Absolute neutrino cross section measurements are presently limited by uncertainties on
ν
fluxes. In this paper, we propose a technique that is based on the reconstruction of large angle positrons in ...the decay tunnel to identify three-body semileptonic
K
+
→
e
+
π
0
ν
e
decays. This tagging facility operated in positron counting mode (“event count mode”) can be employed to determine the absolute
ν
e
flux at the neutrino detector with
O
(
1
%
)
precision. Facilities operated in “event by event tag mode” i.e. tagged neutrino beams that exploit the time coincidence of the positron at source and the
ν
e
interaction at the detector, are also discussed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A single laser pulse with spot size smaller than half its wavelength (w0<λ/2 ) can provide a net energy gain to ultrarelativistic particles. In this paper, we discuss the properties of an optical ...cell consisting of N subcycle pulses that propagate in the direction perpendicular to the electron motion. We show that the energy gain produced by the cell is proportional to N and it is sizable even for O(1TW) pulses.
Liquid chromatography coupled with mass spectrometry (LC-MS) has been increasingly used for screening purposes in forensic toxicology. High versatility and low time/resource consumption are the main ...advantages of this technology. Numerous multi-analyte methods have been validated in order to face the analytical challenge of new psychoactive substances (NPSs). However, forensic toxicologists must focus the attention also on "classical" NPSs and medicines, such as benzodiazepines (BDZs) and prescription opioids. In this paper, a new method for the simultaneous detection of 169 substances (120 NPSs and 49 other drugs) in hair by LC-MS-MS is described. After the decontamination of hair samples with dichloromethane, a 20-mg aliquot of the sample was mixed with 1 mL of methanol (MeOH; 0.1% of formic acid) and then sonicated at room temperature for 2 h. The mixture was then dried under nitrogen stream and reconstituted with 100 µL of MeOH. LC separation was achieved with a 100-mm-long C18 column in 35 min, and mass acquisition was performed in dynamic multiple reaction monitoring mode and in positive ionization. The analysis results were very sensitive, with the limit of quantification ranging from 0.07 to 10.0 pg/mg. Accuracy and precision were always within the acceptable criteria. Matrix effect and recovery rate ranges were from -21.3 to + 21.9% and from 75.0 to 99.3%, respectively. The new method was successfully applied in a preliminary study on the prevalence of NPSs, BDZs and other substances in case of driving license issuance. In 14% of cases, BDZs/antidepressants (mainly trazodone, diazepam/nordiazepam and flunitrazepam) were found. Codeine, ketamine, methylone and mephedrone were also detected.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The European Research Council has recently funded HOLMES, a new experiment to directly measure the neutrino mass. HOLMES ...will perform a calorimetric measurement of the energy released in the decay of ...Ho. The calorimetric measurement eliminates systematic uncertainties arising from the use of external beta sources, as in experiments with beta spectrometers. This measurement was proposed in 1982 by A. De Rujula and M. Lusignoli, but only recently the detector technological progress allowed to design a sensitive experiment. HOLMES will deploy a large array of low temperature microcalorimeters with implanted ...Ho nuclei. The resulting mass sensitivity will be as low as 0.4 eV. HOLMES will be an important step forward in the direct neutrino mass measurement with a calorimetric approach as an alternative to spectrometry. It will also establish the potential of this approach to extend the sensitivity down to 0.1 eV. We outline here the project with its technical challenges and perspectives.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The longitudinal segmentation of shashlik calorimeters is challenged by dead zones and non-uniformities introduced by the light collection and readout system. This limitation can be overcome by ...direct fiber–photosensor coupling, avoiding routing and bundling of the wavelength shifter fibers and embedding ultra-compact photosensors (SiPMs) in the bulk of the calorimeter. We present the first experimental test of this readout scheme performed at the CERN PS-T9 beamline in 2015 with negative particles in the 1–5GeV energy range. In this paper, we demonstrate that the scheme does not compromise the energy resolution and linearity compared with standard light collection and readout systems. In addition, we study the performance of the calorimeter for partially contained charged hadrons to assess the e/π separation capability and the response of the photosensors to direct ionization.
