RI beam facility project at RIKEN and physics programs

In the Radioactive-Isotope Beam Factory (RIBF) project in RIKEN, intense primary beams can be provided at the energies E = 350−400MeV over the whole range of atomic number in the cascade-cyclotron acceleration scheme, for which three cyclotrons, fRC, IRC, and SRC, have been newly constructed. The project proceeds through two phases. In the phase-I program, the superconducting in-flight radioactive-isotope beam separator BigRIPS and the following ZeroDegree spectrometer have been installed as well as the three cyclotrons. In the commissioning, after the successful extraction of a ²³⁸U beam from SRC at E = 345 A MeV in the cascade-acceleration scheme, radioactive-isotope beams were produced and isotope-separated with BigRIPS as designed. The RIBF project is fully capitalized in the phase-II program, in which the construction of several experimental key devices has been proposed. The upgrade of the former fragment separator RIPS is also included there. It allow for a scheme to use intense primary beams at the intermediate energy E = 115 A MeV with RIPS. Remarkably, the produced radioactive-isotope beams at this energy can be spin-polarized taking the advantage of the fragmentation-induced spin orientation phenomena. on behalf of the RIBF project     

Developments at the SLOWRI facility at RIKEN: precision optical spectroscopy of 7,9,10,11Be+ ions

Precision optical spectroscopy of radioactive Be isotopes produced in projectile fragmentation has been performed for the first time at the prototype SLOWRI facility of RIKEN RI-Beam Factory. The ground state hyperfine constants of ⁷Be⁺ and ¹¹Be⁺ were determined with relative accuracies of 6 × 10^?7 and 3 × 10^?8, respectively, by laser-microwave double resonance spectroscopy of laser-cooled ions in a trap. The optical transition energies from the ground S-state to the excited P-state of Be isotope ions were also measured to determine the nuclear charge radii from the isotope shifts. Development of the universal slow RI-beam facility??SLOWRI??based on the rf-carpet ion guide technique is progressing at RIKEN RI-beam factory. An additional capability of providing parasitic slow RI-beams from the projectile fragment separator BigRIPS is also discussed.     

Precision laser spectroscopy of Be isotopes and prospects for SLOWRI facility at RIKEN

Development of a universal slow RI-beam facility based on rf-carpet ion guide technique is being progressing at RIKEN RI-beam factory. With a prototype setup, precision optical spectroscopy experiments were performed for beryllium isotopes. An additional capability of providing parasitic slow RI-beams from the projectile fragment separator BigRIPS is also discussed.     

GENIUS - a new facility of non-accelerator particle physics

The GENIUS ( rmanium in Liquid trogen nderground etup) project has been proposed in 1997 [1] as first third generation double beta decay project, with a sensitivity aiming down to a level of an effective neutrino mass of < m > 0.01 - 0.001 eV. Such sensitivity has been shown to be indispensable to solve the question of the structure of the neutrino mass matrix which cannot be solved by neutrino oscillation experiments alone [2]. It will allow broad access also to many other topics of physics beyond the Standard Model of particle physics at the multi-TeV scale. For search of cold dark matter GENIUS will cover almost the full range of the parameter space of predictions of SUSY for neutralinos as dark matter [3,4]. Finally, GENIUS has the potential to be the first real-time detector for low-energy (pp and ⁷Be) solar neutrinos [6,5]. A GENIUS-Test Facility has just been funded and will come into operation by end of 2001.     

Opportunities for parity violating electron scattering experiments at the planned MESA facility

We suggest to start an accelerator physics project called the Mainz Energy recovering Superconducting Accelerator (MESA) as an extension to our experimental facilities. MESA may allow to introduce an innovative internal target regime based on the ERL principle. A second mode of operation will be to use an external polarized electron beam for parity violating experiments.     

Laser spectroscopy of trapped 7Be and 10Be at a prototype slow RI-beam facility of RIKEN

A next-generation slow radioactive nuclear ion beam facility (SLOWRI) which provides slow, high-purity and small emittance ion beams of all elements is being build as one of the principal facilities at the RIKEN RI-beam factory (RIBF). High energy radioactive ion beams from the projectile fragment separator BigRIPS are thermalized in a large gas catcher cell. The thermalized ions in the gas cell are guided and extracted to a vacuum environment by a combination of dc electric fields and inhomogeneous rf fields (rf carpet ion guide). From there the slow ion beam is delivered via a mass separator and a switchyard to various devices: such as an ion trap, a collinear fast beam apparatus, and a multi-reflection time of flight mass spectrometer. In the R&D works at the present RIKEN facility, an overall efficiency of 5% for a 100A MeV ⁸Li ion beam from the present projectile fragment separator RIPS was achieved and the dependence of the efficiency on the ion beam intensity was investigated. Recently our first spectroscopy experiment at the prototype SLOWI was performed on Be isotopes. Energetic ions of ¹⁰Be and ⁷Be from the RIPS were trapped and laser cooled in a linear rf trap and the specific mass shifts of these isotopes were measured for the first time.     

RI Beam Factory project at RIKEN

The RI Beam Factory is being proposed at RIKEN, which is a project to construct two superconducting ring cyclotrons (SRC-4 and SRC-6), experimental storage rings (MUSES) and experimental facilities. Heavy ions are to be accelerated to energies of up to 400 AMeV for light nuclei and 150 AMeV for the heaviest nuclei by the SRC-6 and up to 1400 AMeV in the MUSES. Wide varieties of radioactive nuclear beams are to be supplied as secondary beams. Electrons, stable nuclei, and highly charged ions in addition to radioactive nuclei can be stored in the storage rings. The MUSES provides various collision methods, such as colliding, merging, and internal target modes. A few of the selected new nuclear-physics opportunities are discussed briefly.     

