Search

The Photon Detection Systems of the first two Liquid Argon Time Projection Chambers (LArTPCs) of the DUNE Far Detector exploit the Horizontal and Vertical Drift technologies and are composed of 6000 and 672 photon detection units respectively, named X-Arapuca. The Photon Detection Systems will complement and improve the calorimetry and vertex reconstruction for beam events and the prompt light detection will enable the trigger for non-beam events, such as Supernova Neutrino Bursts. In the Horizontal Drift, the Photon Detection System is placed behind the anode planes of the LArTPC, while in the Vertical Drift it is located on the cathode, biased at 320 kV, thus requiring targeted solutions to power and read the X-Arapuca devices. The X-Arapuca is a photon trap with two light downshifting stages, where the light is conveyed to SiPMs with a large area Wavelength Shifting light guide. Its Photon Detection Efficiency, and consequently the Photon Detection Systems sensitivity to the DUNE physics reaches, is determined by the grade and coupling of its several components. The Photon Detection Systems of both Horizontal and Vertical Drift are presented and discussed in their individual features, with a focus on the photon collector components and on the performances achieved by the X-Arapuca units measured in laboratory and in the CERN facilities at the Neutrino Platform. Possible changes in the baseline X-Arapuca designs proposed to further enhance the Photon Detection Efficiency of both Horizontal and Vertical Drift are also discussed. The Horizontal and Vertical Drift scale 1:20 prototypes at the NP04 and NP02 CERN Neutrino Platform, instrumented with the baseline versions of the X-Arapuca, will be operated with Liquid Argon throughout 2024. [ABSTRACT FROM AUTHOR]

The use of High Purity Germanium detectors operated in ionization mode at cryogenic temperatures is investigated as an external background mitigation solution for bolometers used in rare-event search experiments. A simple experimental setup, running a 52-g Li 2 WO 4 bolometer sandwiched in-between two 2-cm thick High Purity Germanium cylindrical detectors in a dry cryostat, shows promising rejection to environmental gammas and atmospheric muons backgrounds. The acquired data are used together with a Monte Carlo simulation of the setup to extract the main contributions to the external backgrounds expected in an above ground experiment, such as e.g. current and future experimental efforts targeting the detection of coherent elastic neutrino-nucleus scattering at reactor facilities. Based on all these results, a 4 π coverage similar veto system achieving a O (10 keV) energy threshold is expected to achieve a ≳ 73% and a ≳ 92% rejection power for gamma-like and muon-like events, respectively. [ABSTRACT FROM AUTHOR]

There is a global trend to increase the light yield of CsI scintillators used in neutrino and dark matter detection by operating undoped crystals at cryogenic temperatures. However, high light yield alone is not sufficient to guarantee a low-energy threshold. The response of undoped crystals to nuclear recoils at cryogenic temperatures is equally important. A liquid nitrogen-based cryostat was developed to measure the nuclear quenching factor of a small undoped CsI crystal using monoenergetic neutron beams at the Triangle Universities Nuclear Laboratory (TUNL). To minimize neutron scattering, high-Z materials were reduced around the crystal. The structure and performance of the cryostat are described in detail. Using this cryostat, a system light yield of 33. 4 ± 2. 0 photoelectrons per keV electron-equivalent (PE/keV ee) was observed at 5.9 keV ee , enabling the measurement of nuclear quenching factors at very low energies. The results of the quenching factor measurement will be reported in a subsequent paper. Non-negligible negative overshoot was observed in the tails of the observed light pulses. The origin of this issue and the correction procedure are described in detail. This information may be useful for others who encounter similar technical challenges. [ABSTRACT FROM AUTHOR]

Solid state detectors and low-temperature calorimeters are widely employed in rare event searches, because of their excellent sensitivity and consequent low energy threshold. A common procedure to establish the energy threshold is to define the trigger level at a fixed number of baseline standard deviations (sigmas) above the baseline level, typically 3 σ or 5 σ. This is not an ideal option when the threshold becomes a critical parameter for the detectors, requiring an optimised definition of the trigger. Recorded events with a small amplitude-to-noise ratio likely survive the selection criteria of the analysis chain contributing to the experiment background. We present a method to quantify the lowest trigger threshold achievable as a function of the acceptable amount of noise events triggered for the physics case under investigation. We then apply this novel method to existing experimental and simulated data to validate the model we presented. [ABSTRACT FROM AUTHOR]