The ENUBET project is aimed at designing and experimentally demonstrating the concept of monitored neutrino beams. These novel beams are enhanced by an instrumented decay tunnel, whose detectors ...reconstruct large-angle charged leptons produced in the tunnel and give a direct estimate of the neutrino flux at the source. These facilities are thus the ideal tool for high-precision neutrino cross-section measurements at the GeV scale because they offer superior control of beam systematics with respect to existing facilities. In this paper, we present the first end-to-end design of a monitored neutrino beam capable of monitoring lepton production at the single particle level. This goal is achieved by a new focusing system without magnetic horns, a 20 m normal-conducting transfer line for charge and momentum selection, and a 40 m tunnel instrumented with cost-effective particle detectors. Employing such a design, we show that percent precision in cross-section measurements can be achieved at the CERN SPS complex with existing neutrino detectors.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This paper presents a low noise amplifier for large arrays of silicon photomultipliers (SiPMs) operated in cryogenic environments, especially liquid argon (87 K) and liquid nitrogen (77 K) . The goal ...is for one amplifier to read out a total photosensitive surface of tens of cm2 while retaining the capability to resolve single photoelectron signals. Due to the large capacitance of SiPMs, typically a few nF per cm2, the main contributor to noise is the series (voltage) component. A silicon-germanium heterojunction bipolar transistor (HBT) was selected as the input device of the cryogenic amplifier, followed by a fully differential operational amplifier, operated in an unconventional feedback configuration. The input referred voltage noise of the circuit at 77 K is just below 0.4 nV/ Hz white (above 100 kHz) and 1 nV/ Hz at 10 kHz. The value of the base spreading resistance of the HBT at 77 K was determined from noise measurements at different bias currents. Power consumption of the full circuit is about 2.5 mW . The design gives the flexibility to optimally compensate the feedback loop for different values of the input capacitance, and obtain a gain-bandwidth product in the GHz range. The signal-to-noise ratio obtained in reading out SiPMs is discussed for the case of a 300 kHz low pass filter and compared with the upper limit that would derive from applying optimum filtering algorithms.
Effective longitudinal segmentation of shashlik calorimeters can be achieved taking advantage of the compactness and reliability of silicon photomultipliers. These photosensors can be embedded in the ...bulk of the calorimeter and are employed to design very compact shashlik modules that sample electromagnetic and hadronic showers every few radiation lengths. In this paper, we discuss the performance of a calorimeter made up of 12 such modules and able to sample showers every ~4X 0 . In summer 2016, this prototype has been exposed to electrons, muons, and hadrons at CERN PS (East Area T9 beamline). The performances in terms of energy resolution, linearity, response to minimum ionizing particles, and reconstruction of the shower profile are discussed.
Mouse ovarian surface epithelial cells (MOSEC) were obtained from virgin, mature mice by mild trypsinization and were repeatedly passaged in vitro. Early passage cells (<20 passages) exhibited a ...cobblestone morphology and contact inhibition of growth. After ~20 passages in vitro, cobblestone morphology and contact inhibition of growth was lost. Tumor forming potential was determined by s.c. and i.p. injection of early and late passage cells into athymic and syngeneic C57BL6 mice. Subcutaneous tumors formed in ~4 months and were present only at the injection site. Intraperitoneal injection of late passage MOSEC into athymic and syngeneic mice resulted in growth of tumor implants throughout the abdominal cavity, and production of hemorrhagic ascitic fluid. Early passage MOSEC did not form tumors in vivo. Histopathologic analysis of tumors revealed a highly malignant neoplasm containing both carcinomatous and sarcomatous components. Late passage MOSEC expressed cytokeratin and did not produce ovarian steroids in response to gonadotropin stimulation in vitro. Ten clonal lines were established from late passage MOSEC. Each clone formed multiple peritoneal tumors and ascitic fluid after i.p. injection into C57BL6 mice. Three cell lines examined cytogenetically were polyploid with near-tetraploid modal chromosome numbers. Common clonal chromosome gains and losses included +5, +15, +19 and –X, –3, –4. One cell line had a clonal translocation between chromosomes 15 and 18 and another had a small marker chromosome; common structural abnormalities were not observed. These data describe the development of a mouse model for the study of events related to ovarian cancer in humans. The ability of the MOSEC to form extensive tumors within the peritoneal cavity, similar to those seen in women with Stage III and IV cancer, and the ability of the MOSEC to produce tumors in mice with intact immune systems, makes this model unique for investigations of molecular and immune interactions in ovarian cancer development.
Phosphoinositide 3-OH kinases (PI3Ks) are a group of major intracellular signaling molecules. In our previous study, we found that inhibition of PI3K activity suppressed the androgen receptor ...(AR)-mediated gene expression in prostate cancer cells. The AR has been considered as a critical determinant for the development and progression of human prostate cancers. In this study, we sought to identify the PI3K isoforms involved in AR transactivation. Using a gene-specific small interference RNA (siRNA) approach, we determined that the regulatory isoform p85α and the catalytic isoform p110β, but not p110α, were required for androgen-stimulated AR transactivation and cell proliferation in prostate cancer cells. Consistently, overexpression of wild-type p110β but not p110α gene led to androgen-independent AR transactivation. Silencing p110β gene in prostate cancer cells abolished tumor growth in nude mice. Of the dual (lipid and protein) kinase activities, p110β’s lipid kinase activity was required for AR transactivation. Further analysis by a chromatin immunoprecipitation assay showed that p110β is indispensable for androgen-induced AR–DNA interaction. Finally, gene expression analysis of clinical specimens showed that both p85α and p110β were highly expressed in malignant prostate tissues compared to the nonmalignant compartments, and their expression levels correlated significantly with disease progression. Taken together, our data demonstrated that p85α and p110β are essential for androgen-stimulated AR transactivation, and their aberrant expression or activation might play an important role in prostate cancer progression.
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