Search

In this paper we will describe the characterisation of a rf detection chain based on a travelling wave parametric amplifier (TWPA). The detection chain is meant to be used for dark matter axion searches and thus it is mounted coupled to a high Q microwave resonant cavity. A system noise temperature $T_{\rm sys} = (3.3 \pm 0.1$) K has been measured at a frequency of 10.77 GHz, using a novel scheme allowing measurement of $T_{\rm sys} $ exactly at the cavity output port., Comment: 8 pages

We describe and operate a novel spin-magnetometer based on the phase modulation of cavity magnon polaritons. In this scheme a rf magnetic field is detected through the sidebands it induces on a pump, and the experimental configuration allows for a negligible pump noise and a high frequency readout. The demonstrator setup, based on a copper cavity coupled to an yttrium iron garnet sphere hybrid system, reached a sensitivity of $2.0\,\mathrm{pT/\sqrt{Hz}}$, evading the pump noise and matching the theoretical previsions. An optimized setup can attain a rf magnetic field sensitivity of about $8\,\mathrm{fT/\sqrt{Hz}}$ at room temperature. An orders of magnitude improvement is expected at lower temperatures, making this instrument one of the few magnetometers accessing the sub-fT limit. Due to its natural applications, miniaturization and multiplexing are eventually discussed.

This article presents the measurements of the luminescence and scintillation under X-ray of undoped, Si-doped, and Si, B codoped gallium-arsenide (GaAs) samples at cryogenic temperature over a wide infrared (IR) region using Si and InGaAs photodetectors. The undoped GaAs has a narrow emission band at 838 nm (1.48 eV) and a low light output of about 2 ph/keV. The GaAs:Si has three broad luminescence bands at 830 nm (1.49 eV), 1070 nm (1.16 eV), and 1335 nm (0.93 eV) and a light output of about 67 ph/keV. GaAs:(Si, B) has four luminescence bands at 860 nm (1.44 eV), 930 nm (1.33 eV), 1070 nm (1.16 eV), and 1335 nm (0.93 eV) with a light yield of approximately 119 ph/keV. With advances in photodetection, GaAs promises to be a useful cryogenic scintillator for the detection of electron recoils from MeV/c2 dark matter.

A haloscope of the QUAX--$a\ensuremath{\gamma}$ experiment composed of an oxygen-free high thermal conductivity-Cu cavity inside an 8.1 T magnet and cooled to $\ensuremath{\sim}200\text{ }\text{ }\mathrm{mK}$ is put in operation for the search of galactic axion with mass ${m}_{a}\ensuremath{\simeq}43\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$. The power emitted by the resonant cavity is amplified with a Josephson parametric amplifier whose noise fluctuations are at the standard quantum limit. With the data collected in about 1 h at the cavity frequency ${\ensuremath{\nu}}_{c}=10.40176\text{ }\text{ }\mathrm{GHz}$, the experiment reaches the sensitivity necessary for the detection of galactic QCD-axion, setting the 90% confidence level limit to the axion-photon coupling ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}l0.766\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$.

It is a straightforward result of electromagnetism that dipole oscillators radiate more strongly when they are synchronized, and that if there are $N$ dipoles, the overall emitted intensity scales with $N^2$. In atomic physics, such an enhanced radiative property appears when coherence among two-level identical atoms is established, and is well-known as "superradiance" \cite{Dicke:1954aa}. In superfluorescence (SF), atomic coherence develops via a self-organisation process stemming from the common radiated field, starting from a incoherently prepared population inversion \cite{Bonifacio:1975aa}. First demonstrated in a gas \cite{Skribanowitz:1973} and later in condensed matter systems \cite{Florian:1984}, its potential is currently being investigated in the fields of ultranarrow linewidth laser development for fundamental tests in physics \cite{Meiser:2009,Meiser:2010,Bohnet:2012aa,Norcia:2016, Norcia:2018}, and for the development of devices enabling entangled multi-photon quantum light sources \cite{Raino:2018aa,Angerer:2018aa}. A barely developed aspect in superradiance is related to the properties of the dipole array that generates the pulsed radiation field. In this work we establish the experimental conditions for formation of a macroscopic dipole via superfluorescence, involving the remarkable number of $4\times10^{12}$ atoms. Even though rapidly evolving in time, it represents a flexible test-bed in quantum optics. Self-driven atom dynamics, without the mediation of cavity QED nor quantum dots or quantum well structures, is observed in a cryogenically-cooled rare-earth doped material. We present clear evidence of a decay rate that is enhanced by more than 1-million times compared to that of independently emitting atoms. We thoroughly resolve the dynamics by directly measuring the intensity of the emitted radiation as a function of time.

