SMILETRAP—A Penning trap facility for precision mass measurements using highly charged ions

Bergström, I.; Carlberg, C.; Fritioff, T.; Douysset, Guilhem; Schonfelder, J. L.; Schuch, R.

doi:10.1016/s0168-9002(01)02178-7

Cited by 117 publications

(45 citation statements)

References 47 publications

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“…First experiments have been performed by Bollen et al with the ISOLTRAP installation at CERN [5] and later on by Bergström et al at the SMILETRAP installation in Stockholm [6]. After a series of preparatory steps an ion sample trapped in a hyperbolic precision trap in a state of pure magnetron motion is acted upon by a pulse of quadrupole rf-radiation with a frequency near the true cyclotron frequency, and with well-defined duration and amplitude.…”

Section: Introductionmentioning

confidence: 99%

The Ramsey method in high-precision mass spectrometry with Penning traps: Theoretical foundations

Kretzschmar

2007

International Journal of Mass Spectrometry

158

171

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This paper presents in a quantum mechanical framework a theoretical description of the interconversion of the magnetron and modified cyclotron motional modes of ions in a Penning trap due to excitation by external rf-quadrupole fields with a frequency near the true cyclotron frequency. The work aims at a correct description of the resonance line shapes that are observed in connection with more complicated excitation schemes using several excitation pulses, such as Ramsey's method of separated oscillating fields. Quantum mechanical arguments together with the "rotating wave approximation" suggest a model Hamiltonian that permits a rigorous solution of the corresponding Heisenberg equations of motion. We show that the ion motion in a Penning trap with an additional rf-quadrupole field is dynamically analogous to nuclear-magnetic-resonance. This is done by introducing the concept of the "Bloch vector operator", which is a vector operator obeying the commutation rules of an angular momentum operator and which is the analogue of a nuclear spin. During the quadrupole excitation the expectation value of the Bloch vector operator, which is an ordinary real three-vector, performs a precessional and nutational motion similar to the spin in nuclear-magnetic-resonance experiments. The frequency of the interconversion of the magnetron and modified cyclotron motional modes of the ions is the analogue of the Rabi frequency. Hence the applicability of Ramsey's ideas to Penning trap physics becomes understandable. Resonance line shapes are deduced from the general solution of the dynamical problem for arbitrary values of the excitation time, pulse structure and detuning of the quadrupole radiation. Results are given for excitation schemes with up to five pulses. A comparison of the theoretical results to experimental data is found in the accompanying paper by George et al. [S. George, et al., IJMS, this issue].

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Section: Introductionmentioning

confidence: 99%

The Ramsey method in high-precision mass spectrometry with Penning traps: Theoretical foundations

Kretzschmar

2007

International Journal of Mass Spectrometry

158

171

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“…In high-precision mass spectrometry the idea to use time-separated oscillatory fields to manipulate the radial * Correspondence to: george@uni-mainz.de motions of confined ions in a Penning trap was first put forward at ISOLTRAP by G. Bollen and coworkers in 1992 [9] and later tested at the SMILETRAP experiment [10]. At this time the correct theoretical description of the observed line-shapes was not available.…”

Section: Introductionmentioning

confidence: 99%

The Ramsey method in high-precision mass spectrometry with Penning traps: Experimental results

George

Blaum

Herfurth

et al. 2007

International Journal of Mass Spectrometry

164

112

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The highest precision in direct mass measurements is obtained with Penning trap mass spectrometry. Most experiments use the interconversion of the magnetron and cyclotron motional modes of the stored ion due to excitation by external radiofrequency-quadrupole fields. In this work a new excitation scheme, Ramsey's method of time-separated oscillatory fields, has been successfully tested. It has been shown to reduce significantly the uncertainty in the determination of the cyclotron frequency and thus of the ion mass of interest. The theoretical description of the ion motion excited with Ramsey's method in a Penning trap and subsequently the calculation of the resonance line shapes for different excitation times, pulse structures, and detunings of the quadrupole field has been carried out in a quantum mechanical framework and is discussed in detail in the preceding article in this journal by M. Kretzschmar. Here, the new excitation technique has been applied with the ISOLTRAP mass spectrometer at ISOLDE/CERN for mass measurements on stable as well as short-lived nuclides. The experimental resonances are in agreement with the theoretical predictions and a precision gain close to a factor of four was achieved compared to the use of the conventional excitation technique.

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“…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.…”

mentioning

confidence: 90%

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

et al. 2007

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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...

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SMILETRAP—A Penning trap facility for precision mass measurements using highly charged ions

Cited by 117 publications

References 47 publications

The Ramsey method in high-precision mass spectrometry with Penning traps: Theoretical foundations

The Ramsey method in high-precision mass spectrometry with Penning traps: Theoretical foundations

The Ramsey method in high-precision mass spectrometry with Penning traps: Experimental results

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

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