Possibilities of preparation of exotic radionuclide samples at PSI for scientific investigations

The interactions of high-energy protons with matter produce a large variety of radionuclides due to the diversity of the induced nuclear reactions. Some of those isotopes are very rare, exotic, and, in many cases, difficult to produce by complementary methods. Valuable isotopes, interesting for scientific and technological applications, can be extracted from samples stemming from the surroundings or components of a proton accelerator, in particular if the load of the initial particle current is relatively high (esp. in the Megawatt range). Since PSI operates one of the most powerful high-energy proton accelerators world-wide, this facility is best-suited for an R&D program aimed at "harvesting” such isotopes. An initiative called ERAWAST (Exotic Radionuclides from Accelerator Waste for Science and Technology) was started in 2006 in order to identify and motivate potential users. After six years, first achievements as well as realistic future plans for front-end experiments are available. The present contribution describes radiochemical separation techniques for selected examples, summarizes the most prominent results and gives an outlook on the upcoming experiments within the scope of the ERAWAST progra

Sensitivity of DF-ICP-MS, PERALS and alpha-spectrometry for the determination of actinides: A comparison

We applied three techniques (DF-ICP-MS, PERALS and alpha-spectrometry) for the determination of minor actinides at environmental levels. For each method the limit of detection and the resolution were estimated in order to study the content and isotopic composition of the actinides. Two international reference materials, IAEA-135 (Irish Sea Sediment) and IAEA-300 (Baltic Sea sediment) were analyzed for activity concentrations of 238Pu, 239Pu, 240Pu, 241Pu and 241Am. The sensitivities of the three determination techniques were compare

Radiochemical separation of 7Be from the cooling water of the neutron spallation source SINQ at PSI

7Be is a key radionuclide for investigation of several astrophysical processes and phenomena. In addition, it is used as a tracer in wear measurements. It is produced in considerable amounts in the cooling water (D2O) of the Spallation Induced Neutron Source (SINQ) facility at PSI by spallation reactions on 16O with the generated fast neutrons. A shielded ion-exchange filter containing 100 mL of the mixed-bed ion exchanger LEWATIT was installed as a bypass for the cooling water into the cooling loop of SINQ for three months. The collected activity of 7Be was in the range of several hundred GBq. Further, the 7Be was separated and purified in a hot-cell remotely-controlled using a separation system installed. With the exception of 10Be, radioactive byproducts can be neglected, so that this cooling water could serve as an ideal source for highly active 7Be-samples. The facility is capable of producing 7Be with activities up to 1 TBq per year. The 7Be sample preparation is described in detail and the possible uses are discussed. In particular some preliminary results of 7Be ion beam production are presente

Preparation and characterization of three 7Be targets for the measurement of the 7Be(n,p)7Li and 7Be(n,a)7Li reaction cross sections

This manuscript describes the production of three targets obtained by implantation of different activities of 7Be into thin aluminium disks. Two of the produced targets were used to measure the 7Be(n, p)7Li cross section in the energy range of interest for the Big-Bang Nucleosynthesis. A third target was used to measure the cross sections of 7Be(n, p)7Li and 7Be(n, )7Li nuclear reactions with cold and thermal neutrons, respectively. This paper describes also the characterization of the first two targets, performed after the neutron irradiation, in terms of implanted 7Be activities and spatial distributions.The work has partly been funded by CHANDA (grant agreement No FP7-Fission-2013-605203). The Federal Ministry of Education and Research through the FMeVgrant 05K16PGA, has partially supported the use of the implantation equipment

Experimental setup and procedure for the measurement of the 7Be(n,α)α reaction at n-TOF