We have developed and tested a new way of coupling bolometric light detectors to scintillating crystal bolometers based upon simply resting the light detector on the crystal surface, held in position only by gravity. This straightforward mounting results in three important improvements: (1) it decreases the amount of non-active materials needed to assemble the detector, (2) it substantially increases the light collection efficiency by minimizing the light losses induced by the mounting structure, (3) and it enhances the thermal signal induced in the light detector thanks to the extremely weak thermal link to the thermal bath. We tested this new technique with a 16 cm 2 Ge light detector with thermistor readout sitting on the surface of a large TeO 2 bolometer. The light collection efficiency was increased by greater than 50% compared to previously tested alternative mountings. We obtained a baseline energy resolution on the light detector of 20 eV RMS that, together with increased light collection, enabled us to obtain the best α vs β ∕ γ discrimination ever obtained with massive TeO 2 crystals. At the same time we achieved rise and decay times of 0.8 and 1.6 ms, respectively. This superb performance meets all of the requirements for the CUPID (CUORE Upgrade with Particle IDentification) experiment, which is a 1-ton scintillating bolometer follow up to CUORE. [ABSTRACT FROM AUTHOR]

Scintillators are widely used as particle detectors in particle physics. Scintillation at cryogenic temperatures can give rise to detectors with particle discrimination for rare-event searches such as dark matter detection. We present time-resolved scintillation studies of Cesium Iodide (CsI) under excitation of both α and γ particles over a long acquisition window of 1 ms to fully capture the scintillation decay between room temperature and 4 K. This allows a measurement of the light yield independent of any shaping time of the pulse. We find the light yield of CsI to increase up to two orders of magnitude from that of room temperature at cryogenic temperatures, and the ratio of α to γ excitation to vary significantly, exceeding 1 over a range of temperatures between 10 and 100 K. This property could be useful in separating α backgrounds from the low energy nuclear recoil signal region. We also find the time structure of the emitted light to follow similar exponential decay time constants between α and γ excitation, with the temperature behavior consistent with a model of self-trapped exciton de-excitation. Based on these properties, undoped CsI is an interesting candidate for use in cryogenic particle detectors. [ABSTRACT FROM AUTHOR]

The search for the neutrinoless double beta decay and the direct search for dark matter particles are amongst the most fundamental questions in astroparticle physics and cosmology. To achieve a high sensitivity, detectors with an excellent energy resolution and highly efficient particle identification capabilities are required. In recent years, cryogenic particle detectors have become one of the driving technologies in these fields. Future direct dark matter search experiments aim to improve the sensitivity for low mass dark matter particles ( ≲ 10 GeV / c 2 ) down to the neutrino floor and the next generation of neutrinoless double beta decay experiments aims to improve the sensitivity on the half-life to ∼ 10 26 – 10 27 years , corresponding to the parameter space predicted for the inverted mass ordering and degenerate mass range. To achieve these goals, significant improvements in detector performance and in radiopurity are required and both classes of experiments can benefit from the strong synergies in the fields of detector development and in the production of high purity single-crystals. [ABSTRACT FROM AUTHOR]

The current results of direct dark matter searches are controversial. The long-standing dark-matter claim from the DAMA/LIBRA collaboration is excluded by null-results of several other experiments. However, a comparison of the results by experiments with different detector materials introduces model dependencies. The R&D project COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) aims to develop cryogenic detectors based on (hygroscopic) sodium iodide (NaI). If successful, such detectors could be used in future experiments to investigate the origin of the annual modulation signal seen by the NaI-based scintillation detectors of the DAMA/LIBRA experiment. COSINUS detectors should be able to simultaneously detect phonons and scintillation light produced by a particle interaction inside the NaI crystal. This technique allows for an active suppression of β / γ backgrounds as well as detailed studies of a large variety of dark-matter models predicting nuclear interactions. For such kind of studies only moderate exposures of ≲ 100 kg - days are needed. In addition to the projected sensitivities of COSINUS detectors, we also show the result of first tests using (only mildly hygroscopic) caesium iodide (CsI) crystals as target material. For this measurement we achieved an energy threshold of ∼4.7 keV for nuclear recoils. [ABSTRACT FROM AUTHOR]

