He II. Recently, we have also succeeded in producing high polarization in silver and gold atoms in He II using the characteristic spectra. In near future, we plan to measure the spins and moments of silver isotopes far from the stability line, including $^{94}$Ag, one of the heaviest N=Z nuclei. Details of the development and future prospect will be discussed. [Preview Abstract] |
Wednesday, October 14, 2009 8:30PM - 8:45PM |
BE.00006: Fluorescence detection system for nuclear laser spectroscopy of Rb in superfluid helium A. Sasaki, T. Wakui, T. Furukawa, M. Kazato, M. Wada, T. Sonoda, A. Takamine, T. Kobayashi, M. Nishimura, H. Ueno, A. Yoshimi, N. Aoi, S. Nishimura, Y. Togano, M. Takechi, Y. Kondo, A. Hatakeyama, Y. Matsuura, Y. Kato, A. Odahara, T. Shimoda, K. Asahi, T. Shinozuka, T. Motobayashi, Y. Matsuo Laser spectroscopy in superfluid He (He II) is useful for determining the spins and moments of nuclei. We will apply this method, named OROCHI (Optical RI-atom Observation in Condensed Helium as Ion-catcher), to unstable nuclei. Because more photons of laser-induced fluorescence (LIF) from low-yield unstable nuclei should be observed, a highly efficient fluorescence detection system is indispensable to the project. We thus performed an optical simulation in order to maximize the detection efficiency while minimizing background count rates. The fluorescence detection system has been built based on the simulation results. As the first step of the project, we will perform an experiment to detect LIF from Rb atoms stopped in He II, using our fluorescence detection system. Details of the system and results of the off- and on-line experiments will be presented. [Preview Abstract] |
Wednesday, October 14, 2009 8:45PM - 9:00PM |
BE.00007: Beam Cooling and Laser Spectroscopy (BECOLA) Project at NSCL K. Minamisono, B.R. Barquest, G. Bollen, P.F. Mantica, D.J. Morrissey, R. Ringle, S. Schwarz A new beam line for beam cooling and laser spectroscopy (BECOLA)
has been designed and is being installed at the National
Superconducting Cyclotron Laboratory (NSCL) at Michigan State
University. The BECOLA beam line will be capable of accepting
ions of energy up to 60 keV. A linear Radio Frequency Quadrupole
(RFQ) ion trap [1] will be used to cool and bunch the beam
upstream of the BECOLA beam line. This beam line will have two
dedicated experimental legs, one for collinear-laser spectroscopy
with the bunched beam and another for polarization by optical
pumping of low energy atoms/ions for $\beta$-NMR experiments.
Initial studies at NSCL will include the measurement of $\mu$,
$Q$ and $\left |
Wednesday, October 14, 2009 9:00PM - 9:15PM |
BE.00008: Electromagnetic Moments of $^{28}$P Kensaku Matsuta, M. Mihara, D. Nishimura, M. Fukuda, R. Matsumiya, T. Nagatomo, S. Momota, K. Ohi, T. Izumikawa, T. Ohtsubo, Y. Namiki, M. Nagashima, D.M. Zhou, Y.N. Zheng, D.Q. Yuan, Y. Zuo, P. Fan, S.Y. Zhu, A. Kitagawa, M. Kanazawa, M. Torikochi, S. Sato, T. Sumikama In order to study nuclear structure of proton-rich nucleus $^{28}$P ($I^{\pi}$=3$^+$, $T_{1/2}$ = 270.3 ms), electro magnetic moments of this nucleus have been measured. Obtained precise value of magnetic moment is $|\mu(^{28}$P)$|$ = 0.3115(34) $\mu_N$. The experimental magnetic moment is much quenched from the Schmidt value +0.88, but is well reproduced by the shell model value +0.306. To measure quadrupole moment, $\beta$-NMR has been observed on $^{28}$P implanted in $\alpha$-Al$_2$O$_3$. As a preliminary result, possible resonance was found around quadrupole frequency $|\nu_Q|$ = 200 kHz, which corresponds to the quadrupole moment of about 120 mb, which is consistent with the shell model value. [Preview Abstract] |
Wednesday, October 14, 2009 9:15PM - 9:30PM |
BE.00009: In-Beam M\"{o}ssbauer Spectroscopy Using Heavy Ion Beams at HIMAC M. Mihara, K. Kubo, Y. Kobayashi, T. Nagatomo, Y. Yamada, W. Sato, J. Miyazaki, S. Sato, A. Kitagawa The in-beam M\"{o}ssbauer spectroscopy, in which a short-lived probe nucleus is introduced into a material for on-line measurement, has been applied to materials science and chemistry, because it has unique advantages in investigating microscopic behavior of extremely dilute impurity atoms or exotic chemical states in solids. The short-lived nucleus $^{57}$Mn ($T_{1/2}$ = 1.47 m) is useful for the M\"{o}ssbauer spectroscopy of $^{57}$Fe which is created following the $\beta$ decay of $^{57}$Mn. We have started to develop a $^{57}$Mn secondary beam as the M\"{o}ssbauer probe at Heavy Ion Accelerator in Chiba (HIMAC) in National Institute of Radiological Sciences (NIRS). The $^{57}$Mn nuclei produced through the projectile fragmentation of $^{59}$Co and $^{58}$Fe beams at 500 MeV/nucleon were separated by a fragment separator and were implanted into samples. Clear M\"{o}ssbauer spectra of $^{57}$Fe in some materials were successfully observed under suppression of background events by anti-coincidence with beam-pulse and $\beta$-ray signals. [Preview Abstract] |
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