C. Pobes

University of Zaragoza | UNIZAR · Institute of Material Science (ICMA)

We study the logarithmic transition sensitivities to temperature and current, α and β, of bare Mo/Au TES sensors without any normal metal structure, with and without relevant weak link effects. Both parameters display a smooth dependence with bias. We analyze them as a function of bias, bath temperature and TES size. We observe relevant differences...

Transition edge sensors (TESs) are extremely sensitive thermometers made of superconducting materials operating at their transition temperature, where small variations in temperature give rise to a measurable increase in electrical resistance. Coupled to suitable absorbers, they are used as radiation detectors with very good energy resolution in se...

Sodium Iodide Thallium doped (NaI(Tl)) scintillation detectors have been applied to the direct searches for dark matter since the 1980s and have produced one of the most challenging results in the field—the observation by the DAMA/LIBRA collaboration of an annual modulation in the detection rate for more than twenty cycles. This result is very diff...

Transition-edge sensors (TESs) are used as very sensitive thermometers in microcalorimeters aimed at detection of different wavelengths. In particular, for soft X-ray astrophysics, science goals require very high resolution microcalorimeters which can be achieved with TESs coupled to suitable absorbers. For many applications there is also need for...

Transition-edge sensors (TESs) are used as very sensitive thermometers in microcalorimeters aimed at detection of different wavelengths. In particular, for soft X-ray astrophysics, science goals require very high-resolution microcalorimeters which can be achieved with TESs coupled to suitable absorbers. For many applications, there is also need for...

We report on the sensitivity of superconducting transition tem-perature $(T_c)$ to the individual layers' thickness in Mo/Au prox-imity bilayers to be used in Transition-Edge Sensors. The achieved good reproducibility and quality of the bilayers allow a clear determination of the superconducting critical temperature $T_c$ as a function of the M...

We report on the fabrication and characterization of Mo/Au-based transition-edge sensors (TES), intended to be used in X-ray detectors. We have performed complete dark characterization using I–V curves, complex impedance and noise measurements at different bath temperatures and biases. Devices with two designs, different sizes and different membran...

The R(T,I) shape of the superconducting transition in Transition Edge Sensors (TES) is of crucial importance to determine their ultimate performance. This paper reports a study of the temperature and current dependences of the transition of Mo/Au TESs, focused on the low resistance region, where these devices preferentially operate. A large broaden...

The semimetal character of bismuth and its large photon absorbing power make of this element the most suitable absorber material for X-ray low temperature detectors. This application requires coatings of Bi with thicknesses and properties that only electrodeposition methods may achieve. Although there are studies on electrodeposition of bismuth for...

Application of NaI(Tl) detectors in the search for galactic dark matter particles through their elastic scattering off the target nuclei is well motivated because of the long standing DAMA/LIBRA highly significant positive result on annual modulation, still requiring confirmation. For such a goal, it is mandatory to reach very low threshold in ener...

We report on the development of Mo/Au based Transition Edge Sensors (TESs) aimed at soft X-ray detection. TESs of different sizes with T $_{\hbox{c}}$ ~100 mK and very narrow transitions have been fabricated. Dark characterization based on I-V, complex impedance and noise measurements has allowed us to obtain their basic functional parameters at di...

The ANAIS (Annual modulation with NaI(Tl) Scintillators) experiment aims at the confirmation of the DAMA/LIBRA positive annual modulation signal using the same target and technique at the Canfranc Underground Laboratory (LSC). A first step, named ANAIS-25 (two 12.5 kg NaI(Tl) modules) taking data from December 2012 to February 2015, provided intere...

ANAIS experiment will look for dark matter annual modulation with large mass of ultra-pure NaI(Tl) scintillators at the Canfranc Underground Laboratory (LSC), aiming to confirm the DAMA/LIBRA positive signal in a model-independent way. Two 12.5 kg each NaI(Tl) crystals provided by Alpha Spectra are currently taking data at the LSC. Present status o...

A thorough understanding of the background sources is mandatory in any experiment searching for rare events. The ANAIS (Annual Modulation with NaI(Tl) Scintillators) experiment aims at the confirmation of the DAMA/LIBRA signal at the Canfranc Underground Laboratory (LSC). Two NaI(Tl) crystals of 12.5 kg each produced by Alpha Spectra have been taki...

The ANAIS experiment aims at the confirmation of the DAMA/LIBRA signal. A detailed analysis of two NaI(Tl) crystals of 12.5 kg each grown by Alpha Spectra will be shown: effective threshold at 1 keVee is at reach thanks to outstanding light collection and robust PMT noise filtering protocols and the measured background is well understood down to 3...