A ferromagnetic axion haloscope searches for Dark Matter in the form of axions by exploiting their interaction with electronic spins. It is composed of an axion-to-electromagnetic field transducer coupled to a sensitive rf detector. The former is a photon-magnon hybrid system, and the latter is based on a quantum-limited Josephson parametric amplifier. The hybrid system consists of ten 2.1 mm diameter YIG spheres coupled to a single microwave cavity mode by means of a static magnetic field. Our setup is the most sensitive rf spin-magnetometer ever realized. The minimum detectable field is $5.5\times10^{-19}\,$T with 9 h integration time, corresponding to a limit on the axion-electron coupling constant $g_{aee}\le1.7\times10^{-11}$ at 95% CL. The scientific run of our haloscope resulted in the best limit on DM-axions to electron coupling constant in a frequency span of about 120 MHz, corresponding to the axion mass range $42.4$-$43.1\,\mu$eV. This is also the first apparatus to perform an axion mass scanning by changing the static magnetic field., Comment: 4 pages, 4 figures

Low energy threshold detectors are necessary in many frontier fields of the experimental physics. In particular these are extremely important for probing Dark Matter (DM) possible candidates. We present a novel detection approach that exploits the energy levels of atoms embedded into solid crystals of inert gases maintained at low temperature. We exploit laser-assisted transitions that are triggered by the absorption of the incident particle in the material and leads to a photon or an electron emission . Two possible schemes are thus possible: one is based on light signal while the other takes advantage of high efficiency-in vacuum single-electron detection using microchannel plate or channeltron sensors. Through these schemes, we could be able to detect low energy release in the range from sub eV to tens of eV in large volume crystals opening thus the possibility to investigate light DM candidates.

A photon-magnon hybrid system can be realised by coupling the electron spin resonance of a magnetic material to a microwave cavity mode. The quasiparticles associated with the system dynamics are the cavity magnon polaritons, which arise from the mixing of strongly coupled magnons and photons. We illustrate how these particles can be used to probe the magnetisation of a sample with a remarkable sensitivity, devising suitable spin-magnetometers which ultimately can be used to directly assess oscillating magnetic fields. Specifically, the capability of cavity magnon polaritons of converting magnetic excitations to electromagnetic ones, allows for translating to magnetism the quantum-limited sensitivity reached by state-of-the-art electronics. Here we employ hybrid systems composed of microwave cavities and ferrimagnetic spheres, to experimentally implement two types of novel spin-magnetometers., Comment: 7 pages, 3 figures

The QUAX proposal studies the interaction of dark matter axions with electrons. As the effect of axions can be described as an effective magnetic field, the signal is a magnetization oscillation of a sample. To detect it, the material is placed in a resonant cavity and polarized with a static magnetic field. Here we describe the operation of such a device, with a resonance frequency of 14 GHz, corresponding to an axion mass ma = 58 μeV. Eventually some recent developments on the resonant cavities design and test are detailed.

The potential of photon-magnon hybrid systems as building blocks for quantum information science has been widely demonstrated, and it is still the focus of much research. We leverage the strengths of this unique heterogeneous physical system in the field of precision physics beyond the standard model, where the sensitivity to the so-called "invisibles" is currently being boosted by quantum technologies. Here, we demonstrate that quanta of spin waves, driven by tiniest, effective magnetic field, can be detected in a large frequency band using a hybrid system as transducer. This result can be applied to the search of cosmological signals related, for example, to cold Dark Matter, which may directly interact with magnons. Our model of the transducer is based on a second-quantisation two-oscillators hybrid system, it matches the observations, and can be easily extended to thoroughly describe future large-scale ferromagnetic haloscopes., Comment: 9 pages, 5 figures

