During the first wave of the COVID-19 pandemic, an international and heterogeneous team of scientists collaborated on a social project to produce a mechanical ventilator for intensive care units ...(MVM). MVM has been conceived to be produced and used also in poor countries: it is open-source, no patents, cheap, and can be produced with materials that are easy to retrieve.
The objective of this work is to extract from the experience of the MVM development and software certification a set of lessons learned and then guidelines that can help developers to produce safety-critical devices in similar emergency situations.
We conducted a case study. We had full access to source code, comments on code, change requests, test reports, every deliverable (60 in total) produced for the software certification (safety concepts, requirements specifications, architecture and design, testing activities, etc.), notes, whiteboard sketches, emails, etc. We validated both lessons learned and guidelines with experts.
We contribute a set of validated lessons learned and a set of validated guidelines, together with a discussion of benefits and risks of each guideline.
In this work we share our experience in certifying software for healthcare devices produced under emergency, i.e. with strict and pressing time constraints and with the difficulty of establishing a heterogeneous development team made of volunteers. We believe that the guidelines will help engineers during the development of critical software under emergency.
We report on the characterization of near-ultraviolet high-density silicon photomultiplier (SiPM) developed at Fondazione Bruno Kessler (FBK) at cryogenic temperature. A dedicated setup was built to ...measure the primary dark noise and correlated noise of the SiPMs between 40 and 300 K. Moreover, an analysis program and data acquisition system were developed to allow the precise characterization of these parameters, some of which can vary up to seven orders of magnitude between room temperature and 40 K. We demonstrate that it is possible to operate the FBK near-ultraviolet high density SiPMs at temperatures lower than 100 K with a dark rate below 0.01 cps/mm 2 and total correlated noise probability below 35% at an overvoltage of 6 V. These results are relevant for the development of future cryogenic particle detectors using SiPMs as photosensors.
Using a participatory observation approach, this paper aims at exploring how public and private organizations have collaborated in response to the COVID‐19 pandemic. We examine the case of Mechanical ...Ventilator Milano (MVM), an international project with over 250 contributors and partners; this project aimed to achieve the challenging goal of designing and realizing a mechanical ventilator for mass production in about 6 weeks. The project received the Emergency Use Authorization granted by the U.S. Food and Drug Administration. The MVM ventilator is a reliable, fail‐safe, and easy‐to‐operate mechanical ventilator that can be produced quickly at a large‐scale, based on the readily available parts. The success of the MVM case is unique as it adopts open innovation practices to generate technology innovation, in addition to a lean perspective. Through the MVM project description, this study offers a framework that explains the interplay between open innovation and lean approach, highlighting the different internal and external forces and types of collaborations, and offering fine‐grained insights into the role of universities as platforms of multidisciplinary knowledge. This framework might serve as a basis for future theoretical and empirical research, providing practitioners with new best practices that are essential when facing a severe crisis like COVID‐19.
Silicon photomultipliers (SiPMs) are an excellent candidate for the development of large-area light sensors. Large SiPM-based detectors require low-noise preamplifiers to maximize the signal coupling ...between the sensor and the read-out electronics. This paper reports on the development of a low-noise transimpedance amplifier sensitive to single-photon signals at cryogenic temperature. The amplifier is used to read-out a 1-cm 2 SiPM with a signal-to-noise ratio in excess of 40.
DarkSide-50 has demonstrated the high potential of dual-phase liquid argon time projection chambers in exploring interactions of WIMPs in the GeV/c2 mass range. The technique, based on the detection ...of the ionization signal amplified via electroluminescence in the gas phase, allows us to explore recoil energies down to the sub-keV range. We report here on the DarkSide-50 measurement of the ionization yield of electronic recoils down to ~ 180 eVer, exploiting 37Ar and 39Ar decays, and extrapolated to a few ionization electrons with the Thomas-Imel box model. Moreover, we present a model-dependent determination of the ionization response to nuclear recoils down to ~ 500 eVnr, the lowest ever achieved in liquid argon, using in situ neutron calibration sources and external datasets from neutron beam experiments.