Several detectors for the next generation of particle physics experiments will make use of silicon photo-multipliers (SiPMs) to detect scintillation photons in liquid Argon. Cryogenic operation reduces dark counts by orders of magnitude, and makes it possible to retain single photon sensitivity even if large arrays of SiPMs are readout by a single amplifier. The total capacitance of a SiPM array with a total area of tens of cm 2 can range up to 200 nF. The series noise of the amplifier is the dominant factor that determines the signal to noise ratio of the readout chain. In this contribution, we present a cryogenic amplifier designed to operate in liquid Argon. The base version has a series white noise of 0.37 nV/ H z , while dissipating just 2.4 mW. Design variants have been also tested, which reduce noise to 0.22 nV/ H z , with a power consumption close to 4.5 mW. The amplifier base design and variants have been tested reading out SiPM arrays consisting of up to 96 6 × 6 mm 2 SiPMs, for a total photosensitive area of 35 cm 2 , demonstrating good single photon sensitivity even at low over-voltage values. [ABSTRACT FROM AUTHOR]

We tested the performance of two types of silicon photomultipliers, AdvanSiD ASD-NUV-SiPM3S-P and Hamamatsu 3×3 MM-50 UM VUV2, both at room (300 K) and at liquid nitrogen (77 K) temperature: breakdown voltage, quenching resistance, signal shape, gain and dark counts rate have been studied as function of temperature. The response of the devices to ultra-violet light is also studied. [ABSTRACT FROM AUTHOR]

An evaluation of the behavior of three large cathode area photo-multiplier tubes, Hamamatsu R5912 Mod and R5912-02 Mod, and ETL 9357 KFLB, was carried out both at room and cryogenic temperature, using a 405 nm light source. The main electrical and optical features of the devices were studied; the obtained results were compared with the characteristics of the ETL 9357 FLA tubes, used in the ICARUS experiment. Tubes were also studied as a function of the Earth׳s magnetic field and an evaluation of the quantum efficiency was made in the vacuum ultraviolet light region. [ABSTRACT FROM AUTHOR]

The spectral shape of forbidden beta-decays is a crucial benchmark for nuclear physics calculations and has important implications also for astroparticle physics. Among the interesting isotopes in this field, 115In is an excellent candidate, being a primordial nuclide featuring a good compromise among Q-value (497.489(10) keV) and half-life (4. 41 × 1 0 14 yr). In this paper, we propose to exploit a cryogenic calorimeter based on a In 2 O 3 crystal to perform a high-precision measurement of the β -decay energy spectrum, discussing also the results obtained within a preliminary test of this crystal and the next steps to improve the detector performance. [ABSTRACT FROM AUTHOR]

Abstract: Recent results of CERN RD39 collaboration on the development of radiation hard Si detectors operated at low to cryogenic temperatures will be presented in this paper. It has been found, in comparisons of results of simulation and charge collection data of pad and strip detectors, the charge-injected-diode (CID) operation mode of Si detectors reduces the free carrier trapping, resulting in a much higher charge collection at the SLHC fluence than that in a standard Si detector. The reduction in free carrier trapping by almost a factor of 3 is due to the fact that the CID mode pre-fills the traps, making them neutral and not active in trapping of particle-induced free carriers (signal). It has been found that, electron traps can be pre-filled by injection of electrons from the n+ contact. The CID mode of detector operation can be achieved by a modestly low temperature of ≤−40°C and a operation bias of <600V. Results of one CID detector application as LHC beam-loss-monitor (BLM) will be presented. Non-irradiated Si detectors has been shown, with tests by laser using our cryogenic transient-current-technique (TCT), to work quite well at LHe temperature (4K), which are very stable with no polarization and good charge collection efficiency. [Copyright &y& Elsevier]

Abstract: In order to optimize sapphire as a cryogenic scintillation-phonon detector for dark matter, crystals with different concentrations of doping have been studied using continuous X-ray excitation in the 30–300K temperature range. Light yields vary by 20% for Ti concentrations between 10 and 1000ppm at room temperature; they roughly double as the crystals are cooled from room temperature to 45K. From the analysis of the change in the X-ray luminescence spectra of with the concentration of Ti, it is concluded that the well-known blue emission of Ti-doped is due to the radiative decay of F-centers. Recommendations are given for improving the performance of scintillators. [Copyright &y& Elsevier]

