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 CE: Mini-Symposium on Developments in Re-accelerated Rare Isotope Beam Physics II |
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Chair: Dave Morrissey, Michigan State University Room: Kohala 2 |
Thursday, October 15, 2009 9:00AM - 9:30AM |
CE.00001: A new approach for Next-TRIAC Invited Speaker: TRIAC (Tokai Radioactive Ion Accelerator Complex) is a unique RIB facility in Japan based on the ISOL and post-acceleration scheme. It has been operated as a User Facility since the November of 2005. Fission fragment beams via the proton-induced uranium fissions of 10$^{11}$ fis/sec are available in the acceleration energy range 0 to 1.1 MeV/u. At this moment, before considering an immediate extension (or upgrade) of the present TRIAC in terms of facility, we have proposed a new research program, which is supposed to be one of important physics programs at the next generation of TRIAC-like facility (Next-TRIAC). That is an experimental approach to study unknown nuclei in the vicinity of waiting region for A=195 r-process abundance peak through the multi-nucleon transfer reactions of neutron-rich beams. In the talk, after the brief summary of TRIAC activities, I will introduce an outline of our short term experimental proposal and underlined physics motivation relevant to the future's Next-TRIAC. Also I will mention some important R{\&}D subjects to be solved in the short term project. [Preview Abstract] |
Thursday, October 15, 2009 9:30AM - 9:45AM |
CE.00002: Spectroscopy around N = 126 nuclei produced by multi-nucleon transfer reaction Y. Hirayama, N. Imai, H. Ishiyama, S.C. Jeong, H. Miyatake, K. Niki, M. Okada, M. Oyaizu, Y.X. Watanabe, M. Wada, T. Sonoda, A. Takamine The $\beta $-decay properties of the neutron-rich isotopes with neutron number N = 126 are supposed to play a critical role for better understanding of r-process. We will study $\beta $-decay properties and nuclear structures around N = 126 nuclei by $\beta $-decay and laser spectroscopy. As the first step, we are going to produce $^{202}$Os (Z = 76, N = 126), which has not been produced in any other facilities, by using the multi-nucleon transfer reactions in $^{136}$Xe (stable beam) + $^{198}$Pt (target) collision. The Pt target is used as the window of the gas catcher for collecting all reaction products by the collision, from which the $^{202}$Os will be extracted as singly-charged ions by laser resonance ionization and transported to a detection station after being mass-separated for the spectroscopy. [Preview Abstract] |
Thursday, October 15, 2009 9:45AM - 10:00AM |
CE.00003: Radioactive beams from Californium fission at the CARIBU facility Guy Savard, Richard Pardo, Sam Baker, Cary Davids, Don Peterson, Don Phillips, Rick Vondrasek, Bruce Zabransky, Gary Zinkann The Californium Rare Ion Breeder Upgrade (CARIBU) of the ATLAS superconducting linac facility aims at providing low energy and reaccelerated neutron-rich radioactive beams to address key nuclear physics and astrophysics questions. These beams are obtained from fission fragments of a 1 Ci $^{252}$Cf source, thermalized and collected into a low-energy particle beam by a helium gas catcher, mass analyzed by an isobar separator, and charge breed to higher charge states for acceleration in ATLAS. The method described is fast and universal and short-lived isotope yield scale essentially with Californium fission yields. Expected intensities of reaccelerated beams are up to $\sim $5x10$^{5}$ (10$^{7}$ at low energy) far-from-stability ions per second on target. Initial commissioning is being performed with weaker 2.5 and 80 mCi sources. Commissioning results, together with the nuclear physics and astrophysics program that will be pursued with the neutron-rich beams made available, will be presented. Plans for installation of the 1 Ci source will be discussed. [Preview Abstract] |
Thursday, October 15, 2009 10:00AM - 10:15AM |
