Rare Ion Beams Research Articles

Storage, accumulation and deceleration of secondary beams for nuclear astrophysics

Low-energy investigations on rare ion beams are often limited by the available intensity and purity of the ion species in focus. Here, we present the first application of a technique that combines in-flight production at relativistic energies with subsequent secondary beam storage, accumulation and finally deceleration to the energy of interest. Using the FRS and ESR facilities at GSI, this scheme was pioneered to provide a secondary beam of 118Te52+ for the measurement of nuclear proton-capture at energies of 6 and 7 MeV/u. The technique provided stored beam intensities of about 106 ions at high purity and brilliance, representing a major step towards low-energy nuclear physics studies using rare ion beams.

Understanding radioactive ion beam production at ISAC through yield measurements and simulations

The high-intensity proton beam of the TRIUMF 500 MeV cyclotron offers unique opportunities to produce rare isotopes by irradiating a variety of targets. In particular, the ISAC (Isotope Separation and ACceleration) facility provides the infrastructure to deliver customized rare ion beams for fundamental research in nuclear physics, astrophysics, material science, and nuclear medicine. A continuous effort is made to develop new radioactive ion beams (RIB) and improve their intensity or purity, properties that depend strongly on the type of target, operating conditions, the ion source, and beam transport efficiency. Yield data and theoretical production rates based on FLUKA and Geant4 simulations are collected in the TRIUMF Isotope Database, providing a valuable resource for RIB development and experiment planning. This paper introduces the newly upgraded TRIUMF Isotope Database and presents examples on how its resources can be used to plan experiments and understand the origin of certain RIB. In particular we discuss the collection of 155Tb which is an important component of medical isotope research at TRIUMF.

Development of Chemical Procedures for Isotope Harvesting: Separation of Trace Hafnium from Tungsten

ABSTRACT The separation of trace hafnium from bulk tungsten alloys is of interest for isotope harvesting at the National Superconducting Cyclotron Laboratory and the Facility for Rare Ion Beams because 172Hf, the parent of 172Lu, accumulates in tungsten alloy beam blockers at these facilities. In this work, a procedure for the separation of trace hafnium from a bulk tungsten alloy (454 g) was established using tracer isotopes (175Hf, 88Zr, 173Lu, and 88Y). The procedure employed dissolution in an HF–HNO3 solution followed by a calcium fluoride precipitation, and then extraction chromatography was used for more selective separation steps. Two stages of column separations using LN resin (HDEHP based) and TRU resin (CMPO based) were performed. Gamma-ray spectroscopy and mass spectrometry were used to analyze the final hafnium sample and follow the steps in the chemical processing. The final recovery of hafnium was high (90 ± 8)%, and the mass of tungsten and other transition metals was reduced to near background levels (as determined by ICP-MS of the blank acid solutions). Zirconium follows hafnium quantitatively in this procedure; there was no detectable 173Lu in the final hafnium sample.

Efficacy of radial matching section in enhancing RFQ cooler acceptance and optimization of its injection optics

Radio Frequency Quadrupole (RFQ) cooler is a device used for reducing transverse and longitudinal emittance of ion beams. The cooler employs a time varying field and as a result of which the acceptance ellipse, as seen by the beam while entering the cooler, is dependent on the RF phase. Acceptance ellipses having different orientations corresponding to the changing RF phase have a much smaller phase independent central overlapping area, so the real transmission for an injected DC beam into the RFQ cooler gets reduced. In RFQ linacs radial matching section has long been used for matching “time independent” DC input beam to the “time dependent” RF structure. Our simulation study shows that a similar radial matching section at the entrance of RFQ cooler can enhance the transmission for a DC beam into the RFQ cooler. Optimization of length of the radial matching section and the corresponding deceleration and injection optics shows an enhancement of more than two times in the area of time independent acceptance ellipse for ions over a mass range of 0A=4 to 240. Such innovative design could play a significant role in experiments with rare ion beams which are produced in miniscule quantities.

Estimating ion confinement times from beam current transients in conventional and charge breeder ECRIS.

Cumulative ion confinement times are probed by measuring decaying ion current transients in pulsed material injection mode. The method is applied in a charge breeder and conventional ECRIS yielding mutually corroborative results. The cumulative confinement time estimates vary from approximately 2 ms-60 ms with a clear dependence on the ion charge-to-mass ratio-higher charges having longer residence times. The long cumulative confinement times are proposed as a partial explanation to recently observed unexpectedly high ion temperatures. The results are relevant for rare ion beam (RIB) production as the confinement time and the lifetime of stable isotopes can be used for estimating the extracted RIB production efficiency.

