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We report high-precision mass measurements of $^{50--55}\mathrm{Sc}$ isotopes performed at the LEBIT facility at NSCL and at the TITAN facility at TRIUMF. Our results provide a substantial reduction of their uncertainties and indicate significant deviations, up to 0.7 MeV, from the previously recommended mass values for $^{53--55}\mathrm{Sc}$. The results of this work provide an important update to the description of emerging closed-shell phenomena at neutron numbers $N=32$ and $N=34$ above proton-magic $Z=20$. In particular, they finally enable a complete and precise characterization of the trends in ground state binding energies along the $N=32$ isotone, confirming that the empirical neutron shell gap energies peak at the doubly magic $^{52}\mathrm{Ca}$. Moreover, our data, combined with other recent measurements, do not support the existence of a closed neutron shell in $^{55}\mathrm{Sc}$ at $N=34$. The results were compared to predictions from both ab initio and phenomenological nuclear theories, which all had success describing $N=32$ neutron shell gap energies but were highly disparate in the description of the $N=34$ isotone.

We report the mass measurement of $^{56}\mathrm{Cu}$, using the LEBIT 9.4 T Penning trap mass spectrometer at the National Superconducting Cyclotron Laboratory at Michigan State University. The mass of $^{56}\mathrm{Cu}$ is critical for constraining the reaction rates of the $^{55}\mathrm{Ni}(p,\ensuremath{\gamma})$ $^{56}\mathrm{Cu}(p,\ensuremath{\gamma})$ $^{57}\mathrm{Zn}({\ensuremath{\beta}}^{+})$ $^{57}\mathrm{Cu}$ bypass around the $^{56}\mathrm{Ni}$ waiting point. Previous recommended mass excess values have disagreed by several hundred keV. Our new value, $\mathrm{ME}=\ensuremath{-}38626.7(7.1)\text{ }\text{ }\mathrm{keV}$, is a factor of 30 more precise than the extrapolated value suggested in the 2012 atomic mass evaluation [Chin. Phys. C 36, 1603 (2012)], and more than a factor of 12 more precise than values calculated using local mass extrapolations, while agreeing with the newest 2016 atomic mass evaluation value [Chin. Phys. C 41, 030003 (2017)]. The new experimental average, using our new mass and the value from AME2016, is used to calculate the astrophysical $^{55}\mathrm{Ni}(p,\ensuremath{\gamma})$ and $^{56}\mathrm{Cu}(p,\ensuremath{\gamma})$ forward and reverse rates and perform reaction network calculations of the $rp$ process. These show that the $rp$-process flow redirects around the $^{56}\mathrm{Ni}$ waiting point through the $^{55}\mathrm{Ni}(p,\ensuremath{\gamma})$ route, allowing it to proceed to higher masses more quickly and resulting in a reduction in ashes around this waiting point and an enhancement to higher-mass ashes.

We report the determination of the Q(EC) value of the mirror transition of (11)C by measuring the atomic masses of (11)C and (11)B using Penning trap mass spectrometry. More than an order of magnitude improvement in precision is achieved as compared to the 2012 Atomic Mass Evaluation (Ame2012) [Chin. Phys. C 36, 1603 (2012)]. This leads to a factor of 3 improvement in the calculated Ft value. Using the new value, Q(EC)=1981.690(61) keV, the uncertainty on Ft is no longer dominated by the uncertainty on the Q(EC) value. Based on this measurement, we provide an updated estimate of the Gamow-Teller to Fermi mixing ratio and standard model values of the correlation coefficients.

We report the first direct measurement of the $^{14}\mathrm{O}$ superallowed Fermi $\ensuremath{\beta}$-decay ${Q}_{EC}$ value, the last of the so-called ``traditional nine'' superallowed Fermi $\ensuremath{\beta}$ decays to be measured with Penning trap mass spectrometry. $^{14}\mathrm{O}$, along with the other low-$Z$ superallowed $\ensuremath{\beta}$ emitter, $^{10}\mathrm{C}$, is crucial for setting limits on the existence of possible scalar currents. The new ground state ${Q}_{EC}$ value, 5144.364(25) keV, when combined with the energy of the ${0}^{+}$ daughter state, ${E}_{x}({0}^{+})=2312.798(11)\text{ }\text{ }\mathrm{keV}$ [, Nucl. Phys. A523, 1 (1991)], provides a new determination of the superallowed $\ensuremath{\beta}$-decay ${Q}_{EC}$ value, ${Q}_{EC}(\mathrm{sa})=2831.566(28)\text{ }\text{ }\mathrm{keV}$, with an order of magnitude improvement in precision, and a similar improvement to the calculated statistical rate function $f$. This is used to calculate an improved $\mathcal{F}t$ value of 3073.8(2.8) s.

In anticipation of results from current and future double-$\ensuremath{\beta}$ decay studies, we report a measurement resulting in a $^{82}\mathrm{Se}$ double-$\ensuremath{\beta}$ 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 $^{82}\mathrm{Se}$ neutrinoless double-$\ensuremath{\beta}$ 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-$\ensuremath{\beta}$ decay experiments and for the theoretical interpretations of their observations.

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.

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

The atomic masses of $^{130}\mathrm{Te}$ and $^{130}\mathrm{Xe}$ 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 $M(^{130}\mathrm{Te})=129.906\text{ }222\text{ }744(16)\text{ }\mathrm{u}$ and $M(^{130}\mathrm{Xe})=129.903\text{ }509\text{ }351(15)\text{ }\mathrm{u}$. From the mass difference the double-$\ensuremath{\beta}$-decay $Q$ value of $^{130}\mathrm{Te}$ is determined to be ${Q}_{\ensuremath{\beta}\ensuremath{\beta}}(^{130}\mathrm{Te})=2527.518(13)\text{ }\text{ }\mathrm{keV}$. This is a factor of 150 more precise than the result of the AME2003 [G. Audi et al., Nucl. Phys. A729, 337 (2003)].

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.

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].

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

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 to30 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.

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

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.

Using Doppler-tuned fast-beam laser spectroscopy the 1s2s 1S0-1s2p 3P1 intercombination interval in 28Si12+ has been measured to be 7230.5(2) cm(-1). The experiment made use of a single-frequency Nd:YAG (1.319 microm) laser and a high-finesse optical buildup cavity. The result provides a precision test of modern relativistic and QED atomic theory.