The CUORE experiment is a ton-scale array of
TeO
2
cryogenic bolometers located at the underground Laboratori Nazionali del Gran Sasso of Istituto Nazionale di Fisica Nucleare (INFN), in Italy. The ...CUORE detector consists of 988 crystals operated as source and detector at a base temperature of
∼
10
mK. Such cryogenic temperature is reached and maintained by means of a custom built cryogen-free dilution cryostat, designed with the aim of minimizing the vibrational noise and the environmental radioactivity. The primary goal of CUORE is the search for neutrinoless double beta decay of
130
Te
, but thanks to its large target mass and ultra-low background it is suitable for the study of other rare processes as well, such as the neutrinoless double beta decay of
128
Te
. This tellurium isotope is an attractive candidate for the search of this process, due to its high natural isotopic abundance of 31.75%. The transition energy at (866.7 ± 0.7) keV lies in a highly populated region of the energy spectrum, dominated by the contribution of the two-neutrino double beta decay of
130
Te
. As the first ton-scale infrastructure operating cryogenic
TeO
2
bolometers in stable conditions, CUORE is able to achieve a factor
>
10
higher sensitivity to the neutrinoless double beta decay of this isotope with respect to past direct experiments.
In this contribution we present the achievements of the CUORE experiment so far. It is the first tonne-scale bolometric detector and it is in stable data taking since 2018. We reached to collect ...about 1800 kg×yr of exposure of which more than 1 ton×year have been analysed. The CUORE detector is meant to search for the neutrinoless double β decay (0νββ) of the 130Te isotope. This is a beyond Standard Model process which could establish the nature of the neutrino to be Dirac or a Majorana particle. It is an alternative mode of the two-neutrinos double β decay, a rare decay which have been precisely measured by CUORE in the 130Te. We found no evidence of the 0νββ and we set a Bayesian lower limit of 2.2 ×1025yr on its half-life. The expertise achieved by CUORE set a milestone for any future bolometric detector, including CUPID, which is the planned next generation experiment searching for 0νββ with scintillating bolometers.
Study on calcite precipitation has major implications for both the hydrochemical evolutions of river systems and the global carbon cycle. The precipitation of calcite generally requires the water to ...be 5–10 times supersaturated with respect to calcite, which is usually achieved by the removal of CO
2. Formation of waterfall tufa has been often simply described as the result of water turbulence in fast-flowing water. In this paper, the formation mechanisms of waterfall tufa are discussed and a series of laboratory experiments are designed to simulate the hydrological conditions at waterfall sites. The influences of the air–water interface, the water flow velocity and the solid–water interface on CO
2 outgassing and calcite precipitation are compared and evaluated quantitatively. The results show that the principal cause of waterfall tufa formation is the enhanced inorganic carbon dioxide outgassing resulted from the sudden hydrological changes occurring at waterfall sites, rather than organisms, evaporation or the solid–water interface. The air–water interface area and the water flow velocity are greatly increased at waterfall sites as a result of the “aeration effect”, “low pressure effect” and “jet-flow effect”, which greatly accelerate CO
2 outgassing. Inorganic CO
2 outgassing drives the waters to become highly supersaturated with respect to calcite and, consequently, results in much calcite deposition. The solid–water interface is less important as the air–water interface in affecting calcite precipitation at waterfall sites. Field measurements showed that conductivity, Ca
2+ and HCO
3
− concentrations along Tianhe Creek and Hot Creek decrease downstream while pH rises. Field observations also showed that tufa deposition occurred mainly at waterfall sites.
Sediment grain size is a conventional proxy of climatic changes. Larger sediment grain size is often interpreted to indicate dry climate during lower lake level while smaller sediment grain size ...implies wet climate during higher lake level. Through detailed study on sediment grain sizes in Lake Erhai and Lake Chenghai, this paper reveals the different indication significances of sediment grain sizes in different time scales, different resolution investigations. For long time-scale and low resolution (102a or 103a) studies, larger sediment grain size indicates lower lake level, smaller lake area and drier climate while smaller sediment grain size indicates higher lake level, larger lake area and wetter climate. For short time-scale and high resolution (a or 10a) studies, larger sediment grain size reflects more rainfall and wetter climate while smaller sediment grain size reflects less rainfall and drier climate. Environmental information revealed by lacustrine sediment records is often different in different time scales because of the variance of sedimentation resolution, sampling resolution and dating precision. Therefore, paleoclimate implications of environmental proxies in long time-scale and low resolution investigations could not be mechanically applied to short time-scale and high resolution studies. Only after synthetically analyzing the influence manner and extent of all factors on the sediment records in different time scales, can credible conclusions be obtained.
In Southwest China, 15 million people suffer from fluorosis, more than 3000 people have arsenism, and 477 people have endemic selenium intoxication due to use of high fluorine, arsenic, and selenium ...coal in unvented ovens. The highest fluorine, arsenic, and selenium in contents of these coals are 2000 μg/g, 35,000 μg/g, and more than 8000 μg/g, respectively. This paper describes the epidemic situation and the causes and pathways of endemic fluorosis, arsenism, and selenosis in Southwest China. The occurrence and distribution of high fluorine, high arsenic, and high selenium coals are briefly described.
