Intense radioactive-ion beams produced with the ISOL method

For fifty years the isotope separation on-line (ISOL) technique has been used for the production of radioactive-ion beams (RIBs). Thick-target ISOL facilities can provide very intense RIBs for a wide range of applications. The important design parameters for an ISOL facility are efficiency, rapidity and selectivity of all steps of the separation process. To achieve the anticipated beam intensities with the next-generation RIB facilities, the production rate in the ISOL target has to be increased by orders of magnitude. This is only possible by adapting the projectile beam for optimum production cross-sections and simultaneously minimizing the target heating due to the electronic stopping power of charged-particle projectiles. ISOL beams of 75 different elements have been produced up to now and further beam development is under way to produce a still greater variety of isotopes and to improve existing beams in intensity and purity. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: Ulli.Koster@cern.ch     

(Im-)possible ISOL beams

Refractory elements, i.e. elements with very high melting point and low vapor pressure, cannot be released in atomic form from an ISOL target. Therefore most of these elements are presently not available as ISOL beams. However, when reactive gases are introduced into the target, they may form volatile compounds with the refractory elements, allowing for an easier transport to the ion source. Particularly useful are high-temperature stable fluorides and oxides. By these chemical evaporation methods so far ISOL beams of the refractory elements C, Zr, Hf and Ta have been produced. We discuss how ISOL beams of B, Ti, Nb, Mo, Tc, Ru, W, Re, Os and Ir could be produced in a similar way.     

利用强流ISOL束研究20Na的奇异衰变模式(英文)

北京放射性离子束装置（Beijing Radioactive Ion-beam Facility,BRIF）是基于在线同位素分离器技术的国家大科学平台。在BRIF装置上利用100 MeV的质子束轰击较厚的反应靶产生放射性核素;反应产物经离子源电离和在线分离,在线同位素分离段可引出100~300 keV的放射性核束,质量分辨率达20 000。在基金委科学仪器基础研究专项的支持下,建成了多用途的衰变实验终端,包括束流传输管道、通用靶室、带电粒子和γ探测器、集成电子学和数据获取系统等。利用100 MeV的质子束轰击MgO厚靶产生了流强高达1×105 pps的20Na放射性核束。通过高效率地同时测量β,γ和α,第一次直接观测到20Na非常稀有的β-γ-α衰变模式。Beijing Radioactive Ion-beam Facility(BRIF) has been commissioned as the national Radioactive Ion Beam(RIB) facility based on the Isotope Separator On Line(ISOL) technique since 2016. At BRIF, the radioactive nuclides are produced by the proton beam of 100 MeV bombarding a thick-target, the reaction products diffusing out of the target are ionized by an ion source and delivered to the online mass separator. In addition to the post-accelerated radioactive ion beams, BRIF can provide low-energy ISOL beams of 100 to 300 keV with a mass resolution of 20 000. A general-purpose decay station has been built including the ISOL beam transport line, a conventional reaction chamber, charge-particle and γ detectors with integrated electronics and data acquisition system. An intense 20Na ISOL beam up to 1×105 pps was produced by using the 100 MeV proton beam bombarding a MgO thick target. With high-efficiency measurements of β, γ and α simultaneously, very rare β-γ-α decay mode in 20Na has been directly observed for the first time in the present work.     

ISOL靶－源中铀靶的放射性活度研究

用3种方法计算在线同位素分离器(ISOL)靶－源中铀靶在100MeV, 200μA强流质子束照射下产生的放射性核素活度及γ射线强度随时间的变化, 为铀靶的设计、更换及后期处理提供一定的设计依据.     

BRIF and CARIF progress

China Institute of Atomic Energy (CIAE) is currently constructing Beijing rare ion beam facility (BRIF) and is proposing China advanced rare ion beam facility (CARIF). This paper is aiming at introducing the progress of BRIF project and the conceptual design CARIF. The ISOL type facility BRIF under construction is composed of a 100 MeV 300 μA proton cyclotron, an ISOL with mass resolution of 20000, and a super-conducting LINAC of 2 MeV/q, and will be commissioned in 2013. CARIF facility proposed is planned to use both ISOL and PF techniques. It is based on a China advanced research reactor CARR that was critical, with ISOL separation of fission fragment, post acceleration to 150 MeV/u, and fragmentation of neutron-rich fission fragment beam like ¹³²Sn. Such unique combination will allow CARIF to deliver beam intensity better than the best world facilities by more than one order of magnitude.     

Spectroscopic assignments of the excited B-mesons

The European Physical Journal A - We report on the development and characterization of the first radioactive boron beams produced by the isotope mass separation online (ISOL) technique at...     

在线同位素分离装置的靶系统设计方法

产生放射性核束的在线同位素分离装置的靶系统设计是整个装置产生效率的关键环节.在ORNL的窄高斯分布的离子注入模型的基础上,研究了不同的靶的几何形状和尺寸、不同的温度条件、半衰期不同的放射性核素等对释放时间特性的影响,这对设计具有快速释放过程的靶系统,具有直接的实用价值.基于德国ZFK关于表面物理的实验测量数据,用MonteCarlo统计的方法来模拟放射性核素从靶材料表面到在线离子源的电离室的传输过程,对大量的放射性核素–传输管材料组合,和不同尺寸的传输管进行了统计计算,从这些统计计算中得到了可用于传输管工程设计的图表和经验公式.     

