Hybrid recoil mass analyzer at IUAC — First results using gas-filled mode and future plans

Hybrid recoil mass analyzer (HYRA) is a unique, dual-mode spectrometer designed to carry out nuclear reaction and structure studies in heavy and medium-mass nuclei using gas-filled and vacuum modes, respectively and has the potential to address newer domains in nuclear physics accessible using high energy, heavy-ion beams from superconducting LINAC accelerator (being commissioned) and ECR-based high current injector system (planned) at IUAC. The first stage of HYRA is operational and initial experiments have been carried out using gas-filled mode for the detection of heavy evaporation residues and heavy quasielastic recoils in the direction of primary beam. Excellent primary beam rejection and transmission efficiency (comparable with other gas-filled separators) have been achieved using a smaller focal plane detection system. There are plans to couple HYRA to other detector arrays such as Indian national gamma array (INGA) and 4π spin spectrometer for ER tagged spectroscopic/spin distribution studies and for focal plane decay measurements.     

High Spin States in 70 Ge [Erratum: APH N.S., Heavy Ion Physics 11 (2000) 189]

High spin states in70Ge nucleus have been studied in two different experiments using heavy ion fusion evaporation reaction. The Gamma Detector Array comprising of eight Compton-suppressed High Purity Ge detectors, was used in conjunction with a Recoil Mass Spectrometer — the HIRA — in order to identify and measure the transitions of this weakly populated nucleus. The level scheme is extended up to an excitation energy of13MeV for spin-parity 21- with several newly observed transitions placed in it. A rotational like band is also observed in this nucleus for the first time.     

兰州重离子加速器冷却储存环上强子物理研究计划及现状

An internal target experiment at HIRFL-CSRm is planned for hadron physics, which focuses on hadron spectroscopy, polarized strangeness production and medium effect. A conceptual design of Hadron Physics Lanzhou Spectrometer (HPLUS) is discussed. Related computing framework involves event generation, simulation, reconstruction and final analysis. The R & D works on internal target facilities and sub-detectors are presented briefly.     

The physics of accelerator driven sub-critical reactors

In recent years, there has been an increasing worldwide interest in accelerator driven systems (ADS) due to their perceived superior safety characteristics and their potential for burning actinides and long-lived fission products. Indian interest in ADS has an additional dimension, which is related to our planned large-scale thorium utilization for future nuclear energy generation. The physics of ADS is quite different from that of critical reactors. As such, physics studies on ADS reactors are necessary for gaining an understanding of these systems. Development of theoretical tools and experimental facilities for studying the physics of ADS reactors constitute important aspect of the ADS development program at BARC. This includes computer codes for burnup studies based on transport theory and Monte Carlo methods, codes for studying the kinetics of ADS and sub-critical facilities driven by 14 MeV neutron generators for ADS experiments and development of sub-criticality measurement methods. The paper discusses the physics issues specific to ADS reactors and presents the status of the reactor physics program and some of the ADS concepts under study.      

PEPX-type lattice design and optimization for the High Energy Photon Source

A new generation of storage ring-based light sources, called diffraction-limited storage rings(DLSR), with emittance approaching the diffraction limit for multi-ke V photons by using multi-bend achromat lattice, has attracted worldwide and extensive studies of several laboratories, and been seriously considered as a means of upgrading existing facilities in the imminent future. Among various DLSR proposals, the PEPX design demonstrated that it is feasible to achieve sufficient ring acceptance for off-axis injection in a DLSR, by designing the lattice based on the ‘thirdorder achromat' concept and with a special high-beta injection section. For the High Energy Photon Source(HEPS)planned to be built in Beijing, a PEPX-type lattice has been designed and continuously improved. In this paper, we report the evolution of the PEPX-type design for HEPS, and discuss the main issues relevant to the linear optics design and nonlinear optimization.     

Transmitted wavefront error of a volume phase holographic grating at cryogenic temperature

This paper describes the results of transmitted wavefront error (WFE) measurements on a volume phase holographic (VPH) grating operating at a temperature of 120 K. The VPH grating was mounted in a cryogenically compatible optical mount and tested in situ in a cryostat. The nominal root mean square (RMS) wavefront error at room temperature was 19 nm measured over a 50 mm diameter test aperture. The WFE remained at 18 nm RMS when the grating was cooled. This important result demonstrates that excellent WFE performance can be obtained with cooled VPH gratings, as required for use in future cryogenic infrared astronomical spectrometers planned for the European Extremely Large Telescope.     

The HERMES Recoil Detector

The HERMES Collaboration installed a new Recoil Detector to upgrade the existing spectrometer to study hard exclusive processes which provide access to generalised parton distributions (GPDs) and hence to the orbital angular momentum of quarks. The HERMES Recoil Detector mainly consists of three components: a silicon detector surrounding the target cell inside the beam vacuum, a scintillating fibre tracker and a photon detector with three layers of tungsten and scintillator bars in three different orientations. All three detectors are located inside a solenoidal magnet which provides a 1T longitudinal magnetic field. The Recoil Detector was installed in January 2006 and data taking will last until July of 2007.     

