We performed a time-resolved spectroscopic study of the VUV/UV scintillation of gaseous argon as a function of pressure and electric field, by means of a wavelength sensitive detector operated with ...different radioactive sources. Our work conveys new evidence of distinctive features of the argon light which are in contrast with the general assumption that, for particle detection purposes, the scintillation can be considered to be largely monochromatic at 128 nm (second continuum). The wavelength and time-resolved analysis of the photon emission reveal that the dominant component of the argon scintillation during the first tens of ns is in the range 160, 325 nm. This light is consistent with the third continuum emission from highly charged argon ions/molecules. This component of the scintillation is field-independent up to 25 V/cm/bar and shows a very mild dependence with pressure in the range 1, 16 bar. The dynamics of the second continuum emission is dominated by the excimer formation time, whose variation as a function of pressure has been measured. Additionally, the time and pressure-dependent features of electron-ion recombination, in the second continuum band, have been measured. This study opens new paths toward a novel particle identification technique based on the spectral information of the noble-elements scintillation light.
The Cosmic Ray Cube is a portable tracking device conceived for outreach activities allowing a direct scientific experience for secondary school students. In the context of the PTOLEMY project, the ...detector was used to measure the differential muon flux inside the bunker of Monte Soratte, a suitable location at about 50 km north of Rome (Italy). Its simple operation was crucial to finalise the measurements, carried out during the Covid-19 lockdown in a site devoid of scientific equipment. The fine scanning of the differential muon rate highlights the details of the mountain above the bunker providing a map of the thickness of the rock which surrounds the detector. The result shows a muon flux at the Soratte hypogeum of about two orders of magnitude lower than the one observed on the surface.
We present the results of a search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 20 GeV/c^{2} using a target of low-radioactivity argon with a 6786.0 kg d ...exposure. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso. The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1 keVee. The observed rate in the detector at 0.5 keVee is about 1.5 event/keVee/kg/d and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8 GeV/c^{2} for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6 GeV/c^{2}.
We present a detailed description of the electromagnetic filter for the PTOLEMY project to directly detect the Cosmic Neutrino Background (CNB). Starting with an initial estimate for the orbital ...magnetic moment, the higher-order drift process of E×B is configured to balance the gradient-B drift motion of the electron in such a way as to guide the trajectory into the standing voltage potential along the mid-plane of the filter. As a function of drift distance along the length of the filter, the filter zooms in with exponentially increasing precision on the transverse velocity component of the electron kinetic energy. This yields a linear dimension for the total filter length that is exceptionally compact compared to previous techniques for electromagnetic filtering. The parallel velocity component of the electron kinetic energy oscillates in an electrostatic harmonic trap as the electron drifts along the length of the filter. An analysis of the phase-space volume conservation validates the expected behavior of the filter from the adiabatic invariance of the orbital magnetic moment and energy conservation following Liouville’s theorem for Hamiltonian systems.
In the context of the Ptolemy project, the need for a site with a rather low cosmogenic induced background led us to measure the differential muon flux inside the bunker of Monte Soratte, located ...about 50 km north of Rome (Italy). The measurement was performed with the Cosmic Ray Cube (CRC), a portable tracking device. The simple operation of CRC was crucial to finalize the measurement, as it was carried out in a site devoid of scientific equipment and during the COVID-19 lockdown. The muon flux measured at the Soratte hypogeum is about two orders of magnitude lower than the flux observed on the surface, suggesting the use of the Soratte bunker for hosting astroparticle physics experiments in which a low environmental background is required.
The Aria cryogenic distillation plant, located in Sardinia, Italy, is a key component of the DarkSide-20k experimental program for WIMP dark matter searches at the INFN Laboratori Nazionali del Gran ...Sasso, Italy. Aria is designed to purify the argon, extracted from underground wells in Colorado, USA, and used as the DarkSide-20k target material, to detector-grade quality. In this paper, we report the first measurement of argon isotopic separation by distillation with the 26 m tall Aria prototype. We discuss the measurement of the operating parameters of the column and the observation of the simultaneous separation of the three stable argon isotopes:
36
Ar
,
38
Ar
, and
40
Ar
. We also provide a detailed comparison of the experimental results with commercial process simulation software. This measurement of isotopic separation of argon is a significant achievement for the project, building on the success of the initial demonstration of isotopic separation of nitrogen using the same equipment in 2019.
Neutron production induced by α-decay with Geant4 Mendoza, E.; Cano-Ott, D.; Romojaro, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
960
Journal Article
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Odprti dostop
Neutron production induced by (α,xn) reactions is important in various fields, such as nuclear power technologies or the search for rare events carried out in underground laboratories. One of the ...most relevant scenarios is related to underground dark matter experiments, where the neutrons produced by the α-decay from radioactive contaminants in the detector materials can generate an irreducible background, limiting the sensitivity of the experiment. A precise estimate of the background due to these neutrons is crucial for the experiments currently taking data and for the design of the next generation detectors. In this work, we prove that Geant4 can be used to calculate neutron yields and energy spectra induced by α-decay. Additionally, we provide a Geant4 tool for performing these calculations at http://win.ciemat.es/SaG4n/. These neutrons are produced according to the information compiled in data libraries originally written in the ENDF-6 format. In this article we also review the different databases available, showing the differences and similarities among them. Finally, we compare several Geant4 neutron production yields and spectra with experimental data and other codes.
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