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K. Zuber

Publications and source records attributed to K. Zuber.

At least 109 records · Page 6Linked to original sources
arXiv2006

Deformation Effects in Hot Rotating 46Ti Probed by the Charged Particle Emission and GDR gamma-Decay

The 46Ti* compound nucleus, as populated by the fusion-evaporation reaction 27Al+19F at the bombarding energy of E_lab=144 MeV, has been investigated by charged particle spectroscopy using the multidetector array ICARE at the VIVITRON tandem facility of the IReS (Strasbourg). The light charged particles and high-energy gamma-rays from the GDR decay have been measured in coincidence with selected evaporation residues. The CACARIZO code, a Monte Carlo implementation of the statistical-model code CASCADE, has been used to calculate the spectral shapes of evaporated alpha-particles which are compared with the experimental coincident spectra. This comparison indicates the signature of large deformations (possibly superdeformed and hyperdeformed shapes) present in the compound nucleus decay. The occurrence of the Jacobi shape transition is also discussed in the framework of a newly developed rotating liquid drop model.

nucl-ex↗
arXiv2005

Consensus Report of a Workshop on "Matrix elements for Neutrinoless Double Beta Decay"

This is the consensus of a Workshop on "Matrix elements for Neutrinoless Double Beta Decay" held at the IPPP Durham (UK). The aim of this workshop has been to define a well planned, coherent strategy to reduce the errors on nuclear matrix element calculations for double beta decay to a level of 30% by performing the necessary measurements with currently existing and planned facilities. These measurements should provide reliable input for the theoretical calculations. The outcome of the workshop has been organised in working packages. The consensus might act as a starting point for an international coherent effort to achieve this goal.

nucl-ex↗
arXiv2005

Experimental study of 113Cd beta decay using CdZnTe detectors

A search for the 4-fold forbidden beta decay of \iso{Cd}{113} has been performed with CdZnTe semiconductors. With 0.86 kg $\cdot$ days of statistics a half-life for the decay of $T_{1/2} = (8.2 \pm 0.2 (stat.) ^{+0.2}_{-1.0} (sys.)) \cdot 10^{15}$yrs has been obtained. This is in good agreement with published values. A comparison of the spectral shape with the one given on the Table of Isotopes Web-page shows a severe deviation.

nucl-ex↗
arXiv2005

Experimental neutrino physics

The current experimental status of neutrino physics is reviewed. It contains the evidences for a non-vanishing neutrino rest mass from neutrino oscillation searches. In addition an outlook is given on determining the various mixing matrix elements and mass differences more precisely with new experiments. Of special interest is the value of the mixing angle θ_{13} determining the possibility of detecting leptonic CP violation in the future. The prospect for absolute mass measurements using beta and double beta decay as well as cosmological observations is presented.

hep-ex↗
arXiv2004

GDR Feeding of the Highly-Deformed Band in 42Ca

The gamma-ray spectra from the decay of the GDR in the compound nucleus reaction 18O+28Si at bombarding energy of 105 MeV have been measured in an experiment using the EUROBALL IV and HECTOR arrays. The obtained experimental GDR strength function is highly fragmented, with a low energy (10 MeV) component, indicating a presence of a large deformation and Coriolis effects. In addition, the preferential feeding of the highly-deformed band in 42Ca by this GDR low energy component is observed.

nucl-ex↗
arXiv2004

Study of Deformation Effects in the Charged Particle Emission from 46Ti

The 46Ti compound nucleus, as populated by the fusion-evaporation reaction 27Al + 19F at the bombarding energy of 144 MeV, has been investigated by charged particle spectroscopy using the multidetector array ICARE at the VIVITRON tandem facility of the IReS (Strasbourg). The light charged particles have been measured in coincidence with evaporation residues. The CACARIZO code, a Monte Carlo implementation of the statistical-model code CASCADE, has been used to calculate the spectral shapes of evaporated alpha-particles which are compared with the experimental spectra. This comparison indicates the possible signature of large deformations of the compound nucleus.

nucl-ex↗
arXiv2003

Evidence for the Jacobi shape transition in hot 46Ti

The gamma-rays from the decay of the GDR in 46Ti compound nucleus formed in the 18O+28Si reaction at bombarding energy 105 MeV have been measured in an experiment using a setup consisting of the combined EUROBALL IV, HECTOR and EUCLIDES arrays. A comparison of the extracted GDR lineshape data with the predictions of the thermal shape fluctuation model shows evidence for the Jacobi shape transition in hot 46Ti. In addition to the previously found broad structure in the GDR lineshape region at 18-27 MeV caused by large deformations, the presence of a low energy component (around 10 MeV), due to the Coriolis splitting in prolate well deformed shape, has been identified for the first time.

nucl-ex↗
arXiv2003

A Search for various Double Beta Decay Modes of Cd, Te and Zn Isotopes

Various double beta decay modes of Cd, Zn and Te isotopes are explored with the help of CdTe and CdZnTe semiconductor detectors. The data set is splitted in an energy range below 1 MeV having a statistics of 134.5 g$\cdot$d and one above 1 MeV resulting in 532 g$\cdot$d. No signals were observed in all channels under investigation. New improved limits for the neutrinoless double beta decay of Zn70 of $T_{1/2} > 1.3 \cdot 10^{16} yrs$ (90% CL), the longest standing limit of all double beta isotopes, and 0$νβ^+$EC of Te120 of $T_{1/2} > 2.2 \cdot 10^{16} yrs$ (90% CL) are given. For the first time a limit on the half-life of the 2$ν$ECEC of $^{120}$Te of $T_{1/2} > 9.4 \cdot 10^{15} yrs$ (90% CL) is obtained. In addition, limits on 2$ν$ECEC for ground state transitions of Cd106, Cd108 and Zn64 are improved. The obtained results even under rough background conditions show the reliability of CdTe semiconductor detectors for rare nuclear decay searches.

