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.

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Atomic masses of the neutron-rich isotopes [121][122][123][124][125][126][127][128] 129,131 In, 130−135 Sn, 131−136 Sb, and 132−140 Te have been measured with high precision (10 ppb) using the Penning trap mass spectrometer JYFLTRAP. Among these, the masses of four r-process nuclei 135 Sn, 136 Sb, and 139,140 Te were measured for the first time. An empirical neutron pairing gap expressed as the odd-even staggering of isotopic masses shows a strong quenching across N=82 for Sn, with the Z-dependence that is unexplainable by the current theoretical models.PACS numbers: 21.10. Dr, 27.60.+j The doubly magic 132 Sn nucleus has been probed intensively by nuclear spectroscopy over the last two decades. It has been found to exhibit features of exceptional purity for its single particle structure [1,2]. This provides an ideal starting point for exploring detailed evolution of nuclear structure of more neutron-rich nuclei beyond the N=82 closed shell in the vicinity of Sn. Therefore, it would be necessary to probe the evolution of odd-even staggering of masses [6] around the N =82 neutron shell to learn about the magnitude of pairing and its variation as a function of Z and N beyond 132 Sn.High precision of present-day ion-trap mass spectrometry combined with high sensitivity [7] can provide the needed information on mass differences such as one-and two-nucleon separation energies, shell gaps and empirical pairing energies. For example, the masses of neutronrich Sn and Xe isotopes were recently measured up to 134Sn and 146 Xe with a Penning trap mass spectrometer ISOLTRAP at the CERN ISOLDE facility [8,9]. In this Letter we wish to present new data of high-precision mass measurements of neutron-rich Cd, In, Sn, Sb, and Te isotopes across the N =82 neutron shell by using the JYFLTRAP Penning trap. These nuclides are also of interest for nuclear astrophysics models of element synthesis, in particular, to explain the large r-process abundance peak at A=130 [10], see Fig. 1. In more general context, a vast body of nuclear data on neutron-rich isotopes is needed for r-process nucleosynthesis predictions. Such data include masses, single particle spectra, pairing characteristics as well as decay properties and reaction rates. In all of these the binding energies or masses of ground, isomeric and excited states play key roles [10]. The measurements were performed using the JYFLTRAP Penning trap mass spectrometer [11] which is connected to the Ion Guide Isotope Separator On-Line (IGISOL) mass separator [12]. The ions of interest were produced in proton-induced fission reactions by bombarding a natural uranium target with a proton beam of 25 MeV energy. A thorium target was used in the case of 129 In and isotopes of Sb.Fission products stopped in a helium-filled gas cell at a pressure of about 200 mbar as singly-charged ions were transported out of the gas cell, accelerated to 30 keV energy, and mass separated. A gas-filled radio frequency quadrupole cooler and buncher prepared the ions for the

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A new detection system for the measurement of beta-delayed neutron emission probabilities has been characterized using fission products with well known β-delayed neutron emission properties. The setup consists of BELEN-20, a 4π neutron counter with twenty 3 He proportional tubes arranged inside a large polyethylene neutron moderator, a thin Si detector for β counting and a selftriggering digital data acquisition system. The use of delayed-neutron precursors with different neutron emission windows allowed the study of the effect of energy dependency on neutron, β and β-neutron rates. The observed effect is well reproduced by Monte Carlo simulations. The impact of this dependency on the accuracy of neutron emission probabilities is discussed. A new accurate value of the neutron emission probability for the important delayed-neutron precursor 137 I was obtained, P n = 7.76(14)%.