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

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

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

A Low energy Storage Ring for Partly Stripped Radioactive Ions

Storage rings are well established for the study of stable nuclei with many facilities operating world wide. Radioactive nuclei are being studied in storage rings at GSI and major upgrades are planned to this facility including two new storage rings. The production method at GSI, in-flight, results in fully stripped ions with large transverse and longitudinal emittance. We have studied the possibility of injecting ISOL beams into a storage ring. While the two production methods are considered to be complementary considering the elements that can be produced, the ISOL method yields higher intensities and cooler beams. Furthermore, as the ISOL beam is produced with low kinetic beam energies the beam can be further cooled with e.g. an RFQ cooler. Cool beams will simplify the injection process and result in very bright beams ideally suited for reaction studies and for the more exotic production of e.g. anti-protonic atoms through the so called merging beam method. The proposed design of a low energy storage ring, the acceleration scenario and a possible transfer to a high energy ring will be presented. Estimates for electron cooling time and vacuum half life will be discussed. A possible design for a merging beam facility with two rings and a merging section will be presented together with the physics case for anti-protonic atoms. The possibility of using the ring as a spectrometer to count the resulting ions after anti-proton annihilation will be discussed

SMILETRAP—A Penning trap facility for precision mass measurements using highly charged ions

Inequality between Maori and non-Maori has been an enduring feature of New Zealand society. But in recent decades, it has coincided with another unwelcome development: the growth of income gaps within Maori communities. These inequalities stem from the general social and economic position of Maori in New Zealand society, but also from the policies pursued by both Labour and National governments from 1984-99 and largely retained, although modified and softened, by Labour-led governments from 1999- 2008. Despite the overwhelming evidence that these policies substantially increased inequality, as detailed in this chapter, they have been revived and extended by National-led governments since 2008. This raises controversial questions about the current direction of Maori economic and social development. Who is currently benefiting, and who is not? To what extent do current ideas about Maori development empower some groups of Maori, while disenfranchising or marginalising others

SMILETRAP II

The new Penning trap mass spectrometer SMILETRAP II has been set up at the AlbaNova Research Center, Stockholm. Based on the former spectrometer SMILETRAP I, it uses the merits of highly-charged ions to achieve high precision in the mass measurements. Various improvements over the SMILETRAP I setup will allow to routinely perform mass measurements with relative uncertainties of 10⁻¹⁰ and below. In this paper we will discuss the limitations of SMILETRAP I and present the corresponding improvements of SMILETRAP II. An overview on the SMILETRAP II setup is given

Measurement of radioxenon and radioargon in soil gas collected in the region of Kvarntorp, Sweden

Over 40 soil gas samples were collected both in post-industrial areas as well as in undisturbed areas in the region of Kvarntorp, Sweden. Radioxenon (133Xe) was detected in 15 samples and radioargon was detected in 7 from 10 samples analysed. The concentration of radioxenon and radioargon in soil gas ranged up to 109 mBq/m3 and 19 mBq/m3, respectively. During sample collection other soil gases such as radon, CO2 and O2 were also measured and soil samples were taken along with dose rate measurements. The field experiment presented here shows that it is possible to detect naturally occurring radioxenon and radioargon in soil gas simultaneously