Neutrino-less Double Electron Capture - a tool to research for Majorana neutrinos

The possibility to observe the neutrino-less double $\beta$ decay and thus to prove the Majorana nature of neutrino as well as provide a sensitive measure of its mass is a major challenge of to-day's neutrino physics. As an attractive alternative we propose to study the inverse process, the radiative neutrino-less double electron capture $0 \nu 2EC$. The associated monoenergetic photon provides a convenient experimental signature. Other advantages include the favourable ratio of the $0 \nu 2EC$ to the competing $2\nu 2EC$ capture rates and, very importantly, the existence of coincidence trigger to suppress the random background. These advantages partly offset the expected longer lifetimes. Rates for the $0\gamma 2EC$ process are calculated. High Z atoms are strongly favoured. A resonance enhancement of the capture rates is predicted at energy release comparable to the $2P-1S$ atomic level difference. The resonance conditions are likely to be met for decays to excited states in final nuclei. Candidates for such studies are considered. The experimental feasibility is estimated and found highly encouraging.Comment: New figure added, table updated, physical background discusse

Preparation of cooled and bunched ion beams at ISOLDE-CERN

Abstract.: At ISOLDE a new RadioFrequency Quadrupole ion Cooler and Buncher (RFQCB) is being constructed to improve ion optical properties of low-energy RIBs. The new features of the mechanical design and the status of the test bench, which will serve to test the device, will be presented in this contributio

Mass determination of 20,22^{20,22}Ne, 36,40^{36,40}Ar, and 86^{86}Kr for tests of the performance of a Penning trap when using highly charged ions

Atomic mass values are used in various fields of physics as indispensable parameters often requiring a very high accuracy. Until recently the mass measurements were performed in classical mass spectrometers reaching in the best cases a mass uncertainty of about 10 ppb. Penning traps are now able to determine atomic masses at an accuracy several orders of magnitude better. The Penning trap mass spectrometer SMILETRAP at the Manne Siegbahn Laboratory has been used to determine the masses of a number of isotopes with mass numbers in the region 1-204 and charges from 1+ to 52+. making use of the fact that the precision increases linearly with the charge state of the ion. In this paper we present mass measurements on **2**0**, **2**2Ne, **3**6**, **4**0Ar, and **8**6Kr at an uncertainty about 1 ppb. The masses of the five isotopes are 19.992 440 175 9(20) u, 21.991 385 115(19) u, 35.967 545 105(29) u, 39.962 383 123 2(30) u and 85.910 610 730(110) u respectively. These mass determinstions have been used to determine several properties of the SMILETRAP mass spectrometer. 50 Refs

Measurement of radioxenon and radioargon in air from soil with elevated uranium concentration

Among the most important indicators for an underground nuclear explosion are the radioactive xenon isotopes 131mXe, 133Xe, 133mXe and 135Xe and the radioactive argon isotope 37Ar. In order to evaluate a detection of these nuclides in the context of a nuclear test verification regime it is crucial to have knowledge about expected background concentrations. Sub soil gas sampling was carried out on the oil shale ash waste pile in Kvarntorp, Sweden, a location with known elevated uranium content where 133Xe and 37Ar were detected in concentrations up to 120 mBq/m3 and 40 mBq/m3 respectively. These data provides one of the first times when xenon and argon were both detected in the same sub soil gas. This, and the correlations between the radionuclides, the sub soil gas contents (i.e. CO2, O2, and radon) and uranium concentration in the pile, provide very interesting information regarding the natural background and the xenon concentration levels and can most likely be used as an upper limit on what to be expected naturally occurring

A new determination of the

The atomic and nuclear masses of 4He and 3He have been measured using doubly charged ions in a Penning trap connected to an electron beam ion source. Recent technical improvements allow mass determinations with uncertainties of a few parts in 1010. The obtained atomic masses are 4.002 603 256 8(13) u and 3.016 029 323 5(28) u respectively. These values deviate by as much as 5 standard deviations from the accepted values

Back to the line of stability

The Stockholm Penning trap has been connected to an electron beam ion source named CRYSIS located at the Manne Siegbahn Laboratory. It is combined to a high-resolution isotope separator that can provide singly charged mass selected ions of practically any element. These ions are fed into CRYSIS where it is subject to a very intense electron beam with an energy of 10–20 keV. The mass of the neutral atom is obtained by adding the masses of the missing electrons and subtracting their binding energies. The results on some 16 mass determinations made at an uncertainty from 3 to 0.3 ppb are commented on. In these measurements the mass number varies from 1 to 204 and the ion charges from 1+ to 52+. New mass values are obtained for the $^3$H, $^3$He and $^4$He masses. We have confirmed the Manitoba measurements of the $Q$-value of the double beta-decay of $^{76}$Ge and their mass measurements of the masses of $^{198}$Hg and $^{204}$Hg reaching the higher accuracy that traps offer. At present the mass uncertainty limit is about $3\times10^{-10}$ which is demonstrated by comparing our results with the most accurately measured masses by other groups

On the

We report here the atomic masses of 3H and 3He determined by using the Penning trap mass spectrometer Smiletra