Multiple scattering effects influence the transport properties of excess electrons in gaseous and fluid dielectrics but also affect the energy levels of electrons in delocalized molecular orbitals and can be investigated by carrying out spectroscopic observations. We have measured the infrared cathodoluminescence of the Xe 2 excimer in dense Xe gas, and in Xe-He, and Xe-N 2 mixtures. The large orbital characterizing the weakly bound, optically active electron of Xe 2 encompasses several surrounding atoms and allows us to study their effects on the electron energy. In particular, the Coulomb force screening on the electron due to the atoms polarizability and the mutiple scattering effects described by the quantum scattering length are discussed and a gas density dependence of the Xe 2 energy levels is predicted. A good agreement with the experimental density dependent wavelength shift of the infrared Xe 2 excimer band is found.

A field, which mediates entanglement between two quantum systems, must be of quantum nature. Attempts to witness this way quantumlike features of the gravitational field with tabletop experiments are actively studied recently, in particular by considering to look at two masses in a superposition in two locations, each in one interferometer. Entanglement intervention is probed when the interferometers are put side by side. If the masses interact only via Newtonian attraction, and still some degree of entanglement is found, than the gravitational field must be quantum like, or at least non-classical. The masses considered are mesoscopic, 10–14 Kg to 10–12 Kg, and in one proposal Mach–Zehnder interferometry is considered. Liquid He4 is superfluid below 2.17 K, and shows macroscopic quantum behaviour, in particular matter interferometry, as in the Superfluid He Quantum Inteference Device—SHeQUID. With its Josephson junctions as slits, the SHeQUID parallels a Mach–Zehnder. In this case the matter quantities involved are macroscopic, 10–8 Kg. We propose and analize the feasibility of a scheme on the lines of the above, where the matter field is given by superfluid He4, and the Mach–Zehnder’s are two SHeQUID, put side by side. We find that the proposed experiment is feasible, using only well demonstrated methods and technologies, with no need to extensions beyond the current frontiers.

We present experimental results concerning the direct excitation of the magnetisation in a photon-magnon hybrid system composed of a microwave cavity and an embedded yttrium iron garnet (YIG) sphere. An 11 ps ultrafast pulsed laser, with wavelength of 1064 nm outside the YIG transparence window, directly excite the magnon modes. We measure the energy deposited in the Kittel mode of magnetisation by exploiting its coupling to the TE102 mode of the rectangular microwave cavity in the strong coupling regime. Energy collection is performed by a standard rf detection chain reading an antenna matched to the cavity resonance. This technique can prove to be essential in the study of the dynamics of cavity magnon-polaritons, finding application in dark matter axion searches and future magnon based quantum information studies.

Dark matter (DM) represents one of the most intriguing challenges of modern physics, both for the theoretical predictions and for the experimental setups. The search for the possible DM component candidates regards a wide range of objects and of energy values. In order to detect processes related to very weak interactions, as expected in these cases, it is necessary to improve the performances of the available detectors making them more efficient in terms of energy threshold and mass. Here we present a research activity aimed at the development of a novel type of detector based on laser interrogation of atomic energy levels for species that have been loaded in a solid matrix of a non interacting material at very low temperatures. The laser assisted transitions are only promoted when an incident particle is absorbed in the material, releasing its energy to the embedded atoms. The detection can be obtained via both optical and electronic methods.

The emission spectrum of Erbium-doped fluoride crystals excited by soft X-rays in the (400–1700) nm wavelength range is investigated between 3.2 K and 300 K. The largest component of the crystals emission is observed in the infrared range, which corresponds to a light yield of several tens of photons/keV. Such a large value is caused by energy transfer processes between the Erbium ions which convert the excitation of a dopant ion at high energies into the emission of multiple infrared photons. The present results show that this mechanism could be exploited to realize scintillators of high light yield.

