In this work, we report the study of temperature effects on light yield of siloxane-based scintillators and on n/
γ
discrimination capability, in terms of pulse shape discrimination (PSD). The solid ...scintillators are composed of phenyl containing polysiloxane (PMPS100), as a base polymer, loaded with moderate amounts (6 wt%) of 2,5-diphenyloxazole (PPO) as a primary dye and Lumogen Violet (LV) as waveshifter. The samples were heated in the range of 60–150
∘
C
and scintillation performance were tested both after annealing for 24 h and in real time during heating. Light yield of siloxane-based scintillators containing 6 wt% PPO heated at 100
∘
C
is very close to the room-temperature value, while heating at 120
∘
C
causes a decrease of light yield (LY) of 17%. In addition, the figure of merit (FoM) for n/
γ
discrimination of the scintillator shows a sensible worsening of the discrimination performances in case of prolonged treatment at 120
∘
C
. Similar tests are made using the commercial plastic scintillator EJ-299 (currently named EJ-276), based on polyvinyltoluene (PVT). In this case, the light yield undergoes a much more rapid deterioration with annealing temperature, and at 70
∘
C
it is reduced to 60% of the original value. The discrimination capability of EJ-299 decreases upon heating at 70
∘
C
as well, with a 20% reduction of FoM; meanwhile for T > 70
∘
C
the mechanical and optical features are remarkably degraded. The mass loss of primary dye PPO from the siloxane scintillator as a function of treatment temperature and initial dye concentration has been evaluated and compared to the behaviour of EJ-299. This measurement allows to single out and characterize a series of processes occurring during heating, which are relevant to the whole performance of the system under study, such as sublimation at the interface, thermally induced photooxidation of components, diffusion of fluorophores from the polymer bulk to the surface. The variation in luminescence characteristics have been analyzed by excitation/fluorescence spectroscopy and time-resolved fluorescence spectroscopy, in order to correlate the annealing treatment with the primary dye loss by sublimation, formation of superficial aggregates and/or degradation of the scintillator components in the synthesized siloxane scintillator.
In the frame of the effective Container inspection at BORDer control points (C-BORD) project H2020 program of the European Union (EU), a Rapidly Relocatable Tagged Neutron Inspection System (RRTNIS) ...has been developed for a nonintrusive inspection of cargo containers, aiming at explosives and other illicit goods detection. Twenty large-volume NaI detectors are used to determine the elements composing inspected materials from their specific gamma-ray spectra signatures induced by fast neutrons. The RRTNIS inspection is focused on a specific suspect area selected by X-ray radiography. An unfolding algorithm decomposes the energy spectrum of this suspect area on a database of pure element gamma signatures. A classification is then performed between inorganic materials, such as metals, ceramics, or chemicals, and organic materials like wood, fabrics, or plastic goods. Concerning organic materials, the obtained elemental proportions of carbon, nitrogen, and oxygen allow discriminating explosives from illicit drugs and benign substances. This article reports on the final laboratory tests performed at Commissariat à <inline-formula> <tex-math notation="LaTeX">\text{I}^\prime </tex-math></inline-formula>Énergie Atomique et aux Énergies Alternatives (CEA) Saclay, France, to assess the RRTNIS detection performances before further demonstration tests in a real seaport environment. Simulants of explosives and illicit drugs have been hidden at different depths inside iron or wood cargo materials, which are representative of the different neutron and gamma attenuation properties encountered in real cargo containers. Hundreds of experiments have been performed, showing that a few kilograms of explosives or narcotics can be detected by the RRTNIS in 10-min inspections.
Measuring the variability of incoming neutrons locally would be usefull for the cosmic‐ray neutron sensing (CRNS) method. As the measurement of high energy neutrons is not so easy, alternative ...particles can be considered for such purpose. Among them, muons are particles created from the same cascade of primary cosmic‐ray fluxes that generate neutrons at the ground. In addition, they can be easily detected by small and relatively inexpensive detectors. For these reasons they could provide a suitable local alternative to incoming corrections based on remote neutron monitor data. The reported measurements demonstrated that muon detection system can detect incoming cosmic‐ray variations locally. Furthermore the precision of this measurement technique is considered adequate for many CRNS applications.
Plain Language Summary
The measurement of the variability of the incident neutron flux is of fundamental importance for the cosmic‐ray neutron sensing technique. This type of measurement is not easy to use to have local and instantaneous values. For this reason in this work it is reported how this type of information can be obtained through the measurement of the flux of cosmic muons, which are correlated with the flux of cosmic neutrons. This type of measurement, being easier to perform, allows you to have a local and real time value in a very simple way.
Key Points
Incoming correction in cosmic‐ray neutron sensing observations based on local muon measurements at ground
The possibility to detect fast neutrons as a distinct signal from that one of γ-rays background is surely of great importance for several topics, spanning from homeland security to radiation ...monitoring in nuclear physics research plants. Nowadays, Helium-3 based detectors are extremely expensive, while the use of large volume liquid scintillators presents serious concerns related to spillage risks and waste disposal. A very attractive alternative is the use of commercially available solid scintillators, which exploits an aromatic polymer matrix entrapping very high loadings of primary dye, thereby enabling the use of pulse shape analysis (PSA) to discriminate between fast neutrons and γ-rays. In this work, we analyse in detail the optical features of a solid scintillator composed by polymethylphenylsiloxane (PMPS) as base polymer loaded with moderate amounts of 2,5-diphenyloxazole (PPO). Furthermore, fluorescence decay kinetics have been correlated to the observed pulse shape discrimination capabilities of this radiation and thermally resistant scintillator, whose performances have been discussed in terms of conformational features and excimers formation revealed by the optical analyses.
