In this article a comprehensive description and performance of the double Penning trap setup JYFLTRAP will be detailed. The setup is designed for atomic mass measurements of both radioactive and stable ions and additionally serves as a very high resolution mass separator. The setup is coupled to the IGISOL facility at the accelerator laboratory of the University of Jyväskylä. The trap has been online since 2003 and it was shut down in summer 2010 for relocation to upgraded IGISOL facility. Numerous atomic mass and decay energy measurements have been performed using the time-of-flight ion-cyclotron resonance technique. Also the trap has been used in several decay spectroscopy experiments as a high-resolution mass filter.

The laser ion source project at the IGISOL facility, Jyväskylä, has motivated the development and construction of an rf sextupole ion beam guide (SPIG) to replace the original skimmer electrode. The SPIG has been tested both off-line and on-line in protoninduced fission, light-ion and heavy-ion induced fusion-evaporation reactions and, in each case, has been directly compared to the skimmer system. For both fission and light-ion induced fusion, the SPIG has improved the mass-separated ion yields by a factor of typically 4 to 8. Correspondingly, the transmission efficiency of both systems has been studied in simulations with and without space charge effects. The transport capacity of the SPIG has been experimentally determined to be ∼10 12 ions s −1 before space charge effects start to take effect. A direct comparison with the simulation has been made using data obtained via light-ion fusion evaporation. Both experiment and simulation show an encouraging agreement as a function of current extracted from the ion guide.

The feeding probability of 102;104;105;106;107 Tc, 105 Mo, and 101 Nb nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the component of the decay heat for 239 Pu in the 4-3000 s range. DOI: 10.1103/PhysRevLett.105.202501 PACS numbers: 23.40.Às, 27.60.+j, 28.41.Fr, 29.30.Kv Nuclear reactors provide a significant fraction of the world's electricity. A burgeoning population and an associated growth in economic activity suggest that world demand will double by 2050. Until now, the bulk of this has come from the burning of fossil fuels. There is general concern that reserves of fossil fuels are limited and their burning damages the environment. In particular, it contributes to the emission of large amounts of CO 2 . In this context, nuclear power, based on the fission process, will be less damaging to the environment. Accordingly there is now a renaissance in the building of nuclear power stations around the world. Modern reactor designs, based on many years of operating experience, are much more efficient, more economical, and safer than earlier designs. Although the basic principles are well established, we still lack certain information, such as a knowledge of the decay properties of specific nuclei that are important contributors to the heating of the reactor during and after operation. The estimation and control of the heat emitted by the decay of fission products plays a key role in the safe operation of reactors. The primary aim of this work is to study the decay properties of specific nuclei that are important contributors to this source of heat.Approximately 8% of the total energy generated during the fission process is related to the energy released in the natural decay of fission products, and is commonly called decay heat [1]. Once the reactor is shut down, the energy released in radioactive decay provides the main source of heating. Hence, coolant needs to be maintained after termination of the neutron-induced fission process in a reactor, and the form and extent of this essential requirement needs to be specified on the basis of decay-heat summation calculations. Decay heat varies as a function of time after shutdown and can be determined theoretically from known nuclear data. Such computations are based on the inventory of nuclei created during the fission process and after reactor shutdown and their radioactive decay characteristics:where fðtÞ is the power function, E i is the mean decay energy of the ith nuclide ( , , and components), i is the decay constant of the ith nuclide, and N i ðtÞ is the number of nuclide i at cooling time t. These calculations require extensive libraries of cross sections, fission yields, and decay data. Obviously, an accurate assessment of the decay heat is highly relevant...

The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. 92 Rb makes the dominant contribution to the reactor antineutrino spectrum in the 5-8 MeV range but its decay properties are in question. We have studied 92 Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed.

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The uncertainty on the Argonne neutrino spectrum shown in Fig. 27(c) is incorrect. Here, we bring the same figure with the correct uncertainty as given in Ref. [19]. We note that this uncertainty includes the theoretical uncertainty from the recoil-order corrections which is roughly half as large as the uncertainty from the α-spectrum measurement [19]. The conclusions of the paper are unaffected. FIG. 27. (Color online) (a) Neutrino spectrum calculated using the E x distribution obtained in the present study neglecting recoil terms and radiative corrections. Note that the end point of the neutrino spectrum (16.96 MeV) is slightly outside the energy range chosen for the plot due to insufficient numerical precision above 16 MeV. (b) 1σ statistical and systematic uncertainties on the present neutrino spectrum. (c) Relative deviation with respect to the neutrino spectrum calculated using the Argonne E x distribution.

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The Penning trap mass spectrometer JYFLTRAP, coupled to the Ion-Guide Isotope Separator On-Line (IGISOL) facility at Jyväskylä, was employed to measure the atomic masses of neutron-rich 85−92 Br and 94−97 Rb isotopes with a typical accuracy less than 10 keV. Discrepancies with the older data are discussed. Comparison to different mass models is presented. Details of nuclear structure, shell and subshell closures are investigated by studying the two-neutron separation energy and the shell gap energy.