Axions, originally proposed to solve the strong CP problem of quantum chromodynamics, emerge now as leading candidates of WISP dark matter. The rich phenomenology associated to the light and stable QCD axion can be described as an effective magnetic field that can be experimentally investigated. For the QUAX experiment, dark matter axions are searched by means of their resonant interactions with electronic spins in a magnetized sample. In principle, axion-induced magnetization changes can be detected by embedding a sample in an rf cavity in a static magnetic field. In this work we describe the operation of a prototype ferromagnetic haloscope, with a sensitivity limited by thermal fluctuations and receiver noise. With a preliminary dark matter search, we are able to set an upper limit on the coupling constant of DFSZ axions to electrons $$g_{aee}

Low energy threshold detectors are necessary in many frontier fields of the experimental physics. In this work, we present a novel detection approach based on pure or doped matrices of inert gases solidified at cryogenic temperatures. The small energy release of the incident particle can be transferred directly (in pure crystals) or through a laser-driven ionization (in doped materials) to the electrons of the medium that are then converted into free electrons. The charge collection process of the electrons that consists in their drift within the crystal and their extraction through the solid–vacuum interface gives rise to an electric signal that we exploit for preliminary tests of charge collection and crystal quality. Such tests are carried out in different matrices of neon and methane using an UV-assisted apparatus for electron injection in crystals.

We demonstrate an all-optical method for manipulating the magnetization in a 1-mm YIG (yttrium-iron-garnet) sphere placed in a $\sim0.17\,$T uniform magnetic field. An harmonic of the frequency comb delivered by a multi-GHz infrared laser source is tuned to the Larmor frequency of the YIG sphere to drive magnetization oscillations, which in turn give rise to a radiation field used to thoroughly investigate the phenomenon. The radiation damping issue that occurs at high frequency and in the presence of highly magnetizated materials, has been overcome by exploiting magnon-photon strong coupling regime in microwave cavities. Our findings demonstrate an effective technique for ultrafast control of the magnetization vector in optomagnetic materials via polarization rotation and intensity modulation of an incident laser beam. We eventually get a second-order susceptibility value of $\sim10^{-7}$ cm$^2$/MW for single crystal YIG., 5 pages, 4 figures

The feasibility of an electron-polarized, active target to be used as detector in neutrino scattering experiments, suggested by several theoretical papers, has been investigated. We report on the properties of the paramagnetic crystal Gd2SiO5 (GSO), in which 7.7% of the total number of electrons present can be polarized by lowering the temperature and applying an intense external magnetic field. The material magnetic susceptibility has been measured down to cryogenic temperatures showing that for H¼ 5 T and T¼ 4 K about 80% of the maximum allowed magnetization can be attained. Also the spectral and time response of the crystal have been characterized and the scintillation process has been studied using a photomultiplier to measure the response to gamma rays irradiation and cosmic rays operating the GSO crystal at 13.5 K. An avalanche photodiode (APD) readout of the scintillation signal from the GSO crystal has also been performed, since the magnetic field-independent response of this device allows it to be placed close to the crystal in the cryogenic environment.

We propose a new technique to measure the infrared scintillation light yield of rare earth (RE) doped crystals by comparing it to near UV-visible scintillation of a calibrated Pr:(Lu$_{0.75}$Y$_{0.25}$)$_{3}$Al$_5$O$_{12}$ sample. As an example, we apply this technique to provide the light yield in visible and infrared range up to \SI{1700}{nm} of this crystal., Comment: submitted to NIM A

A silicon p-i-n diode of thickness 1 cm has been studied experimentally at liquid helium temperature. This preliminary study is aimed at the construction of a much bigger detector to detect low energy neutrino events.

We show that a very thin conducting film (whose thickness can be much smaller than the skin depth), placed nearby a wall of an electromagnetic cavity, can produce the same shift of the resonance frequency as a bulk conducting slab, provided the displacement of the film from the wall is much bigger than the skin depth. We derive a simple analytical formula for the frequency shift and compare it with exact numerical calculations and experimental data.

