arXiv subjects

F. J. Iguaz

Publications and source records attributed to F. J. Iguaz.

At least 109 records · Page 6Linked to original sources

arXiv2012

Characterization of microbulk detectors in argon- and neon-based mixtures

A recent Micromegas manufacturing technique, so called Microbulk, has been developed, improving the uniformity and stability of this kind of detectors. Excellent energy resolutions have been obtained, reaching values as low as 11% FWHM at 5.9 keV in Ar+5%iC4H10. This detector has other advantages like its flexible structure, low material budget and high radio-purity. Two microbulk detectors with gaps of 50 and 25 um have been characterized in argon- and neon-based mixtures with ethane, isobutane and cyclohexane. The results will be presented and discussed. The gain curves have been fitted to the Rose-Korff gain model and dependences of the electron mean free path and the threshold energy for ionization have been obtained. The possible relation between these two parameters and the energy resolution will be also discussed.

physics.ins-det↗

arXiv2012

SiPMs coated with TPB : coating protocol and characterization for NEXT

Silicon photomultipliers (SiPM) are the photon detectors chosen for the tracking readout in NEXT, a neutrinoless ββ decay experiment which uses a high pressure gaseous xenon time projection chamber (TPC). The reconstruction of event track and topology in this gaseous detector is a key handle for background rejection. Among the commercially available sensors that can be used for tracking, SiPMs offer important advantages, mainly high gain, ruggedness, cost-effectiveness and radio-purity. Their main drawback, however, is their non sensitivity in the emission spectrum of the xenon scintillation (peak at 175 nm). This is overcome by coating these sensors with the organic wavelength shifter tetraphenyl butadienne (TPB). In this paper we describe the protocol developed for coating the SiPMs with TPB and the measurements performed for characterizing the coatings as well as the performance of the coated sensors in the UV-VUV range.

physics.ins-det↗

arXiv2011

MIMAC: A micro-tpc matrix project for directional detection of dark matter

Directional detection of non-baryonic DarkMatter is a promising search strategy for discriminating WIMP events from background ones. This strategy requires both a measurement of the recoil energy down to a few keV and 3D reconstruction of tracks down to a few mm. The MIMAC project, based on a micro-TPC matrix, filled with CF4 and CHF3 is being developed. The first results of a chamber prototype of this matrix, on low energy nuclear recoils (1H and 19F) obtained with mono-energetic neutron fields are presented. The discovery potential of this search strategy is illustrated by a realistic case accessible to MIMAC.

astro-ph.IM↗

arXiv2011

Low X-ray bakground measurements at the Underground Canfranc Laboratory

Micromegas detectors, thanks to the good spatial and temporal discrimination capabilities, are good candidates for rare event search experiments. Recent X-ray background levels achieved by these detectors in the CAST experiment have motivated further studies in the nature of the background levels measured. In particular, different shielding configurations have been tested at the Canfranc Underground Laboratory, using a microbulk type detector which was previously running at the CAST experiment. The first results underground show that this technology, which is made of low radiative materials, is able to reach background levels up to $2 \times 10^{-7}$keV$^{-1}$s$^{-1}$cm$^{-2}$ with a proper shielding. Moreover, the experimental background measurements are complemented with Geant4 simulations which allow to understand the origin of the background, and to optimize future shielding set-ups.

physics.ins-det↗

arXiv2011

New developments in Micromegas Microbulk detectors

A new Micromegas manufacturing technique, based on kapton etching technology, has been recently developed, improving the uniformity and stability of this kind of readouts. Excellent energy resolutions have been obtained, reaching 11% FWHM for the 5.9 keV photon peak of 55Fe source and 1.8% FWHM for the 5.5 MeV alpha peak of the 241Am source. The new detector has other advantages like its flexible structure, low material and high radio-purity. The two actual approaches of this technique will be described and the features of these readouts in argon-isobutane mixtures will be presented. Moreover, the low material present in the amplification gap makes these detectors approximate the Rose and Korff model for the avalanche amplification, which will be discussed for the same type of mixtures. Finally, we will present several applications of the microbulk technique.

physics.ins-det↗

arXiv2011

The discrimination capabilities of Micromegas detectors at low energy

The latest generation of Micromegas detectors show a good energy resolution, spatial resolution and low threshold, which make them idoneous in low energy applications. Two micromegas detectors have been built for dark matter experiments: CAST, which uses a dipole magnet to convert axion into detectable x-ray photons, and MIMAC, which aims to reconstruct the tracks of low energy nuclear recoils in a mixture of CF4 and CHF3. These readouts have been respectively built with the microbulk and bulk techniques, which show different gain, electron transmission and energy resolutions. The detectors and the operation conditions will be described in detail as well as their discrimination capabilities for low energy photons will be discussed.

