Intense Radioactive Ion Beams Research Articles

The SPES target ion source automated storage system

At the SPES (Selective Production of Exotic Species) facility, intense Radioactive Ion Beams (RIBs) are produced by the interaction of a 40 MeV proton beam with a multi-foil uranium carbide target employing the Isotope Separation On-Line (ISOL) technique. The Target Ion Source (TIS) unit constitutes the core of the isotope production process. TIS units are replaced on a periodic basis during operation to maintain high performance. An automated storage system has been designed to accept highly radioactive TIS units and house them during a cooling period prior to decommissioning. The system is conceived to meet strict functional and safety requirements. Its peculiar design allows for improved reliability and availability during critical operations, as well as minimization of staff exposure to ionizing radiation during maintenance tasks. This contribution describes the design and control architecture of the Temporary Storage System (TSS). The equipment is part of a structured framework of remote manipulation, consisting of various machines interlocked with the Access Control System (ACS) and the Machine Protection System (MPS).

An implantation Diamond detector as a beam monitor for an intense radioactive ion beam

We present the characterization of a Diamond detector and its response as a beam rate monitor with full stopping of radioactive ion beams of high intensity. The detector has been implemented in the VAMOS focal plane at GANIL and utilised in conjunction with AGATA and MUGAST detector systems. In the present experiment, for the first time, the beam has been fully stopped, rather than being recorded by a transmission detector. The Diamond detector has been tested for use as a particle counter for monitoring a high intensity, radioactive ion beam in the study of the alpha transfer reaction 7Li(15O,t)19Ne. The present experiment, which took place in July 2019, has used a 15O radioactive beam with a high intensity of 107 particles per second due to the weak reaction population and it has been measured using the VAMOS spectrometer and the AGATA and MUGAST arrays. Detailed monitoring of beam intensities in the range of 106 – 107 particles per second is particularly challenging in radioactive ion beam experiments. Thus, the chosen method involves the diamond detector due to its sub-nanosecond response time as well as its radiation hardness. The study of the alpha transfer reaction 7Li(15O,t)19Ne will be performed to determine the radiative alpha capture rate on 15O which is a key breakout route from the Hot-CNO cycle which leads to a explosive nucleosynthesis in X-ray bursts.

Design of a compact shielding envelope and elements of radiological protection at the TRIUMF-ARIEL facility

The Advanced Rare Isotope Laboratory (ARIEL) is currently under construction at TRIUMF. ARIEL's mission is to supply existing experiments with more diverse and more intense radioactive ion beams (RIB) produced via the Isotope Separation On-Line (ISOL) method. The drivers inducing the nuclear reactions at ARIEL include a 500 MeV proton beam from the main cyclotron as well as a 35 MeV electron beam with the intent of simultaneous operation using two separate additional target stations. The generated RIB will be made available to experiments in condensed matter and subatomic physics as well as practical applications such as medical isotopes for life sciences research.This work details the various simulations performed using the Monte Carlo (MC) particle transport and interaction code FLUKA. The code was systematically employed to predict prompt and residual radiation levels to characterize the radiation fields generated via the irradiation of various types of targets. An iterative combined development process between CAD-based engineering of the shielding envelope, nuclear physics optimization of the target system and particle tracing simulations was established.Preliminary simulation studies resulted in the selection of shielding materials and respective thicknesses with the goal of maximizing attenuation while mitigating residual activation. The results provide clear operational constraints and aid in determination of expected dose rates outside of shielding in high occupancy areas. A series of optimization steps followed the preliminary work, testing various parameters including beam power, target material and shielding configurations. These results were evaluated considering technical feasibility, safety, and economic impacts on ARIEL construction and eventual operation.Although the project, in its infancy, is expected to proceed through stages of increasing complexity, the shielding and radiation transport modeling completed to date helps to define and validate nominal operation and failure scenario procedures for all future project stages.