During the COVID-19 pandemic, many researchers all over the world have offered their time and competencies to face the heavy consequences of the disease. This is the case of a group of physicists, ...engineers, and physicians that around the middle of March 2020 started to develop a simplified mechanical lung ventilator, called MVM (Mechanical Ventilator Milano), to answer the high request of ventilators for Acute Respiratory Distress Syndrome (ARDS) in intensive care units. A prototype was ready in around one month. Since medical software malfunctions can lead to injuries or death of patients, before marketing MVM ventilators and distributing them in hospitals, software certification in accordance with the IEC 62304 standard was mandatory to guarantee system reliability. The team was then complemented by computer scientists specifically devoted to this task. The software re-engineering process, which lasted around two months from the end of the prototype, brought to a strong re-implementation of the device software components, which involved all the stakeholders in a continuous integration setting. In this paper, we report the experience of the MVM control SW re-engineering necessary to show evidence that the SW adheres to the standards and to consequently obtain the certification. We share results and lessons learned from this social project, where more than 100 volunteer researchers worked towards software certification at the extreme of their strength to get a real device finished in a rush since strongly required to support physicians in treating COVID-19 patients.
We report on the realization of a novel silicon photomultiplier (SiPM)-based, cryogenic photosensor with an active area of 24 cm 2 that operates as a single-channel analog detector. The device is ...capable of single-photon counting with a signal-to-noise ratio better than 13, a dark rate lower than 10 -2 Hz/mm 2 , and an overall photon detection efficiency significantly larger than traditional photomultiplier tubes. This development makes SiPM-based photosensors strong candidates for the next generation of dark matter and neutrino detectors, which will require multiple square meters of photosensitive area, low levels of intrinsic radioactivity, and a limited number of detector channels.
Borexino is a low-background liquid scintillation detector currently acquiring solar and terrestrial neutrino data at the Gran Sasso underground laboratory in Italy. Since the start of operations in ...2007, Borexino has produced measurements of
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Be,
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B, and pep solar neutrinos, as well as measurements of terrestrial and long-baseline reactor antineutrinos. The measurements were made possible by the development of low-background scintillator spectroscopy that enabled direct detection of sub-MeV solar neutrinos. The general design features of the detector are described together with current results and prospects for future measurements.
While cosmic ray muons themselves are relatively easy to veto in underground detectors, their interactions with nuclei create more insidious backgrounds via (i) the decays of long-lived isotopes ...produced by muon-induced spallation reactions inside the detector (ii) spallation reactions initiated by fast muon-induced neutrons entering from outside the detector, and (iii) nuclear recoils initiated by fast muon-induced neutrons entering from outside the detector. These backgrounds, which are difficult to veto or shield against; are very important for solar, reactor, dark matter, and other underground experiments, especially as increased sensitivity is pursued. We used FLUKA to calculate the production rates and spectra of all prominent secondaries produced by cosmic ray muons, in particular focusing on secondary neutrons, because of their importance. Since the neutron spectrum is steeply falling, the total neutron production rate is sensitive to just the relatively soft neutrons and not the fast-neutron component. We show that the neutron spectrum in the range {approx}10-100 MeV can instead be probed by the (n,p)-induced isotope production rates {sup 12}C(n,p){sup 12}B and {sup 16}O(n,p){sup 16}N in oil- and water-based detectors. The result for {sup 12}B is in good agreement with the recent KamLAND measurement. Besides testing the calculation of muon secondaries, these results are also of practical importance, since {sup 12}B (T{sub 1/2}=20.2 ms, Q=13.4 MeV) and {sup 16}N (T{sub 1/2}=7.13 s, Q=10.4 MeV) are among the dominant spallation backgrounds in these detectors.
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