CE.00004: Recent activities with slow and stopped RI at Tohoku-Cyclotron Takashi Wakui, Yuji Miyashita, Kenzi Shimada, Nozomi Sato, Sayo Hoshino, Hiroyuki Ouchi, Ayako Sasaki, Sayaka Izumi, Tsutomu Shinozuka An overview will be presented of our recent activities with slow and stopped radioactive isotopes (SSRIs) at Cyclotron and Radioisotope Center (CYRIC), Tohoku University. Slow RI beams are mainly provided by the RF ion guide isotope separator on-line (RF-IGISOL) in which neutron rich nuclei in medium mass region are produced by proton induced fission reactions with a Uranium target. Using the RF-IGISOL, some experimental programs have been carried out, such as measurements of g-factors and half-lives of excited states. A brief description of some ongoing projects utilizing the SSRIs will also be given. This description includes the production of spin polarization and installation of a new ECR ion source. Furthermore, the future prospects with SSRIs will be mentioned with emphasis on further development of the RF-IGISOL. [Preview Abstract] |
Thursday, October 15, 2009 10:15AM - 10:30AM |
CE.00005: Half-Life and Magnetic Moment of the First Excited State in $^{132}$I S. Izumi, M. Tanigaki, H. Ouchi, A. Sasaki, S. Hoshino, Y. Miyashita, N. Sato, K. Shimada, T. Wakui, T. Shinozuka, Y. Ohkubo The half-life and the magnetic moment of the first excited state in $^{132}$I are reported. There have been a long time confusion on the half-life measurements of the first excited state in $^{132}$I. Several groups performed the lifetime measurements, but the reported values range from 1 ns to 7 ns. The only reported value of the magnetic moment for this state was measured by Singh, but their result should be treated as unreliable because the time-integral perturbed angular correlation technique (TIPAC), which requires the life time data of this state, was used in their measurement. From this point of view, the half-life and the magnetic moment of this state were measured. $^{132}$I was obtained as the radioactive beam of $^{132}$Te and $^{132}$Sb from the newly developed RF-IGISOL (Radio Frequency IGISOL system) at Tohoku University. The half-life for this state was determined to be 1.120 $\pm $ 0.015 ns by a conventional coincidence technique with a pair of BaF$_{2}$ detectors. The TDPAC measurement for the $^{132}$I implanted kinematically into nickel was performed with the help of a strong hyperfine field at iodine site in nickel, and the magnetic moment of this state was determined to be $\mu $=+ (2.06 $\pm $ 0.18)$\mu _{N}$. The configuration of this state based on the present results will be discussed. [Preview Abstract] |
Thursday, October 15, 2009 10:30AM - 10:45AM |
CE.00006: High precision Penning trap mass spectrometry of rare isotopes produced by projectile fragmentation Anna Kwiatkowski, C. Bachelet, B.R. Barquest, G. Bollen, C.M. Campbell, R, Ferrer, C. Guenaut, D. Lincoln, D.J. Morrissey, G.K. Pang, A.M. Prinke, R. Ringle, J. Savory, S. Schwarz, M. Block, P. Schury, C.M. Folden III, D. Melconian, S.K.J. Sjue The Low Energy Beam and Ion Trap (LEBIT) facility combines high precision Penning trap mass spectrometry with fast beam projectile fragmentation and high pressure gas stopping techniques. Advanced ion manipulation, such as high efficiency continuous mass selection in an ion-guide and radio-frequency ion accumulation and bunching, are used to purify, cool, and pulse the beam. Recent mass measurements include $^{63-66}$Fe, $^{66}$As, and $^{32}$Si. The neutron-rich iron isotopes access the N = 40 subshell closure. The new significantly lower mass uncertainty makes $^{66}$As a candidate to test the CVC hypothesis. $^{32}$Si, member of the A = 32, T = 2 quintet, provides the most precise test of the isobaric multiplet mass equation . An overview of the various aspects of ion manipulation and some of the resulting measurements will be presented. [Preview Abstract] |
Thursday, October 15, 2009 10:45AM - 11:00AM |