Synthesis of new superheavy elements using the Dubna Gas-Filled Separator: The complex of technologies

All the new isotopes of superheavy elements in the reactions with ⁴⁸Ca ions and actinide targets, synthesized at the Flerov Laboratory of Nuclear Reactions (FLNR), have been obtained at the Dubna Gas-Filled Recoil Separator (DGFRS). Success was achieved with the use of several techniques, algorithms and approaches with record performance in their area. The most sophisticated of them are rare event detection technology, methods of measuring the effective equilibrium charges of heavy ions and nuclei in hydrogen at low pressure, modified approaches to evaluation of probabilistic characteristics of detected multichain events, beam-free test methods of detection equipment, and some other ones. The author analyzes the approaches that have led ultimately to a real breakthrough and an advance in experiments on the synthesis of superheavy elements. The development of detection systems also attracts the authors’ attention. Contributions from some facilities—such as SHIP, TASCA, and GARIS (RIKEN)—to synthesis experiments are partially noted. Under consideration are methods of automation of similar experiments, including the development of control and shielding systems for operation with highly active actinide targets. Some techniques for detecting α decay of heavy nuclei that came before the current experiments with electromagnetic separators are reviewed briefly. The methods, algorithms and hardware presented cover a more than twenty-year period of commissioning and application in long-term experiments at FLNR DGFRS.     

Characterization of 1550 nm sub-picoseconds optical pulse using a gain-switching distributed feedback laser with CW-mode external-injection and pulse-mode self-injection

In this paper, we experimentally demonstrated the 1550 nm short optical pulses generation using a TO-packaged gain-switching distributed feedback (DFB) semiconductor laser driving by 2.5 GHz radio frequency (RF) signals and combining with optical injection techniques. The characteristics of the generated optical pulse by the proposed CW-mode external-injection and pulse-mode self-injection schemes are characterized in the side mode suppression ratio (SMSR), spectrum line-width, pulse-width and root-meansquare (RMS) jitter. In the CW-mode external-injection case, the SMSR of 35.5 dB, line-width of 0.235 nm, pulse-width of 47.69 ps, and RMS jitter of 1.4 ps are obtained when the optical injection ratio of 5 dB. In the pulse-mode self-injection, however, the SMSR of 61.2 dB, spectrum line-width of 0.189 nm, pulse-width of 58.46 ps, and RMS jitter of 1 ps are achieved and its overall performances are better than CW-mode externalinjection one.     

兰州重离子医疗装置同步环安装控制网设计

介绍了兰州重离子医疗装置(HIMM)建造中准直安装方案里核心的测量控制网设计。同步环准直测量控制网是基于Leica AT401激光跟踪仪和综合测量软件SA建立的三维测量控制网,在控制网设计中采用9个基准柱和2个激光干涉测量得到的基准长度参考,以及Leica DNA03数字水准仪协同测量,使全局三维控制网设计精度达到0.04mm,最终确保同步环四极磁铁安装精度达到0.10mm的要求指标,为将来束流的稳定运行做好可靠的保证。     

Measurement of Timing Jitter in Wavelength Tunable Femtosecond Soliton Pulses

We investigated the root mean square (RMS) timing jitter and RMS intensity noise of the wavelength tunable femtosecond soliton pulses using the technique of radio-frequency spectrum analysis. We obtained interesting results that the generated solitons have almost constant RMS timing jitter and RMS intensity noise of approximately 410 fs and 0.03% in the wavelength region of 1600-1750 nm. It is therefore believed that the magnitudes of the jitter and noise are not greatly increased in the process of wavelength tunable soliton pulse generation. The wavelength tunable soliton pulse is confirmed to be stable and useful for practical applications.     

ESRF-type lattice design and optimization for the High Energy Photon Source

A new generation of storage ring-based light sources,called diffraction-limited storage rings(DLSRs),with emittance approaching the diffraction limit for multi-keV photons by means of multi-bend achromat lattices,has attracted extensive studies worldwide.Among various DLSR proposals,the hybrid multi-bend achromat concept developed at the European Synchrotron Radiation Facility(ESRF) predicts an effective way of minimizing the emittance while keeping the required chromatic sextupole strengths to an achievable level.For the High Energy Photon Source planned to be built in Beijing,an ESRF-type lattice design consisting of 48 hybrid seven-bend achromats is proposed to reach emittance as low as 60 pm-rad with a circumference of about 1296 m.Sufficient dynamic aperture,allowing vertical on-axis injection,and moderate momentum acceptance are achieved simultaneously for a promising ring performance.     

Development Towards a Laser Ion Source Trap for the Production of Exotic Species

A new type of resonance ionization laser ion source (RILIS) is presently being developed and tested at the off-line mass separator at Mainz University for future use at on-line exotic rare isotopes production facilities. For highest isobaric selectivity, this RILIS approach decouples the evaporation and ionization process. A further advantage is the generation of full temporal control of the resulting high quality ion beam. These facts are realized by a combination of atomizer – ion repeller – ion cooler and trap, which is operated together with a state-of-the-art, all solid state laser system. The principle and performance of this laser ion source trap (LIST) system are discussed applying simulation studies for the repeller-trap combination and first measurements for characterization.     