Abstract: Cryogenic spectrometers offer an energy resolution an order of magnitude higher than conventional high-purity Germanium detectors, since low-temperature operation reduces thermal fluctuations and the associated noise. They have been developed over the last several decades, initially driven by particle and astrophysics applications, more recently also for material science, biophysics and nuclear science applications. The Advanced Detector Group at LLNL is developing cryogenic Gamma-ray and fast-neutron spectrometers for nuclear diagnostics in fundamental science and national security. They are based on measuring the increase in temperature upon photon or particle absorption with a sensor operated at the transition between its superconducting and its normal state. The approach can be adapted for different types of radiation with the appropriate choice of absorber material. We describe our Gamma-ray spectrometers consisting of a bulk Sn absorber attached to a superconducting Mo/Cu multilayer sensor. The detectors are operated at a temperature of ∼0.1K the end of a cold finger in a two-stage adiabatic demagnetization refrigerator, and have, depending on design, achieved an energy resolution between 50 and 150eV FWHM for energies below 100keV. Here we give an overview about cryogenic detectors for nuclear diagnostics, and discuss the application of this detector technology to the measurement of uranium enrichment. [Copyright &y& Elsevier]

Abstract: We are studying the operation of silicon microstrip detector with readout electronics in the temperature range from 90 to 130K. The sensor can be operated in the current-injection mode which significantly improves its radiation hardness. A first module prototype has been built, with APV25 readout chips and an embedded microtube, providing efficient low-mass cooling of the whole module with a two-phase flow of or Ar. First pedestal and pulse shape temperature dependencies are presented for this module. We have also built an edgeless test module with two pairs of laser cut sensors, with both angular and parallel cuts with respect to the strips (at pitch). We are studying the efficiency of the microstrip sensors very close () to the physical border of the cut silicon crystal and present here some electrical characteristics. [Copyright &y& Elsevier]

Abstract: We are interested in developing a photodetector sensitive to liquid noble gas scintillation light which is able to operate in cryogenic environment down to liquid nitrogen temperature (77K). It has to be a simple, cheap and compact device, with a photocathode surface comparable to that of photomultipliers, and it has to be able to produce fast signals for timing and triggering purposes. It could offer a cheap alternative to the photomultiplier use in large volume time projection chambers operating in liquid noble gas. We studied the possibility to couple a standard photocathode to a suitable electron multiplication system in gas. The results of the evaluation of the maximum gain attainable in gas employing pure argon and argon/methane mixture at low temperature are presented. [Copyright &y& Elsevier]

Abstract: We are developing a photodetector sensitive to liquid noble gas scintillation light which is able to operate down to liquid nitrogen temperature (77K). It has to be a simple, cheap and compact device, with a photocathode surface comparable to that of photomultipliers and it has to be able to produce fast signals for timing and triggering purposes. We studied the possibility of coupling a standard photocathode to a suitable electron multiplication system in gas; this would offer a cheap alternative to the use of photomultipliers. Gas avalanche multiplication at cryogenic temperatures and low pressure was observed in a small prototype chamber. Gains of the order of were obtained in pure argon, while gains up to were achieved using argon/methane mixture in cryogenic environment. [Copyright &y& Elsevier]

Abstract: Two crystal bolometers of 1.3kg each, the largest single crystals ever operated with this technique, have been successfully realized and tested below 10mK, in a dilution refrigerator located deep underground in the Gran Sasso National Laboratories. The calibration spectrum, obtained using an external 232Th -ray source, shows an energy resolution of 3–4keV FWHM from 0.5 to 2.6MeV, for both detectors. In the region, a 4.3keV FWHM resolution has been observed on the 5407keV peak due to the decay of 210Po, a natural contaminant of crystals. [Copyright &y& Elsevier]

Abstract: In this paper we report on the design, construction, and operation of a cryogenic system designed to cool a Superheated Superconducting Granule (SSG) detector for dark matter search. The volume accommodating SSG detector is 20cm in diameter and 67cm long. The system provides a lowest operating temperature of 115mK for long-lasting (several months) experiments in the Bern Underground Laboratory. [Copyright &y& Elsevier]

Several aspects of the analysis of the data obtained with the cryogenic heat-and-ionization Ge detectors used by the EDELWEISS dark matter search experiment are presented. Their calibration, the determination of their energy threshold, fiducial volume and nuclear recoil acceptance are detailed. [Copyright &y& Elsevier]

