Three species of chrysidoid wasps,
Palaeobethylus longicollis
(Chrysididae),
Dryinus wunderlichi
and
D. reifi
(Dryinidae) are recorded for the first time for Rovno amber from the basin of Styr River ...(Voronki), and one species,
Palaeoanteon janzeni
(Dryinidae), is recorded for the first time for Rovno amber from the basin of Stokhod River (Kukhotskaya Volya). Taking into account the new records of chrysidoid wasps and myrmiciine ants, a total of 64 species of Rovno hymenopterans (52%) are registered at Baltic amber. All known fossil records of the wasps in the superfamily Chrysidoidea are listed.
The last immature instar and the mature larva of Bocchus scobiolae are described and illustrated for the first time. The affinities of both immature and mature larvae of Bocchus scobiolae and ...Mystrophorus formicaeformis are discussed to define larval characters of the subfamily Bocchinae.
Next-generation experiments searching for rare events must satisfy increasingly stringent requirements on the bulk and surface radioactive contamination of their active and structural materials. The ...measurement of surface contamination is particularly challenging, as no existing technology is capable of separately measuring parts of the 232Th and 238U decay chains that are commonly found to be out of secular equilibrium. We will present the results obtained with a detector prototype consisting of 8 silicon wafers of 150 mm diameter instrumented as bolometers and operated in a low-background dilution refrigerator at the Gran Sasso Underground Laboratory of INFN, Italy. The prototype was characterized by a baseline energy resolution of few keV and a background <100 nBq/cm2 in the full range of α energies, obtained with simple procedures for cleaning of all employed materials and no specific measures to prevent recontamination. Such performance, together with the modularity of the detector design, demonstrate the possibility to realize an alpha detector capable of separately measuring all alpha emitters of the 232Th and 238U chains, possibly reaching a sensitivity of few nBq/cm2.
•Material screening.•Bolometric alpha detector.•Low-radioactivity measurements.
RES-NOVA is a newly proposed experiment for detecting neutrinos from astrophysical sources, mainly Supernovae, using an array of cryogenic detectors made of PbWO
4
crystals produced from ...archaeological Pb. This unconventional material, characterized by intrinsic high radiopurity, enables low-background levels in the region of interest for the neutrino detection via Coherent Elastic neutrino-Nucleus Scattering (CE
ν
NS). This signal lies at the detector energy threshold,
O
(1 keV), and it is expected to be hidden by naturally occurring radioactive contaminants of the crystal absorber. Here, we present the results of a radiopurity assay on a 0.84 kg PbWO
4
crystal produced from archaeological Pb operated as a cryogenic detector. The crystal internal radioactive contaminations are:
232
Th <40
μ
Bq/kg,
238
U <30
μ
Bq/kg,
226
Ra 1.3 mBq/kg and
210
Pb 22.5 mBq/kg. We also present a background projection for the final experiment and possible mitigation strategies for further background suppression. The achieved results demonstrate the feasibility of realizing this new class of detectors.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
The multi-TeV energy region of the cosmic-ray spectra has
been recently explored by direct detection experiments that used
calorimetric techniques to measure the energy of the cosmic
...particles. Interesting spectral features have been observed in both
all-electron and nuclei spectra. However, the interpretation of the
results is compromised by the disagreements between the data
obtained from the various experiments, that are not reconcilable
with the quoted experimental uncertainties. Understanding the
reason for the discrepancy among the measurements is of fundamental
importance in view of the forthcoming high-energy cosmic-ray
experiments planned for space, as well as for the correct
interpretation of the available results.
The purpose of this work is to investigate the possibility that a
systematic effect may derive from the non-proportionality of the
light response of inorganic crystals, typically used in high-energy
calorimetry due to their excellent energy-resolution performance.
The main reason for the non-proportionality of the crystals is that
scintillation light yield depends on ionisation density.
Experimental data obtained with ion beams were used to characterize
the light response of various scintillator materials. The obtained
luminous efficiencies were used as input of a Monte Carlo simulation
to perform a comparative study of the effect of the light-yield
non-proportionality on the detection of high-energy electromagnetic
and hadronic showers. The result of this study indicates that, if
the calorimeter response is calibrated by using the energy deposit
of minimum ionizing particles, the measured shower energy might be
affected by a significant systematic shift, at the level of few
percent, whose sign and magnitude depend specifically on the type of
scintillator material used.