BRIF and CARIF progress

China Institute of Atomic Energy (CIAE) is currently constructing Beijing rare ion beam facility (BRIF) and is proposing China advanced rare ion beam facility (CARIF). This paper is aiming at introducing the progress of BRIF project and the con ceptual design CARIF. The ISOL type facility BRIF under construction is composed of a 100 MeV 300 ?A proton cyclotron, an ISOL with mass resolution of 20000, and a super-conducting LINAC of 2 MeV/q, and will be commissioned in 2013. CARIF facility proposed is planned...     

Radioactive beam facilities: European perspectives

During the last ten years, the cooperation in Nuclear Physics between the different European countries has significantly increased, in particular through extensive discussions initiated by NuPECC, the Nuclear Physics European Collaboration Committee. In this context, perspectives in physics with radioactive beams have been reviewed and a high priority has been given to the developments of performing facilities in Europe including both in-flight and ISOL facilities. In this presentation, the main challenges are recalled and the various existing national and transnational projects are reviewed as well as the accompanying research and development programs. A special attention is given to the EURISOL project, a European program aiming at a preliminary design study of a second-generation European ISOL radioactive beam facility. Received: 1 May 2001 / Accepted: 4 December 2001     

Production of low- and high-energy radioactive-ion beams by fragmentation

The physics opportunities made possible by beams of rare isotopes are among the richest available in nuclear science. The rare-isotope accelerator (RIA) now under development is an innovative accelerator that will define the state of the art for all such facilities. A novel aspect of the RIA project is the conversion of the most intense high-energy heavy-ion beams into both fast and reaccelerated exotic beams. Along with target fragmentation in next-generation high-power ISOL targets, RIA will use projectile fragmentation in a high-energy separator/gas-filled ion collector system to provide an extensive range of thermalized ions for reacceleration. In addition, a second high-energy separator will provide the same or larger range of ions for high-energy experiments. A brief overview of the RIA accelerator concept, the layout of the facility, and production techniques will be given along with information on the present R&D efforts in gaseous-ion collection. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: morrissey@nscl.msu.edu     

Status of Rare Isotope Science Project in Korea

The Rare Isotope Science Project (RISP) is launched in Korea to build the IF and ISOL facilities. Current status of RISP is introduced.     

Temperature and concentration gradient effects on heat and mass transfer in micropolar fluid

We report here the development of collinear laser spectroscopy (CLS) system at VECC for the study of hyperfine spectrum and isotopic shift of stable and unstable isotopes. The facility is first of its kind in the country allowing measurement of hyperfine splitting of atomic levels using atomic beams. The CLS system is installed downstream of the focal plane of the existing isotope separator online (ISOL) facility at VECC and is recently commissioned by successfully resolving the fluorescence spectrum of the hyperfine levels in \(^{85,87}\)Rb. The atomic beams of Rb were produced by charge exchange of 8 keV Rb ion beam which were produced, extracted and transported to the charge exchange cell using the ion sources, extractor and the beam-line magnets of the ISOL facility. The laser propagating opposite to the ion / atom beam direction was allowed to interact with the atom beam and fluorescence spectrum was recorded. The experimental set-up and the experiment conducted are reported in detail. The measures needed to be carried out for improving the sensitivity to a level necessary for studying short-lived exotic nuclei have also been discussed.     

ISAC-I and ISAC-II: Present status and future perspectives

The ISAC facility at TRIUMF utilizes up to 100 μA from the 500 MeV H^- cyclotron to produce the RIB using the Isotopic Separation On Line (ISOL) method. The ISAC-I facility comprised the RNB production target stations, the mass separator and the beam delivery to low energy area and to a room temperature linear accelerator composed of a 4-rod RFQ and an inter-digital H type structure Drift Tube LINAC. ISAC-I linear accelerator can provide beam from A = 3 to 30 amu with an energy range from 0.15 to 1.5 A MeV. Since the beginning of operations target development program has been to increase proton beam currents on targets. Now we routinely operate our target at 50 to 85 μA and recently we have operated our target at 100 μA. Other developments are in place to add other ion sources, laser, FEBIAD and ECRIS to the actual surface ion source. The last two five year plans were mainly devoted to the construction of a heavy ion superconducting LINAC (ISAC-II), that will upgrade the mass and the energy range from 30 to 150 and 1.5 to 6.5 A MeV, respectively. We are now commissioning the medium β section and first experiment is scheduled for the fall 2006.     

