arXiv subjects

K. Blaum

Publications and source records attributed to K. Blaum.

At least 145 records · Page 8Linked to original sources

arXiv2013

Emergent Collectivity in Nuclei and Enhanced Proton-Neutron Interactions

Enhanced proton-neutron interactions occur in heavy nuclei along a trajectory of approximately equal numbers of valence protons and neutrons. This is also closely aligned with the trajectory of the saturation of quadrupole deformation. The origin of these enhanced p-n interactions is discussed in terms of spatial overlaps of proton and neutron wave functions that are orbit-dependent. It is suggested for the first time that nuclear collectivity is driven by synchronized filling of protons and neutrons with orbitals having parallel spins, identical orbital and total angular momenta projections, belonging to adjacent major shells and differing by one quantum of excitation along the z-axis. These results may lead to a new approach to symmetry-based theoretical calculations for heavy nuclei.

nucl-th↗

arXiv2013

Nuclear charge radii of potassium isotopes beyond N=28

We report on the measurement of optical isotope shifts for $^{38,39,42,44,46\text{-}51}$K relative to $^{47}$K from which changes in the nuclear mean square charge radii across the N=28 shell closure are deduced. The investigation was carried out by bunched-beam collinear laser spectroscopy at the CERN-ISOLDE radioactive ion-beam facility. Mean square charge radii are now known from $^{37}$K to $^{51}$K, covering all $νf_{7/2}$-shell as well as all $νp_{3/2}$-shell nuclei. These measurements, in conjunction with those of Ca, Cr, Mn and Fe, provide a first insight into the $Z$ dependence of the evolution of nuclear size above the shell closure at N=28.

nucl-ex↗

arXiv2013

The Electron Capture $^{163}$Ho Experiment ECHo: an overview

The determination of the absolute scale of the neutrino masses is one of the most challenging present questions in particle physics. The most stringent limit, $m(\barν_{\mathrm{e}})<2$eV, was achieved for the electron anti-neutrino mass \cite{numass}. Different approaches are followed to achieve a sensitivity on neutrino masses in the sub-eV range. Among them, experiments exploring the beta decay or electron capture of suitable nuclides can provide information on the electron neutrino mass value. We present the Electron Capture $^{163}$Ho experiment ECHo, which aims to investigate the electron neutrino mass in the sub-eV range by means of the analysis of the calorimetrically measured energy spectrum following electron capture of $^{163}$Ho. A high precision and high statistics spectrum will be measured with arrays of metallic magnetic calorimeters. We discuss some of the essential aspects of ECHo to reach the proposed sensitivity: detector optimization and performance, multiplexed readout, $^{163}$Ho source production and purification, as well as a precise theoretical and experimental parameterization of the calorimetric EC spectrum including in particular the value of $Q_{\mathrm{EC}}$. We present preliminary results obtained with a first prototype of single channel detectors as well as a first 64-pixel chip with integrated micro-wave SQUID multiplexer, which will already allow to investigate $m(ν_{\mathrm{e}})$ in the eV range.

physics.ins-det↗

arXiv2013

Schottky mass measurements of heavy neutron-rich nuclides in the element range $70\leZ \le79$ at the ESR

Storage-ring mass spectrometry was applied to neutron-rich $^{197}$Au projectile fragments. Masses of $^{181,183}$Lu, $^{185,186}$Hf, $^{187,188}$Ta, $^{191}$W, and $^{192,193}$Re nuclei were measured for the first time. The uncertainty of previously known masses of $^{189,190}$W and $^{195}$Os nuclei was improved. Observed irregularities on the smooth two-neutron separation energies for Hf and W isotopes are linked to the collectivity phenomena in the corresponding nuclei.

nucl-ex↗

arXiv2013

The Electron Capture $^{163}$Ho Experiment ECHo

The determination of the absolute scale of the neutrino masses is one of the most challenging questions in particle physics. Different approaches are followed to achieve a sensitivity on neutrino masses in the sub-eV range. Among them, experiments exploring the beta decay and electron capture processes of suitable nuclides can provide necessary information on the electron neutrino mass value. In this talk we present the Electron Capture 163-Ho experiment ECHo, which aims to investigate the electron neutrino mass in the sub-eV range by means of the analysis of the calorimetrically measured energy spectrum following the electron capture process of 163-Ho. A high precision and high statistics spectrum will be measured by means of low temperature magnetic calorimeter arrays. We present preliminary results obtained with a first prototype of single channel detectors as well as the participating groups and their on-going developments.

