Radioactive beams

In principle the density dependence of the SE at higher densities (and further away from N = Z) can be probed by means of heavy-ion reactions using neutron rich radioactive beams. In ref. [35] possible observable effects from the isovector field are considered in terms of the RMF model. Of particular... 

Knowledge of fission and its consequences is important for the nuclear power industry and the related fields of nuclear waste management and environmental cleanup. From the point of view of basic research, fission is interesting in its own right as a large-scale collective motion of the nucleus, as an important exit channel for many nuclear reactions, and as a source of neutron-rich nuclei for nuclear structure studies and use as radioactive beams. 

The more recently constructed COMBAS device at the JINR at Dubna, Russia has a significantly larger acceptance and is based on using combined function magnets. The A1200 (now retired) and the A1900(MSU) (shown schematically in Fig. 14.14), RCNP(Osaka), and FRS(GSl) separators are positioned at the beginning of the beam distribution system to allow delivery of radioactive beams to any experimental area. 

G. J. Mathews, R. C. Haight, and R. W. Bauer, "Proceedings of the Workshop on the Prospects for Research with Radioactive Beams from Heavy-Ion Accelerators", J. M. Nitschke (ed.) (Washington, DC 1984). 

Several groups at ISOLDE are planning further improvements of their techniques. For each element the most appropriate experimental scheme has to be found. Today, collinear laser spectroscopy is the most general high-resolution and sensitive method for optical spectroscopy on radioactive beams delivered by on-line mass separators. Its sensitivity ranges from 10 - 10 atoms/s depending on the strength and multiplicity of the optical transitions. 

Nuclear properties (spins, moments, charge radii) revealed by the analysis of hyperfine structure and isotope shift of atomic levels have been obtained in decades of experiments. Since 1975 with the introduction of tunable dye laser, the rebirth of the methods, some already known since 1930, had led to many on line experiments on short lived isotopes not investigated before. I report here a sample of the experiments done by the Orsay, Mainz groups at CERN. Although experiments have been carried out by the Orsay group using the proton beam of the CERN Proton Synchrotron, most of the experiments have been done at Isolde, the on - line mass separator at CERN, whose radioactive beams are essential to the success of these experiments [RAV 84]. 

Developing an Accelerated Radioactive Beams Facility Using an On-Line Isotope Separator as an Injector... 

ISOLDE at CERN (SC), make it feasible to consider using such secondary ions as projectiles for nuclear reactions. A pressing need for reaction rate data involving radioactive species exists in nuclear astrophysics. This requires having available projectiles (A < 60) in the energy range from about 200 keV/amu to 1.5 MeV/amu. It has been proposed to install an ISOL device at the TRIUMF facility to utilize the available intermediate energy (200-500 MeV), intense (<100 yA) proton beam as the primary production source. The mass analyzed, radioactive beam (RB),... 

In summary, a proposal for a TRIUMF-ISOL facility including a preliminary version of a post-accelerator to boost the radioactive beam energies up... 

PR085] The TRIUMF-ISOL FACILITY, A Proposal for an Intense Radioactive Beams Facility, June 1985. 

KLE84] Klein, H., 1984. Private communication, to be published in Proceedings of the Radioactive Beams Workshop, Parksville, B.C., Canada. [DAU85] D Auria, J.M. et al., 1985 ibid. 

H. Geifiel, "Fragment Separation at SIS", contribution to the Accelerated Radioactive Beam Workshop, Parksville, September 5-7, 1985. 

An opportunity for the continuation of experiments in the region of SHEs at decreasing cross sections afford, among others, further accelerator developments. High current beams and radioactive beams are options for the... 

Figure 9. View of the essential parts of the crossed beam apparatus using short-lived radioactive labeling and detection (23) Ay radioactive beam source By scrubber-furnace C, LN -cooled collimator D, shut-off plug Ey nozzle beam furnace and cryopump F, gate valve G, hodoscope H, LN -coohd beam trap 7, calibrated beam monitor /, silicon surface barrier detectors K, halogen crossed beam L, radioactive beam M, rotary feed-through used to close the source stopcock.

In the seven decades since the discovery of nuclear fission, experimental studies on low-energy fission have been restricted to about 80 fissionable nuclei. They represent only about 15% of all known nuclei with Z > 82. However, recently a novel experimental technique has been introduced. The fission of relativistic secondary projectiles has now been studied in flight. The benefit of the radioactive beams for studying the fission process is clear, but no fission probabilities below the fission barrier have been determined so far (Schmidt et al. 1994). 

Isotopes investigated in low-energy fission are indicated on the chart of nuclides. Circles Mass distributions measured for excitation energies less than 10 MeV above the fission barrier and those from SF. Crosses Data obtained using the Coulomb fission by using the relativistic radioactive beams (Schmidt et al. 2000)... 

Implantation reactions are interesting because of their similarity as regards reaction mechanisms to hot atom reactions. (However, some features are specific to recoil implantation reactions.) Ion implantation-induced chemical reactions have such features as well, but difficulty hes in keeping surface temperature as low as possible and in obtaining radioactive beams without contamination by other stable isotopes (which may result in severe damage in the target substance). These demerits restricted usefidness of ion implantation. Recoil implantation can be performed simply in the mixture of a recoil source and a catcher (receptor) material. In some cases, thin films of source and catcher could be combined in order to control recoil energy. 

Livingston RS, Jones RJ (1954) Rev Sci Instrum 25(6) 552 Loiselet M, Berger G, Breyne D, Daras Th, Goffiiux H, Postiau N, Ryckwaert G, Ryckwaert J (1996) Production and acceleration of radioactive beams at Louvain-la-Neuve. In Cornell J (ed) Proceedings of... 

Production of radioactive beams for the synthesis of heavy nuclei and for the questions of the nucleosynthesis in stars... 

Evaporation residues arising in complete-fusion reactions between actinide targets and radioactive-beam particles are controlled by the same < r /Ff > and dynamical hindrance effects as are the reaction products from stable-ion beam irradiations. It has been observed that fusion cross sections for reactions with neutron-rich radioactive beam particles can be enhanced over those with stable-isotope beams at the same Z, possibly due to an effective lowering of the fusion barrier with the increasing neutron number of the projectile facilitated by neutron flow in the dinuclear reaction intermediate [226, 454, 458]. It is unclear how dynamical hindrance effects and a reduced resistance to deexcitation by fission at high excitation energies in heavier systems will influence the formation of evaporation residues. It has been suggested that the formation of products at the... 

When not constrained to the stable nuclei, beams of particles with neutron numbers out to the neutron-drip line can be considered as possible reactants. Though the lack of suitable accelerator facilities makes this a hypothetical exercise, there are practical concerns governing production of the radioactive species for acceleration as the secondary beam. Continuous production of large quantities of these nuclides is required for the generation of a radioactive beam that is sufficiently intense for a superheavy element synthesis experiment. This limits our discussions to radioactive species close to the line of stability, because of both primary production rate and half-life. To confine the following discussion, only radioactive ions within four mass numbers of the heaviest stable isotope of each element will be considered as projectiles unless there is a stable isotope of a nearby element at higher neutron number (e.g., " Ar, at the same neutron number as Ca). 

Schmitt, C., Nadtochy, P.N., Heinz, A., Jurado, B., Kelic, A., Schmidt, K.-H. First experiment on fission transients in highly fissile spherical nuclei produced by fragmentation of radioactive beams. Phys. Rev. Lett. 99, 042701(4) (2007)... 

Miinzenberg, G. Synthesis and investigation of superheavy elements perspectives on radioactive beams. Philos. Trans. R. Soc. Lond. A356, 2083-2104 (1998)... 

---