Results from the CUORE experiment Campani, A; Adams, DQ; Alduino, C ...
HAL (Le Centre pour la Communication Scientifique Directe),
2019, Letnik:
42, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Neutrinoless double beta decay (0νββ) is a rare, second-order nuclear transition that occurs only if neutrinos are massive Majorana particles or through new physics beyond Standard Model. This ...process explicitly violates the lepton number (L) by two units and, therefore, the observation of 0νββ would demonstrate that L is not a symmetry of nature. Combined with flavour mixing and cosmological measurements, it can provide unique contraints on neutrino mass scale and establish whether neutrinos are Dirac or Majorana particles. The Cryogenic Underground Observatory for Rare Events (CUORE) is an experiment located at the LNGS searching for 0νββ decay of 130Te. CUORE exploits the bolometric technique to reach high resolution around the Q-value (2527.5 keV). It consists of an array of 988 natural TeO2 cubic crystals grouped into 19 towers. With a total active mass of 742 kg (~206 kg of 130Te), CUORE is operated at very low temperature with a new 3He/4He refrigerator. Data taking started at the beginning of 2017. After a brief introduction on the detector and the way data analysis is performed, I describe CUORE first results for the search of the 0νββ decay that were published in March 2018.
Sediment cores were collected from Lake Erhai, which is located on the Yunnan–Guizhou Plateau, a landform formed by the uplift of the Himalayas. These sediments were deposited up to about 697±15 ...years ago based on
210Pb
ex and
137Cs dating.
δ
13C
inorg,
δ
18O
inorg and
δ
13C
org values and concentrations of C
inorg, C
org, N and P within the sediment cores have been measured. C
org has an average deposition flux of 12.7
g/m
2, and an accumulation flux of 7.20
g/m
2. The calculated decomposition rate constant is 0.017
a
−1 with a half life of 40
a.
δ
13C
inorg and
δ
18O
inorg values range from −1.6 to −7.9‰ and −5.7 to −13.6‰, respectively, and show similar trends over the past 700 years, which is interpreted to be controlled mainly by temperature, corresponding to climatic changes of two and half periods of a ‘warm–cold–warm’ cycle.
δ
13C
org ranges from −25 to −28‰, indicating that the organic matter originated mainly from land-derived plants, with overprinting from anthropogenic activities over the past 460 years (since 1537
ad). N and P
org concentrations show a similar vertical distribution to C
org. Atomic ratios of organic carbon and nitrogen (C/N) are 5.8 and 6.8 for the deposition and accumulation stages, respectively, similar to the Redfield ratio in the ocean. The C/P ratio, however, is higher than that in the ocean. The vertical distribution of carbon in the sediment cores indicates that Lake Erhai has the characteristics of both an inland lake (land-derived organic matter) and the ocean (similar C/N ratio). The lower C/N and C/P ratios in the lake Erhai sediments are characteristic for a lake at high altitude and in a subtropical region. This ‘low latitude–high altitude effect’ is probably related to the uplift of the Himalayas.
On the basis of concentrations of 21 major and minor elements in a well-dated sediment core from the deepwater part of Lake Erhai, principal component analysis (PCA) reveals three main factors ...controlling the inorganic chemical composition of lake sediments. These are physical erosion in the watershed (Component 1), autochthonous calcite precipitation in lake water (Component 2) and early diagenesis in sediments (Component 3). Variations of factor scores of Component I and Component 3 may reflect fluctuations in rainfall and temperature, respectively in the lake region. High factor scores of Component 3 correlate with low factor scores of Component 1 in sediments within the intervals AD 1340-1550 and AD 1890-1950, indicating two warm-dry episodes. Low factor scores of Component 3 correlate with high factor scores of Component 1 from AD 1550-1890, indicating a cold-wet climate corresponding to the ‘Little Ice Age’ in Europe. Our study provides a new approach to reconstructing palaeoclimate, and adds to a growing body of evidence for a widespread cooling during the ‘Little Ice Age’. The alternation between warm-dry and cool-humid conditions possibly implies different climate change characteristics between the southwest monsoon zone and the southeast monsoon zone where the climate pattern is warm-humid and cool-dry.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A novel Schottky barrier thin-film transistor (SBTFT) with silicided source/drain and field-induced drain (FID) extension is proposed and demonstrated. In the new device configuration, a metal ...field-plate (or sub-gate) lying on the passivation oxide is employed to induce a sheet of carriers in a channel offset region located between the silicided drain and the active channel region underneath the main gate. The new device thus allows ambipolar device operation by simply switching the polarity of the bias applied to the field plate. In contrast to the conventional SBTFT that suffers from high GIDL (gate-induced drain leakage)-like off-state leakage current, the new SBTFT with FID is essentially free from the GIDL-like leakage current. In addition, unlike the conventional SBTFT that suffers from low on-off current ratio, the new device exhibits high on/off current ratio up to 10/sup 6/ for both n- and p-channel modes of operation. Moreover, the implantless feature and the ambipolar capability of the new device also result in extra low mask count for CMOS process integration. These excellent device characteristics, coupled with its simple processing, make the new device very promising for future large-area electronic applications.
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