12 research outputs found
Development and characterisation of high-resolution microcalorimeter detectors for the ECHo-100k experiment
The goal of the ECHo experiment is a direct determination of the absolute
scale of the neutrino mass by the analysis of the end-point region of the
Ho-163 electron capture (EC) spectrum. The results of the first phase of the
experiment, ECHo-1k, have paved the way for the current phase, ECHo-100k, which
aims at a sensitivity below 2 eV on the effective electron neutrino mass. In
order to reach this goal, a new generation of high-resolution magnetic
microcalorimeters with embedded Ho-163 have been developed and characterised.
The design has been optimised to meet all the challenging requirements of the
ECHo-100k experimental phase, such as excellent energy resolution, wafer scale
implantation and multi-chip operation with multiplexing read-out. We present
the optimisation studies, the final design of the detector array and the first
characterisation studies. The results demonstrate that the detectors fully
match and even surpass the requirements for the current experimental phase,
ECHo-100k
High kinetic inductance NbTiN films for quantum limited travelling wave parametric amplifiers
A wide-bandwidth and low-noise amplification chain in the microwave regime is
crucial for the efficient read-out of quantum systems based on superconducting
detectors, such as Microwave Kinetic Inductance Detectors (MKIDs), Transition
Edge Sensors (TESs), Magnetic Microcalorimeters (MMCs), and RF cavities, as
well as qubits. Kinetic Inductance Travelling Wave Parametric Amplifiers
(KI-TWPAs) operated in a three-wave mixing fashion have demonstrated
exceptional dynamic range and low-noise performance, approaching the quantum
limit. These amplifiers can be fabricated using a single layer of a high
kinetic inductance film as weakly dispersive artificial transmission lines,
with the ability to control the phase-matched bandwidth through dispersion
engineering. In this study, we present the optimisation of the rf
sputter-deposition process of NbTiN films using a Nb80%T20 target, with the
goal of achieving precise control over film characteristics, resulting in high
kinetic inductance while maintaining a high transition temperature. The
parameter landscape related to the different sputtering conditions, such as
pressure, power, and nitrogen flow, has been explored and the film thickness
has been used as a fine-tuning parameter to adjust the properties of the final
NbTiN films used for the fabrication of KI-TWPAs. As a final result, we have
obtained a NbTiN film with a kinetic inductance of 8.5 pH/sq which we have
exploited to fabricate KI-TWPA prototype devices, showing promising
amplification performance
The Electron Capture in Ho Experiment - a Short Update
The definition of the absolute neutrino mass scale is one of the main goals of the Particle Physics today. The study of the end-point regions of the β- and electron capture (EC) spectrum offers a possibility to determine the effective electron (anti-)neutrino mass in a completely model independent way, as it only relies on the energy and momentum conservation.
The ECHo (Electron Capture in 163Ho) experiment has been designed in the attempt to measure the effective mass of the electron neutrino by performing high statistics and high energy resolution measurements of the 163 Ho electron capture spectrum. To achieve this goal, large arrays of low temperature metallic magnetic calorimeters (MMCs) implanted with with 163Ho are used. Here we report on the structure and the status of the experiment
Development and characterisation of high-resolution metallic magnetic calorimeter arrays for the ECHo neutrino mass experiment
This work is focused on the development of cryogenic metallic magnetic calorimeter detectors with implanted Ho-163 source for the ECHo (Electron Capture in Ho-163)experiment for the determination of the effective electron neutrino mass by studying the Ho-163 electron capture spectrum. The detector prototype fabricated for the first experimental phase, ECHo-1k, has been fully characterised, in terms of thermodynamic properties, detector response, energy resolution and Ho-163 activity per detector pixel. The specific heat per holmium ion in silver has been determined, comparing the response of detector pixels with and without implanted Ho-163. This accurate measurement indicates a lower value of the Ho-163 half-life with respect to the value reported in literature. Two implanted ECHo-1k detector chips have been operated in parallel in a dilution refrigerator which has been equipped with a 64-channel read-out chain. A high-statistics measurement with more than 10^8 Ho-163 electron capture events has been performed and the analysis of the resulting spectrum will allow to reach a sensitivity below 20 eV on the effective electron neutrino mass. Based on the outcomes of the ECHo-1k experimental phase, a novel detector design has been conceived in order to achieve the detector performance required for the succeeding experimental phase, ECHo-100k. The new ECHo-100k detector has been successfully fabricated and fully characterised, showing an improved detector response and an excellent energy resolution that reaches 3 eV FWHM, matching the designed value. The results obtained in this thesis set the starting point of the
ECHo-100k experiment
Numerical Calculation of the Thermodynamic Properties of Silver Erbium Alloys for Use in Metallic Magnetic Calorimeters - Data
Data from simulations of the specific heat and magnetization of Ag:Er alloys. The parameter range we consider are temperatures between 1mK and 1K, external magnetic fields of up to 20mT, and erbium concentrations of up to 2000ppm.Part of this research was performed in the framework of the DFG Research Unit
FOR2202 "Neutrino Mass Determination by Electron Capture in 163Ho, ECHo" (funding under EN 299/7-1
and EN 299/7-2, EN 299/8-1, GA 2219/2-1 and GA 2219/2-2). The research leading to these results has received
funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant
Agreement no 824109 (European Microkelvin Platform). A. Barth and F. Mantegazzini acknowledge funding
from the Research Training Group HighRR (GRK 2058) funded through the Deutsche Forschungsgemeinschaft,
DFG
Numerical Calculation of the Thermodynamic Properties of Silver Erbium Alloys for Use in Metallic Magnetic Calorimeters
