Ramsey Method of Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry

Abstract

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...

Plumbing Neutron Stars to New Depths with the Binding Energy of the Exotic NuclideZn82

“…3 In total, five measurements could be completed in 16 h with a total number of 1754 detected 82 Zn þ ions. These experiments included three conventional ToF-ICR measurements, one with 100 ms and two with 200 ms rf-excitation time, and two Ramsey-type ToF-ICR resonances [35] with an excitation-waiting-excitation scheme of 20 ms-160 ms-20 ms. [8] were performed to drill deeper down into the neutron-star crust. To this end the nuclides which minimize the Gibbs free energy per nucleon were determined as a function of the pressure in the neutron-star crust.…”

Toward precision mass measurements of neutron-rich nuclei relevant to r-process nucleosynthesis

“…The prerequisite for the Ramsey method is an understanding of the observed TOF cyclotron resonance curves using time-separated oscillatory fields. Its validity was recently demonstrated experimentally by measuring the mass of 38 Ca [T 1/2 = 440(12) ms] using the Penning trap mass spectrometer ISOLTRAP at CERN [36]. The relative uncertainty was determined to be 1.1×10 −8 .…”

Determination of theQECvalues of theT=1/2mirror nucleiNaEibach1, Bollen2, Brodeur3 et al. 2015Phys. Rev. CSelf Cite15070View full textAdd to dashboardCite

“…As its Q EC value was only deduced from mass measurements [14][15][16] we present here the first direct measurement of the Q EC value of the transition 21 Na( ) 21 Ne using Penning trap mass spectrometry. We also present the first direct mass measurement of 29 P to obtain the Q EC value of the decay 29 P( ) 29 Si, whose uncertainty is exclusively determined by the 28 Si(p, γ) 29 P reaction [16], while the mass of its daughter nuclide, 29 Si, was determined independently with very high precision [17][18][19].…”