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Accelerator Ion Source

#2257


Proton Accelerator Based Intense Source of Radioactive Ions for Nuclear Physics Experiments

Tech Area / Field

  • PHY-PFA/Particles, Fields and Accelerator Physics/Physics
  • PHY-ANU/Atomic and Nuclear Physics/Physics

Status
8 Project completed

Registration date
13.07.2001

Completion date
09.10.2006

Senior Project Manager
Malakhov Yu I

Leading Institute
Budker Institute of Nuclear Physics, Russia, Novosibirsk reg., Akademgorodok

Supporting institutes

  • VNIITF, Russia, Chelyabinsk reg., Snezhinsk

Collaborators

  • Istituto Nazionale di Fisica Nucleare (INFN) / Laboratori Nazionali di Legnaro, Italy, Padova\nJohannes Gutenberg-Universitaet Mainz, Institute of Physik, Germany, Mainz

Project summary

The aim of this proposal is to develop a conceptual design of a high-intensity ion source for experiments in the physics of nucleus of an ISOL (Isotope Separator On Line) type. The aim of the project shall be reached through carrying out the required research, design and experiments.

The production of high-intensity radioactive ion beams (RIB) opens vast perspectives for fundamental studies both in nuclear physics and in many other fields. Special attentions is paid to the ion beams with a high content of neutrons in the nuclei obtained as a result of exposing special targets to neutron fluxes. Let us consider only a few fields where the use of RIB can make an essential contribution to fundamental studies. These are the nuclear physics and astrophysics, check of the Standard Model and fundamental conservation laws, atom physics and solid state physics, study of material and medical applications. For each of these fields one can choose the isotopes that most adequately correspond to the tasks set; and for each task the parameters like the half-decay period, kinetic and decay energy or chemical properties can be chosen.

At the present moment experiments with RIB of the first generation have yielded important results. But the first generation RIB facilities are often limited by the low intensity of the beams. This is why there have been discussed and developed quite a number of new projects with a new generation RIB (KEK, Tsukuba; ARENAS REX ISOLDE, CERN; ARGONNE; HRIBF, Oak Ridge). The SPES project at LNL (Italy) also belongs here.

The proposed project is aimed at an R&D study of a conversion element in the framework of the SPES program at LNL. LNL has proposed a double-acceleration scheme of producing an ISOL type RIB. A primary proton beam accelerated at a superconducing RFQ linac is directed to a special neutron target and produces an intense (3×1014 cm-2×s-1) flux of fast neutrons. The parameters of the primary beam are: the energy is up 100 MeV, the average power is up to 300 kW, the diameter is 1 cm. The thus obtained neutron flux then comes to a hot thick target of a 238U compound. The vapors of the radionuclides get ionized, extracted from the target at an energy of 20-60 keV and then being separated by isotopes get into the experimental zone for low-energy experiments or further accelerated to an energy of up to 1-5 MeV/nucleon.

The conversion element consisting of a neutron target and a source of radioactive ions play a most important role in this scheme. The main problems which are faced within the development of this element are the following:

– the neutron target should accept and dissipate a great power – up to 300 kW;


– the capsule of the ion source should stand a high temperature, which is required for a sufficient amount of the radionuclide vapors and their ionization;
– both the neutron target and the ion source should be under vacuum ~ 10-6 Torr;
– the whole element is located in the zone of an intense radiation flux and therefore should be surrounded with a bio-protection shielding.

These requirements set specific rigid limits to the choice of the construction and materials of the conversion element. Besides, the choice of the material of the operation zone of the neutron target is also limited by the isotopes 7Li, 9Be, 13C and their compounds, which have the maximum area of the neutron production at the interaction with protons.

The following basic results are planned to be obtained while realizing this project:

– the energy and angular distribution of the neutrons shall be calculated at the output of the total absorption target made of 7Li, 9Be, 13C, the target being exposed by a irradiated proton beam at an energy of up to 100 MeV;

– various constructions of the neutron target shall be studied and optimized, both cold, where the heat is extracted from the operation zone with a heat-carrying agent, and hot, when the cooling is done by radiation. In particular:

– thermal and mechanical modes of the target operation shall be calculated;
– the design and material for the target shall be chosen;
– the geometrical parameters of the target shall be optimized;
– the neutron target shall be matched with the ion source;
– an optimum circuit for the target and the target parameters shall be chosen.


– a concept design of an optimal target shall be done;

– the parameters of the ion source shall be studied and optimized. In particular:

– there shall be calculated the spectrum and the yield of various radionuclides of the source material affected by the neutron flux from the neutron target;
– there shall be calculated the thermal and mechanical modes of the source operation;
– there shall be selected the design and the materials for the ion source.


– a concept design of the ion source shall be developed;

– a concept design of the bio-protection shall be done;

– sample materials shall be prepared (the material should have an extended content of 13С) and experiments shall be carried out with these samples. In particular:

– the behavior of samples shall be studied when heated up to the operation temperature by an electrical current and by an electron beam;
– the samples’ behavior and the output of neutrons shall be studied when simulating the operation conditions with the help of a low-power (~1 kW) proton beam.


With all the studies done and the results obtained there will be prepared a feasibility project and a concept design of the radioactive ion source for the SPES project.

It should be noted that INP has gained a great experience in building various conversion systems and sources of charged particles. In particular, in the framework of the INP-LNL collaboration there was designed a high-intensity hot carbon deuteron-neutron target (~1014 per second), studies are performed on the radioactive ion source – there was built a model of the hot source, which worked under the operation conditions for over 100 hours.

Foreign collaborators will take an active part in the discussions on the project, in reviewing the technical reports and in experimental studies. A very close interaction with the collaborators means that they will regularly and directly participate in the discussions on the project, in consultations on the problems that may arise during the implementation of the project, in reviewing the reports. In particular, it is planned to have a number of workshops for discussing the results to be obtained during the execution of the project. Some experiments are also planned to be carried out together with the collaborator at the facilities that he provides for a temporary use for this project.

The participation of researchers and engineers from VNIITF will help them to proceed from the development of nuclear applications to military purposes to civil research and engineering activities. They can also use the experience they have gained while working with radioactive materials, radiation protection, etc. for securing environmental safety in the course of research and experiments with a high level of radiation. Thus, there will be built a basis for integrating the specialists from this institute to the world research community and carrying out a joint research work with their colleagues from other countries.


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