electrochemical-etching-characterization-sharp-field-emission-points

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. ...

Central Michigan University

The atomic mass of 136Xe has been measured by comparing cyclotron frequencies of single ions in a Penning trap. The result, with 1 standard deviation uncertainty, is M(136Xe)=135.907 214 484 (11) u. Combined with previous results for the mass of 136Ba [Audi, Wapstra, and Thibault, Nucl. Phys. A 729, 337 (2003)10.1016/j.nuclphysa.2003.11.003], this gives a Q value (M[136Xe]-M[136Ba])c(2)=2457.83(37) keV, sufficiently precise for ongoing searches for the neutrinoless double-beta decay of 136Xe.

Mass and double-beta-decay Q value of 136Xe.

By trapping pairs of ions in a Penning trap, alternating each ion between large and small cyclotron orbits, we have measured the cyclotron frequency ratios 12C2H4+/28Si+, 13C2H2+/28Si+, 28SiH3+/31P+, and 16O2+/31PH+, all to <30 ppt precision. The 16O2+/31PH+ data exhibit a bimodal distribution due to the polarizability of the Lambda-doubling components of the PH+ ground state, from which we obtain the electric dipole moment of 31PH+, 0.331(8) ea0. Combined with other atomic mass measurements we also obtain improved values for m(28Si), 27.976 926 535 0(6) u, and m(31P), 30.973 761 998 9(9) u.

Dipole moment of PH+ and the atomic masses of 28Si, 31P by comparing cyclotron frequencies of two ions simultaneously trapped in a penning trap.

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 of 130Te and 130Xe and double-beta-decay Q value of 130Te.

Using precision, cryogenic, Penning-trap mass spectrometry we have measured the atomic mass difference M[;{115}In]-M[;{115}Sn] to be 497.489(10) keV/c;{2}. Combined with the energy of the 3/2;{+} first excited state of ;{115}Sn [J. Blachot, Nuclear Data Sheets 104, 967 (2005)10.1016/j.nds.2005.03.003], the Q value of the ;{115}In(9/2;{+}) --> ;{115}Sn(3/2;{+}) beta decay is determined to be 155(24) eV. This confirms the inference of Cattadori [Nucl. Phys. A 748, 333 (2005)10.1016/j.nuclphysa.2004.10.025] that this small branching-ratio beta decay has the lowest-known Q value. We also report improved values of the individual atomic masses: M[;{115}In] = 114.903 878 774(16) u and M[;{115}Sn] = 114.903 344 697(17) u.

Q value of ;{115}In --> ;{115}sn(3/2;{+}): the lowest known energy beta decay.

In anticipation of results from current and future double-β decay studies, we report a measurement resulting in a (82)Se double-β decay Q value of 2997.9(3) keV, an order of magnitude more precise than the currently accepted value. We also present preliminary results of a calculation of the (82)Se neutrinoless double-β decay nuclear matrix element that corrects in part for the small size of the shell model single-particle space. The results of this work are important for designing next generation double-β decay experiments and for the theoretical interpretations of their observations.

Matthew Redshaw

Department of Physics

Central Michigan University

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

Matthew Redshaw

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Physics

Central Michigan University

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

Department of Physics