The Casimir effect is a well-known macroscopic consequence of quantum vacuum fluctuations, but whereas the static effect (Casimir force) has long been observed experimentally, the dynamic Casimir effect is up to now undetected. From an experimental viewpoint a possible detection would imply the vibration of a mirror at gigahertz frequencies. Mechanical motions at such frequencies turn out to be technically unfeasible. Here we present a different experimental scheme where mechanical motions are avoided, and the results of laboratory tests showing that the scheme is practically feasible. We think that at present this approach gives the only possibility of detecting this phenomenon., Comment: Submitted to the Physical Review Letters. RevTeX. 4 pages, 2 figures

A multisection liquid-argon ionization detector has been developed by the DBA collaboration to study double β decay of 100Mo. The experiment has been carried out in the Gran Sasso underground laboratory in Italy. The detector design and main characteristics are described. The limits on the 42Ar and 222Rn concentrations in liquid Ar are ≤4.3 · 10–21 g/g and ≤1.2 · 10–3 Bq/kg, respectively.

Relative light yield (LY) dependence on temperature for Yb:YAG crystals containing 10% to 100% of Yb dopant is studied for γ and α excitation. The maximum LY is achieved at 120 K T K . LY=(13.5±2.5)×103 Ph/MeV at T=140 K for (Yb 25%) YAG. Linearity of the light output is checked. α/γ ratio is found to be 0.42±0.02. Pulse shapes induced by γ and α particles and cosmic rays are investigated by analysing a set of single events recorded. γ events are fast (τ

Relative light yield (LY) dependence on temperature for Yb:YAG crystals containing from 10% to 100% of Ybdopant is studied for g and a excitations. The maximum LY is achieved at 120KoTo140K. LY=(13.572.5) 10 3 ph/MeVatT=140Kfor(Yb25%)YAG.Linearityofthelightoutputischecked.a/g ratioisfoundtobe0.4270.02.Pulseshapes induced by gamma and alpha particles and cosmic rays are investigated by analyzing a set ofsingle eventsrecorded. Gamma events are fast to4ns), while other kinds ofradiation give rise to more complicated and longerprofiles, allowing particle discrimination. Dependence ofscintillation properties on concentration ofYb and purity isdiscussed. r 2002 Elsevier Science B.V. All rights reserved. PACS: 05.57. c; 07.77.ka; 29.40.Mc; 78.60.HkKeywords: Infrared; Neutrino; Temperature 1. IntroductionThe interest in luminescence ofYb 3+ is two-fold:1. Yb 3+ ion seems to be the fast and effectivecolor center in some sense competing with Ce 3+ which is widely investigated recently.2. If a fast and effective scintillator loaded withYb is feasible it would be a good device forneutrino physics [1].Besides, being a good laser media some ofYb-containing crystals may turn out to be IRscintillators with high light yield (LY) thoughslow.The present article is devoted to the study oflight output vs. temperature and decay kinetics ofUV and IR scintillation for a set of Yb:YAGsamples. More details can be found in Ref. [2].2. SamplesunderinvestigationInformation about samples is summarized inTable 1. All the samples were transparent(l

We report on the development and characterization of a device aimed at measuring macroscopic forces in the micrometre range. The apparatus is designed to detect Casimir forces in a parallel plane configuration and to search for Yukawa-like extra-gravitational forces in the submillimetre range. The sensitivity limits for the detection of both forces are also discussed.

We report on the study of infrared emission from gaseous argon excited by MeV protons in the wavelength range 0.7-1.8 mun. The dependence of the light yield on the applied electric field has been measured at different pressures. At zero held (prompt emission) the yield does not depend on pressure. When a field is applied the light emission increases linearly with the field strength above a critical value (drift emission) and a dependence from pressure is observed. Prompt and drift emission are consistent with transitions between the lowest atomic states of neutral argon. Drift emission is generated by electrons which gain energy from the electric field and excite atoms through collisions. (C) 2001 Elsevier Science B.V. All rights reserved.

We report on our efforts to give direct limits to the existence of forces other than gravitational ones in the submillimetre range. The technique used involves looking at the expected shifts to the resonant frequency of microresonators whose motion is monitored through a fibre optic interferometer.

The emission of infrared photons has been observed in an ionization chamber filled with standard gases. The primary emission light has been analyzed and some results are reported. The light produced by the electron drifting in the gaseous media is presented as a function of the electric field.

We have measured the branching ratio of the radiative decay π → μνγ . The energies of the gamma-ray and of the muon were both measured and the Dalitz-plot distribution of the decay was obtained. The data agree well with the theoretical prediction (QED internal bremsstrahlung) down to a γ-ray energy of 1 MeV. The discrepancy reported in a previous experiment is not confirmed.