Abstract Objectives Despite representing an important component of current dental adhesives, HEMA has been said to negatively influence the long-term stability of adhesion to dentine and enamel. The ...aim of this randomised clinical trial was to evaluate the 3-year clinical performance of two one-step self-etch adhesives. Methods Thirty patients had 175 non-carious cervical lesions restored with composite (Gradia Direct Anterior, GC) using either the HEMA-rich adhesive Clearfil Tri-S Bond (C3S; Kuraray) or the HEMA-free adhesive G-Bond (GB; GC). The restorations were evaluated by two examiners at baseline, 6, 12, 24 and 36 months regarding retention, caries recurrence, marginal integrity and discoloration and post-operative sensitivity. The data were statistically analysed with GEE and McNemar tests ( p < 0.05). Results The recall rate at 6 and 12 months was 100% and decreased to 96.7% at 24 and 36 months. At 3 years, the retention rate was 93.8% for C3S and 98.8% for GB ( p = 0.14). A pairwise comparison showed no significant differences between the two adhesives for all the parameters evaluated, irrespective of the recall ( p > 0.05). After 3 years, both adhesives presented an increase in the percentage of clinically acceptable marginal discoloration (C3S: 32.9% and GB: 26.8%) normally associated to clinically acceptable marginal defects (C3S: 35.8% and GB: 26.5%). Only 1 dentine margin of a GB restoration presented a severe marginal defect (1.2%) and 1 C3S restoration presented caries recurrence. The overall 3-year clinical success rate was 92.6% for C3S and 97.6% for GB ( p = 0.16). Conclusion Both one-step self-etch adhesives presented an equally favourable clinical effectiveness at 3 years. Clinical significance HEMA is a monomer frequently present in dental adhesives in order to increase their wettability and hydrophilicity. However, this monomer negatively influences hydrolytic stability and durability of the adhesive interface complex. In this 3-year clinical trial no significant difference in bonding effectiveness was noticed between a HEMA-rich and HEMA-free one-step adhesive.
Hundreds of landslides were triggered by the mainshocks (up to Mw 6.5) that occurred in 2016 in Central Italy during the seismic sequence that originated in the Apennine and ended in January 2017. ...These landslides were studied via field-based investigation and remote sensing techniques during the weeks immediately after the mainshocks occurred. EarthQuake-triggered Landslides (EQtLs) mostly consisted of rockfalls and rockslides. The spatial distribution of the examined EQtLs with respect to the epicentres of the main shocks resulted in very good agreement with the available empirical curves of maximum distance vs. magnitude. Based on the collected dataset, approximately 70% of the landslides impacted transportation routes (national, provincial and secondary roads linking towns and mountain villages) since they principally detached from road cuts. The landslides caused traffic interruption, and some delayed rescue vehicles from reaching the zones most damaged by earthquakes; moreover, some landslides caused the temporary isolation of several localities in the epicentre area. Even if it seems obvious that road cuts favour slope failure under shaking conditions, the dataset reported here is the first one for Italy where such an effect is quantified. Moreover, a statistical analysis was conducted to explore the relationships between the spatial distribution of EQtLs and some selected causative factors, including both natural (i.e., earthquake and terrain) and anthropogenic factors (i.e., presence of roads and trackways). Among the considered combinations of causative factors (both natural and anthropogenic), this study demonstrates that the occurrence of the uphill road cuts at the bottom of deep incised V-shaped valleys strongly influenced the spatial clustering of the EQtL triggered in 2016 in Central Italy.
In this work we present the characterization of a large area 200 mm ×200 mm EJ-444 scintillation detector to be used for monitoring gross alpha and beta activity in tap water plants. Specific tests ...were performed in order to determine the best setup to read-out the light from the detector side. The possibility to stack many detectors and get a compact device with total active area of the order of 1 m 2 has been explored. Alpha/beta discrimination, efficiency and homogeneity tests were carried out with alpha and beta sources. Background from ambient radioactivity was measured as well. Alpha/beta real-time monitoring in drinking water is a goal of the EU project TAWARA_RTM.
Purpose
We aimed to accurately determine ureteral stricture (US) rates following urolithiasis treatments and their related risk factors.
Methods
We conducted a systematic review and meta-analysis ...following the PRISMA guidelines using databases from inception to November 2023. Studies were deemed eligible for analysis if they included ≥ 18 years old patients with urinary lithiasis (Patients) who were subjected to endoscopic treatment (Intervention) with ureteroscopy (URS), percutaneous nephrolithotomy (PCNL), or shock wave lithotripsy (SWL) (Comparator) to assess the incidence of US (Outcome) in prospective and retrospective studies (Study design).
Results
A total of 43 studies were included. The pooled US rate was 1.3% post-SWL and 2.1% post-PCNL. The pooled rate of US post-URS was 1.9% but raised to 2.7% considering the last five years’ studies and 4.9% if the stone was impacted. Moreover, the pooled US rate differed if follow-ups were under or over six months. Patients with proximal ureteral stone, preoperative hydronephrosis, intraoperative ureteral perforation, and impacted stones showed higher US risk post-endoscopic intervention with odds ratio of 1.6 (
P
= 0.05), 2.6 (
P
= 0.009), 7.1 (
P
< 0.001), and 7.47 (
P
= 0.003), respectively.
Conclusions
The overall US rate ranges from 0.3 to 4.9%, with an increasing trend in the last few years. It is influenced by type of treatment, stone location and impaction, preoperative hydronephrosis and intraoperative perforation. Future standardized reporting and prospective and more extended follow-up studies might contribute to a better understanding of US risks related to calculi treatment.
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