State of the art measurements with TexAT

In the past several years, there has been a large interest of Time Projection Chambers (TPCs) for use in experimental nuclear physics. This has continued in tandem with the requirement for high efficiency detectors with low intensity radioactive ion beams. TexAT is a Active Target TPC (AT-TPC) built at Texas A&M University utilizing MICRO MEsh GASeous (MicroMegas) pads and GET electronics developed specifically for TPCs. This design combines good TPC pixelation with a surrounding shell of Si/CsI telescopes to make an extremely versatile detector capable of a wide range of different experimental techniques with only minor modifications to the electronics setup. Two recent experiments performed at the Cyclotron Institute, Texas A&M University, are detailed here demonstrating versatility beyond the usual Thick Target Inverse Kinematics (TTIK) or transfer reactions that these TPCs are more typically used for. The first, a measurement of the 12N → 12C* → 3α decay demonstrates the capabilities of TexAT as a low-energy detector operating at low pressure (20 Torr) to measure β-delayed particle decay. The second, a direct measurement of the 8B+40Ar fusion cross section shows the advantages of operating in active target mode where the target also functions as the detector gas.

A new multi-reflection time-of-flight mass spectrograph for the SLOWRI facility

A new multi-reflection time-of-flight mass spectrograph for nuclear mass measurements with high precision has been constructed at the SLOWRI facility at RIKEN-RIBF. We aim to couple this new device to a cryogenic gas cell operated at the BigRIPS facility of RIBF. It is part of the SLOWRI project for slowing down and stopping intense radioactive ion beams provided downstream of RIKEN’s superconducting ring cyclotron accelerator. In particular, this device is dedicated to be located at the end of the BigRIPS beam line to access ions that are presently guided to beam dumps during in-beam experiments. In this article the apparatus is described in detail.

Gas detectors for nuclear physics experiments

In this lecture I will present the operation principle and the different kinds of gas detecting systems for charged particles employed in high-energy and low-energy physics environments, with particular focus on the requirements of nuclear physics experiments with low-energy Radioactive Ion Beams (RIBs). I will show in more details an example of gas detector used at the RIB in-flight facility EXOTIC, for the ion beam tracking and for time of flight measurements. Finally, I will discuss the use of an active target in nuclear physics experiments with RIBs together with some key improvements of first generation devices required for facing the challenges of more intense RIBs.

The SPES High Power ISOL production target

SPES (Selective Production of Exotic Species) is a facility under construction at INFN-LNL (Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro), aimed to produce intense neutron-rich radioactive ion beams (RIBs). These will be obtained using the ISOL (Isotope Separation On-Line) method, bombarding a uranium carbide target with a proton beam of 40MeV energy and currents up to 200 μA. The target configuration was designed to obtain a high number of fissions, up to 1013 per second, low power deposition and fast release of the produced isotopes. The exotic isotopes generated in the target are ionized, mass separated and re-accelerated by the ALPI superconducting LINAC at energies of 10AMeV and higher, for masses in the region of A = 130amu, with an expected rate on the secondary target up to 109 particles per second. In this work, recent results on the R&D activities regarding the SPES RIB production target-ion source system are reported.

Thick target for high-power ISOL facilities

The future frontier of the Isotope Separation On-Line (ISOL) method is to increase the intensity of the Radioactive Isotope Beams (RIB) by many orders of magnitude in order to satisfy challenging experiments such as Rn-Electric Dipole Moment, Fr-Parity Non Conservation…and in general for radiative proton-capture relevant for nuclear astrophysics processes. The most direct method to obtain higher RIB intensity is to increase the driver beam intensity. New techniques were developed such as composite targets, where the target material is deposited onto a high thermal conductive substrate allowing a better heat dissipation. Combined with high-power target using radial finned for radiative cooling, these targets are capable of dissipating up to 20kW depending on the target material operating temperature. Another method to increase RIB intensity is the use of indirect ISOL method, where secondary particle beam (n or γ) interacts with a fissile target material. By decoupling the power deposition in the system composed of a converter and ISOL target allows for much higher primary beam power. Indirect ISOL-target method permit reach several hundred of kW to MW of driver beam power, allowing the production of intense fission products beams. This paper reviews the thick ISOL target approach for producing intense radioactive ion beams.