The ANAIS experiment aims at the confirmation of the DAMA/LIBRA signal using the same target and technique at the Canfranc Underground Laboratory (LSC) in Spain. ANAIS detectors consist of large NaI crystals coupled to two photomultipliers (PMTs). In this work we present Single Electron Response (SER) data for several units of the Hamamatsu R12669S...

ANAIS (Annual modulation with NaI Scintillators) is a project aiming to set up at the new facilities of the Canfranc Underground Laboratory (LSC), a large scale NaI(Tl) experiment in order to explore the DAMA/LIBRA annual modulation positive result using the same target and technique. Two 12.5 kg each NaI(Tl) crystals provided by Alpha Spectra took...

The cosmogenic production of long-lived radioactive isotopes in materials is an hazard for experiments demanding ultra-low background conditions. Although NaI(Tl) scintillators have been used in this context for a long time, very few activation data were available. We present results from two 12.5 kg NaI(Tl) detectors, developed within the ANAIS pr...

The production of long-lived radioactive isotopes in materials due to the exposure to cosmic rays on Earth surface can be an hazard for experiments demanding ultra-low background conditions, typically performed deep underground. Production rates of cosmogenic isotopes in all the materials present in the experimental set-up, as well as the correspon...

ANAIS (Annual modulation with NAI Scintillators) experiment aims to look for dark matter annual modulation with 250 kg of ultrapure NaI(Tl) scintillators at the Canfranc Underground Laboratory (LSC), in order to confirm the DAMA/LIBRA positive signal in a model-independent way. The detector will consist in an array of close-packed single modules, e...

The X-ray spectroscopy telescope Athena has been designed to implement the science theme "the hot and energetic universe", selected by the European Space Agency as the second large mission of its Cosmic Vision program. X-IFU, one of the two interchangeable focal plane instruments of Athena, is a high resolution X-ray spectrometer made of a large ar...

Dark matter particles scattering off some target nuclei are expected to deposit very small energies in form of nuclear recoils (below 100 keV). Because of the low scintillation efficiency for nuclear recoils vs. electron recoils, in most of the scintillating targets considered in the search for dark matter, the region below 10 keVee concentrates mo...

The ANAIS (Annual modulation with NaI(Tl) Scintillators) experiment aims at the confirmation of the DAMA/LIBRA signal using the same target and technique at the Canfranc Underground Laboratory (LSC). 250 kg of ultra pure NaI(Tl) crystals will be used as target, divided into 20 modules, 12.5 kg mass each, and coupled to two high e?ciency photomultip...

NaI(Tl) large crystals are applied in the search for galactic dark matter particles through their elastic scattering off the target nuclei in the detector by measuring the scintillation signal produced. However, energies deposited in the form of nuclear recoils are small, which added to the low efficiency to convert that energy into scintillation,...

Samples from different materials typically used as optical windows or light guides in scintillation detectors were studied in a very low background environment, at the Canfranc Underground Laboratory, searching for scintillation. A positive result can be confirmed for natural quartz: two distinct scintillation components have been identified, not b...

Despite that it is widely used as a scintillator at room temperature, the hygroscopicity of NaI complicates its handling and limits its application for many purposes, for example as a cryogenic detector. To overcome this problem we study coating materials that can act as humidity barriers, in particular parylene, a polymer that can be deposited in...

Dark matter direct search experiments with scintillators need an accurate knowledge of Light Relative Efficiency Factors (REF) between electron and nuclear recoils to estimate the energy of the recoiling nuclei from the scintillation signal (if the light signal is used with this purpose) or to implement an effective background rejection based on th...

The Athena+ mission concept is designed to implement the Hot and Energetic Universe science theme submitted to the European Space Agency in response to the call for White Papers for the definition of the L2 and L3 missions of its science program. The Athena+ science payload consists of a large aperture high angular resolution X-ray optics and twelv...

The ANAIS (Annual Modulation with NaI(Tl) Scintillators) experiment aims at the confirmation of the DAMA/LIBRA signal using the same target and technique at the Canfranc Underground Laboratory. 250 kg of ultrapure NaI(Tl) crystals will be used as a target, divided into 20 modules, each coupled to two photomultipliers. Two NaI(Tl) crystals of 12.5 k...

Several large NaI(Tl) detectors, produced by different companies, have been operated in the Canfranc Underground Laboratory (LSC) in the frame of the ANAIS (Annual modulation with NaI Scintillators) project devoted to the direct detection of dark matter. A complete background model has been developed for a 9.6 kg detector (referred as ANAIS-0 proto...