The newly built second experimental area EAR2 of the n-TOF spallation neutron source at CERN allows to perform (n, charged particles) experiments on short-lived highly radioactive targets. This paper describes a detection apparatus and the experimental procedure for the determination of the cross-section of the 7Be(n,α)α reaction, which represents one of the focal points toward the solution of the cosmological Lithium abundance problem, and whose only measurement, at thermal energy, dates back to 1963. The apparently unsurmountable experimental difficulties stemming from the huge 7Be γ-activity, along with the lack of a suitable neutron beam facility, had so far prevented further measurements. The detection system is subject to considerable radiation damage, but is capable of disentangling the rare reaction signals from the very high background. This newly developed setup could likely be useful also to study other challenging reactions requiring the detectors to be installed directly in the neutron beam

Achievements and perspectives of ERAWAST

The ERAWAST initiative (Exotic Radionuclides from Accelerator Waste for Science and Technology) was started at PSI in 2006 and is aimed to acquire resources from the PSI accelerator facilities for the preparation of rare long-lived radionuclides for several scientific purposes [1]. One of the application fields where such radionuclides like 60Fe, 53Mn, 44Ti, 26Al, 7/10Be are urgently needed is nuclear astrophysics. First laboratory-scale separations have been carried out, with the result that two samples of around 1016 atoms of 60Fe each could be provided for experiments [2]. A re-determination of the half-life of 60Fe was performed with the first one [3], and the neutron capture cross section of 60Fe at stellar energies was measured for the first time [4] using the second one. These successes encouraged us to put more efforts into the development of remote- controlled separation systems in order to gain higher amounts and the exploitation of new sources of the desired isotopes. These works are currently ongoing and for the first time, separation of about 5 GBq 7Be from the cooling water of the Swiss Spallation Neutron Source (SINQ) was succeeded. Moreover, about 50  g of 10Be are now available after its separation from graphite samples of the target E station at PSI [5]. Considerable amounts of 60Fe, 53Mn, 26Al and others from an irradiated copper beam dump can be expected in the near future. In addition, a scientific program was originated to determine half-lives and neutron capture cross-section of astrophysical interesting radionuclides. In a first step a confirmation of the new measured 60Fe half-life in two independent experiments was started. First studies aimed to re-measure the half-life of 10Be are currently ongoing. Experiments to determine the neutron capture cross-section of 53Mn using cold and ultra-cold neutrons as well as its half-life at PSI are planned

Achievements and perspectives of ERAWAST

The ERAWAST initiative (Exotic Radionuclides from Accelerator Waste for Science and Technology) was started at PSI in 2006 and is aimed to acquire resources from the PSI accelerator facilities for the preparation of rare long-lived radionuclides for several scientific purposes [1]. One of the application fields where such radionuclides like 60Fe, 53Mn, 44Ti, 26Al, 7/10Be are urgently needed is nuclear astrophysics. First laboratory-scale separations have been carried out, with the result that two samples of around 1016 atoms of 60Fe each could be provided for experiments [2]. A re-determination of the half-life of 60Fe was performed with the first one [3], and the neutron capture cross section of 60Fe at stellar energies was measured for the first time [4] using the second one. These successes encouraged us to put more efforts into the development of remote- controlled separation systems in order to gain higher amounts and the exploitation of new sources of the desired isotopes. These works are currently ongoing and for the first time, separation of about 5 GBq 7Be from the cooling water of the Swiss Spallation Neutron Source (SINQ) was succeeded. Moreover, about 50  g of 10Be are now available after its separation from graphite samples of the target E station at PSI [5]. Considerable amounts of 60Fe, 53Mn, 26Al and others from an irradiated copper beam dump can be expected in the near future. In addition, a scientific program was originated to determine half-lives and neutron capture cross-section of astrophysical interesting radionuclides. In a first step a confirmation of the new measured 60Fe half-life in two independent experiments was started. First studies aimed to re-measure the half-life of 10Be are currently ongoing. Experiments to determine the neutron capture cross-section of 53Mn using cold and ultra-cold neutrons as well as its half-life at PSI are planned

Possibilities of preparation of exotic radionuclide samples at PSI for scientific investigations

ISSN:0033-8230ISSN:2193-340