Review of double beta experiments

This paper is the first part of the manuscript written in April 2012 for my academic Accreditation to supervise research. It offers a review of the double beta experimental techniques. My purpose is to detail, for each technique, the different origins of background, how they can be identified, and how they can be reduced. Advantages and limitations are discussed. This review is organized as follows. First, the question of the possible Majorana nature for the neutrino is presented and the physic of neutrinoless double beta decay is summarized. Then I begin by presenting the tracko-calo NEMO-3 and SuperNEMO experiments. I've worked on these two experiments since 15 years. So it was natural to start with them with a relatively more exhaustive description. I will then present the germanium technique. I will then review the bolometer technique. I will describe in detail the recent progress in scintillating bolometers because I think that it is one of the most promising techniques. Finally I will review the large liquid scintillator detectors and Xenon TPC. The last chapter offers a summary of the different techniques and projects.Comment: 100 pages; Manuscript for Accreditation to supervise research (Univ. Paris-Sud 11), May 201

The Contribution of EUV from Clusters of Galaxies to the Cosmic Ionizing Background

Recent observations with the Extreme Ultraviolet Explorer (EUVE) suggest that at least some clusters of galaxies are luminous sources of extreme ultraviolet (EUV) radiation. It is not clear yet whether EUV emission is a general feature of clusters; for the purposes of limiting the contribution to the background radiation, we assume that it is true of most clusters. Assuming that the source of the EUV emission is inverse Compton (IC) scattering of the Cosmic Microwave Background photons by relativistic electrons, we construct a simple model for the expected average emission from clusters as a function of their mass and the redshift of interest. Press-Schechter theory is used to determine the abundance of clusters of various masses as a function of redshift. We determine the amount of background radiation produced by clusters. The total mean intensity, spectrum, and the ionization rates for HI and HeII are determined at present and at a variety of redshifts. Because clusters form by the merger of smaller subclusters, the amount of EUV background radiation should be larger at present than in the past. We compare our results to the ionizing background expected from quasars. We find that while clusters do contribute a significant EUV background, it is less than a percent of that expected from quasars.Comment: 13 pages in emulateapj5 style with 7 figures, accepted for publication in Astrophysical Journa

Astronomical Site Ranking Based on Tropospheric Wind Statistics

We present comprehensive and reliable statistics of high altitude wind speeds and the tropospheric flows at the location of five important astronomical observatories. Statistical analysis exclusively of high altitude winds point to La Palma as the most suitable site for adaptive optics, with a mean value of 22.13 m/s at the 200 mbar pressure level. La Silla is at the bottom of the ranking, with the largest average value 200 mbar wind speed(33.35 m/s). We have found a clear annual periodicity of high altitude winds for the five sites in study. We have also explored the connection of high to low altitude atmospheric winds as a first approach of the linear relationship between the average velocity of the turbulence and high altitude winds (Sarazin & Tokovinin 2001). We may conclude that high and low altitude winds show good linear relationships at the five selected sites. The highest correlation coefficients correspond to Paranal and San Pedro Martir, while La Palma and La Silla show similar high to low altitude wind connection. Mauna Kea shows the smallest degree of correlation, which suggests a weaker linear relationship. Our results support the idea of high altitude winds as a parameter for rank astronomical sites in terms of their suitability for adaptive optics, although we have no evidence for adopting the same linear coefficient at different sites. The final value of this linear coefficient at a particular site could drastically change the interpretation of high altitude wind speeds as a direct parameter for site characterization.Comment: 18 pages, 5 figures. Accepted in MNRA