We study the performances of gaseous and two-phase (liquid-gas) cryogenic detectors of ionizing radiation based on gas electron multipliers (GEMs) and operated in an avalanche mode in pure noble gases. The gas amplification in He, Ar and Kr is systematically studied at low temperatures, using triple-GEM multipliers. High gains, exceeding 104, were obtained in these gases in the range of 120–300 K. Stable electron avalanching was demonstrated in a saturated Kr vapor in the two-phase mode. These results are relevant for understanding basic mechanisms of electron avalanching at low temperatures and for applications in cryogenic particle detectors, in particular in dark matter and solar neutrino detectors. [Copyright &y& Elsevier]

High energy resolution and broadband efficiency enable the use of cryogenic detectors in biological research. Two areas where they have found initial application are X-ray absorption spectroscopy (XAS) and time-of-flight mass spectrometry (TOF-MS). In synchrotron-based fluorescence-detected XAS cryogenic detectors are used to examine the role of metals in biological systems by measuring their oxidation states and ligand symmetries. In TOF-MS cryogenic detectors increase the sensitivity for biomolecule detection and identification for masses above ∼50 kDa, and thus enable TOF-MS on large protein complexes or even entire viruses. More recently, cryogenic detectors have been proposed as optical sensors for fluorescence signals from biomarkers. We discuss the potential for cryogenic detectors in biological research, as well as the challenges the technology faces. [Copyright &y& Elsevier]

Our research group has successfully developed photon detectors capable of both time-stamping and energy-resolving individual photons at very high rates in a wide band from the near-IR through optical and into the near-UV. We have fabricated 32-pixel arrays of these Transition-Edge Sensor (TES) devices and have mounted them in an adiabatic demagnetization refrigerator equipped with windows for direct imaging. We have characterized single pixel behavior; we have also begun operating multiple pixels simultaneously, starting the scaling process towards use of the full array. We emphasize the development of a metalized mask for our array that blocks photons from hitting the inter-pixel areas and reflects them onto the TESs. We also present calibration data on detector resolution, electronics noise, and optical alignment. [Copyright &y& Elsevier]

We report on the performance of the SHARC II detector, a 12×32 array of ion implanted Si pop-up bolometers. This 384 element detector array was built as a prototype for the High Angular Resolution Widefield Camera for the Stratospheric Observatory for Infrared Astronomy. We will discuss the design process, the characterization of the detectors, and the performance of the array in the SHARC II instrument. SHARC II is now a facility instrument on the Caltech Submillimeter Observatory, providing background-limited imaging at 350 and 450 μm. [Copyright &y& Elsevier]

The development of a large, far-infrared telescope in space has taken on a new urgency with breakthroughs in detector technology and recognition of the fundamental importance of the far-infrared spectral region to questions ranging from cosmology to our own Solar system. The Single Aperture Far-InfraRed (SAFIR) Observatory is 10 m-class far-infrared observatory that would begin development later in this decade to meet these needs. SAFIR''s science goals are driven by the fact that youngest stages of almost all phenomena in the universe are shrouded in absorption by and emission from cool dust that emits strongly in the far-infrared, 20 μm–1 mm. Its operating temperature (4 K) and instrument complement would be optimized to reach the natural sky confusion limit in the far-infrared with diffraction-limited performance down to at least the atmospheric cutoff at 40 μm. This would provide a point source sensitivity improvement of several orders of magnitude over that of SIRTF. In order to achieve this, large arrays of detectors with NEPs ranging from a few to a hundred zeptowatts/sqrt(Hz) are needed. Very low temperature superconducting transition edge sensors and far-infrared “photon counting” detectors are critical technologies requiring development for the SAFIR mission. [Copyright &y& Elsevier]

We summarize a continuing investigation into using ion implantation to alter the transition temperature of superconducting thin films. The primary motivation for the work presented here was to study the feasibility of using magnetic ion doping to replace the bi-layer Tc control process currently used for certain cryogenic detector applications at National Institute for Standards and Technology. The results from work with various ion species implanted into aluminum, molybdenum, titanium and tungsten host films are presented. [Copyright &y& Elsevier]

In the framework of the ATHENA experiment a combined tracking and photon detector, operating close to liquid nitrogen temperatures, was developed to determine simultaneously the vertex of an antiproton annihilation and energy and direction of photons stemming from a positron annihilation. The photon detector consists of 192 pure-CsI scintillation crystals (&ap;4 cm3) coupled to 5×5 mm2 avalanche photo-diodes, which are read by electronic chips realised in VLSI CMOS technology. These read out chips are also operational at liquid nitrogen temperature and feature a self-triggering capability. [Copyright &y& Elsevier]