Very large thallium doped sodium iodide crystals operated underground and in very low background environment in the context of a dark matter search experiment have been used to determine scintillation components in the tens of ms range in the light pulse induced by different interacting particles: gammas/muons and alphas.

NaI(Tl) is a widely-used scintillator at room temperature, and it is particularly interesting as a target for dark matter searches. Its hygroscopic character however makes it unsuitable for many applications, in particular for bolometric particle detection at very low temperature. Despite that, a NaI scintillating bolometer would provide unique fea...

Scintillating bolometers, in which the simultaneous detection of light and heat allows to discriminate the nature of the interacting particle, are one of the most promising detectors for Dark Matter (DM) searches. One main advantage is the wide range of materials that can be used as target, that could provide a key for WIMP identification. The EURE...

NaI (Tl) is a well known high light yield scintillator. Very large crystals can be grown to be used in a wide range of applications. In particular, such large crystals are very good-performing detectors in the search for dark matter, where they have been used for a long time and reported first evidence of the presence of an annual modulation in the...

The ROSEBUD collaboration measured the differential flux of fast neutrons inside a shielding of lead irradiated with a source of 252Cf using two scintillating bolometers of LiF and Al2O3 at 20 mK. We compare an unfolding method using a three parameter model for the fast component of the neutron flux with a multigroup method in which the energy inte...

ANAIS experiment will look for dark matter annual modulation using NaI(Tl) scintillators at the Canfranc Underground Laboratory (LSC). Highly purified NaI(Tl) crystals are being developed to reach the required sensitivity. In a parallel way, the ANAIS-0 module (made with a low background St Gobain NaI(Tl) crystal) has been taking data at the LSC, t...

The ROSEBUD Collaboration has dedicated several underground runs to study different types of bolometers, mainly for the search of dark matter. Some of these runs, profiting from the good energy resolution of one bolometer of BGO and the ultra-low background of the underground laboratory of Canfranc (LSC), allowed the measurement of the L/K electron...

Scintillating bolometers are particle detectors with a high particle discrimination power with many applications in nuclear and particle physics. This discrimination power is based on the different scintillation yield for different particles, and is strongly dependent on the target used. At the very low temperatures required for the operation of th...

EURECA (European Underground Rare Event Calorimeter Array) is an astro-particle physics facility aiming to directly detect galactic dark matter. The Laboratoire Souterrain de Modane has been selected as host laboratory. The EURECA collaboration unites CRESST, EDELWEISS and the Spanish-French experiment ROSEBUD, thus concentrating and focussing effo...

We report the status of the ANAIS (Annual modulation with NAI Scintillators) experiment focusing on the developments towards the improvement of the background level of our detectors and the reduction of the energy threshold.

The ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) Collaboration has tested scintillating bolometers of BGO (Bi4Ge3O 12), Al2O3 and LiF in a common experimental set-up in an ultralow background environment at the Canfranc Underground Laboratory. We present the new results of a recent analysis of the data obtained. The BGO heat and light...

Scintillating bolometers of LiF and Al2O3 can monitor the fast neutrons flux in WIMPs searches. With both materials we merge the traditional fast neutron detection methods of induced reactions and scattering. The ROSEBUD collaboration devoted an underground run in the old Canfranc laboratory to study the response of LiF and Al2O3 to fast neutrons f...

In the frame of the ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) collaboration, we have tested at surface level (Orsay) and underground (Canfranc) properties at low temperature of a BGO scintillating bolometer developed as a prototype for dark matter searches. The response of the detector to different particles, both in heat and light,...

A 46 g BGO (Bi4Ge3O12) scintillating bolometer has been tested at 20 mK as a prototype for dark matter direct detection in the frame of the ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) collaboration. The bolometer has been operated first in Orsay and then in an ultra-low background environment at the Canfranc Underground Laboratory. We...

EURECA (European Underground Rare Event Calorimeter Array) is an astro-particle physics facility aiming to directly detect galactic dark matter. The Laboratoire Souterrain de Modane has been selected as host laboratory. The EURECA collaboration unites CRESST, EDELWEISS and the Spanish-French experiment ROSEBUD, thus concentrating and focussing effo...

The European Underground Rare Event Calorimeter Array (EURECA) will be an astro-particle physics facility in the Laboratoire Souterrain de Modane, aiming to directly detect galactic dark matter. The EURECA collaboration unites CRESST, EDELWEISS and the Spanish-French experiment ROSEBUD, thus concentrating and focussing effort on cryogenic detector...

