On the Masses of²⁸Si and the Proton Determined in a Penning Trap

Abstract

The masses of the three silicon isotopes are important parameters for a re-de¢nition of the kilogram based on atomic properties. Using the Penning trap mass spectrometer SMILETRAP at the Manne Siegbahn Laboratory the mass of 28 Si was determined from the cyclotron frequencies of 28 S 14þ , 28 S 13þ and 28 S 12þ using 12 C 6þ , 12 C 5þ and 12 C 4þ as well as H þ 2 as mass references. Since H 2 þ ions were used as intermediate mass reference the mass of the proton could be determined using in addition 20 Ne 10,9þ and 40 Ar 16þ,14þ ions as mass references. By comparing the value of the proton mass determined this way with the accurate accepted value we could set an experimental limit of 0.35 ppb ppb for the total uncertainties in our mass determinations. Avalue of 27.976 926 533.9 (80) u was obtained for the mass of 28 Si con¢rming the more accurate value obtained by the MIT-group using an entirely di¡erent method. Thus the mass of 28 Si has been determined by using two very di¡erent methods agreeing within an uncertainty <0.35 ppb.

Proton-electron mass ratio from laser spectroscopy of HD + at the part-per-trillion level

“…Progress toward solution of the puzzle was made after most of the recent r p determinations from electron-proton scattering and atomic hydrogen spectroscopy were found to be consistent with the muonic hydrogen value (4-7). A similar need for alternative measurements is indicated for m p /m e -an important dimensionless quantity that sets the scale of rotations and vibrations in molecules-because recent Penning trap measurements of the relative atomic masses of light atomic nuclei [including those of the proton (m p ), deuteron (m d ), and helion (m h )] differed from earlier results by several standard deviations (8)(9)(10)(11)(12)(13)(14)(15). For example, Heiße et al (11) determined m p with a precision of 32 parts per trillion (ppt), three times as high as the then-accepted CODATA-2014 value, but also found it to be smaller by 3s (11,12).…”

Dipole Moment ofPH+and the Atomic Masses ofSi28,PRedshaw1, McDaniel2, Myers3 2008Phys. Rev. Lett.733610View full textAdd to dashboardCite

“…Otherwise, ions of the two species to be compared must be alternately introduced into the trap and their cyclotron frequencies measured, alternating between them as frequently as possible, e.g., see refs. [4,5]. As has been demonstrated in a 90 ppt comparison of the masses of H ÿ and the antiproton [6], it is also possible to simultaneously trap single ions of the two species in the same trap, but with one ion at the center of the trap-where its cyclotron frequency is measured-while the other ion is ''parked'' in a large-radius cyclotron orbit.…”

High-Precision Atomic Mass Measurements for Fundamental Constants

“…Also notable was the use of the high axial frequency of 3.5 MHz, which reduces some anharmonic shifts and leads to a lower cyclotron temperature after cyclotron-to-axial coupling. The third is a measurement by the SMILETRAP group [75] using their time-of-flight detection technique to measure the CFRs of H 2 + relative to several charge states of 12 C, but also of 28 Si, 14 N, 20 Ne, and 40 Ar, making use of measurements of these atoms at the 10 −10 level by MIT [41]. The fourth is another measurement by the SMILETRAP group [38], but making use of the Ramsey variant of their TOF method, and measuring H 2 + against D + as a reference.…”