physics.ins-det↗

arXiv2011

The CAST experiment: status and perspectives

The status of the solar axion search with the CERN Axion Solar Telescope (CAST) will be discussed. Results from the first part of CAST phase II where the magnet bores were filled with 4He gas at variable pressure in order to scan axion masses up to 0.4 eV will be presented. 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 < 2.17 x 10^10 GeV$-1 at 95% CL for axion masses lower than 0.4 eV, the exact result depending on the pressure setting. Our search for axions with masses up to about 1.2 eV using 3He as a buffer gas is in progress in the second part of CAST phase II. Expectations for sensibilities will be given. Near future perspectives as well as more long term options for a new helioscope experiment will be evoked.

hep-ex↗

arXiv2011

Status of R&D on Micromegas for Rare Event Searches: The T-REX project

The T-REX project aims at developing novel readout techniques for Time Projection Chambers in experiments searching for rare events. The enhanced performance of the latest Micromegas readouts in issues like energy resolution, gain stability, homogeneity, material budget, combined with low background techniques, is opening new windows of opportunity for their application in this field. Here we review the latest results regarding the use and prospects of Micromegas readouts in axion physics (CAST and the future helioscope), as well as the R&D carried out within NEXT, to search for the neutrinoless double-beta decay.

physics.ins-det↗

arXiv2011

Micromegas detector developments for MIMAC

The aim of the MIMAC project is to detect non-baryonic Dark Matter with a directional TPC. The recent Micromegas efforts towards building a large size detector will be described, in particular the characterization measurements of a prototype detector of 10 $\times$ 10 cm$^2$ with a 2 dimensional readout plane. Track reconstruction with alpha particles will be shown.

physics.ins-det↗

arXiv2011

Towards a new generation axion helioscope

We study the feasibility of a new generation axion helioscope, the most ambitious and promising detector of solar axions to date. We show that large improvements in magnetic field volume, x-ray focusing optics and detector backgrounds are possible beyond those achieved in the CERN Axion Solar Telescope (CAST). For hadronic models, a sensitivity to the axion-photon coupling of $\gagamma\gtrsim {\rm few} \times 10^{-12}$ GeV$^{-1}$ is conceivable, 1--1.5 orders of magnitude beyond the CAST sensitivity. If axions also couple to electrons, the Sun produces a larger flux for the same value of the Peccei-Quinn scale, allowing one to probe a broader class of models. Except for the axion dark matter searches, this experiment will be the most sensitive axion search ever, reaching or surpassing the stringent bounds from SN1987A and possibly testing the axion interpretation of anomalous white-dwarf cooling that predicts $m_a$ of a few meV. Beyond axions, this new instrument will probe entirely unexplored ranges of parameters for a large variety of axion-like particles (ALPs) and other novel excitations at the low-energy frontier of elementary particle physics.

hep-ex↗

arXiv2011

Micromegas detector developments for Dark Matter directional detection with MIMAC

The aim of the MIMAC project is to detect non-baryonic Dark Matter with a directional TPC using a high precision Micromegas readout plane. We will describe in detail the recent developments done with bulk Micromegas detectors as well as the characterisation measurements performed in an Argon(95%)-Isobutane(5%) mixture. Track measurements with alpha particles will be shown.

physics.ins-det↗

arXiv2011

MIMAC : A micro-tpc matrix for directional detection of dark matter

Directional detection of non-baryonic Dark Matter is a promising search strategy for discriminating WIMP events from background. However, this strategy requires both a precise measurement of the energy down to a few keV and 3D reconstruction of tracks down to a few mm. To achieve this goal, the MIMAC project has been developed. It is based on a gaseous micro-TPC matrix, filled with CF4 and CHF3. The first results on low energy nuclear recoils (H, F) obtained with a low mono-energetic neutron field are presented. The discovery potential of this search strategy is discussed and illustrated by a realistic case accessible to MIMAC.

astro-ph.CO↗

arXiv2010

MIMAC : A micro-tpc matrix for directional detection of dark matter

Directional detection of non-baryonic Dark Matter is a promising search strategy for discriminating WIMP events from background. However, this strategy requires both a precise measurement of the energy down to a few keV and 3D reconstruction of tracks down to a few mm. To achieve this goal, the MIMAC project has been developed. It is based on a gaseous micro-TPC matrix, filled with 3He, CF4 and/or C4H10. The first results on low energy nuclear recoils (1H and 19F) obtained with a low mono-energetic neutron field are presented. The discovery potential of this search strategy is discussed and illustrated by a realistic case accessible to MIMAC.