We present a preliminary study to develop a large area photodetector, based on a semiconductor crystal placed inside a superconducting resonant cavity. Laser pulses are detected through a variation of the cavity impedance, as a consequence of the conductivity change in the semiconductor. A novel method, whereby the designed photodetector is simulated by finite element analysis, makes it possible to perform pulse-height spectroscopy on the reflected microwave signals. We measure an energy sensitivity of 100 fJ in the average mode without the employment of low noise electronics and suggest possible ways to further reduce the single-shot detection threshold, based on the results of the described method.

The performance of a liquid xenon time projection chamber as a detector for gamma rays between 0 and 30 MeV has been studied by comparing data collected with radioactive sources to a Monte Carlo simulation. The detector was designed for the study of the pion radiative decay. Both the scintillation light and the ionization charge signals were exploited. The light signals were used in the trigger logic and for the measurement of the chamber trigger acceptance. The minimum triggerable energy turned out to be 170 keV. The charge signals were used to measure the gamma ray energy. The noise introduced by the electronics was about 140 keV and the minimum measurable energy 230 keV with an electric drift field of 0.5 kV/cm. All the charge and light spectra were in good agreement with the simulation. The overall apparatus acceptance, taking into account geometry, trigger efficiency and offline reconstruction losses, was independent of the gamma ray energy above 2 MeV and equal to 10%.

The feasibility of fully floating high voltage (HV) generation was demonstrated producing a prototype of a modular HV system. The primary power source is provided by a high efficiency semiconductor power cell illuminated by a laser system ensuring the floating nature of each module. The HV is then generated by dc-dc conversion and a HV multiplier. The possibility of series connection among modules was verified.

We have measured the time evolution of the scintillation light in mixtures of liquid argon and xenon at different concentrations of xenon. The xenon shifts the scintillation light wavelength from 125 to 175 nm, even at concentration as low as 114 ppm. The time shape of the light has been found to be dependent on the xenon concentration. At a few percent xenon concentration the decay time is some tens nanosecond long. The light shape is understandable assuming that the primary excitation is transferred from the Ar to the Xe atoms via both radiative and non-radiative (collisional) processes.

A high voltage generator built by a series connection of 100 kV modules was produced. The series connection feasibility is ensured by the inherent floating character of each module which is wireless powered by high efficiency photovoltaic cells illuminated by a laser system. Each module is equipped with a control and monitoring board allowing excellent stabilization of the high voltage output. The performance of the system in terms of reliability, stability, and efficiency was evaluated. In particular using a three module setup, we achieved a maximum voltage of 234 kV with stability better than 0.1%.

We detected the ionization charge and the scintillation light produced in liquid xenon by the interactions of γ-rays emitted by radioactive sources. We could distinguish the multiple interactions of the photons and, by using the prompt scintillation signal, determine the distance of the tracks from the anode. Applying an electric field of 0.4 kV/cm, we obtained an intrinsic energy resolution of (8.4 ± 0.9)% at 1 MeV and found that the free-ion yield is 4.24 ± 0.43 independent on the photon energy within few percent in the explored range between 500 keV and 2 MeV. The experimental spectra are the sum of the total energy peaks and the Compton continuum. By selecting the γ-rays with multiple interactions we could strongly reduce the Compton background and enhance the total energy peaks. All the spectra were consistent with a Monte Carlo simulation of the apparatus. With a sensitive volume of about 200 cm 3 we measured a peak-to-total ratio ranging from almost 100% (500–600 keV γ-rays) to more than 60% for 2 MeV photons.

