Abstract
Active Pixel sensors play a crucial role in enabling successful low-light scientific experiments due to their inherent advantages and capabilities. Such devices not only offer high spatial ...resolution but also feature individual pixels with integrated amplifiers, allowing for direct signal amplification at the pixel level. This results in reduced readout noise and improved signal-to-noise ratio (SNR), which are particularly vital when dealing with limited photon counts in low-light environments. This holds particularly true for scientific CMOS (sCMOS) sensors, acknowledged as an advanced evolution of Active Pixel sensors. However, despite their advantages, such sensors can still exhibit limitations such as higher cost and presence of noise artifacts that should be closely investigated. In particular, CYGNO project fits in a global effort aimed at direct detection of Dark Matter particles. CYGNO collaboration intends to build a detector based on a Time Projection Chamber making use of Gas Electron Multipliers for the amplification of ionization electrons. The GEM multiplication process produces photons that can be readout by a high-resolution sCMOS sensor. Such detection system is being designed to have enough sensitivity to detect low-energy particles and to measure released energy with enough granularity so to reconstruct direction and energy profile along their trajectories. The image sensor has an important role in the detector performance, having a direct impact on the SNR of the experiment. This work proposes a study on the performance of three different sCMOS sensors with respect to their sensitivity to low-energy particles and their intrinsic noise, which are of the utmost importance for various scientific experiments.
We describe the purification of xenon from traces of the radioactive noble gas radon using a cryogenic distillation column. The distillation column was integrated into the gas purification loop of ...the XENON100 detector for online radon removal. This enabled us to significantly reduce the constant Formula omittedRn background originating from radon emanation. After inserting an auxiliary Formula omittedRn emanation source in the gas loop, we determined a radon reduction factor of Formula omitted (95% C.L.) for the distillation column by monitoring the Formula omittedRn activity concentration inside the XENON100 detector.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
The CYGNO experiment aims to study rare events related to the search for low-mass dark matter and solar neutrino events. One of the main components of background comes from cosmic rays that ...generate long tracks in the detector’s images. The interaction of such particles with the gas releases a variable energy profile along its trajectory to form tracks with multiple cores that can be easily reconstructed erroneously by being split into more than one cluster. Thus, this work offers a newly adapted version of the well-known density-based spatial clustering of applications with noise (DBSCAN) algorithm, called iDDBSCAN, which exploits the directional characteristics of the clusters found by the DBSCAN to improve its clustering efficiency when dealing with multi-core tracks. This paper provides a detailed explanation of this algorithm, covering its parameter validation and evaluating its influence when integrated into the experiment’s event selection routine. To generate background events, data acquisition was performed with the detector installed in an overground laboratory, leaving it exposed to natural radiation. To produce signals in the energy range of interest for the experiment, a
55
Fe radioactive source was used. The achieved results showed that the iDDBSCAN algorithm is capable of improving the background rejection of the experiment, through a more accurate reconstruction of the tracks produced by natural radiation such as cosmic rays, without deteriorating its signal detection efficiency and energy estimation.
The XENON1T experiment aims for the direct detection of dark matter in a detector filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by ...radioactive decays inside the detector has to be sufficiently low. One major contributor is the
β
-emitter
85
Kr which is present in the xenon. For XENON1T a concentration of natural krypton in xenon
nat
Kr
/
Xe
<
200
ppq
(parts per quadrillion,
1
ppq
=
10
-
15
mol
/
mol
) is required. In this work, the design, construction and test of a novel cryogenic distillation column using the common McCabe–Thiele approach is described. The system demonstrated a krypton reduction factor of
6.4
·
10
5
with thermodynamic stability at process speeds above 3 kg/h. The resulting concentration of
nat
Kr
/
Xe
<
26
ppq
is the lowest ever achieved, almost one order of magnitude below the requirements for XENON1T and even sufficient for future dark matter experiments using liquid xenon, such as XENONnT and DARWIN.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Precision spectroscopy of light muonic atoms provides unique information about the atomic and nuclear structure of these systems and thus represents a way to access fundamental interactions, ...properties and constants. One application comprises the determination of absolute nuclear charge radii with unprecedented accuracy from measurements of the 2S - 2P Lamb shift. Here, we review recent results of nuclear charge radii extracted from muonic hydrogen and helium spectroscopy and present experiment proposals to access light muonic atoms with Z ≥ 3. In addition, our approaches towards a precise measurement of the Zemach radii in muonic hydrogen (μp) and helium (μ3He+) are discussed. These results will provide new tests of bound-state quantum-electrodynamics in hydrogen-like systems and can be used as benchmarks for nuclear structure theories.