In-trap decay of 61Mn and Coulomb excitation of 61Mn/61Fe

At ISOL (Isotope Separator On-Line) facilities, which utilize thick primary production targets, beams of neutron-rich iron isotopes are difficult to obtain due to the long extraction time of these isotopes out of the target matrix. At REX-ISOLDE, an exploratory experiment was carried out to investigate the possibility of producing a post-accelerated beam of neutron-rich iron isotopes by the in-trap decay of neutron-rich manganese isotopes, which are available at ISOLDE using the Resonance Ionization Laser Ion Source (RILIS). This production mechanism was tested for the first time at REX-ISOLDE with an intense and short-lived beam of ⁶¹Mn isotopes. In this work, the proof of principle of this method is demonstrated, although the technical details of the trapping process are currently not well understood and are still under investigation. The first physics results on the Coulomb excitation of ⁶¹Mn and ⁶¹Fe are presented and compared to shell model calculations.     

In-source laser spectroscopy developments at TRILIS—towards spectroscopy on actinium and scandium

Resonance Ionization Laser Ion Sources (RILIS) have become a versatile tool for production and study of exotic nuclides at Isotope Separator On-Line (ISOL) facilities such as ISAC at TRIUMF. The recent development and addition of a grating tuned spectroscopy laser to the TRIUMF RILIS solid state laser system allows for wide range spectral scans to investigate atomic structures on short lived isotopes, e.g., those from the element actinium, produced in uranium targets at ISAC. In addition, development of new and improved laser ionization schemes for rare isotope production at ISAC is ongoing. Here spectroscopic studies on bound states, Rydberg states and autoionizing (AI) resonances on scandium using the existing off-line capabilities are reported. These results allowed to identify a suitable ionization scheme for scandium via excitation into an autoionizing state at 58,104 cm^???1 which has subsequently been used for ionization of on-line produced exotic scandium isotopes.     

Neutron-rich nuclei and fission; recent developments and future aspects

Production and studies of neutron-rich nuclei produced in fission are reviewed. Some recent experiments performed with the ISOL technique at the IGISOL and the ISOLDE facilities are reviewed. The manipulation of neutron-rich nuclei is discussed with a special focus on radioactive ion cooling and trapping techniques under construction worldwide. Perspectives of obtaining intense post accelarated beams of fission products are discussed. Received: 1 May 2001 / Accepted: 4 December 2001     

Nuclear Physics Programs for the Future RIBs Facility in Korea

We present nuclear physics programs based on the planned experiments using rare isotope beams (RIBs) for the future Korean Rare Isotope Beams Accelerator facility(KRIA). This ambitious facility has both an Isotope Separation On Line (ISOL) and fragmentation capability for producing RIBs and accelerating beams of wide range mass of nuclides with energies of a few to hundreds MeV per nucleon. Low energy RIBs at Elab = 5 to 20 MeV per nucleon are for the study of nuclear structure and nuclear astrophysics toward and beyond the drip lines while higher energy RIBs produced by inflight fragmentation with the reaccelerated ions from the ISOL enable to explore the neutron drip lines in intermediate mass regions. The planned programs have goals for investigating internal structures of the exotic nuclei toward and beyond the nucleon drip lines by addressing the following issues: how the shell structure evolves in areas of extreme proton to neutron imbalance; whether the isospin symmetry maintains in isobaric mirror nuclei at and beyond the drip lines; how two-proton radioactivity affects abundances of the elements; what the role of the continuum states including resonant states above protondecay threshold in exotic nuclei is in astrophysical nuclear reaction processes, and how the nuclear reaction rates triggered by unbound proton-rich nuclei make an effect on rapid proton capture processes in a very hot stellar plasma.     

ISAC targets

The TRIUMF-ISAC radioactive ion beam facility was designed and constructed to allow irradiation of thick targets with up to 100  $\upmu $ A proton beam intensities. Since beginning operation in 1998, beam intensities on ISAC targets have progressively increased toward the 100  $\upmu $ A design limit. Routine operation with p^?+? intensities up to 75  $\upmu $ A is currently possible for both refractory metal target materials and for composite metal carbide materials; full 99  $\upmu $ A p^?+? intensity has been achieved for Nb foil target material. Consideration must be given to the beam power deposition, the power dissipation and the limiting temperature criteria of each target material. Increased beam power dissipation has been achieved by modifying target materials and target containers. Increasing irradiation currents have produced benefits, drawbacks and unexpected results for ISOL operations.     

Post-accelerator LINAC design for the VECC RIB project

Variable Energy Cyclotron Centre (VECC) is presently developing an ISOL post-acclerator type of RIB facility. The scheme utilises the existing K=130 room temperature variable energy cyclotron machine as the primary accelerator for the production of RIBs and radio frequency quadrupole (RFQ) and LINAC modules for the post-acceleration. The design aspects of these post-accelerator LINAC modules will be discussed in this paper.     

Secondary-beam production: Protons versus heavy ions

The construction of two new-generation complementary RIB facilities in Europe, one based on the in-flight fragmentation or fission (IFF) method (FAIR) and the other on the isotope separation on-line (ISOL) method (EURISOL) is expected in the next 10-15 years. The reaction mechanisms, responsible for the production of the secondary nuclei, along with the technical constrains, have to be considered for the designs of the facilities. In this work, we study which reaction mechanisms can be exploited at best for the production of the secondary beams in the two facilities.