CE.00007: Status of Multi-Reflection Time-of-Flight Spectrometer for Radio-Isotopes at RIKEN Peter Schury, Michiharu Wada, Tetsu Sonoda, Aiko Takamine, Yasunori Yamazaki, Hermann Wollnik The new Radioactive Ion Beam Factory at RIKEN will provide unprecedented access to exotic neutron-rich isotopes such as are important for r-process nucleosynthesis. To utilize these exotic RI beams, we continue to develop a Multi- Reflection Time-of-Flight (MRTOF) spectrograph. Our system will make use on an advanced gas cell to thermalize relativistic ions of exotic radioactive ions and transfer them to high-vacuum quickly and efficiently. An RF ion trap of novel geometry will cool and bunch ions extracted from the gas cell. A pair of electrostatic mirrors creates an extended flight path of 1 km or more for the ions. By combining high-quality ion pulses with the long flight path, simulations have indicated that the device should be capable to achieve mass resolving powers of $R=\frac{m}{\Delta m}>500,000$. The high-resolving power will allow the MRTOF spectrograph to be competitive with Penning trap mass spectrometers. We will present the current state of development of our MRTOF along with an overview of our anticipated impact on the nuclear landscape. [Preview Abstract] |
Thursday, October 15, 2009 11:00AM - 11:15AM |
CE.00008: ORISS: A compact isomer and isobar separator for study of exotic decays A. Piechaczek, V. Shchepunov, H.K. Carter, J.C. Batchelder, E.F. Zganjar A compact isobar and isomer spectrometer and separator ORISS (Oak Ridge Isomer Separator and Spectrometer), based on the multi-pass-time-of-flight principle, is being constructed. A mass resolving power of 110,000 (fwhm) and a transmission of 50{\%} have been achieved as a spectrometer with an off-line ion source with large emittance. As a separator, molecules of N$_{2}$ and CO with a mass difference of 1/2500 or 10.433 MeV were separated with ToF peaks corresponding to a mass resolution of 40,000. For injection of radioactive ions into ORISS and to further improve its mass resolution, we have constructed cooler/buncher RF quadrupoles and demonstrated a bunch width of 9 ns (fwhm) and a transmission of 75 -- 80 {\%}. With this bunch width, ORISS can achieve a mass resolution of $\sim $ 400,000 and will be able to separate nuclei or isomers with a mass difference of 1/200,000, corresponding to 470 keV at mass A=100. At present, the quadrupoles are being integrated into the ORISS system. ORISS will be used for decay spectroscopy to provide isotopically pure samples of exotic species around $^{100}$Sn and of neutron rich nuclei. In addition, ORISS will allow a fast and efficient search for isomers within an entire isobaric chain. [Preview Abstract] |
Thursday, October 15, 2009 11:15AM - 11:30AM |
CE.00009: Parasitic production of slow RI-beam from a projectile fragment separator by ion guide Laser Ion Source (PALIS) Tetsu Sonoda The projectile fragment separator BigRIPS of RIBF at RIKEN provides a wide variety of short-lived radioactive isotope (RI) ions without restrictions on their lifetime or chemical properties. A universal slow RI-beam facility (SLOWRI) to decelerate the beams from BigRIPS using an RF-carpet ion guide has been proposed as a principal facility of RIBF. However, beam time at such a modern accelerator facility is always limited and operational costs are high. We therefore propose an additional scheme as a complementary option to SLOWRI to drastically enhance the usability of such an expensive facility. In BigRIPS, a single primary beam produces thousands of isotopes but only one isotope is used for an experiment while the other $>$99.99{\%} of isotopes are simply dumped in the slits or elsewhere in the fragment separator. We plan to locate a compact gas cell with 1 bar Ar at the slits. The thermalized ions in the cell will be quickly neutralized and transported to the exit by gas flow and resonantly re-ionized by lasers. Such low energy RI-beams will always be provided without any restriction to the main experiment. It will allow us to run parasitic experiments for precision atomic or decay spectroscopy, mass measurements.~Furthermore, the resonance ionization in the cell itself can be used for high-sensitive laser spectroscopy, which will expand our knowledge of the ground state property of unstable nuclei. [Preview Abstract] |
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