Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session CH: Instrumentation I: Radioactive Ion Beams |
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Chair: Mark Stoyer, Lawrence Livermore National Laboratory Room: Queen's 4 |
Wednesday, October 8, 2014 7:00PM - 7:15PM |
CH.00001: Performance of the Linear Gas Cell at the NSCL Kortney Cooper, David Morrissey, Ryan Ringle, Stefan Schwarz, Chandana Sumithrarachchi, Guy Savard Beam thermalization allows projectile fragmentation facilities to produce low-energy ion beams. The beam thermalization technique employed by the National Superconducting Cyclotron Laboratory (NSCL) involves high-energy ion beams first passing through solid degraders to remove the bulk of the beam's kinetic energy. The remaining kinetic energy is then dissipated through collisions with the buffer gas atoms of a linear gas cell constructed by Argonne National Lab (ANL). Numerous experiments have been performed for the commissioning and online operation of the gas cell. These experiments used incident ions that ranged from $^{\mathrm{29}}$Mg, $^{\mathrm{29}}$P, $^{\mathrm{33}}$Cl, $^{\mathrm{37}}$K, $^{\mathrm{40}}$S, $^{\mathrm{46}}$Ar, to $^{\mathrm{76}}$Ga at incoming rates ranging from 10$^{\mathrm{2}}$ pps to 10$^{\mathrm{7}}$ pps. The extraction efficiency as well as the overall efficiency of the system has been analyzed for each experiment. LISE$++$, particle-in-cell (PIC), and SIMION simulations have been carried out for the data obtained with $^{\mathrm{76}}$Ga ions. Both the experimental and simulated results for the gas cell's performance will be presented and discussed. [Preview Abstract] |
Wednesday, October 8, 2014 7:15PM - 7:30PM |
CH.00002: Performance of ion surfing rf-carpets for RI beam gas catcher Fumiya Arai, Yuta Ito, Ichirou Katayama, Peter Schury, Tetsu Sonoda, Michiharu Wada, Hermann Wollnik High-energy RI beams produced in-flight by fragmentation or fission are used in ion trap-based precision experiments after being stopped in a gas catcher. The stopped ions can be extracted from the gas catcher as a low energy ion beam. In order to transport and extract ions quickly and efficiently, an rf-carpet (RFC) method utilizing a dc potential gradient has been the standard technique [1]. However, such a method is restricted by the transport time to longer half-life isotopes due to the maximum dc gradient that can be supported before electric discharges occur in the gas catcher. To avoid that limitation, a hybrid technique wherein the dc gradient is replaced by a traveling potential wave was proposed, called ``ion surfing'' [2,3]. Recently, we have demonstrated ion extraction using a circular RFC under low [4] and intermediate pressures. For the first time we demonstrated the ion extraction using an rf-carpet in high-pressure He gas. An efficiency of nearly 100\% was obtained at 200 mbar He gas pressure for $K^{+}$ ions.\\[4pt] [1] M. Wada et al., Nucl. Instr. Meth. B204 (2003) 570.\\[0pt] [2] G. Bollen, Int. J. Mass Spectrom. 299 (2011) 131.\\[0pt] [3] M. Brodeur, et al., Int. J. Mass Spectrom. 336 (2013) 53.\\[0pt] [4] F. Arai, et al., Int. J. Mass Spectrom. 362 (2014) 56. [Preview Abstract] |
Wednesday, October 8, 2014 7:30PM - 7:45PM |
CH.00003: ABSTRACT WITHDRAWN |
Wednesday, October 8, 2014 7:45PM - 8:00PM |
CH.00004: A windowless gas-cell cooler-buncher at RIKEN/SLOWRI Fumiya Arai, Yuta Ito, Ichiro Katayama, Peter Schury, Tetsu Sonoda, Michiharu Wada, Hermann Wollnik For future experiments at RIKEN/SLOWRI, ion preparation, e.g., cooling and bunching, are indispensable for various precision experiments. The ion beams from SLOWRI gas cells will be continuous with a beam energy of $\le$30~keV/$q$, and must be decelerated and cooled in an ion trap to bunch ions. In order to achieve higher efficiency with much simpler structures than conventional RFQ cooler-buncher [1,2], we are developing an windowless gas-cell cooler-buncher (GCCB). The GCCB consists of a gas cell with a small hole at the entrance and an RF-carpet followed by a flat trap [3]. The GCCB will be cryogenically cooled to $\sim$77~K and filled with He gas at up to 2 mbar. According to calculations with TRIM, a stopping efficiency of 100\% can be obtained for any $\le$30~keV/q beams with $Z > 3$ if the GCCB is at least 420 mm long. A large radial geometry will provide a larger effective acceptance than any conventional RFQ cooler-buncher, allowing for higher efficiency. This will allow further reach into exotic nuclei. We will present current status and future outlook.