In this paper, we describe some results in the modelling of a Cryogenic Detector. These detectors use the heat generated from an X-ray event to determine the event''s time and position. The model makes the basic assumption that the heat transport can be represented through by linear diffusion process and that the times at which the temperature changes reach the edge sensors can be used to determine the position of the event. The paper develops a finite element model of the device and performs a series of numerical experiments. The results of these experiments are compared with a simple analytic model. Two methods of determining the event position are presented: one based on an analytic solution and a second using neural network. [Copyright &y& Elsevier]

Cryogenic macro-calorimeters instrumented with NTD thermistors have been developed for several decades. The choice of the optimal bias current is crucial for a proper operation of these detectors, both in terms of energy resolution and stability. In this paper we present a set of automatic measurements and analysis procedures for the characterization and optimization of the working configuration of the NTD thermistors. The presented procedures were developed for CUORE, an array of 988 cryogenic macro-calorimeters instrumented with NTD thermistors that has been taking data since 2017. These procedures made it possible to characterize a large number of detectors in a reliable way. They are suitable enough to be used also in other large arrays of cryogenic detectors, such as CUPID. [ABSTRACT FROM AUTHOR]

Abstract: Superconducting microwave microresonators are low temperature detectors compatible with large-scale multiplexed frequency domain readout. We aim to develop detector arrays for calorimetric measurement of the energy spectra of 163Ho EC decay ( ) for a direct measurement of the neutrino mass. We plan to investigate nitrides of high-Z materials, like TaN and HfN, that are appropriate for containing the energy of keV decay events, exploring the properties relevant to our detectors, such as quality factor, penetration depth and recombination time. [Copyright &y& Elsevier]

The growing interest in clarifying the controversial situation in the Dark Matter sector has driven the experimental efforts towards new ways to investigate the long-standing DAMA/LIBRA result. Among them, low-temperature calorimeters based on Na-containing scintillating crystals offer the possibility to clarify the nature of the measured signal via particle identification. Here we report the first preliminary measurement of Na-containing crystals, based on a material different from NaI, i.e. Na 2 Mo 2 O 7 and Na 2 W 2 O 7 , pointing out their performance in terms of energy resolution, light yield, and particle identification. [ABSTRACT FROM AUTHOR]

CUPID-0 is the first large mass neutrino-less double beta decay (0 ν β β) experiment based on cryogenic calorimeters with dual read-out of light and heat for background rejection. The detector assembly, consisting of 26 ZnSe crystals, 2 natural and 24 enriched at 95% in 82Se, all coupled with bolometric light detectors, has been constructed respecting very strict protocols and procedures, from the material selection during crystal growth to the new and innovative detector framework, in the attempt to achieve the best performance of the array. The successful construction of the detector lead to promising preliminary results, here presented. The array is in fact taking data underground at LNGS (Italy) since March 2017 and the particle identification, enabled by the light read-out, provides an unprecedented background level, for cryogenic calorimeters, of only 3.2 counts keV − 1 t − 1 yr − 1 in the region of interest of the 0 ν β β search for 82Se, namely around 3 MeV. [ABSTRACT FROM AUTHOR]

Abstract: We present the characterization of the cold preamplifier set-up of the CUORICINO Experiment. It consists of two single boxes located inside the cryostat, linked to the 4.2K stage. Each box has 12 independent differential buffer channels, composed of 12 pairs of Silicon JFET transistors in source follower configuration and 48 pairs of load resistors for thermistor biasing. The operating temperature of the JFETs is . The figure of merit of the set-up is a series input noise of about in the 0–12Hz detector bandwidth. Parallel noise is limited only by the load resistors to be about . In order to build a 1000 channels bolometric array a further progress in the performances of the cold stage has been studied. [Copyright &y& Elsevier]

Abstract: A Stanford/NIST collaboration is developing an imaging detector suitable for IR/optical/UV astronomical observations based on the Transition Edge Sensor, a cryogenic quantum microcalorimeter. Currently, the 32 pixel detector can in time and energy resolve single photons with high event rates and at 2.33eV and more than 10kHz/pixel). We report on current progress with the first imaging TES instrument, focusing on recent advances in instrumentation including focusing, reflection masking and infrared filtering. [Copyright &y& Elsevier]

