Mario Martinez

Investigating halo substructures with annual modulation signature

Galaxy hierarchical formation theories, numerical simulations, the discovery of the Sagittarius Dwarf Elliptical Galaxy (SagDEG) in 1994 and more recent investigations suggest that the dark halo of the Milky Way can have a rich phenomenology containing non-thermalized substructures. In the present preliminary study, we investigate the case of the SagDEG (the best known satellite galaxy in the Milky Way crossing the solar neighborhood) analyzing the consequences of its dark matter stream contribution to the galactic halo on the basis of the DAMA/NaI annual modulation data. The present analysis is restricted to some WIMP candidates and to some of the astrophysical, nuclear and particle physics scenarios. Other candidates such as e.g. the light bosonic ones we discussed elsewhere, and other non-thermalized substructures are not yet addressed here.

Radiative corrections to the process e+e−→ννγ

Abstract We present a detailed calculation of the process e + e − →ν ν γ . For the lowest order, the calculation is done keeping a finite mass for the W boson and the results apply for unpolarized as well as longitudinally polarized beams. One-loop QED corrections are calculated and, together with the hard bremsstrahlung process e + e − →ν ν γγ , are implemented in an unweighted Monte Carlo generator of events. Results for a realistic experimental set-up are presented, amounting to corrections of the order of 17%.

Monte Carlo evaluation of the external gamma, neutron and muon induced background sources in the CUORE experiment

CUORE is a 1 ton scale cryogenic experiment aiming at the measurement of the Majorana mass of the electron neutrino. The detector is an array of 988 TeO2 bolometers used for a calorimetric detection of the two electrons emitted in the ββ(0ν) of Te. The sensitivity of the experiment to the lowest Majorana mass is determined by the rate of background events that can mimic a ββ(0ν). In this paper we investigate the contribution of external sources i.e. environmental gammas, neutrons and cosmic ray muons to the CUORE background and show that the shielding setup designed for CUORE guarantees a reduction of this external background down to a level < 10 counts/kgkeVyr at the Q-value, as required by the physical goal of the experiment.

Model independent fitting to the Z line shape

An improved model independent formula to fit theZ line shape parameters is presented. The accuracy of the QED radiative corrections used in the formula is estimated, as is the absolute accuracy of the formula itself. The precision of the formula is compared with existing fitting formulae, in terms of cross sections produced and in terms of theZ parameters returned from a fit. The errors which the LEP-SLC experiments can expect to achieve on theZ parameters are examined as a function of total integrated luminosity. The formula presented here can fit theZ parameters with high accuracy: below 1 MeV for theZ mass, the order of 1 MeV for total width, and below 0.04% for the hadronic and leptonic peak cross sections. Such biases will remain much below the expected experimental uncertainties from LEP and SLC.

A method to enhance the sensitivity of photomultipliers for air Cherenkov telescopes

A simple method to enhance the sensitivity of photomultipliers (PMTs) will be described. The method is based on applying onto the cathode window a specially prepared lacquer containing a wavelength shifter (WLS). A rapidly evaporating lacquer solvent results in a milky surface that acts as a photon scatterer. Applying the method to the ET 9116A PMT (hemispherical borosilicate window and Rubidium-bialkali photocathode) resulted in a good sensitivity in the short-wave UV range as well as an \20% increase above 330 nm: Details of the study, the procedure and a simple model for the explanation of the enhancement are presented. r 2003 Published by Elsevier Science B.V.

Cosmogenic radionuclide production in NaI(Tl) crystals

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 corresponding cosmic rays exposure history, must be both well known in order to assess the relevance of this effect in the achievable sensitivity of a given experiment. Although NaI(Tl) scintillators are being used in experiments aiming at the direct detection of dark matter since the first nineties of the last century, very few data about cosmogenic isotopes production rates have been published up to date. In this work we present data from two 12.5 kg NaI(Tl) detectors, developed in the frame of the ANAIS project, which were installed inside a convenient shielding at the Canfranc Underground Laboratory just after finishing surface exposure to cosmic rays. The very fast start of data taking allowed to identify and quantify isotopes with half-lives of the order of tens of days. Initial activities underground have been measured and then production rates at sea level have been estimated following the history of detectors; values of about a few tens of nuclei per kg and day for Te isotopes and 22Na and of a few hundreds for I isotopes have been found. These are the first direct estimates of production rates of cosmogenic nuclides in NaI crystals. A comparison of the so deduced rates with calculations using typical cosmic neutron flux at sea level and a carefully selected description of excitation functions will be also presented together with an estimate of the corresponding contribution to the background at low and high energies, which can be relevant for experiments aiming at rare events searches.

First array of enriched Zn

The R&D activity performed during the last years proved the potential of ZnSe scintillating bolometers to the search for neutrino-less double beta decay, motivating the realization of the first large-mass experiment based on this technology: CUPID-0. The isotopic enrichment in

Se bolometers to search for double beta decay

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