\\[4pt] [1] F.\ Herfurth et al., Nucl.\ Instrum.\ Meth.\ A 469, 254 (2001)\\[0pt] [2] T.\ Brunner et al., Nucl.\ Instrum.\ Meth.\ A 676, 32 (2012)\\[0pt] [3] Y.\ Ito et al., Nucl.\ Instrum.\ Meth.\ B 317, 544 (2013) [Preview Abstract] |
Wednesday, October 8, 2014 8:00PM - 8:15PM |
CH.00005: Production of neutron-rich beam using mulinucleon transfer reactions for KOBRA Kyoungho Tshoo, George Souliotis, YoungKwan Kwon, JunYoung Moon, Junesic Park, Yong-Kyun Kim, Tetsuro Komatsubara, Takashi Hashimoto, Kwangbok Lee Recoil spectrometer, named as KOBRA (KOrea Broad Acceptance Recoil spectrometer and Apparatus), is being developed for RISP (Rare Isotope Science Project) in Korea. The spectrometer will be utilized not only to produce rare isotope (RI) beams but also to study nuclear physics, using stable beams from superconducting Linac or RI beams from ISOL facility. The neutron-rich RI beams will be produced by employing the mulinucleon transfer reactions at beam energy of 15$-$25 MeV/nucleon, from which high current of the RI beam can be obtained by larger production cross section than projectile-like fragmentation in intermediate energy. The calculated production cross sections are compared with the experimental data, and its reaction mechanism is briefly introduced. [Preview Abstract] |
Wednesday, October 8, 2014 8:15PM - 8:30PM |
CH.00006: Off-line production of transition-metal ions at BECOLA Caleb Ryder, Hillary Asberry, Justin Harris, Paul Mantica, Kei Minamisono, Dominic Rossi, Ryan Strum, April Smith Collinear laser spectroscopy (CLS) of stable reference beams produced using off-line methods is critical in CLS experiments for calibrating the beam energy during experimental runs, developing atomic laser excitation schemes and reliably deducing nuclear properties from hyperfine spectra collected from on-line beams of radioisotopes. The BEam COoler and LAser Spectroscopy (BECOLA) facility [1] at the National Superconducting Cyclotron Laboratory at Michigan State University employs several ion sources for off-line stable beam production, each specializing in ion generation from specific materials. The focus of this talk will be on the Penning Ionization Gauge (PIG) ion source [2], a plasma sputtering source that has been recently implemented at BECOLA to readily produce transition metal ion beams. \\[4pt] [1] K. Minamisono et al., Nucl. Instrum. Methods Phys. Res. A 709, 85 (2013).\\[0pt] [2] Z. Nouri et al., Nucl. Instrum. Methods Phys. Res. A 614,174 (2010). [Preview Abstract] |
Wednesday, October 8, 2014 8:30PM - 8:45PM |
CH.00007: Design of the polarized radioactive ion beams with RISP for nuclear structure, reaction and astrophysics experiments Wooyoung Kim, Aleksey Gladkov, Yonggeun Seon, JongWon Kim, Chongcheull Yun Polarized RI beams have been designed with RISP for the study of the nuclear structure, reaction and astrophysics. A powerful methods has been adopted for this work - production of polarized RI-beam via projectile fragmentation. The in-flight system line was designed for this purpose at Rare Isotope Science Project (RISP) using projectile fragmentation method. Working principle, schematic design and experiments to be performed at RISP will be presented. [Preview Abstract] |
Wednesday, October 8, 2014 8:45PM - 9:00PM |
