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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Background: Classical novae are cataclysmic nuclear explosions occurring when a white dwarf in a binary system accretes hydrogen-rich material from its companion star. Novae are partially responsible for the galactic synthesis of a variety of nuclides up to the calcium (A ∼ 40) region of the nuclear chart. Although the structure and dynamics of novae are thought to be relatively well understood, the predicted abundances of elements near the nucleosynthesis endpoint, in particular Ar and Ca, appear to sometimes be in disagreement with astronomical observations of the spectra of nova ejecta. Purpose: One possible source of the discrepancies between model predictions and astronomical observations is nuclear reaction data. Most reaction rates near the nova endpoint are estimated only from statistical model calculations, which carry large uncertainties. For certain key reactions, these rate uncertainties translate into large uncertainties in nucleosynthesis predictions. In particular, the 38 K(p,γ ) 39 Ca reaction has been identified as having a significant influence on Ar, K, and Ca production. In order to constrain the rate of this reaction, we have performed a direct measurement of the strengths of three candidate = 0 resonances within the Gamow window for nova burning, at 386 ± 10 keV, 515 ± 10 keV, and 689 ± 10 keV. Method: The experiment was performed in inverse kinematics using a beam of unstable 38 K impinged on a windowless hydrogen gas target. The 39 Ca recoils and prompt γ rays from 38 K(p,γ ) 39 Ca reactions were detected in coincidence using a recoil mass separator and a bismuth-germanate scintillator array, respectively. Results: For the 689 keV resonance, we observed a clear recoil-γ coincidence signal and extracted resonance strength and energy values of 120 +50 −30 (stat.) +20 −60 (sys.) meV and 679 +2 −1 (stat.)±1(sys.) keV, respectively. We also performed a singles analysis of the recoil data alone, extracting a resonance strength of 120 ± 20(stat.)±15(sys.) meV, consistent with the coincidence result. For the 386 keV and 515 keV resonances, we extract 90% confidence level upper limits of 2.54 meV and 18.4 meV, respectively. Conclusions: We have established a new recommended 38 K(p,γ ) 39 Ca rate based on experimental information, which reduces overall uncertainties near the peak temperatures of nova burning by a factor of ∼250. Using the rate obtained in this work in model calculations of the hottest oxygen-neon novae reduces overall uncertainties on Ar, K, and Ca synthesis to factors of 15 or less in all cases.

Ramsey's method of separated oscillatory fields is applied to the excitation of the cyclotron motion of short-lived ions in a Penning trap to improve the precision of their measured mass values. The theoretical description of the extracted ion-cyclotron-resonance line shape is derived and its correctness demonstrated experimentally by measuring the mass of the short-lived 38 Ca nuclide with an uncertainty of 1:1 10 ÿ8 using the Penning trap mass spectrometer ISOLTRAP at CERN. The mass of the superallowed beta emitter 38 Ca contributes for testing the theoretical corrections of the conserved-vector-current hypothesis of the electroweak interaction. It is shown that the Ramsey method applied to Penning trap mass measurements yields a statistical uncertainty similar to that obtained by the conventional technique but 10 times faster. Thus the technique is a new powerful tool for high-precision mass measurements. DOI: 10.1103/PhysRevLett.98.162501 PACS numbers: 21.10.Dr, 07.75.+h, 27.30.+t, 32.10.Bi In 1989 the Nobel prize for physics was awarded in part to N. F. Ramsey [1] in recognition of his molecular beam resonance method with spatially separated oscillatory fields [2,3]. In 1992, G. Bollen et al. [4] demonstrated the use of time-separated oscillatory fields for the excitation of the cyclotron motion of an ion confined in the Penning trap spectrometer ISOLTRAP. Along with further experiments [5,6], this showed that the method could improve the precision of mass measurements with Penning trap -on the condition that a sound theoretical basis be provided to describe the shape of the ion-cyclotron resonance curve.In this Letter, we introduce the correct theoretical description of the application of the Ramsey method to ions stored in a Penning trap. We also demonstrate its validity for the first time with a mass measurement. Comparison with the conventional excitation scheme [7,8] shows that the linewidth of the resonance is reduced by almost a factor of 2 and the statistical uncertainty of the extracted resonance frequency is more than a factor of 3 smaller. We show that the Ramsey method allows a measurement with the same statistical uncertainty but 10 times more rapidly. Faster experiments are desirable in any field since they make measurements less vulnerable to systematic errors and equipment failure. In particular, measurements of short-lived species at radioactive-beam facilities [9] benefit greatly due to the low production rates and extremely limited beam time. Such is the case of 38 Ca, measured here (T 1=2 4408 ms). This nuclide is of interest for testing the conserved-vector-current (CVC) hypothesis of the standard model of particle interactions [10,11] for which a particularly high precision is required (10 ÿ8 ).The prerequisite for the successful implementation of the Ramsey method to stored ions is the detailed understanding of the observed time-of-flight cyclotron resonance curves using time-separated oscillatory fields. While here only the most important parts of the theory and its experimental...

The masses of very neutron-deficient nuclides close to the astrophysical rp-and νp-process paths have been determined with the Penning trap facilities JYFLTRAP at JYFL/Jyväskylä and SHIP-TRAP at GSI/Darmstadt. Isotopes from yttrium (Z = 39) to palladium (Z = 46) have been produced in heavy-ion fusion-evaporation reactions. In total 21 nuclides were studied and almost half of the mass values were experimentally determined for the first time:88 Tc,