The SPES radioactive ion beam project of LNL: status and perspectives

A new Radioactive Ion Beam (RIB) facility (SPES) is presently under construction at the Legnaro National Laboratories of INFN. The SPES facility is based on the ISOL method using an UCx Direct Target able to sustain a power of 8 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 35-70 MeV and a beam current of 0.2-0.7 mA. Neutron-rich radioactive ions are produced by proton induced fission on an Uranium target at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting LINAC at energies of 10A MeV for masses in the region A=130 amu. The expected secondary beam rates are of the order of 107 - 109 pps. Aim of the SPES facility is to deliver high intensity radioactive ion beams of neutron rich nuclei for nuclear physics research as well as to be an interdisciplinary research centre for radio-isotopes production for medicine and for neutron beams.

Nuclear Structure Studies with Stable and Radioactive Beams: The SPES radioactive ion beam project

A new Radioactive Ion Beam (RIB) facility (SPES) is presently under construction at the Legnaro National Laboratories of INFN. The SPES facility is based on the ISOL method using an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 35-70 MeV and a beam current of 0.2-0.5 mA. Neutron-rich radioactive ions are produced by proton induced fission on an Uranium target at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting LINAC at energies of 10A MeV for masses in the region A=130 amu. The expected secondary beam rates are of the order of 107 – 109 pps. Aim of the SPES facility is to deliver high intensity radioactive ion beams of neutron rich nuclei for nuclear physics research as well as to be an interdisciplinary research centre for radio-isotopes production for medicine and for neutron beams.

The SPES Radioactive Ion Beam facility of INFN

A new Radioactive Ion Beam (RIB) facility (SPES) is presently under construction at the Legnaro National Laboratories of INFN. The SPES facility is based on the ISOL method using an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 40 MeV and a beam current of 0.2-0.5 mA. Neutron-rich radioactive ions are produced by proton induced fission at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting LINAC at energies of 10A MeV for masses in the region A=130 amu. The expected secondary beam rates are of the order of 107 – 109 pps. Aim of the SPES facility is to deliver high intensity radioactive ion beams of neutron rich nuclei for nuclear physics research as well as to be an interdisciplinary research center for radio-isotopes production for medicine and for neutron beams.

The SPES project of INFN: Facility and detectors

The SPES Radioactive Ion Beam facility at INFN-LNL is presently in the construction phase. The facility is based on the Isol (Isotope separation on-line) method with an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 35-70 MeV and a beam current of 0.2-0.5 mA. Neutron-rich radioactive ions are produced by proton induced Uranium fission at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting Linac at energies of 10A MeV for masses in the region A = 130 amu. The expected secondary beam rates are of the order of 107 - 109 pps. Aim of the SPES project is to provide a facility for high intensity radioactive ion beams for nuclear physics research as well as to develop an interdisciplinary research center based on the cyclotron proton beam.

Transport of radioactive ion beams and related safety issues: the 132Sn+ case study.

The transport of intense radioactive ion beam currents requires a careful design in order to limit the beam losses, the contamination and thus the dose rates. Some investigations based on numerical models and calculations have been performed in the framework of the SPIRAL 2 project to evaluate the performance of a low energy beam transport line located between the isotope separation on line (ISOL) production cell and the experiment areas. The paper presents the results of the transverse phase-space analysis, the beam losses assessment, the resulting contamination, and radioactivity levels. They show that reasonable beam transmission, emittance growth, and dose rates can be achieved considering the current standards.

The SPES radioactive ion beam project of INFN

The SPES Radioactive Ion Beam facility at INFN-LNL is presently in the construction phase. The facility is based on the Isol (Isotope separation on-line) method with an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 35-70 MeV and a beam current of 0.20.5 mA. Neutron-rich radioactive ions are produced by proton induced Uranium fission at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting Linac at energies of 10A MeV for masses in the region A = 130 amu. The expected secondary beam rates are of the order of 107 – 109 pps. Aim of the SPES project is to provide a facility for high intensity radioactive ion beams for nuclear physics research as well as to develop an interdisciplinary research center based on the cyclotron proton beam.