Muon facility plans towards JHP

The future muon facility planned for the future Japanese accelerator project (Japanese Hadron Project) and related activities towards advanced muon facilities are described.     

ECR ion source based low energy ion beam facility

Mass analyzed highly charged ion beams of energy ranging from a few keV to a few MeV plays an important role in various aspects of research in modern physics. In this paper a unique low energy ion beam facility (LEIBF) set up at Nuclear Science Centre (NSC) for providing low and medium energy multiply charged ion beams ranging from a few keV to a few MeV for research in materials sciences, atomic and molecular physics is described. One of the important features of this facility is the availability of relatively large currents of multiply charged positive ions from an electron cyclotron resonance (ECR) source placed entirely on a high voltage platform. All the electronic and vacuum systems related to the ECR source including 10 GHz ultra high frequency (UHF) transmitter, high voltage power supplies for extractor and Einzel lens are placed on a high voltage platform. All the equipments are controlled using a personal computer at ground potential through optical fibers for high voltage isolation. Some of the experimental facilities available are also described.     

Scientific Review: New Opportunities for Data Analysis Software: An International Collaboration

On three continents major new neutron scattering facilities are under construction that will provide unprecedented opportunities for scientific discovery. The Spallation Neutron Source (SNS) under construction at Oak Ridge National Laboratory (ORNL) will become operational in 2006, the Japanese Spallation Source is planned for completion in 2007, and the second target station at ISIS is due to come on-line in 2008. All three will be equipped with state-of-the-art instrumentation, large detector arrays and, with the associated increases in flux, will deliver orders of magnitude increases in data volume. Current data visualization and analysis software will be seriously challenged to keep pace with these changes.     

气固化学反应体系产生单重态氧的初步实验研究

 介绍了一种新的产生单重态氧（O₂（¹△g）的气固化学反应体系,即在固定床式反应器中采用固体过氧化钠粉末与氯气（Na₂O₂/Cl₂）进行反应的气固化学反应体系。实验分别通过用对近红外敏感的光谱仪和锗探头监测了反应产生的（O₂（¹△g）的发射光谱和1 270 nm的光信号,同时通过数据采集系统监测了反应池固体反应层和测试池中气体的温度的变化曲线。实验测得了（O₂（¹△g）在1 270 nm附近的特征发射光谱,此光谱表明该体系是一个很好的产生（O₂（¹△g）的体系,同时,实验现象表明该反应是强放热反应。     

Program for studying fundamental interactions at the PIK reactor facilities

A research program aimed at studying fundamental interactions by means of ultracold and polarized cold neutrons at the GEK-4-4′ channel of the PIK reactor is presented. The apparatus to be used includes a source of cold neutrons in the heavy-water reflector of the reactor, a source of ultracold neutrons based on superfluid helium and installed in a cold-neutron beam extracted from the GEK-4 channel, and a number of experimental facilities in neutron beams. An experiment devoted to searches for the neutron electric dipole moment and an experiment aimed at a measurement the neutron lifetime with the aid of a large gravitational trap are planned to be performed in a beam of ultracold neutrons. An experiment devoted to measuring neutron-decay asymmetries with the aid of a superconducting solenoid is planned in a beam of cold polarized neutrons from the GEK-4′ channel. The second ultracold-neutron source and an experiment aimed at measuring the neutron lifetime with the aid of a magnetic trap are planned in the neutron-guide system of the GEK-3 channel. In the realms of neutrino physics, an experiment intended for sterile-neutrino searches is designed. The state of affairs around the preparation of the experimental equipment for this program is discussed.     

Fully coherent hard X-ray generation by two-stage phase-merging enhanced harmonic generation

Cascading stages of seeded free electron lasers (FELs) is a promising way to produce fully coherent X-ray radiation. We study a new approach to produce coherent hard X-rays by cascading the recently proposed phase-merging enhanced harmonic generation (PEHG) The scheme consists of one dogleg and two PEHG configurations, and may be one of the leading candidates for the extracted undulator branch in future X-ray FEL facilities. FEL physics studies show that such a scheme is feasible within the present technology and can provide high brightness X-ray radiation pulses with narrow bandwidth and full coherence The radiated peak power at 1 Å wavelength converted from an initial 200 nm seed laser is over 2 GW.     

News and views

Medical application of synchrotron radiation (SR) is a fast-growing field of research. Since the advent of the angiography studies at SSRL first and then at NSLS in the U.S. in the 1990s, preclinical and clinical research protocols have been developed at Hasylab (Germany), Photon Factory (Japan), ELETTRA (Italia) and at the ESRF (France). Despite the fact that there are only a few dedicated beamlines in the world (two new ones are under construction at the Australian and Canadian synchrotrons), medical research is carried out in almost all synchrotron facilities.