The Atlas project-a new pulsed power facility for high energydensity physics experiments

Atlas is a facility being designed at Los Alamos National Laboratory (LANL) to perform high-energy-density experiments in support of weapon physics and basic research programs. It is designed to be an international user facility, providing experimental opportunities to researchers from national laboratories and academic institutions. For hydrodynamic experiments, it will be capable of achieving a pressure exceeding 30 Mbar in a several cubic centimeter volume. With the development of a suitable opening switch, it will be capable of producing more than 3 MJ of soft X-rays. The capacitor bank design consists of a 36 MJ array of 240 kV Marx modules. The system is designed to deliver a peak current of 45-50 MA with a 4-5-μs rise time. The Marx modules are designed to be reconfigured to a 480-kV configuration for opening switch development. The capacitor bank is resistively damped to limit fault currents and capacitor voltage reversal. An experimental program for testing and certifying prototype components is currently under way. The capacitor bank design contains 300 closing switches. These switches are a modified version of a railgap switch originally designed for the DNA-ACE machines. Because of the large number of switches in the system, individual switch prefire rates must be less than 10^-4 to protect the expensive target assemblies. Experiments are under way to determine if the switch-prefire probability can be reduced with rapid capacitor charging     

Startup of superheavy element chemistry at RIKEN

A review is given on the startup of the superheavy element (SHE) chemistry at RIKEN. A gas-jet transport system for the SHE chemistry has been coupled to the gas-filled recoil ion separator GARIS at the RIKEN Linear Accelerator. The performance of the system was appraised using ²⁰⁶Fr and ²⁴⁵Fm produced in the ¹⁶⁹Tm (⁴⁰Ar, 3n) ²⁰⁶Fr and ²⁰⁸Pb (⁴⁰Ar, 3n) ²⁴⁵Fm reactions, respectively. The α particles of ²⁰⁶Fr and ²⁴⁵Fm separated with GARIS and transported by the gas-jet were identified with a rotating wheel system for α spectrometry under desired low background condition. The high gas-jet efficiencies over 80% were independent of the beam intensities up to 2 particle μA. A gas-jet coupled target system for the production of SHEs was also installed on the beam line of the RIKEN K70 AVF cyclotron. The gas-jet transport of ²⁵⁵No and ²⁶¹Rf produced in the ²³⁸U (²²Ne, 5n) ²⁵⁵No and ²⁴⁸Cm (¹⁸O, 5n) ²⁶¹Rf reactions, respectively, was conducted for the future chemical studies of ²⁶⁵Sg via the ²⁴⁸Cm (²²Ne, 5n) ²⁶⁵Sg reaction.     

Probing new top physics at the LHCb experiment

We suggest that top quark physics can be studied at the LHCb experiment and that top quark production could be observed. Since LHCb covers a large pseudorapidity region in the forward direction, it has unique abilities to probe new physics in the top quark sector. Furthermore, we demonstrate that LHCb may be able to measure a t ?t production rate asymmetry and, thus, indirectly probe an anomalous forward-backward t ?t asymmetry in the forward region, a possibility suggested by the enhanced forward-backward asymmetry reported by the CDF experiment.     

Atomic parity-violation and precision physics

The atomic parity-violation (APV) parameter for a nucleus with n neutrons and z protons has been included in the list of pseudo-observables accessible with the codes TOPAZ0 and ZFITTER. In this way one can add the APV results in the LEP EWWG “global” electroweak fits, checking the corresponding effect when added to the existing precision measurements. Received: 8 March 2001 / Published online: 21 September 2001     

Collinear laser spectroscopy at the new IGISOL 4 facility

In 2011 the collinear laser spectroscopy programme at the University of Jyväskylä Accelerator Laboratory (JYFL), Finland, will move to the new IGISOL 4 facility. With its own dedicated cyclotron, this new laboratory will offer unparalleled access to beam time for both technique development and exploitation. Production of sub-millisecond states is available, including elements of a refractory nature.     

Physics opportunities with the RI Beam Factory at RIKEN

The RI Beam Factory (RIBF) is presently the top world-class radioactive-isotope (RI) beam facility in the world. Construction of the factory is now in the process of being completed. This facility is based on the in-flight method to produce fast RI beams. High-energy and intense primary beams accelerated by a superconducting ring cyclotron (SRC) are converted, via the projectile fragmentation or fission reaction channels, to RI beams at a new fragment separator called BigRIPS. Construction of major experimental installations is expected to commence in 2007. Physics opportunities with the RIBF are discussed herein.     

量子频标中的原子物理

频率是自然界中测量得最准的物理量.量子频标是频率的测量标准,它是利用原子跃迁谱线的稳定而准确的频率作为参考频率.频标研究中存在几乎所有的原子物理问题,如原子结构与光谱、原子与电磁场的相互作用以及原子碰撞等问题值得深入研究.本文就量子频标的基本原理和应用,量子频标中存在的原子物理问题做以简要评述.     

Atomic hyperfine structure in micromaser physics

In this paper, we examine the effect of atomic hyperfine structure in micromaser physics which has not been considered so far. We examine both the case of completely degenerate hyperfine levels and small hyperfine splittings and show that the dynamics of the micromaser can be significantly modified. We also describe possible strategies to realize a quasi two-level system in the micromaser.     

Diphoton resonance and new physics at 1 TeV

The diphoton excess with invariant mass ~750 GeV observed at the 13 TeV LHC run is studied in the extension of the Standard Model with an extra scalar S which decays can be responsible for the excess. Two scenarios of S production are considered: gluon fusion through a loop of heavy isosinglet quark(s) and photon fusion through a loop of heavy isosinglet leptons.