39 research outputs found
The 11-years solar cycle as the manifestation of the dark Universe
The solar luminosity in the visible changes at the 10-3 level, following an
11 years period. In X-rays, which should not be there, the amplitude varies
100000 times stronger, making their mysterious origin since the discovery in
1938 even more puzzling, and inspiring. We suggest that the multifaceted
mysterious solar cycle is due to some kind of dark matter streams hitting the
Sun. Planetary gravitational lensing enhances (occasionally) slow moving flows
of dark constituents towards the Sun, giving rise to the periodic behaviour.
Jupiter provides the driving oscillatory force, though its 11.8 years orbital
period appears slightly decreased, just as 11 years, if the lensing impact of
other planets is included. Then, the 11 years solar clock may help to decipher
(overlooked) signatures from the dark sector in laboratory experiments or
observations in space.Comment: 7 pages, 1 Figure, to appear in the proceedings of the 9th Patras
workshop, Mainz, German
Impact of Conformational Effects on the Ring–Chain Equilibrium of Hydrogen-Bonded Dinucleosides
This is the peer reviewed version of the following article: Chemistry - A European Journal 24.46 (2018): 11983-11991, which has been published in final form at https://doi.org/10.1002/chem.201801704 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsSupramolecular ring-versus-chain equilibria are ubiquitous in biological and synthetic systems. Understanding the factors that decide whether a system will fall on one side or the other is crucial to the control of molecular self-assembly. This work reports results with two kinds of dinucleoside monomers, in which the balance between closed cycles and open polymers is found to depend on subtle factors that rule conformational equilibria, such as steric hindrance, intramolecular interactions, or π-conjugation pathwaysFunding from the European Research Council (ERC-StG 279548) and MINECO (CTQ2014-27729-P and CTQ2017-84727-P) is gratefully acknowledged (DGR). CFG gratefully acknowledges financial support from the Netherlands Organization for Scientific Research NWO (ECHO
Results and perspectives of the solar axion search with the CAST experiment
The status of the solar axion search with the CERN Axion Solar Telescope
(CAST) will be presented. Recent results obtained by the use of He as a
buffer gas has allowed us to extend our sensitivity to higher axion masses than
our previous measurements with He. With about 1 h of data taking at each of
252 different pressure settings we have scanned the axion mass range 0.39 eV 0.64 eV. From the absence of an excess of x rays when the
magnet was pointing to the Sun we set a typical upper limit on the axion-photon
coupling of g GeV at 95% C.L., the
exact value depending on the pressure setting. CAST published results represent
the best experimental limit on the photon couplings to axions and other similar
exotic particles dubbed WISPs (Weakly Interacting Slim Particles) in the
considered mass range and for the first time the limit enters the region
favored by QCD axion models. Preliminary sensitivities for axion masses up to
1.16 eV will also be shown reaching mean upper limits on the axion-photon
coupling of g GeV at 95% C.L.
Expected sensibilities for the extension of the CAST program up to 2014 will be
presented. Moreover long term options for a new helioscope experiment will be
evoked.Comment: 4 pages, 2 pages, to appear in the proceedings of the 24th Rencontres
de Blois V2 A few affiliations were not corrected in previous version V3
Author adde
CAST solar axion search with 3^He buffer gas: Closing the hot dark matter gap
The CERN Axion Solar Telescope (CAST) has finished its search for solar
axions with 3^He buffer gas, covering the search range 0.64 eV < m_a <1.17 eV.
This closes the gap to the cosmological hot dark matter limit and actually
overlaps with it. From the absence of excess X-rays when the magnet was
pointing to the Sun we set a typical upper limit on the axion-photon coupling
of g_ag < 3.3 x 10^{-10} GeV^{-1} at 95% CL, with the exact value depending on
the pressure setting. Future direct solar axion searches will focus on
increasing the sensitivity to smaller values of g_a, for example by the
currently discussed next generation helioscope IAXO.Comment: 5 pages, 2 figures. Last version uploade
Solar axion search with the CAST experiment
The CAST (CERN Axion Solar Telescope) experiment is searching for solar
axions by their conversion into photons inside the magnet pipe of an LHC
dipole. The analysis of the data recorded during the first phase of the
experiment with vacuum in the magnet pipes has resulted in the most restrictive
experimental limit on the coupling constant of axions to photons. In the second
phase, CAST is operating with a buffer gas inside the magnet pipes in order to
extent the sensitivity of the experiment to higher axion masses. We will
present the first results on the data taking as well as the
system upgrades that have been operated in the last year in order to adapt the
experiment for the data taking. Expected sensitivities on the
coupling constant of axions to photons will be given for the recent run just started in March 2008.Comment: Proceedings of the ICHEP 2008 conferenc
Search for low Energy solar Axions with CAST
We have started the development of a detector system, sensitive to single
photons in the eV energy range, to be suitably coupled to one of the CAST
magnet ports. This system should open to CAST a window on possible detection of
low energy Axion Like Particles emitted by the sun. Preliminary tests have
involved a cooled photomultiplier tube coupled to the CAST magnet via a
Galileian telescope and a switched 40 m long optical fiber. This system has
reached the limit background level of the detector alone in ideal conditions,
and two solar tracking runs have been performed with it at CAST. Such a
measurement has never been done before with an axion helioscope. We will
present results from these runs and briefly discuss future detector
developments.Comment: Paper submitted to the proceedings of the "4th Patras Workshop on
Axions, WIMPs and WISPs", DESY, Hamburg Site - Germany, 18-21 June 2008.
Author affiliations are reported on the title page of the paper. In version
2: 1 affiliation change, 3 references adde