Scintillating bolometers of sapphire, BGO and LiF have been recently tested both at the Institut d’Astrophysique Spatiale (IAS) and the Laboratorio Subterráneo de Canfranc (LSC) in the frame of the ROSEBUD collaboration. We report on their response to different particles (α, β, γ and nuclear recoils) both in the heat and light channel. Signal outpu...

In previous work of the ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) collaboration, undoped sapphire has shown high light yield at very low temperature and low particle discrimination energy threshold which convert sapphire scintillating bolometers in very suitable detectors for dark matter searches. Measuring the nuclear recoil therma...

Scintillating bolometers are very suitable detectors for dark matter searches. They offer a wide absorber choice allowing to tune up different masses and couplings of WIMPs, background rejection capability and high efficiency in the conversion into heat of nuclear recoil energy releases. In a previous work we have shown that undoped sapphire can be...

ROSEBUD (Rare Objects Search with Bolometers UndergrounD) is a collaboration focused on the development of scintillating bolometers for WIMP (Weakly Interacting Massive Particles) searches. In this work we present the results of tests performed with three small scintillating bolometers (50 g sapphire, 46 g BGO and 33 g LiF) used simultaneously in t...

Dark matter experiments face two main challenges: low rate and low energy detection. Background reduction techniques are widely in development in order to improve sensitivity. Energy threshold is more technique-dependent and so it requires specific efforts for each detection approach. In this work we present some improvements in this line that open...

A 107 kg NaI(Tl) experiment is projected at the Canfranc Underground Laboratory to look for dark matter particles by the annual modulation in their interaction rate. It will consist of 10 crystals selected from a set of 14 that remain underground since 1986. A first stage aiming at background and threshold reduction was performed with a 10.7 kg NaI...

A lasting Dark Matter Search Program is being carried out in the facilities of the Canfranc Underground Laboratory since 1990 with the participation of the University of Zaragoza (UZ) Nuclear and Astroparticle Physics group. A brief summary of the most relevant experiments will be followed by the report on the status of the present experimental eff...

The particle discrimination capability of various scintillating bolometers has been tested, proving their suitability for dark matter searches. In particular, BGO and undoped sapphire have shown low particle discrimination energy threshold (down to around 20 and 10 keV, respectively). We report on the present status of the ROSEBUD (Rare Objects SEa...

The scintillation properties of undoped sapphire at very low temperature have been studied in the framework of the ROSEBUD (Rare Objects SEarch with Bolometers UnDerground) Collaboration devoted to dark matter searches [1]. We present an estimation of its light yield under gamma, alpha and neutron excitation.

A large mass dark matter search experiment with NaI scintillators at the Canfranc Underground Laboratory is underway. A 10.7 kg prototype with improved light collection efficiency and special low-background improvements has been tested and started taking data underground in summer 2005. Preliminary results and prospects for the experiment are prese...

Measurements of radioactivity and composition of rock from the main hall of the new Canfranc underground laboratory are reported. Estimates of neutron production by spontaneous fission and (α, n) reactions are given.

A new estimate of the production rates of several long-lived isotopes cosmogenically induced in germanium is presented, paying attention to those products relevant in Double Beta Decay searches. Special care has been taken in the selection of reliable excitation functions.

Sodium Iodide scintillators are very interesting particle and radiation detectors. Low background requirements could limit their application in a variety of fields. We report the e.orts to understand and reduce the background in a set of 14 NaI detectors, stored underground since 1988, undertaken in the frame of the ANAIS experiment [1] in several...

In this letter, we report on the performance of scintillating sapphire bolometers developed in the framework of the ROSEBUD (Rare Objects Search with Bolometers UnDerground) Collaboration devoted to dark matter searches. The simultaneous measurement of heat and light allows the discrimination of the type of particle increasing the sensitivity for t...

This paper describes the forthcoming enlargement of the Canfranc Underground Laboratory (LSC) which will allow to host new international Astroparticle Physics experiments and therefore to broaden the European underground research area. The new Canfranc Underground Laboratory will operate in coordination (through the ILIAS Project) with the Gran Sas...

Preliminary results on double beta decay (DBD) of Te-130, obtained in the first run of the CUORICINO experiment are presented. The set-up consists of an array of 62 crystals of TeO2 operating as bolometers in a deep underground dilution unit at a temperature of about 10 mK. Due to a total mass of about 41 kg, CUORICINO represents by far the most ma...