Removal of molecular contamination in low-energy RIBs by the isolation-dissociation-isolation method

Experiments with low-energy rare ion beams often suffer from a large amount of molecular contaminant ions. We present the simple isolation-dissociation-isolation method to suppress this kind of contamination. The method can be applied to almost all types of low-energy beamlines. In a first step, a coarse isolation of the mass-to-charge ratio of interest is performed, e.g. by a dipole magnet. In a second step, the ions are dissociated. The last step is again a coarse isolation of the mass-to-charge ratio around the ion of interest. The method was tested at the FRS Ion Catcher at GSI with a radioactive ion source installed inside the cryogenic stopping cell as well as with relativistic ions delivered by the synchrotron SIS-18 and stopped in the cryogenic stopping cell. The isolation and dissociation, here collision-induced dissociation, have been implemented in a gas-filled RFQ beamline. A reduction of molecular contamination by more than 4 orders of magnitude was achieved.

Approaching the Gamow Window with Stored Ions: Direct Measurement of ^{124}Xe(p,γ) in the ESR Storage Ring.

We report the first measurement of low-energy proton-capture cross sections of ^{124}Xe in a heavy-ion storage ring. ^{124}Xe^{54+} ions of five different beam energies between 5.5 and 8AMeV were stored to collide with a windowless hydrogen target. The ^{125}Cs reaction products were directly detected. The interaction energies are located on the high energy tail of the Gamow window for hot, explosive scenarios such as supernovae and x-ray binaries. The results serve as an important test of predicted astrophysical reaction rates in this mass range. Good agreement in the prediction of the astrophysically important proton width at low energy is found, with only a 30% difference between measurement and theory. Larger deviations are found above the neutron emission threshold, where also neutron and γ widths significantly impact the cross sections. The newly established experimental method is a very powerful tool to investigate nuclear reactions on rare ion beams at low center-of-mass energies.

Recent Results from ISOLDE and HIE-ISOLDE

ISOLDE is the CERN facility dedicated to the production of rare ion beams for many different experiments in the fields of nuclear and atomic physics, materials science and life sciences. The HIE-ISOLDE, Higher Intensity and Energy upgrade has finished its stage 1 dedicated to upgrade the energy up to 5.5 MeV/u, producing the first radioactive beams with this energy in September 9th 2016. Recent results from the low energy and post-accelerated beams are given in this contribution.

Development of the $(d,n)$ Proton-transfer Reaction in Inverse Kinematics for Structure Studies

Transfer reactions have provided exciting opportunities to study the structure of exotic nuclei and are often used to inform studies relating to nucleosynthesis and applications. In order to benefit from these reactions and their application to rare ion beams (RIBs) it is necessary to develop the tools and techniques to perform and analyze the data from reactions performed in inverse kinematics, that is with targets of light nuclei and heavier beams. We are continuing to expand the transfer reaction toolbox in preparation for the next generation of facilities, such as the Facility for Rare Ion Beams (FRIB), which is scheduled for completion in 2022. An important step in this process is to perform the (d,n) reaction in inverse kinematics, with analyses that include Q-value spectra and differential cross sections. In this way, proton-transfer reactions can be placed on the same level as the more commonly used neutron-transfer reactions, such as (d,p), (9Be,8Be), and (13C,12C). Here we present an overview of the techniques used in (d,p) and (d,n), and some recent data from (d,n) reactions in inverse kinematics using stable beams of 12C and 16O.

“Other” indirect methods for nuclear astrophysics

In the house of Trojan Horse Method (THM), I will say a few words about “other” indirect methods we use in Nuclear Physics for Astrophysics. In particular those using Rare Ion Beams that can be used to evaluate radiative proton capture reactions. I add words about work done with the Professore we celebrate today. With a proposal, and some results with TECSA, for a simple method to produce and use isomeric beam of 26m Al.

Production of rare earths ion beams in arc discharge ion source using their oxides

Production of rare earths ion beams in arc discharge ion source using their oxides

Nuclear Astrophysics at IFIN-HH

I will present the possibilities and some results of doing nuclear astrophysics research in IFIN-HH Bucharest-Magurele. There are basically two lines of experimental activities: (1) direct measurements with beams from the local accelerators, in particular with the new 3 MV Tandetron accelerator. This facility turns out to be competitive for reactions induced by a-particles and light ions. Extra capabilities are given by the ultra-low background laboratory we have in a salt mine about 2.5 hrs. driving north of Bucharest; (2) indirect measurements done with beams at international facilities, in particular at those providing Rare Ion Beams. Completely new and unique opportunities will be provided by ELI-NP, under construction in our institute.