physics.ins-det↗

arXiv2013

Spins and Magnetic Moments of $^{49}$K and $^{51}$K: establishing the 1/2$^+$ and 3/2$^+$ level ordering beyond $N$ = 28

The ground-state spins and magnetic moments of $^{49,51}$K have been measured using bunched-beam high-resolution collinear laser spectroscopy at ISOLDE-CERN. For $^{49}$K a ground-state spin $I = 1/2$ was firmly established. The observed hyperfine structure of $^{51}$K requires a spin $I > 1/2$ and from its magnetic moment $μ(^{51}\text{K})= +0.5129(22)\, μ_N$ a spin/parity $I^π=3/2^+$ with a dominant $π1d_{3/2}^{-1}$ hole configuration was deduced. This establishes for the first time the re-inversion of the single-particle levels and illustrates the prominent role of the residual monopole interaction for single-particle levels and shell evolution.

nucl-ex↗

arXiv2013

Spins, Electromagnetic Moments, and Isomers of 107-129Cd

The neutron-rich isotopes of cadmium up to the N=82 shell closure have been investigated by high-resolution laser spectroscopy. Deep-UV excitation at 214.5 nm and radioactive-beam bunching provided the required experimental sensitivity. Long-lived isomers are observed in 127Cd and 129Cd for the first time. One essential feature of the spherical shell model is unambiguously confirmed by a linear increase of the 11/2- quadrupole moments. Remarkably, this mechanism is found to act well beyond the h11/2 shell.

nucl-ex↗

arXiv2013

Demonstration of the Double Penning Trap Technique with a Single Proton

Spin flips of a single proton were driven in a Penning trap with a homogeneous magnetic field. For the spin-state analysis the proton was transported into a second Penning trap with a superimposed magnetic bottle, and the continuous Stern-Gerlach effect was applied. This first demonstration of the double Penning trap technique with a single proton suggests that the antiproton magnetic moment measurement can potentially be improved by three orders of magnitude or more.

physics.atom-ph↗

arXiv2013

Resolution of Single Spin-Flips of a Single Proton

The spin magnetic moment of a single proton in a cryogenic Penning trap was coupled to the particle's axial motion with a superimposed magnetic bottle. Jumps in the oscillation frequency indicate spin-flips and were identified using a Bayesian analysis.

physics.atom-ph↗

arXiv2012

Q value and half-life of double-electron capture in Os-184

Os-184 has been excluded as a promising candidate for the search of neutrinoless double-electron capture. High-precision mass measurements with the Penning-trap mass spectrometer TRIGA-TRAP resulted in a marginal resonant enhancement with = -8.89(58) keV excess energy to the 1322.152(22) keV 0+ excited state in W-184. State-of-the-art energy density functional calculations are applied for the evaluation of the nuclear matrix elements to the excited states predicting a strong suppression due to the large deformation of mother and daughter states. The half-life of the transition in Os-184 exceeds T_{1/2} > 1.3 10^{29} years for an effective neutrino mass of 1 eV.

nucl-ex↗

arXiv2012

A new mass value for 7Li

A high-accuracy mass measurement of 7Li was performed with the Smiletrap Penning trap mass spectrometer via a cyclotron frequency comparison of Li3+ and H2+. A new atomic mass value of 7Li has been determined to be 7.016,003,425,6,(45)u with a relative uncertainty of 0.63 ppb. It has uncovered a discrepancy as large as 14 sigma (1.1 micro u) deviation relative to the literature value given in the Atomic-Mass Evaluation AME 2003. The importance of the improved and revised 7Li mass value, for calibration purposes in nuclear-charge radii and atomic mass measurements of the neutron halos 9Li and 11Li, is discussed.

nucl-ex↗

arXiv2012

Direct mass measurements of cadmium and palladium isotopes and their double-beta transition Q-values

The Q-value of the double-electron capture in Cd-108 has been determined to be (272.04 +/- 0.55) keV in a direct measurement with the double-Penning trap mass spectrometer TRIGA-TRAP. Based on this result a resonant enhancement of the decay rate of Cd-108 is excluded. We have confirmed the double-beta transition Q-values of Cd-106 and Pd-110 recently measured with the Penning-trap mass spectrometers SHIPTRAP and ISOLTRAP, respectively. Furthermore, the atomic masses of the involved nuclides Cd-106, Cd-108, Cd-110, Pd-106, Pd-108 and Pd-110 have been directly linked to the atomic mass standard.