CH.00008: Development of the electron spectrometer for the SCRIT experiment A. Enokizono, M. Hara, Y. Haraguchi, T. Hori, S. Ichikawa, K. Kurita, S. Matsuo, T. Ohnishi, T. Suda, T. Tamae, M. Togasaki, K. Tsukada, T. Tsuru, M. Wakasugi, S. Wang, S. Yoneyama The charge density distribution of protons in an atomic nucleus can be precisely measured by electron elastic scattering and provides the detailed information of the nuclear structure. Although the detailed structure of stable nuclei have been measured by former experiments, those have yet to be observed for unstable nuclei due to the difficulty of making a solid target to obtain an enough luminosity for electron scattering. SCRIT (Self-Confining Radioactive isotope Ion Target) device has been developed at RIKEN to make the electron-unstable nuclei scattering experiment possible. With the electron storage ring (E$_{\mathrm{beam\thinspace }}=$ 150MeV$\sim $300MeV), test experiments have been performed for stable Cs and Xn in 2011-2012 and achieved a luminosity above 10$^{\mathrm{26}}$ cm$^{\mathrm{-2}}$ s$^{\mathrm{-1}}$. Now the SCRIT facility is being upgraded aiming at the world first experiment for electron-unstable nuclei scattering. One of the key components in the upgrade is WiSES (Window-frame Spectrometer for Electron Scattering) which consists of a dipole magnet and front/rear drift chambers, covering a solid angle of $\sim $100 mSr with a momentum resolution of $\Delta p/p \sim $ 10$^{\mathrm{-3}}$ for scattered electrons. In this talk, we will report the latest status of the construction and test of WiSES. [Preview Abstract] |
Wednesday, October 8, 2014 9:00PM - 9:15PM |
CH.00009: Development of a dual-gain multiplication in CNS Active Target for high-intensity heavy-ion beam injection CheongSoo Lee, Shinsuke Ota, Yoki Aramaki, Raphael Saiseau, Hiroshi Tokieda, Yuni Watanabe We are developing a gaseous deuterium active target, called CAT, for the purpose of the detection of deuteron inelastic scattering off near Sn, especially, the deduction of Isoscalar Giant Monopole Resonance by measuring the forward angle scatterings. The CAT consists of Time Projection Chamber (TPC) where Gas Electron Multipliers (GEMs) is employed as a multiplication device and Silicon detectors and detects the beam and recoiled particles at the same time. When we set the gas gain of GEMs high to measure the low-energy depositing particles at a high-intensity about 10$^{5-6}$Hz heavy-ion beam, TPC became unstable because of the energy loss of beam particles is about 100 times larger than that of recoiling deuterons. This may cause a negative effect on the resolution and the accuracy. As a solution for this problem, we tried to make a dual-gain multiplication system on GEM-TPC which provides about 100 times lower gas gain at beam trajectory region than recoil particle region by dividing the electrodes of GEM into three area, two recoil sides and the beam side. In this presentation, the test of a dual-gain multiplication in CAT at HIMAC with a high-intensity 100 MeV/u $^{132}$Xe beam and the results will be reported. [Preview Abstract] |
Wednesday, October 8, 2014 9:15PM - 9:30PM |
CH.00010: SPiRIT-TPC with GET readout electronics for the study of density dependent symmetry energy of high dense matter with Heavy RI collisions Tadaaki Isobe The nuclear Equation of State (EoS) is a fundamental property of nuclear matter that describes the relationships between the parameters for a nuclear system, such as energy, density and temperature. An international collaboration, named SPiRIT, to study the nuclear EoS has been formed recently. One of the main devices of experimental setup is a Time Projection Chamber (TPC) which will be installed into the SAMURAI dipole magnet at RIKEN-RIBF. The TPC can measure charged pions, protons and light ions simultaneously in heavy RI collisions, and those will be used as probes to study the asymmetric dense nuclear matter. In addition to the status of the SPiRIT project, testing of SPiRIT-TPC with GET electronics will be presented in this talk. GET, general electronics for TPC, is a project for the development of novel electronics for TPC supported by NSF and ANR. This work is supported in part by the Japan Grant-in-Aide award and the US DOE grant DE-SC0004835 and JUSEIPEN. [Preview Abstract] |
Wednesday, October 8, 2014 9:30PM - 9:45PM |