ANURIB – Advanced National facility for Unstable and Rare Ion Beams

An ISOL post-accelerator type of RIB facility is being developed at Variable Energy Cyclotron Centre (VECC), Kolkata, India. In this scheme, Rare Ion Beams (RIBs) will be produced using light ion beams (p, α) from the K=130 cyclotron, the RIB of interest will be separated from the other reaction products and accelerated up to about 2 MeV /u using a number of linear accelerators. Recently, a few RIBs have been produced and accelerated using this facility. As an extention of this effort, another RIB facility – ANURIB will be developed in a new campus as a green-field project. ANURIB will have two driver accelerators – a superconducting electron LINAC to produce n-rich RIBs using photofission route and a 50 MeV proton cyclotron for producing p-rich RIBs. In this paper, the status of the RIB facility in the present campus and future plans with the ANURIB facility will be discussed.

Beijing Isotope-Separation-On-Line Neutron-Rich Beam Facility and its application prospects

Radioactive-ion beam (RIB) experiments open up new exciting fields and frontiers in nuclear physics and nuclear astrophysics. The experiments can provide unprecedented opportunities to explore new phenomena such as new magic numbers and probe the isospin mechanisms occurring in shell evolution. Other experiments probe the limits of nuclear stability on the neutron-rich side, provide insights into the synthesis of superheavy elements and nuclear giant halo structures, and offer the possibility to investigate new nuclear decay modes as well as the nucleosynthesis of nuclides beyond Iron. To achieve this goal, many nuclear physics laboratories all over the world are building large-scale powerful new RIB facilities. The “Beijing Isotope-Separation-On-Line Neutron-Rich Beam Facility (BISOL)” is a joint project proposed by the China Institute of Atomic Energy (CIAE) and Peking University. This facility will combine two techniques: Projectile fragmentation (PF) and isotope separation on line (ISOL). The BISOL facility will operate based on a dual driver system, including reactor driving and intense deuteron-beam driving modes. The existing high flux research reactor, the China Advanced Research Reactor at CIAE provides reactor driving. At the BISOL facility ISOL separation of fission fragments, post acceleration, and fragmentation of neutron-rich fission fragment beams will be available. By combining ISOL and PF techniques in one facility the technical advantages of both can be merged. The BISOL will deliver intensive rare ion beams of very neutron-rich isotopes; the intensity of these beams will be of the order of at least 1-2 magnitudes higher than currently available ones. Intense deuteron-beam driving is an established technology, which provides an intense neutron beam source and can be operated independently in the facility. Characterizing material performance and performing lifetime experiments are the challenges facing researchers working on the current and next-generation nuclear energy systems. Intense radiation sources, especially neutron sources, are indispensable for these experiments. The intense deuteron accelerator proposed in this project will be able to generate intense neutron beam. These beams will be able to probe nuclear materials and will provide vital results to push forward the boundaries of nuclear physics.

Peripheral elastic and inelastic scattering ofO17,18on light targets at 12 MeV/nucleon

A study of interaction of neutron-rich oxygen isotopes $^{17,18}\mathrm{O}$ with light targets has been undertaken in order to determine the optical potentials needed for the transfer reaction $^{13}\mathrm{C}(^{17}\mathrm{O},^{18}\mathrm{O})^{12}\mathrm{C}$. Optical potentials in both incoming and outgoing channels have been determined in a single experiment. This transfer reaction was used to infer the direct capture rate to the $^{17}\mathrm{F}(p,\ensuremath{\gamma})^{18}\mathrm{Ne}$ which is essential to estimate the production of $^{18}\mathrm{F}$ at stellar energies in ONe novae. The success of the asymptotic normalization coefficient (ANC) as indirect method for astrophysics is guaranteed if the reaction mechanism is peripheral and the distorted wave Born approximation cross-section calculations are warranted and stable against the optical model potential (OMP) used. We demonstrate the stability of the ANC method and the OMP results by using good-quality elastic and inelastic-scattering data with stable beams before extending the procedures to rare-ion beams. The peripherality of our reaction is inferred from a semiclassical decomposition of the total-scattering amplitude into barrier and internal barrier components. Comparison between elastic scattering of $^{17}\mathrm{O}$, $^{18}\mathrm{O}$, and $^{16}\mathrm{O}$ projectiles is made.