Core-collapse Supernovae (SNe) are one of the most energetic events in the Universe, during which almost all the star's binding energy is released in the form of neutrinos. These particles are direct ...probes of the processes occurring in the stellar core and provide unique insights into the gravitational collapse. RES-NOVA will revolutionize how we detect neutrinos from astrophysical sources, by deploying the first ton-scale array of cryogenic detectors made from archaeological lead. Pb offers the highest neutrino interaction cross-section via coherent elastic neutrino-nucleus scattering (CEνNS). Such process will enable RES-NOVA to be equally sensitive to all neutrino flavours. For the first time, we propose the use archaeological Pb as sensitive target material in order to achieve an ultra-low background level in the region of interest (O(1 keV)). All these features make possible the deployment of the first cm-scale neutrino telescope for the investigation of astrophysical sources. In this contribution, we will characterize the radiopurity level and the performance of a small-scale proof-of-principle detector of RES-NOVA, consisting in a PbWO
crystal made from archaeological-Pb operated as cryogenic detector.
The direct observation of high-energy cosmic rays, up to the PeV energy region, will increasingly rely on highly performing calorimeters, and the physics performance will be primarily determined by ...their geometrical acceptance and energy resolution. Thus, it is extremely important to optimize their geometrical design, granularity and absorption depth, with respect to the total mass of the apparatus, which is amongst the most important constraints for a space mission. CaloCube is an homogeneous calorimeter whose basic geometry is cubic and isotropic, obtained by filling the cubic volume with small cubic scintillating crystals. In this way it is possible to detect particles arriving from every direction in space, thus maximizing the acceptance. This design summarizes a three-year R&D activity, aiming to both optimize and study the full-scale performance of the calorimeter, in the perspective of a cosmic-ray space mission, and investigate a viable technical design by means of the construction of several sizable prototypes. A large scale prototype, made of a mesh of 5 × 5 × 18 CsI(Tl) crystals, has been constructed and tested on high-energy particle beams at CERN SPS accelerator. In this paper we describe the CaloCube design and present the results relative to the response of the large scale prototype to electrons.
The direct detection of high-energy cosmic rays up to the PeV region is one of the major challenges for the next generation of space-borne cosmic-ray detectors. The physics performance will be ...primarily determined by their geometrical acceptance and energy resolution. CaloCube is a homogeneous calorimeter whose geometry allows an almost isotropic response, so as to detect particles arriving from every direction in space, thus maximizing the acceptance. A comparative study of different scintillating materials and mechanical structures has been performed by means of Monte Carlo simulation. The scintillation-Cherenkov dual read-out technique has been also considered and its benefit evaluated.
Two new species of Dryinidae are described and illustrated Dryinus auratus Martins, Lara, Perioto & Olmi sp. nov. and Gonatopus mariae Martins, Lara, Perioto & Olmi sp. nov., both from areas of ...Atlantic Rainforest at São Paulo State, Brazil. Keys to species are provided.
Given the good performances in terms of geometrical acceptance and energy resolution, calorimeters are the best suited detectors to measure high energy cosmic rays directly in space. However, in ...order to exploit this potential, the design of calorimeters must be carefully optimized to take into account all limitations related to space missions, due mainly to the mass of the experimental apparatus. CaloCube is a three years R&D project, approved and financed by INFN in 2014, aiming to optimize the design of a space-borne calorimeter by the use of a cubic, homogeneous and isotropic geometry. In order to maximize detector performances with respect to the total mass of the apparatus, comparative studies on different scintillating materials, different sizes of crystals and different spacings among them have been performed making use of Monte Carlo simulations. In parallel to this activity, several prototypes instrumented with CsI:Tl cubic crystals have been constructed and tested with particle beams (muons, electrons, protons and ions). Both simulations and prototypes showed that the CaloCube design leads to a good particle energy resolution (< 2% for electromagnetic showers, < 40% for hadronic showers) and a good effective geometric factor (> 3:5 m2 sr for electromagnetic showers, > 2:5 m2 sr for hadronic showers). Thanks to these performances, in 5 years of operation it would be possible to measure the ux of electrons+positrons up to some tens of TeV and the uxes of protons and nuclei up to some units of PeV/nucleon, hence extending these measurements by at least one order of magnitude in energy compared to the experiments currently operating in space.
PDF