CH.00011: Neutron-Induced Charged Particle Studies at LANSCE Hye Young Lee, Robert C. Haight Direct measurements on neutron-induced charged particle reactions are of interest for nuclear astrophysics and applied nuclear energy. LANSCE (Los Alamos Neutron Science Center) produces neutrons in energy of thermal to several hundreds MeV. There has been an effort at LANSCE to upgrade neutron-induced charged particle detection technique, which follows on (n,z) measurements made previously here and will have improved capabilities including larger solid angles, higher efficiency, and better signal to background ratios. For studying cross sections of low-energy neutron induced alpha reactions, Frisch-gridded ionization chamber is designed with segmented anodes for improving signal-to-noise ratio near reaction thresholds. Since double-differential cross sections on (n,p) and (n,a) reactions up to tens of MeV provide important information on deducing nuclear level density, the ionization chamber will be coupled with silicon strip detectors (DSSD) in order to stop energetic charged particles. In this paper, we will present the status of this development including the progress on detector design, calibrations and Monte Carlo simulations. This work is funded by the US Department of Energy - Los Alamos National Security, LLC under contract DE-AC52-06NA25396. [Preview Abstract] |
Wednesday, October 8, 2014 9:45PM - 10:00PM |
CH.00012: Hyperfine structure measurement of $^{87}$Rb atoms injected into superfluid helium as highly energetic ion beam Kei Imamura, Takeshi Furukawa, Xiaofei Yang, Tomomi Fujita, Takashi Wakui, Yousuke Mitsuya, Miki Hayasaka, Yuichi Ichikawa, Atsushi Hatakeyama, Tohru Kobayashi, Hitoshi Odashima, Hideki Ueno, Yukari Matsuo We have developed a new nuclear laser spectroscopy technique that is called OROCHI (Optical RI-atoms Observation in Condensed Helium as Ioncatcher). In OROCHI, highly energetic ion beam is injected into superfluid helium (He II) and is trapped as atoms. Hyperfine structure (HFS) and Zeeman splitting of trapped atoms is measured using laser-microwave (MW) / radiofrequency (RF) double resonance method. We deduce nuclear moments and spin values from the measured splittings, respectively So far, we measured Zeeman splitting of $^{84-87}$Rb atoms To evaluate the validity of the OROCHI method, it is necessary to investigate the following two points not only for Zeeman but also for HFS splitings. (i) What is the accuracy in frequency in our measurement? (ii) How high beam intensity is necessary to observe resonance spectra? For this purpose we conducted online experiment using $^{87}$Rb beam and measured the HFS splitting of injected $^{87}$Rb atoms in He II. [Preview Abstract] |
Wednesday, October 8, 2014 10:00PM - 10:15PM |
CH.00013: Sublevel laser spectroscopy of $^{197}$Au atom in superfluid helium Tomomi Fujita, Takeshi Furukawa, Kei Imamura, Xiaofei Yang, Yousuke Misuya, Miki Hayasaka, Taubasa Sagayama, Shota Kishi, Tohru Kobayashi, Hideki Ueno, Tadashi Shimoda, Yukari Matsuo We have developed a new laser spectroscopy technique named Optical Radioisotope atom Observation in Condensed Helium as Ion-catcher (OROCHI) for investigating the structure of exotic nuclei. This method is in combination with the observation of atomic Zeeman splitting (ZMS) and hyperfine splitting (HFS) in superfluid helium (He II) with laser-radio frequency/microwave double resonance spectroscopy based on the optical pumping technique We can derive nuclear spins and electromagnetic moments from atomic ZMS and HFS, respectively The characteristic optical properties of atoms in He II, caused by pressure from surrounding He atoms, enable us to apply the optical pumping technique to the various elements effectively. As for the future measurement of Au isotopes we measured the ZMS and HFS in the ground state of stable $^{197}$Au atoms supplied into He II by laser sputtering technique. We succeeded in producing high atomic spin polarization (\textgreater 80{\%}) of $^{197}$Au in He II with optical pumping by using the pumping laser light of fourth harmonics of a LD-pumped pulsed Nd:YLF laser. [Preview Abstract] |
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