The ANURIB project at VECC – Plans and preparations

VECC is planning to develop a rare ion beam facility called ANURIB1ANU stands for “Atom in Sanskrit”.1 (Advanced National facility for Unstable and Rare Isotope Beams) at the upcoming new campus at New Town in Kolkata. ANURIB aims to attract a wide user community in nuclear physics, nuclear-astrophysics, material science and biology and will provide India with world class accelerator facilities. ANURIB will be built around a 50MeV 100kW superconducting electron linac (e-Linac) photo-fission driver and is planned to be a combined ISOL and PFS type facility. Construction of the facility will also enable next generation research into production of medical isotopes.In preparation for ANURIB, a low energy ISOL type facility has been built around the existing K130 cyclotron at VECC. Developed for the past decade, this facility was aimed at completing major R&D steps involved in the construction of ANURIB. Presently this facility accelerates beams up to energy of 415keV/u and recently first radioactive beams have been produced. Development of a 10MeV Injector Cryo Module for the e-Linac has been started in collaboration with TRIUMF. In this paper the plans for ANURIB project and present status of the R&D activities will be presented.

Nuclear astrophysics with exotic nuclei and rare ion beams

Nuclear astrophysics has become a major motivation for nuclear physics research in the latest few decades. The quests to understand grand scale cosmic phenomena, the origin of elements and isotopes, the sources of energy in stars, were advanced by studies at the microscopic scale of nuclei. Advances in the production, separation and acceleration of unstable nuclei lead not only to new knowledge in the structure of nuclei and nuclear matter, but also have revolutionized nuclear physics for astrophysics. I will review some of the many contributions that nuclear astrophysics made to our fundamental knowledge, and then will describe a few indirect methods used in nuclear astrophysics using radioactive beams, concentrating on those used by the groups I work with.

Ionization probabilities of sputtered indium atoms under atomic and polyatomic Aum− ion bombardment

The ionization probability of indium atoms sputtered from a polycrystalline indium surface under bombardment with 10‐keV Aum− cluster ions was measured by comparative secondary ion and neutral time‐of‐flight (ToF) mass spectrometry. The gold projectile ion beam for time‐of‐flight spectrum acquisition was interleaved with a 5‐keV Ar+ ion beam to maintain a dynamically sputter cleaned state of the surface, thereby avoiding contamination from both residual gas adsorption as well as accumulating gold from the cluster projectile beam. It is found that under these conditions the ionization probability does not significantly change as a function of cluster projectile nuclearity, a result which is in marked contrast with similar experiments where the interleaved rare gas ion beam was not used. The comparison of both experiments reveals that in the latter case the ionization probability is strongly influenced by surface contamination. Interestingly, the magnitude of this influence seems to depend on the projectile cluster size. This finding is interpreted in terms of the change in the ejection mechanism between atomic and polyatomic projectiles leading to different average escape depths of the sputtered atoms. Copyright © 2012 John Wiley & Sons, Ltd.

Light ion source for proton/deuteron production at CEA Saclay for the Spiral2 project

The production of rare radioactive ion beam (RIB) far from the valley of stability is one of the final purposes of the Spiral2 facility in Caen. The RIB will be produced by impinging a deuteron beam onto a carbon sample to produce a high neutron flux, which will interact with a uranium target. The primary deuteron beam is produced by an ion source based on ECR plasma generation. The deuteron source and the low energy beam transport (LEBT) has been assembled and tested at CEA Saclay. Diagnostics from other laboratories were implemented on the LEBT in order to characterize the deuteron beam produced and compare it to the initial simulations. The ion source has been based on a SILHI-type source, which has demonstrated good performances in pulsed and continuous mode, and also a very good reliability on long term operation. The 5 mA of deuteron beam required at the RFQ entrance is extracted from the plasma source at the energy of 40 kV. After a brief description of the experimental set-up, this article reports on the first beam characterization experiments.

The Development of Ion Nano-beams - A Review

With the advent of the super-tip ion source very favourable conditions for generating ion nano-beams have been provided. The basic physical principles for a super-tip-gas field ion source are described As a consequence of a very small source emittance of ? ~ 10-24 m2sr ultra-bright rare gas ion beams of about 1016 A/m2.sr can be produced. As a further consequence, very narrow probe sizes are obtainable, of dp< 1 nm, with spatial resolutions far below the classical limits of light-optics and even below the novel stimulated-emission-depletion microscopy [*STED (microscopy) = stimulated emission depletion (microscopy) Th. A. Klar, S. W. Hell, Opt.Lett. 24 (1999) 954-956]. Various ion-nanobeam applications in both materials modification, and analysis are envisaged.