nucl-ex↗

arXiv2011

Q-Value and Half-Lives for the Double-Beta-Decay Nuclide 110Pd

The 110Pd double-beta decay Q-value was measured with the Penning-trap mass spectrometer ISOLTRAP to be Q = 2017.85(64) keV. This value shifted by 14 keV compared to the literature value and is 17 times more precise, resulting in new phase-space factors for the two-neutrino and neutrinoless decay modes. In addition a new set of the relevant matrix elements has been calculated. The expected half-life of the two-neutrino mode was reevaluated as 1.5(6) E20 yr. With its high natural abundance, the new results reveal 110Pd to be an excellent candidate for double-beta decay studies.

nucl-ex↗

arXiv2011

Evaluation of the resonance enhancement effect in neutrinoless double-electron capture in 152Gd, 164Er and 180W atoms

We study the resonant neutrinoless double-electron capture (0nECEC) in 152Gd, 164Er and 180W atoms, associated with the ground-state to ground-state nuclear transitions. The corresponding matrix elements are calculated within the deformed QRPA using the realistic Bonn-CD nucleon-nucleon interaction. The half-lives are estimated with the use of the most recent precision data on the Q-values of these processes. Perspectives of experimental search for the 0nECEC with the isotopes 152Gd, 164Er and 180W are discussed.

hep-ph↗

arXiv2011

Probing the nuclide 180W for neutrinoless double-electron capture exploration

The mass difference of the nuclides 180W and 180Hf has been measured with the Penning-trap mass spectrometer SHIPTRAP to investigate 180W as a possible candidate for the search for neutrinoless doubleelectron capture. The Q-value was measured to 143.20(27)keV. This value in combination with the calculations of the atomic electron wave functions and other parameters results in a half-life of the 0+ \rightarrow 0+ ground-state to ground-state double-electron capture transition of approximately 5\cdot10E27 years/ ^2.

nucl-ex↗

arXiv2011

PENTATRAP: A novel cryogenic multi-Penning trap experiment for high-precision mass measurements on highly charged ions

The novel five-Penning trap mass spectrometer PENTATRAP is developed at the Max-Planck-Institut für Kernphysik (MPIK), Heidelberg. Ions of interest are long-lived highly charged nuclides up to bare uranium. PENTATRAP aims for an accuracy of a few parts in 10^12 for mass ratios of mass doublets. A physics program for PENTATRAP includes Q-values measurements of β-transitions relevant for neutrino physics, stringent tests of quantum electrodynamics in the regime of extreme electric fields, and a test of special relativity. Main features of PENTATRAP are an access to a source of highly charged ions, a multi-trap configuration, simultaneous measurements of frequencies, a continuous precise monitoring of magnetic field fluctuations, a fast exchange between different ions, and a highly sensitive cryogenic non-destructive detection system. This paper gives a motivation for the new mass spectrometer PENTATRAP, presents its experimental setup, and describes the present status.

physics.atom-ph↗

arXiv2011

The trap design of PENTATRAP

A novel Penning trap tower consisting of five compensated cylindrical Penning traps is developed for the PENTATRAP mass spectrometer at the Max-Planck-Institut für Kernphysik in Heidelberg, Germany. An analytical expression for the electrostatic potential inside the trap tower is derived to calculate standard Penning trap properties like the compensation of anharmonicities and an orthogonal geometry of the trap electrodes. Since the PENTATRAP project described in the preceding article aims for ultra high-precision mass-ratio measurements of highly charged ions up to uranium, systematic effects for highly charged ions inside the trap tower are considered for the design process as well. Finally, a limit due to remaining anharmonic shifts at large amplitudes is estimated for the resulting geometry, which is important for phase-sensitive measurements of the reduced cyclotron frequency of the ions.

physics.atom-ph↗

arXiv2011

Observation of Spin Flips with a Single Trapped Proton

Radio-frequency induced spin transitions of one individual proton are observed for the first time. The spin quantum jumps are detected via the continuous Stern-Gerlach effect, which is used in an experiment with a single proton stored in a cryogenic Penning trap. This is an important milestone towards a direct high-precision measurement of the magnetic moment of the proton and a new test of the matter-antimatter symmetry in the baryon sector.

physics.atom-ph↗