Using a liquid argon ionization chamber, the 2νββ decay of 100 Mo was detected with its half- life of (7.5 ± 1.1(stat.) ± 1.5(syst.)) · 10 18 y. The limits on half-lives for the 0ν and 0νχ 0 decays of 100 Mo were estimated as 9.3(5.0) · 10 21 and 4.3(2.7) · 10 20 y respectively at 68 % (90%) C.L. Available world data for the 2νββ decay of 100 Mo lead to the average ®worldvalue of the half-life, T1/2 =( 8.0 ± 0.7) · 10 18 y, which corresponds to the nuclear matrix element, MGT =0 .118 ± 0.005. �·¨ ¨¸¸²¥¤µ¢ ´¨¨ 2νββ-· ¸¶ ¤ 100 Mo ¸ ¶µ³µÐOO ¨µ´¨§ I¨µ´´µ° ± ³¥·O ´ |¨¤±µ³ ·£µ´¥ ¶µ²EI¥´ ¶·¥¤¥² ´ ¶¥·¨µ¤ ¶µ²E· ¸¶ ¤ (7,5 ± 1,1(¸E E.) ± 1,5(¸¨¸E.)) · 10 18 ²¥E. �·¥¤¥²O ¤²O 0ν- ¨ 0νχ 0 -³µ¤O · ¸¶ ¤ 100 Mo µI¥´¥´O ¸µµE¢¥E¸E¢¥´´µ ´ E·µ¢´¥ 9,3(5,0) · 10 21 ¨ 4,3(2,7) · 10 20 ²¥E ¤²O 68 % (90 %) C.L. "µ¸E¨£´EEO¥ ³¨·µ¢O¥ §´ I¥´¨O ¶¥·¨µ¤ ¶µ²E· ¸¶ ¤ 100 Mo ¤²O 2νββ-³µ¤O ¤ OE ¸·¥¤´¥¥ §´ I¥´¨¥ OEµ° ¢¥²¨I¨´O T1/2 =( 8,0 ± 0,7) · 10 18 ²¥E, IEµ ¸µµE¢¥E¸E¢E¥E O¤¥·´µ³E

Particles can be detected through the acoustic signal induced in a solid body in which their energy is released and converted into a localized and adiabatic heating. It is important to optimize the size of the target to enhance the amplitude of the displacements induced by the energy release. Transduction of displacements of a small resonator at room temperature using a tunnelling tip has been shown and compared to the performances of a capacitive electromechanical transducer.

We measured the mobility and lifetime of excess electrons in high-purity liquid Ar-Xe mixtures as a function of the electric field for several Xe concentrations x in Ar at T = 83.7 K by using a pulsed photoemission technique. We found an unexpected dependence of mobility and lifetime on the concentration of Xe. We discuss cluster formation as a possible mechanism explaining our data.

An array of 148 sharp tips was used to inject large quantities of free electrons in liquid argon and to purify it at a level · 0.09 ppb in few hours. We also evaluated the gettering capability of the stainless steel surface and measured the I–V characteristic of the array.

Light yield and spectrum of infrared (IR) scintillation in Xe are different in gaseous and liquid phases. In gas, the spectrum consists mainly of a broad line centered at 1300 nm. In liquid, light is emitted primarily below 1200 nm and with a lower yield. (C) 2001 Elsevier Science B.V. All rights reserved.

We have carried out a systematic study of the electron multiplication in liquid argon on an array of 52 sharp tips. We found a multiplication factor for a single tip of at least 100 and a plateau region in the counting-rate vs tip-voltage curve of about 150 V. The results make us hopeful in exploiting such mechanism for a new kind of detectors.

We have measured the electron mobility in high purity liquid methane as a function of the temperature in the range 92⩽ T ⩽122 K, using a pulsed photoemission technique. We have found a mobility 30 to 50% larger than most of the literature data. This discrepancy can be ascribed to the better gas purification method and to the measuring technique as well. Moreover, the mobility data agree fairly well with the Basak and Cohen theory assuming an electron effective mass m ∗ smaller than the electron mass.

We report new measurements of the linear polarization of thermal radiation emitted by incandescent thin tungsten wires, with thicknesses ranging from five to hundred microns. Our data show very good agreement with theoretical predictions, based on Drude-type fits to measured optical properties of tungsten., Comment: 12 pages, 4 encapsulated figures. This new version matches the one published in New. J. Phys.. Improved presentation, more references added, and one new figure included

A new purification method for liquid argon has been developed. The electronic capture mechanism has been exploited, the electrons being generated by a strong gamma-ray source. High purity level and stability, comparable to those obtained with standard gaseous-phase procedures, have been reached.