Wear diagnostics of industrial material using RI beams of 7Be and 22Na

As a possible example of radioactive ion (RI) beams for industrial application, intense beams of 7Be and 22Na used for wear diagnostics of mechanical parts is considered. For wear diagnostics, radioactive nuclei which have appropriate long life-time such as from several weeks to a few years are applicable. As those nuclei are located near the stable line, an in-flight RI beam separator can provide intense RI beams with enough high energy for implantation in atmosphere. Beam studies were performed to evaluate the intensity, uniformity, and depth profile of the implanted RI. We could achieve peak activity of 1.3 and 0.08 (kBq/μm)/(1pμA×1h irradiation) at 13 and 50μm peak depth with 20 and 150μm maximum depth from the surface of an aluminum sample for 7Be and 22Na, respectively.

Control of RILIS lasers at IGISOL facilities using a compact atomic beam reference cell

The choice and proper operation of the laser systems for laser ion sources at on-line facilities using multi-step resonance ionization processes is the basis for production of intense and pure radioactive ion beams. These pave the way for numerous fundamental studies in nuclear and astrophysics. A comparison between systems of medium or high repetition rate pulsed tunable lasers based on dyes or crystals as active medium has been carried out at the IGISOL facility at Louvain-la-Neuve. The importance of properly controlling the operation conditions of the individual lasers via a reference atomic beam chamber is highlighted and design and implementation of such a compact device for permanent monitoring as well as possible regulation of the various laser parameters of relevance is discussed.

Studies with radioactive ion beams in the A ~ 80 region

The availability of good quality radioactive ion beams is allowing unique research in nuclear physics and nuclear astrophysics. Coulomb Excitation is a mechanism with a relatively large cross sections that allows the use of low intensity radioactive ion beams, and therefore it has become in a powerful experimental tool for the study of nuclei consirderably far from stability. Among the data of interest for nuclear models that can be obtained using Coulomb excitation are: reduced transition probabilities; electric quadrupole moments; and magnetic moments. This work gives an overview of experimental studies on the mass 80 region in which I have been involved.

Absolute cross-sections from X– [formula omitted] coincidence measurements

An activation technique using coincidences between characteristic X-rays and γ -rays to obtain absolute cross-sections is described. This method is particularly useful in the case of nuclei that decay by electron capture. In addition to the reduction of possible contamination, an improved detection sensitivity is achieved as compared to inclusive measurements, thereby allowing the extraction of absolute fusion cross-sections in the nano-barn range. Results of this technique for Li 6 + Pt 198 system, at energies around the Coulomb barrier are described. Future applications with low intensity radioactive ion beams are also discussed.

Production of intense radioactive beams at ISAC using low-energy protons

A proof-of-principle approach for the production of intense (~108/s) radioactive ion beams, which differs from the standard ISOL (Isotope Separation On-Line) technique, has been demonstrated successfully using 11C at the TRIUMF laboratory. This approach uses 13 MeV protons produced by a medical cyclotron and should be useful for a range of radioisotopes of interest to the nuclear astrophysics research programme.PACS No.: 29.25.Rm

Application of Low Energy Spin Polarized Radioactive Ion Beams in Condensed Matter Research

The new ISAC facility at TRIUMF (Canada), produces some of the world's most intense radioactive ion beams (RIBs). Although the primary scientific motivation for these facilities lies in nuclear physics and nuclear astrophysics, RIBs also have applications in condensed matter (CM). Many pioneering CM experiments have already been performed at the ISOLDE facility (CERN). Continuing on this path at ISAC we have recently polarized a beam of 8Li+ to be used as a magnetic probe of ultra-thin films and interfaces. We report here on progress in developing this new application of low energy RIBs, which is based on the technique of β-detected nuclear magnetic resonance (β- NMR)