Edmund G. Myers

Masses of Te-130 and Xe-130 and Double-beta-Decay Q Value of Te-130

The atomic masses of 130Te and 130Xe have been obtained by measuring cyclotron frequency ratios of pairs of triply charged ions simultaneously trapped in a Penning trap. The results, with 1 standard deviation uncertainty, are M(130Te)=129.906 222 744(16) u and M(130Xe)=129.903 509 351(15) u. From the mass difference the double-beta-decay Q value of 130Te is determined to be Qbetabeta(130Te)=2527.518(13) keV. This is a factor of 150 more precise than the result of the AME2003 [G. Audi, Nucl. Phys. A729, 337 (2003)10.1016/j.nuclphysa.2003.11.003].

Masses ofTe130andXe130and Double-β-DecayQValue ofTe130

The atomic masses of 130Te and 130Xe have been obtained by measuring cyclotron frequency ratios of pairs of triply charged ions simultaneously trapped in a Penning trap. The results, with 1 standard deviation uncertainty, are M(130Te)=129.906 222 744(16) u and M(130Xe)=129.903 509 351(15) u. From the mass difference the double-beta-decay Q value of 130Te is determined to be Qbetabeta(130Te)=2527.518(13) keV. This is a factor of 150 more precise than the result of the AME2003 [G. Audi, Nucl. Phys. A729, 337 (2003)10.1016/j.nuclphysa.2003.11.003].

World Year of Physics: A direct test of E=mc2

One of the most striking predictions of Einsteins special theory of relativity is also perhaps the best known formula in all of science: E=mc2. If this equation were found to be even slightly incorrect, the impact would be enormous — given the degree to which special relativity is woven into the theoretical fabric of modern physics and into everyday applications such as global positioning systems. Here we test this mass–energy relationship directly by combining very accurate measurements of atomic-mass difference, Δm, and of γ-ray wavelengths to determine E, the nuclear binding energy, for isotopes of silicon and sulphur. Einsteins relationship is separately confirmed in two tests, which yield a combined result of 1−Δmc2/E=(−1.4±4.4)×10−7, indicating that it holds to a level of at least 0.00004%. To our knowledge, this is the most precise direct test of the famous equation yet described.

Laser spectroscopy of the 1s22s2p 3P2-3P1 transition in beryllium-like argon using the Oxford EBIT

A study of the 1s22s2p 3P2-3P1 fine-structure transition in beryllium-like argon is planned on the Oxford electron beam ion trap (EBIT), using laser-induced resonance. This transition wavelength was measured previously as 594.373(4) nm, which is accessible using a dye laser. The ions are produced and excited in the EBIT and are confined during laser irradiation using the magnetic trapping mode. The 3P2 level population is depleted by the laser and by subsequently monitoring the emitted fluorescence a laser resonance signal can be obtained.

Determination of the on-target polarization of an optically-pumped polarized lithium ion beam☆

Abstract An optically-pumped polarized lithium ion source has been built and is currently producing highly polarized 6 Li − beams with on-target 6 Li 3+ currents up to 150 nA. An absolute measurement of the on-target tensor polarization was made during a one week calibration run, which yielded t 20 = −0.938±0.013, averaged over the entire run. The on-target vector polarization is typically t 10 = 1.02±0.06. The nuclear polarization of the atomic beam at the source has been measured by laser-induced fluorescence to be typically t 10 = 1.14±0.06 and t 20 = −1.14±0.06. A 4 He gas polarimeter has been calibrated as a secondary standard for monitoring both vector and tensor polarizations.

An optically pumped polarized lithium ion source

Abstract A laser-optically-pumped polarized lithium ion source is being developed to provide beams of nuclear polarized 6,7Li− for injection into the FSU tandem Van de Graaff-linac. Electro-optically modulated, circularly polarized light optically pumps a lithium atomic beam into a single magnetic substate, M I = I, M J = 1 2 . No inhomogeneous magnetic field (sextupole or quadrupole Adiabatic rf transitions enable the polarization to be changed by transferring the population into different magnetic substates. Using a second electro-optic to modulate a second beam from the same laser, and Zeeman tuning, the polarization of the atomic beam is obtained by laser induced fluorescence. The polarized atomic beam is ionized to Li+ and then charge exchanged to Li−.

Laser resonance measurements in highly ionized atoms

Abstract Recent experiments using the fast-beam laser technique to measure transition intervals in highly ionized atoms are briefly reviewed. These include: (1) measurements of the n = 2 Lamb shift in hydrogenic phosphorus, sulphur and chlorine, and (2) measurement of the 1s2p 3p1−3p2 fine structure interval in helium-like fluorine.

Towards a Precision Measurement of the Lamb Shift in Hydrogen-Like Nitrogen

Measurements of the 2S 1/2-2P 1/2 and 2S 1/2-2P 3/2 transitions in moderate Z hydrogen-like ions can test Quantum-Electrodynamic calculations relevant to the interpretation of high-precision spectroscopy of atomic hydrogen. There is now particular interest in testing calculations of the two-loop self-energy. Experimental conditions are favorable for a measurement of the 2S 1/2 - 2P 3/2 transition in N 6+ using a carbon dioxide laser. As a preliminary experiment, we have observed the 2S 1/2 - 2P 3/2 transition in 14 N 6+ using a 2.5 MeV/amu foil-stripped ion beam and a continuous-wave CO2 laser operating on the hot band of 12C16O2. The measured value of the transition centroid, 834.94(7) cm-1, agrees with, but is less precise than theory. However, the counting rate and signal-to-background ratio obtained indicate, that with careful control of systematics, a precision test of the theory is practical. Work towards constructing such a set-up is in progress.

Laser Spectroscopy of Hydrogen-Like and Helium-Like Ions

Laser spectroscopy of hydrogen-like and helium-like ions is reviewed. Emphasis is on the fast-beam laser resonance technique, measurements in moderate-Z ions which provide tests of relativistic and quantum-electrodynamic atomic theory, and future experimental directions.

Operational experience with the FSU optically pumped polarized lithium ion source

Abstract The dye-laser optically pumped polarized 6,7 Li − ion source of the FSU tandem-linac heavy-ion accelerator has completed its first year of operation. The ion source has produced highly polarized beams of 6 Li for nuclear physics experiments with on-target currents of 6 Li 3+ greater than 150 nA. Absolute measurements of the on-target 6 Li polarization have yielded P yy = −1.33± 0.02 and P y > 0.74 ± 0.03 for the nuclear tensor and vector polarization, respectively. No loss of polarization due to acceleration by the linac booster was observed.