nucl-ex↗
arXiv2003

Search for the Jacobi shape transition in light nuclei

The gamma-rays following the reaction 105 MeV 18O + 28Si have been measured using the EUROBALL IV, HECTOR and EUCLIDES arrays in order to investigate the predicted Jacobi shape transition. The high-energy gamma-ray spectrum from the GDR decay indicates a presence of large deformations in hot 46Ti nucleus, in agreement with new theoretical calculations based on the Rotating Liquid Drop model.

nucl-ex↗
arXiv2002

An alternative search for the electron capture of Te-123

A search for the electron capture of Te-123 has been performed using CdZnTe detectors. After a measuring time of 195 h no signal could be found resulting in a lower half-life limt of $T_{1/2} > 3.2 \cdot 10^{16}$ yrs (95 % CL) for this process. This clearly discriminates between existing experimental results which differ by six orders of magnitude and our data are in strong favour of the result with longer half-lifes.

nucl-ex↗
arXiv2002

Spectroscopy of low energy solar neutrinos using CdTe detectors

The usage of a large amount of CdTe(CdZnTe) semiconductor detectors for solar neutrino spectroscopy in the low energy region is investigated. Several different coincidence signals can be formed on five different isotopes to measure the Be-7 neutrino line at 862 keV in real-time. The most promising one is the usage of Cd-116 resulting in 89 SNU. The presence of Te-125 permits even the real-time detection of pp-neutrinos. A possible antineutrino flux above 713 keV might be detected by capture on Cd-106 .

astro-ph↗
arXiv2002

Long baseline neutrino oscillation experiments

Evidences for neutrino oscillations coming from atmospheric and solar observations can be probed by terrestrial long baseline experiments. This requires accelerator beams or nuclear power plants. The current status of these searches as well as future activities are discussed. A precise determination of all matrix elements and searches for a leptonic CP-violation will be possible with high intensity accelerator beams currently discussed in the context of neutrino factories.

hep-ex↗
arXiv2001

Physics with Low-Energy Muons at a Neutrino Factory Complex

The physics potential of an intense source of low-energy muons is studied. Such a source is a necessary stage towards building the neutrino factories and muon colliders which are being considered at present. The CERN Neutrino Factory could deliver muon beams with intensities 3-4 orders of magnitude higher than available now, with large freedom in the choice of the time structure. Low-energy muon physics contributes to many fields of basic research, including rare muon decays, i.e., decays that do not conserve muon number, measurements of fundamental constants, the muon anomalous magnetic moment, determination of the Lorentz structure of the weak interaction, QED tests, CPT tests, proton and nuclear charge distributions (even for short-lived isotopes), and condensed matter physics. In studying the experimental programme, we analyse the present limitations, list the requirements on the new muon beams, and describe some ideas on how to implement these beam lines in a CERN neutrino factory complex.

hep-ph↗
arXiv2001

Kaon physics with a high-intensity proton driver

We study opportunities for future high-precision experiments in kaon physics using a high-intensity proton driver, which could be part of the front-end of a muon storage ring complex. We discuss in particular the rare decays $K_L\toπ^0ν\barν$, $K^+\toπ^+ν\barν$, $K_L\toπ^0e^+e^-$, and lepton-flavour violating modes such as $K_L\toμe$ and $K\toπμe$. The outstanding physics potential and long-term interest of these modes is emphasized. We review status and prospects of current and planned experiments for the processes under consideration, and indicate possible improvements and strategies towards achieving the necessary higher sensitivity. Finally, we outline the machine requirements needed to perform these high-precision kaon experiments in the context of a muon storage ring facility.

hep-ph↗
arXiv2001

COBRA - Double beta decay searches using CdTe detectors

A new approach (called COBRA) for investigating double beta decay using CdTe (CdZnTe) semiconductor detectors is proposed. It follows the idea that source and detector are identical. This will allow simultaneous measurements of 5 $β^-β^-$ - and 4 $β^+β^+$ - emitters at once. Half-life limits for neutrinoless double beta decay of Cd-116 and Te-130 can be improved by more than one order of magnitude with respect to current limits and sensitivities on the effective Majorana neutrino mass of less than 1 eV can be obtained. Furthermore, for the first time a realistic chance of observing double electron capture processes exists. Additional searches for rare processes like the 4-fold forbidden Cd-113 $β$-decay, the electron capture of Te-123 and dark matter detection can be performed. The achievable limits are evaluated for 10 kg of such detectors and can be scaled accordingly towards higher detector masses because of the modular design of the proposed experiment.

nucl-ex↗
arXiv2001

"Neutrinoless Double Beta Decay" at a Neutrino Factory

We examine the prospects of detecting an analogous process of neutrinoless double beta decay at a neutrino factory from a high energy muon storage ring. Limits from LEP experiments, neutrinoless double beta decay as well as from global fits have to be incorporated and severely restrict the results. We investigate what limits on light and heavy effective Majorana neutrino masses can be obtained and compare them with existing ones. Discussed are also contributions from right-handed neutrinos and purely right-handed interactions. Other ``new physics'' contributions to the same final state might produce large event numbers.

hep-ph↗
arXiv2000

Effective Majorana neutrino masses

A generalisation of the neutrinoless double beta decay process is presented. Neutrinoless double beta decay measures only one out of nine possible effective Majorana neutrino masses in case of three flavours. Limits obtained for all the matrix elements - some of them for the first time - are presented using data from $μ- e$ conversion, neutrino-nucleon scattering, HERA and rare kaon decays. An outlook towards future possibilities to improve on the bounds is given.

hep-ph↗