Abstract: For an active suppression of the gamma and electron background in the Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) dark matter experiment both phonons and scintillation light generated in a CaWO4 crystal are detected simultaneously. The phonon signal is read out by a transition edge sensor (TES) on the CaWO4 crystal. For light detection a silicon absorber equipped with a TES is employed. An efficient background discrimination requires very sensitive light detectors. The threshold can be improved by applying an electric field to the silicon crystal leading to an amplification of the thermal signal due to the Neganov–Luke effect. Measurements showing the improved sensitivity of the light detectors as well as future steps for reducing the observed extra noise will be presented. [Copyright &y& Elsevier]

Abstract: The detectors of CRESST are able to distinguish electron recoils as induced by ionizing radiation from nuclear recoils as expected from heavy dark matter particles (WIMPs) thanks to the coincident measurement of the phonon and scintillation light signals produced in an event. For a detailed understanding of the detector response to nuclear recoils, especially the light yield or quenching factor, measurements with different neutron sources have been performed. Standard neutron sources such as Am–Be yield some information but a better separation of the signals from the different nuclei can be obtained by a monoenergetic pulsed neutron source when additionally measuring the scattered neutrons. Such an experiment has been set up at the tandem accelerator at the Maier–Leibnitz Laboratory in Garching. Results from a first series of measurements at room temperature will be presented as well as the status of the experiment towards cryogenic measurements. [Copyright &y& Elsevier]

Abstract: The final results of the EDELWEISS-I dark matter search using cryogenic heat-and-ionization Ge detectors are presented. The final data sample corresponds to an increase by a factor five in exposure relative to the previously published results. A recoil energy threshold of 13keV or better was achieved with three 320g detectors working simultaneously over four months of stable operation. Limits on the spin-independent cross-section for the scattering of a WIMP on a nucleon are derived from an accumulated fiducial exposure of 62kgday. [Copyright &y& Elsevier]

Abstract: AgReO4 microcalorimeters are planned to be used in the next generation of calorimetric neutrino mass experiments with sensitivity down to 0.2eV. The understanding and characterization of all possible sources of systematic uncertainties is crucial. In this work, we focus on two of these sources which have been studied in the ten detectors of the Milano AgReO4 array experiment (MIBETA): (1) the solid-state beta environmental fine structure (BEFS) observed for the first time in AgReO4; (2) the detector energy response for internal beta events, which has been investigated with a dedicated measurement using a 44Ti gamma source. The possible effects on neutrino mass experiments due to the incomplete understanding of these two aspects are briefly discussed. [Copyright &y& Elsevier]

Abstract: The CRESST dark matter experiment uses the simultaneous measurement of the scintillation light and the heat signal of a CaWO4 crystal to discriminate between background electron recoil and nuclear recoil events. At the Technical University of Munich calibration measurements have been performed to characterize the detectors. These measurements include the determination of the light output and scintillation time constants of CaWO4 at temperatures below 50mK. The setup used in these measurements consist of a CaWO4 crystal, which is mounted in a reflective housing together with a silicon light detector carrying an Ir/Au transition edge sensor (TES) evaporated directly onto it. [Copyright &y& Elsevier]

Abstract: We report the present results of the CUORICINO experiment, a cryogenic experiment on neutrinoless Double Beta Decay (DBD) of 130Te consisting of an array of crystals with a total active mass of . The array is framed inside a dilution refrigerator, heavily shielded against environmental radioactivity and high-energy neutrons, and it is operated at a temperature of in the Gran Sasso Underground Laboratory. After several improvements the live time of the experiment is near 75%. [Copyright &y& Elsevier]

Abstract: The calorimetric determination of the neutrino mass by means of cryogenic detectors could play a significant role, being in principle able to investigate the 10−1 eV/c 2 region. But the question if the developments in this new technique will allow verify the expected performances is still open. A step forward in the advancement of this technology is represented by the incoming second-generation experiment on the β-decay of Re187 with superconducting rhenium, microcalorimeters, MANU-2. It is expected that this new experiment with about 300 detectors will achieve a sensitivity of 1.5eV/c 2 (90% CL), in 1yr, that allow to cover or improve the present best limit from tritium beta spectroscopy. [Copyright &y& Elsevier]

