Double Penning Trap Mass Spectrometer for Direct Gamma-Ray Standard Calibrations, Determination of Fundamental Constants, and Tests of Special Relativity

Grant Details


Einstein's famous relation E=mc^2 expresses the equivalence of mass and energy and is one of the most well-known formulae in physics. It is a consequence of the theory of special relativity. A direct test of E=mc^2 can be performed by comparing the mass difference between two nuclear states to the energy that is released when a transition between those two states occurs. In this research we will measure the mass difference between two isotopes of chlorine, 35Cl and 36Cl, and compare it to the result of precise gamma ray spectroscopy measurements of the energy released after 35Cl captures a neutron. The atomic masses of 35Cl and 36Cl will be determined using Penning trap mass spectrometry, in which the mass of an ion is measured via the frequency of its motions in a combined magnetic and electric field. At Central Michigan University (CMU) a novel double Penning trap will be constructed and housed inside a 12 tesla superconducting magnet. This apparatus will be used to perform measurements on pairs of ions stored in two identical traps, which will enable the effect of magnetic field variations to be reduced. A comparison of the 35Cl and 36Cl mass difference with the gamma-ray spectroscopy energy measurement will also enable a calibration of gamma-ray energy standards used by detectors in nuclear physics applications in terms of atomic masses. In addition, it can be used to provide a precise determination of two important fundamental constants of nature: the Molar Planck constant and the fine structure constant, and could impact experimental data required for a possible redefinition of the kilogram.

The research program under development at CMU will provide training of Masters and undergraduate students who will gain research experience in modern experimental atomic and nuclear physics techniques, creating an avenue for them to go on to pursue a Ph.D. or enter positions in the technical workforce. The CMU Penning trap will use ions produced by an external ion source and injected into the trap. This will enable many additional precision mass measurements to be performed on a wide range of isotopes, such as those with very low natural abundances, and long-lived radioactive isotopes and isomers, with applications in atomic, nuclear and neutrino physics. The techniques being developed could impact other high sensitivity mass spectrometry applications such as the single-ion Penning trap for rare-isotopes under development at nearby Michigan State University, and mass spectrometers used in national security applications for trace chemical detection.

Effective start/end date08/1/1308/31/16


  • National Science Foundation: $120,000.00


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