The mechanical and EM simulations of the CryoAC for the ATHENA X-IFU

The design phase of the CryoAC DM for the ATHENA X-IFU has concerned numerical simulations to exploit different fabrication possibilities. The mechanical simulations have accounted for the peculiar detector structure: 4 silicon chips asymmetrically suspended by means of 4 microbridges each. A preliminary study was performed to analyze the response to acceleration spectra in the frequency domain, shocks and time domain random displacement, prior to a real vibration test campaign. EM simulations to spot unwanted magnetic fields have been conducted as well. In this work we will show the latest advance in the design of the new detectors, showing the main results coming from various simulations

Mesoporous Titanium Dioxide Thin Films on Quartz via Electrochemical Anodisation Process

Titanium dioxide (TiO2) thin films were prepared by means of electrochemical anodisation or anodic spark deposition (ASD) from thin and flat metallic titanium (Ti) films pre-deposited on high quality quartz substrates by electron beam evaporation. AFM analysis indicates the formation of uniform mesoporous layers and a definite increase about 50% of the film thickness upon anodisation and about 90% upon annealing. Anodised mesoporous TiO2 films have been characterized by Raman spectroscopy, which indicates the presence of well-defined peaks related to anatase structure. Phase transformation from anatase to rutile was observed after annealing at temperatures up to 900\ub0C for 3h

One step into Holmes project. Simulation of the deposition of a metallic Ho film on a target.

This work shows one of the activity of the group in the framework of the HOLMES project for direct neutrino mass search. Starting from Ho oxide and working at high temperature, it is possible to obtain the deposition of a metal Ho film which is necessary for the implantation into cryogenic detectors. A simulation has been developed to evaluate the distribution of the deposition of metallic Holmium onto a target used as a trap and to estimate the efficiency of the process and eventually optimize controllable parameters. Object of this work is the simulation itself, its design, implementations and a discussion of the results

Fabrication and electromechanical actuation of epitaxial SrTiO3 (0 0 1) microcantilevers

We report on the fabrication, mechanical characterization and electrostatic actuation of dielectric STO(0 0 1) thin film microcantilevers (MCs). Finite element analysis (FEA) is used for mechanical analysis and for calculating the distribution and the magnitude of the dielectric forces on the actual devices. The actuation of insulating oxide microstructures is of potential interest in the field of ferroelectric/multiferroic materials as well as for developing novel detecting schemes on dielectric oxides. \ua9 2013 IOP Publishing Ltd

Multistate Memory Devices Based on Free-standing VO2/TiO2 Microstructures Driven by Joule Self-Heating

Two-terminal multistate memory elements based on VO2/TiO2 thin film microcantilevers are reported. Volatile and non-volatile multiple resistance states are programmed by current pulses at temperatures within the hysteretic region of the metal-insulator transition of VO2. The memory mechanism is based on current-induced creation of metallic clusters by self-heating of micrometric suspended regions and resistive reading via percolation

Mesoporous Titanium Dioxide Thin Layers for Gas Sensor Applications: Vacuum Deposition and Electrochemical Anodization

Titanium dioxide (TiO2) thin films were prepared by means of Anodic Spark Deposition (ASD) from thin and flat metallic titanium (Ti) films pre-deposited on high quality quartz slides by electron beam evaporation. AFM analysis indicates the formation of uniform mesoporous layers and a definite increase (about 50%) of the film thickness upon anodisation. The oxide mesoporous films have been characterized by XPS and Raman spectroscopy. Raman spectra of mesoporous TiO2 films were characterized by well-defined peaks related to anatase structure. An incomplete phase transition from anatase to rutile was observed upon annealing at temperatures up to 900 \ub0C for 3h

Direct Search for Low Energy Nuclear Isomeric Transition of Th-229m with TES Detector

Precise knowledge of the energy and lifetime of 229mTh isomeric state has notable importance as a basis for a nuclear clock. Such a clock would be capable to extend precision on the oscillator frequency by up to four orders of magnitude compared to the presently best atomic clocks. However, the technique proposed for the clock requires that the isomeric state energy is accessible with existing laser systems. Previous measurement placed this state at 3c8 eV (150 nm), in the Vacuum Ultra Violet (VUV) range of the electromagnetic spectrum. A precise direct measurement of the energy of this state is necessary to determine whether the nuclear clock can be made using existing laser technology. We are developing a cryogenic microcalorimeter to measure the energy and lifetime of the 229mTh isomeric state directly. The experiment will use a 233U source whose alpha-decay will populate the 229mTh isomeric state with 2% probability. The subsequent decay of 229mTh will be measured by a Transition Edge Sensor (TES) with <1 eV resolution. Such a technique will allow to observe all possible types of decays of 229mTh in the range of energy from 3 to 50 eV and lifetimes >5 microseconds. The single-photon TES has sufficient resolving power combined with high efficiency in the whole energy band for this experiment. Here we present a prototype of TES based on a 200 nm thick iridium-gold (Ir/Au) film which was tested with a pulsed laser source and demonstrated 3c0.8 eV energy resolution and 5.8 \ub1 2.1 \u3bcs signal recovery time

The cryogenic anticoincidence detector for ATHENA X-IFU: Preliminary test of AC-S9 towards the demonstration model

Our team is developing the Cryogenic Anticoincidence Detector (CryoAC) of the ATHENA X-ray Integral Field Unit (X-IFU). It is a 4-pixels TES-based detector, which will be placed less than 1 mm below the main TES array detector. We are now producing the CryoAC Demonstration Model (DM): a single pixel prototype able to probe the detector critical technologies, i.e. The operation at 50 mK thermal bath, the threshold energy at 20 keV and the reproducibility of the thermal conductance between the suspended absorber and the thermal bath. This detector will be integrated and tested in our cryogenic setup at INAF/IAPS, and then delivered to SRON for the integration in the X-IFU Focal Plane Assemby (FPA) DM. In this paper we report the status of the CryoAC DM development, showing the main result obtained with the last developed prototype, namely AC-S9. This is a DM-like sample, which we have preliminary integrated and tested before performing the final etching process to suspend the silicon absorber. The results are promising for the DM, since despite the limitations due to the absence of the final etching (high thermal capacity, high thermal conductance, partial TES surface coverage), we have been able to operate the detector with TB= 50 mK and to detect 6 keV photons, thus having a low energy threshold fully compatible with our requirement (20 keV)

The cryogenic anticoincidence detector for ATHENA-XMS: Preliminary results from the new prototype

ATHENA has been the re-scoped IXO mission, and one of the foreseen focal plane instrument was the X-ray Microcalorimeter Spectrometer (XMS) working in the energy range 0.3-10 keV, which was a kilo-pixel array based on TES (Transition Edge Sensor) detectors. The need of an anticoincidence (AC) detector is legitimated by the results performed with GEANT4 simulations about the impact of the non x-ray background onto XMS at L2 orbit (REQ. < 0.02 cts/cm2/s/keV). Our consortium has both developed and tested several samples, with increasing area, in order to match the large area of the XMS (64 mm2). Here we show the preliminary results from the last prototype. The results achieved in this work offer a solution to reduce the particle background not only for the presently study mission, but also for any satellite/balloon borne instrument that foresees a TES-based microcalorimeters/bolometers focal plane (from millimeter to x-ray domain). \uc2\ua9 2012 SPIE