Abstract
Digital Hadronic Calorimeters (DHCAL) were suggested for future Colliders as part of the particle-flow concept. Though studied mainly with RPC, studies focusing on sampling elements based on ...Micro-Pattern Gaseous Detector have shown the potential advantages; they can be operated with environment-friendly gases and reach similar detection efficiency at lower average pad multiplicity. We summarize here the experimental test-beam results of a small-size DHCAL prototype, incorporating six Micromegas and two RPWELL sampling elements, interlaced with steel-absorber plates. It was investigated with 2–6 GeV pion beams at the CERN/PS beam facility. The data permitted validating a GEANT4 simulation framework of a DHCAL, and evaluating the expected pion energy resolution of a full-scale RPWELL-based calorimeter. The pion energy resolution derived for the RPWELL concept is competitive to that of glass RPC and Micromegas sampling techniques.
The CREMA collaboration is pursuing a measurement of the ground-state
hyperfine splitting (HFS) in muonic hydrogen
(
\mu
μ
p)
with 1 ppm accuracy by means of pulsed laser spectroscopy to determine
...the two-photon-exchange contribution with
2\times10^{-4}
2
×
10
−
4
relative accuracy. In the proposed experiment, the
\mu
μ
p
atom undergoes a laser excitation from the singlet hyperfine state to
the triplet hyperfine state, then is quenched back to the singlet
state by an inelastic collision with a H
_2
2
molecule. The resulting increase of kinetic energy after the collisional
deexcitation is used as a signature of a successful laser transition
between hyperfine states. In this paper, we calculate the combined
probability that a
\mu
μ
p
atom initially in the singlet hyperfine state undergoes a laser
excitation to the triplet state followed by a collisional-induced
deexcitation back to the singlet state. This combined probability has
been computed using the optical Bloch equations including the inelastic
and elastic collisions. Omitting the decoherence effects caused by the
laser bandwidth and collisions would overestimate the transition
probability by more than a factor of two in the experimental
conditions. Moreover, we also account for Doppler effects and provide
the matrix element, the saturation fluence, the elastic and inelastic
collision rates for the singlet and triplet states, and the resonance
linewidth. This calculation thus quantifies one of the key unknowns of
the HFS experiment, leading to a precise definition of the requirements
for the laser system and to an optimization of the hydrogen gas target
where
\mu
μ
p
is formed and the laser spectroscopy will occur.
We review the status of the proton charge radius puzzle. Emphasis is given to the various experiments initiated to resolve the conflict between the muonic hydrogen results and the results from ...scattering and regular hydrogen spectroscopy.
The CYGNO collaboration is developing next generationdirectional Dark Matter (DM) detection experiments, using gaseousTime Projection Chambers (TPCs), as a robust method for identifyingWeakly ...Interacting Massive Particles (WIMPs) below the NeutrinoFog. SF6 is potentially ideal for this since it provides a highfluorine content, enhancing sensitivity to spin-dependentinteractions and, as a Negative Ion Drift (NID) gas, reduces chargediffusion leading to improved positional resolution. CF4,although not a NID gas, has also been identified as a favourable gastarget as it provides a scintillation signal which can be used for acomplimentary light/charge readout approach. These gases can operateat low pressures to elongate Nuclear Recoil (NR) tracks andfacilitate directional measurements. In principle, He could be addedto low pressure SF6/CF4 without significant detriment to thelength of 16S, 12C, and 19F recoils. This wouldimprove the target mass, sensitivity to lower WIMP masses, and offerthe possibility of atmospheric operation; potentially reducing thecost of a containment vessel. In this article, we present gas gainand energy resolution measurements, taken with a Multi-Mesh ThickGaseous Electron Multiplier (MMThGEM), in low pressure SF6 andCF4:SF6 mixtures following the addition of He. We find thatthe CF4:SF6:He mixtures tested were able to produce gas gainson the order of 104 up to a total pressure of 100 Torr. Theseresults demonstrate an order of magnitudeimprovement 1 in charge amplification in NID gasmixtures with a He component.
Understanding the brain mechanisms involved in diagnostic reasoning may contribute to the development of methods that reduce errors in medical practice. In this study we identified similar brain ...systems for diagnosing diseases, prescribing treatments, and naming animals and objects using written information as stimuli. Employing time resolved modeling of blood oxygen level dependent (BOLD) responses enabled time resolved (400 milliseconds epochs) analyses. With this approach it was possible to study neural processes during successive stages of decision making. Our results showed that highly diagnostic information, reducing uncertainty about the diagnosis, decreased monitoring activity in the frontoparietal attentional network and may contribute to premature diagnostic closure, an important cause of diagnostic errors. We observed an unexpected and remarkable switch of BOLD activity within a right lateralized set of brain regions related to awareness and auditory monitoring at the point of responding. We propose that this neurophysiological response is the neural substrate of awareness of one's own (verbal) response. Our results highlight the intimate relation between attentional mechanisms, uncertainty, and decision making and may assist the advance of approaches to prevent premature diagnostic closure.
![Online [Formula omitted]Rn ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1434-6044/small "Online [Formula omitted]Rn removal by cryogenic distillation in the XENON100 experiment")
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