The ArDM project: a Dark Matter Direct Detection Experiment based on Liquid Argon

The Dark Matter part of the universe presumably consists of WIMPs (Weakly Interacting Massive Particles). The ArDM project aims at measuring signals induced by WIMPs in a liquid argon detector. A 1-ton prototype is currently developed with the goal of demonstrating the feasibility of such a direct detection experiment with large target mass. The technical design of the detector aims at ind ependently measuring the scintillation light and the ionization charge originating from an interaction of a WIMP with an argon nucleus. The principle of the experiment and the conceptual design of the detector are described.Comment: 4 pages, 1 figure, Invited talk at 2nd Workshop On TeV Particle Astrophysics, 28-31 August 2006, Madison, WI, US

ICANOE and OPERA experiments at the LNGS/CNGS

We discuss two experiments ICANOE and OPERA that have been proposed within the context of long-baseline and atmospheric neutrino experiments in Europe. The joint ICANOE/OPERA program aims at further improving our understanding of the effect seen in atmospheric neutrinos. This program is based on (1) a continuation of the observation of atmospheric neutrinos with the improved technique of ICANOE/ICARUS (2) a sensitive numu->nue and numu->nutau appearance program with the accelerator neutrinos coming from CERN (CNGS) from a distance of 730 km.Comment: 8 pages; Invited talk at the XIX International Conference on Neutrino Physics and Astrophysics (Neutrino 2000), Sudbury, Canada, June 16-21, 2000; new version fix typo

Measurement of the ortho-positronium confinement energy in mesoporous thin films

In this paper, we present measurements of the ortho-positronium emission energy in vacuum from mesoporous films using the time of flight technique. We show evidence of quantum mechanical confinement in the mesopores that defines the minimal energy of the emitted Ps. Two samples with different effective pore sizes, measured with positron annihilation lifetime spectroscopy, are compared for the data collected in the temperature range 50-400 K. The sample with smaller pore size exhibits a higher minimal energy ($73\pm$5 meV), compared to the sample with bigger pores ($48\pm$5 meV), due to the stronger confinement. The dependence of the emission energy with the temperature of the target is modeled as ortho-positronium being confined in rectangular boxes in thermodynamic equilibrium with the sample. We also measured that the yield of positronium emitted in vacuum is not affected by the temperature of the target.Comment: 8 pages, 9 figures *Added references. * Corrected typos and Fig. 3 label. * Revised argument in section IV B abd C, results unchanged

TCT investigation of the one-sided depletion of low-temperature covalently bonded silicon sensor P-N diodes

In the context of particle detectors, low-temperature covalent wafer-wafer bonding allows for integration of high-Z materials as absorbing layers with readout chips produced in standard CMOS processes. This enables for instance the fabrication of novel highly efficient X-ray imaging sensors. In order to investigate the effects of the covalent bonding on the signal generated in such sensors, wafer-wafer bonded silicon-silicon P-N pad diodes have previously been produced. The behaviour of these test samples is being investigated with transient current technique (TCT) measurements. In this paper we present an overview of the TCT setup as well as a custom sandwich-type sample holder used for these measurements. A review of the results presented in a previous paper shows, that the bonded P-N structures show a highly asymmetric depletion behaviour under reverse bias. IR edge TCT measurements confirm that only the P-side of the samples is being depleted. Comparing the integral of the TCT signals with the expected values based on the Shockley-Ramo theorem reveals an excess of signal being collected. This excess seems to be linked to a long exponential tail which is observed in the time domain TCT signals.Comment: To be submitted to JINST, 18 pages, 10 figures, 2 table

Direct detection of Earth matter effects (MSW) in flavor oscillations at neutrino beams from stored muon decays

We explore the possibility of a neutrino oscillation experiment with a very long baseline in the range of $6500\ \rm km$ and a neutrino beam produced by the decays of muons circulating in a storage ring. The recent developments in view of muon colliders allow us to envisage neutrino sources of a sufficiently high intensity. We first consider \nue\leftrightarrow\numu oscillations within a three flavor oscillation framework. Evidence for this oscillation implies that the (1-3) mixing is non-zero. We study the effect of the neutrino propagation through matter (MSW effect). Given the density of the Earth, the existence of the MSW resonance can be experimentally proven by comparing the oscillated spectra of neutrinos obtained from the decays of muons of positive and negative charges. Moreover, a precision study of the oscillations of all three flavors could be performed since neutrinos are above the tau production threshold (appearance searches)

Artificial intelligence for improved fitting of trajectories of elementary particles in inhomogeneous dense materials immersed in a magnetic field

In this article, we use artificial intelligence algorithms to show how to enhance the resolution of the elementary particle track fitting in inhomogeneous dense detectors, such as plastic scintillators. We use deep learning to replace more traditional Bayesian filtering methods, drastically improving the reconstruction of the interacting particle kinematics. We show that a specific form of neural network, inherited from the field of natural language processing, is very close to the concept of a Bayesian filter that adopts a hyper-informative prior. Such a paradigm change can influence the design of future particle physics experiments and their data exploitation

ArDM: a ton-scale liquid Argon experiment for direct detection of Dark Matter in the Universe

The ArDM project aims at developing and operating large noble liquid detectors to search for direct evidence of Weakly Interacting Massive Particle (WIMP) as Dark Matter in the Universe. The initial goal is to design, assemble and operate a $\approx$1 ton liquid Argon prototype to demonstrate the feasibility of a ton-scale experiment with the required performance to efficiently detect and sufficiently discriminate backgrounds for a successful WIMP detection. Our design addresses the possibility to detect independently ionization and scintillation signals. In this paper, we describe this goal and the conceptual design of the detector.Comment: 5 pages, 3 figures, Talk given at IXth international conference on Topics in Astroparticle and Underground Physics (TAUP05), Zaragoza, (Spain

Underground Neutrino Detectors for Particle and Astroparticle Science: the Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER)

The current focus of the CERN program is the Large Hadron Collider (LHC), however, CERN is engaged in long baseline neutrino physics with the CNGS project and supports T2K as recognized CERN RE13, and for good reasons: a number of observed phenomena in high-energy physics and cosmology lack their resolution within the Standard Model of particle physics; these puzzles include the origin of neutrino masses, CP-violation in the leptonic sector, and baryon asymmetry of the Universe. They will only partially be addressed at LHC. A positive measurement of $\sin^22\theta_{13}>0.01$ would certainly give a tremendous boost to neutrino physics by opening the possibility to study CP violation in the lepton sector and the determination of the neutrino mass hierarchy with upgraded conventional super-beams. These experiments (so called ``Phase II'') require, in addition to an upgraded beam power, next generation very massive neutrino detectors with excellent energy resolution and high detection efficiency in a wide neutrino energy range, to cover 1st and 2nd oscillation maxima, and excellent particle identification and $\pi^0$ background suppression. Two generations of large water Cherenkov detectors at Kamioka (Kamiokande and Super-Kamiokande) have been extremely successful. And there are good reasons to consider a third generation water Cherenkov detector with an order of magnitude larger mass than Super-Kamiokande for both non-accelerator (proton decay, supernovae, ...) and accelerator-based physics. On the other hand, a very massive underground liquid Argon detector of about 100 kton could represent a credible alternative for the precision measurements of ``Phase II'' and aim at significantly new results in neutrino astroparticle and non-accelerator-based particle physics (e.g. proton decay).Comment: 31 pages, 14 figure