Using dilute silver erbium alloys as a paramagnetic temperature sensor in metallic magnetic calorimeters (MMCs) has the advantage of the host material not having a nuclear quadrupole moment, in contrast to the alternative of using gold erbium alloys. We present numerical calculations of the specific heat and magnetization of Ag:Er, which are necessary for designing and optimizing MMCs using this type of alloy as sensor material. The parameter ranges we consider are temperatures between 1{mK} and 1{K}, external magnetic fields of up to 20{mT}, and erbium concentrations of up to 2000{ppm}. The system is dominated by an interplay of crystal field effects, Zeeman splitting, and the RKKY interaction between erbium ions, with certain specific constellations of erbium ions having noticeable effects on the specific heat. Increasing the external magnetic field or assuming a decreased strength of the RKKY interaction leads to a higher magnetization and a narrowing of the main Schottky peak, while changes in the erbium concentration can be well described by parameter scaling
Specific Heat of Holmium in Gold and Silver at Low Temperatures
The specific heat of dilute alloys of holmium in gold and in silver plays a major role in the optimization of low temperature microcalorimeters with enclosed , such as the ones developed for the neutrino mass experiment ECHo. We investigate alloys with atomic concentrations of at temperatures between 10 and . Due to the large total angular momentum and nuclear spin of ions, the specific heat of Au:Ho and Ag:Ho depends on the detailed interplay of various interactions, including contributions from the localized 4f electrons and nuclear contributions via hyperfine splitting. This makes it difficult to accurately determine the specific heat of these materials numerically. Instead, we measure their specific heat by using three experimental setups optimized for different concentration and temperature ranges. The results from measurements on six holmium alloys demonstrate that the specific heat of these materials is dominated by a large Schottky anomaly with its maximum at , which we attribute to hyperfine splitting and crystal field interactions. RKKY and dipole–dipole interactions between the holmium atoms cause additional, concentration-dependent effects. With regard to ECHo, we conclude that for typical operating temperatures of , silver holmium alloys with are suited best
Microwave Photon Emission in Superconducting Circuits
Quantum computing requires a novel approach to store data as quantum states, opposite to classical bits. One of the most promising candidates is entangled photons. In this manuscript, we show the photon emission in the range of microwave frequencies of three different types of superconducting circuits, a SQUID, a JPA, and a JTWPA, often used as low-noise parametric amplifiers. These devices can be operated as sources of entangled photons. We report the experimental protocol used to produce and measure microwave radiation from these circuits, as well as data simulations. The collected spectra are obtained by performing single-tone measurements with a direct rf pump on the devices; the output spectra at low powers (below −100 dBm) are well interpreted by the dynamical Casimir model, while at high powers (above −100 dBm) the system is well described by the Autler–Townes fluorescence of a three-level atom
High kinetic inductance NbTiN films for quantum limited travelling wave parametric amplifiers
A wide-bandwidth and low-noise amplification chain in the microwave regime is crucial for the efficient read-out of quantum systems based on superconducting detectors, such as Microwave Kinetic Inductance Detectors (MKIDs), Transition Edge Sensors (TESs), Magnetic Microcalorimeters (MMCs), and RF cavities, as well as qubits. Kinetic Inductance Travelling Wave Parametric Amplifiers (KI-TWPAs) operated in a three-wave mixing fashion have demonstrated exceptional dynamic range and low-noise performance, approaching the quantum limit. These amplifiers can be fabricated using a single layer of a high kinetic inductance film as weakly dispersive artificial transmission lines, with the ability to control the phase-matched bandwidth through dispersion engineering. In this study, we present the optimisation of the rf sputter-deposition process of NbTiN films using a Nb80%Ti20% target, with the goal of achieving precise control over film characteristics, resulting in high kinetic inductance while maintaining a high transition temperature. The parameter landscape related to the different sputtering conditions, such as pressure, power, and nitrogen flow, has been explored and the film thickness has been used as a fine-tuning parameter to adjust the properties of the final NbTiN films used for the fabrication of KI-TWPAs. As a final result, we have obtained a NbTiN film with a kinetic inductance of 8.5 pH/sq which we have exploited to fabricate KI-TWPA prototype devices, showing promising amplification performance
Characterization of Traveling-Wave Josephson Parametric Amplifiers at T = 0.3 K
The growing interest in quantum technologies, from fundamental physics experiments to quantum computing, demands for extremely performing electronics only adding the minimum amount of noise admitted by quantum mechanics to the input signal (i.e., quantum-limited electronics). Superconducting microwave amplifiers, due to their dissipationless nature, exhibit outstanding performances in terms of noise (quantum limited), and gain. However, bandwidth and saturation power still show space for substantial improvement. Within the DARTWARS 1 1
DARTWARS (Detector Array Readout with Traveling Wave AmplifieRS), funded by Italian National Nuclear Institute (INFN), is a quantum technologies project targeted at the development of wideband superconducting amplifiers with noise at the quantum limit and the implementation of a quantum-limited readout in different types of superconducting detectors and qubit.
We are developing state-of-the-art microwave superconducting amplifiers based on Josephson junction arrays and on distributed kinetic inductance transmission lines. Here we report the realization of a setup for the characterization of the performances of Josephson traveling-wave parametric amplifiers at a temperature of 300 mK. Although in the final experimental setup, these amplifiers will operate at a base temperature of about 20 mK, their characterization at 300 mK allows to evidence the main aspects of their performances, but the ultimate noise level. This represents a quick and relatively inexpensive way to test these superconductive devices that can be of help to improve their design and fabrication