Abstract: Recent years have witnessed many exciting breakthroughs in subnuclear and astroparticle physics. The detection of neutrino oscillations has proved that neutrino are massive particles and cosmological observations suggest that about 25% of the universe matter is dark and non-Baryonic. However, the neutrino mass scale needs still to be fixed and the non-Baryonic matter is still undetected with its real nature unknown. Cryogenic detectors can play a crucial role in addressing the still open questions, but a new generation of detectors is required. The present and future roles of cryogenic detectors in neutrino and astroparticle physics are discussed. [Copyright &y& Elsevier]

The front-end approach for the readout of two arrays of bolometric detectors is described. The first front-end is for an array of μ-bolometers, while the second is for an array of macro-bolometers. Analogies and differences in the adopted strategies are put into evidence. [Copyright &y& Elsevier]

The Gallium-Neutrino-Experiment at GNO measures solar neutrinos radiochemically via the reaction 71Ga(ν,e)71Ge. In order to reduce statistical and systematic uncertainties in detecting the decay of 71Ge to 71Ga, a favourable way could be the use of high-resolution cryogenic detectors instead of the presently integrated miniaturized proportional counters. After the successful development of a highly efficient 4π-detector, optimization of thermal Ge-deposition and decoupling of deposition and detection, present activity concentrates on low background considerations, enhancement of external and internal shielding of the cryostat and a long-term run with artificially activated 71Ge to prove the feasibility of ‘cryoGNO’ in our Underground Laboratory in Garching. [Copyright &y& Elsevier]

I would like first to express my deep gratitude to Flavio Gatti and to the Organizing committee for inviting me to introduce the tenths of these Workshops, which have become more and more stimulating with years. I cannot avoid to emphasize how much I miss, and I am sure we all miss, Sandro Vitale, who started this activity in Genoa. He was for me not only a dear friend, but also, despite our similar ages, an inspiring teacher. I cannot obviously review what will be reported in this week here, which looks already very exciting just at a glance to the program. I will limit myself to some personal recollection and to some arguments which I personally see of great interest for the application of low-temperature detectors in nuclear, subnuclear and astroparticle physics. [Copyright &y& Elsevier]

After 3 years of project study and development, a 40 kg, 62-crystal, thermal detector array CUORICINO started last February. It is supposed to test the two claimed, but still not confirmed, evidences in Dark Matter and in Double Beta Decay (DBD) reported in the last few years and it will have a first glance on Solar Axion. The technical goals that were forseen for this experiment would be the confirmation on the feasibility of the CUORE experiment, a 1 ton multipurpose experiment with bolometers, that could open a new era in DBD physics. [Copyright &y& Elsevier]

To detect 511 keV γ-rays from positron annihilations, a detector with 192 pure-CsI crystals and APD readout was developed to determine the energy and direction of the two back-to-back γ-rays. The working temperature of the detector is ∼140 K. The performance of crystal and APD at cryogenic temperatures are described. [Copyright &y& Elsevier]

Abstract: The international project “Microcalorimeter Arrays for a Rhenium Experiment” (MARE) aims at the direct and calorimetric measurement of the electron anti-neutrino mass with sub-electronvolt sensitivity. The experimental strategy consists in studying the beta spectrum of 187Re near the end-point looking for the spectral distortion expected for a finite anti-neutrino mass. The MARE project has a staged approach: in the final experimental phase (MARE-2), several large arrays with as many as 10000 detectors each will be deployed to collect the statistics required to probe the anti-neutrino mass with a sensitivity of at least 0.2eV, comparable to the one expected for the Katrin experiment (KATRIN LoI, 2001, ). In the short term, smaller scale experiments are planned to reach sensitivities of the order of 1eV (MARE-1). This contribution reports on the Milano group activity for the MARE project. [Copyright &y& Elsevier]

Abstract: We are developing a photodetector sensitive to liquid noble gas scintillation light which is able to operate down to liquid nitrogen temperature (77K). It has to be able to produce fast signals for timing and triggering purposes in multi-kiloton liquid argon time projection chambers. We studied the possibility to couple a standard photocathode to a suitable electron multiplication system in gas. In the first part of the programme the gas avalanche multiplication at cryogenic temperature and low pressure was studied. The second part of the programme foresees the production of a photocathode able to operate at low temperature. A complete detector prototype is going to be set up. It will consist of a simple CsSb photocathode and a multiplication stage made of 100 m stainless steel wires. We present the results of the evaluation of the gain attainable with different gas mixtures. [Copyright &y& Elsevier]