astro-ph.IM↗

arXiv2010

Probing New Physics Models of Neutrinoless Double Beta Decay with SuperNEMO

The possibility to probe new physics scenarios of light Majorana neutrino exchange and right-handed currents at the planned next generation neutrinoless double beta decay experiment SuperNEMO is discussed. Its ability to study different isotopes and track the outgoing electrons provides the means to discriminate different underlying mechanisms for the neutrinoless double beta decay by measuring the decay half-life and the electron angular and energy distributions.

hep-ex↗

arXiv2010

Spectral modeling of scintillator for the NEMO-3 and SuperNEMO detectors

We have constructed a GEANT4-based detailed software model of photon transport in plastic scintillator blocks and have used it to study the NEMO-3 and SuperNEMO calorimeters employed in experiments designed to search for neutrinoless double beta decay. We compare our simulations to measurements using conversion electrons from a calibration source of $\rm ^{207}Bi$ and show that the agreement is improved if wavelength-dependent properties of the calorimeter are taken into account. In this article, we briefly describe our modeling approach and results of our studies.

physics.ins-det↗

arXiv2010

Micromegas readouts for double beta decay searches

Double beta $ββ$ decay experiments are one of the most active research topics in Neutrino Physics. The measurement of the neutrinoless mode $0νββ$ could give unique information on the neutrino mass scale and nature. The current generation of experiments aims at detector target masses at the 100 kg scale, while the next generation will need to go to the ton scale in order to completely explore the inverse hierarchy models of neutrino mass. Very good energy resolutions and ultra-low background levels are the two main experimental requirements for a successful experiment. The topological information of the $ββ$ events offered by gaseous detectors like gas Time Projection Chambers (TPC) could provide a very powerful tool of signal identification and background rejection. However only recent advances in TPC readouts may assure the competitiveness of a high pressure gas TPCs for $ββ$ searches, especially regarding the required energy resolution. In this paper we present first results on energy resolution with state-of-the-art microbulk Micromesh Gas Amplification Structure (Micromegas) using a 5.5 MeV alpha source in high pressure pure xenon. Resolutions down to 2 % FWHM have been achieved for pressures up to 5 bar. These results, together with their recently measured radiopurity , prove that Micromegas readouts are not only a viable option but a very competitive one for $ββ$ searches.

physics.ins-det↗

arXiv2010

Radiopurity of Micromegas readout planes

Micromesh Gas Amplification Structures (Micromegas) are being used in an increasing number of Particle Physics applications since their conception fourteen years ago. More recently, they are being used or considered as readout of Time Projection Chambers (TPCs) in the field of Rare Event searches (dealing with dark matter, axions or double beta decay). In these experiments, the radiopurity of the detector components and surrounding materials is measured and finely controlled in order to keep the experimental background as low as possible. In the present paper, the first measurement of the radiopurity of Micromegas planes obtained by high purity germanium spectrometry in the low background facilities of the Canfranc Underground Laboratory (LSC) is presented. The obtained results prove that Micromegas readouts of the microbulk type are currently manufactured with radiopurity levels below 30 microBq/cm2 for Th and U chains and ~60 microBq/cm2 for 40K, already comparable to the cleanest detector components of the most stringent low background experiments at present. Taking into account that the studied readouts were manufactured without any specific control of the radiopurity, it should be possible to improve these levels after dedicated development.

physics.ins-det↗

arXiv2010

Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils

The development of BiPo detectors is dedicated to the measurement of extremely high radiopurity in $^{208}$Tl and $^{214}$Bi for the SuperNEMO double beta decay source foils. A modular prototype, called BiPo-1, with 0.8 $m^2$ of sensitive surface area, has been running in the Modane Underground Laboratory since February, 2008. The goal of BiPo-1 is to measure the different components of the background and in particular the surface radiopurity of the plastic scintillators that make up the detector. The first phase of data collection has been dedicated to the measurement of the radiopurity in $^{208}$Tl. After more than one year of background measurement, a surface activity of the scintillators of $\mathcal{A}$($^{208}$Tl) $=$ 1.5 $μ$Bq/m$^2$ is reported here. Given this level of background, a larger BiPo detector having 12 m$^2$ of active surface area, is able to qualify the radiopurity of the SuperNEMO selenium double beta decay foils with the required sensitivity of $\mathcal{A}$($^{208}$Tl) $<$ 2 $μ$Bq/kg (90% C.L.) with a six month measurement.

physics.ins-det↗